Saturday. Went to Yufuin hot springs with Nozomi-san. It was great! I want to go there again.
1107.5046
Are halo and galaxy formation histories correlated?
Tinker, Wetzel, Conroy
* Assembly bias: properties of DM haloes (including mass growth) correlates with large-scale environment, at fixed mass.
Does assembly bias manifest itself in galaxy properties? Use group-finders on SDSS DR7 to determine centrals and satellites; use 4000A break as a measure of SFH (*how?*), examine correlation between quenched fraction f_q, and large-scale environment, rho. There is a positive, monotonic relationship between f_q and rho, at all galaxy magnitudes. Use group catalog to decompose correlation into the contribution from central and stellite galaxies. Observed correlation primarily due to variations of the halo-mass function as a function of the environment rho (causes larger fraction of satellites galaxies at high rho). Low mass central galaxies (M < 1e11Msun/h^2) show no correlation between f_q and rho, which is inconsistent with the strong assembly bias of DM halos seen in this mass regime, if galaxy formation is correlated with with halo growth (demonstrated by N-body simulation). Also, mean stellar age of quenched central galaxies is independent of rho at fixed M, while the formation time of low mass halos vary significantly (but does it correlate with rho?). Conclude: processes that halt the star formation of low mass central galaxies not correlated to the formation histories of their host halos; old galaxies do not reside preferentially in old halos.
* how is rho defined?
1107.5056
The final parsec problem: aligning a binary with an external accretion disc
Nixon, King, Pringle
Consider a binary system with an external accretion disc with a misaligned angular momentum (e.g., galaxy merger with SMBH centers, formation of stellar mass binaries in star clusters). Calculate gravitational torque between binary and disc. Their angular momenta J_b and J_d stably counteralign if their initial orientation is sufficiently retrograde (cos(theta) < -J_d/2J_b) on a short time compared with the mass gain time of the accretors. J_b remains unchanged in this process. Counteralignment can promote rapid merger of supermassive black hole binaries; formation of coplanar but retrograde planets around stars in binary systems.
1106.4404
Scale dependent bias from primordial non-Gaussianity with trispectrum
Gong, Yokoyama
Study scale-dependent bias of the halo power spectrum arising from primordial non-Gaussianity. Present analytic result of the halo bias including up to the trispectrum contributions. Find scale-dependent bias opens a new possibility of probing the relation between the non-linearity parameters f_nl and t_nl.
Saturday, July 30, 2011
Day 52
Friday. On my way from Seoul to Busan on KTX.
1107.4631
A more general model for the intrinsic scatter in SNIa distance moduli
Marriner, Bernstein, Kessler, Lampeitl, Miquel, Mosher, Nichol, Sako, Schneider, Smith
* SALT2 model parameters alpha and beta
Better way to determine the aforementioned parameters, using covariance matrix instead of a single parameter to describe the intrinsic scatters. Beta is larger, and the uncertainty larger than conventional method (of course). Beta: value expected for extinction by the type of dust found in the MW. Modeling the distribution of SNIa in color show strong evidence that variation in color is a significant contributor to the scatter of SNIa around their standard candle magnitude.
1107.5060
Physical properties of galaxies from z=2-4
Shapley
Census of the method used to find distant galaxies and the empirical constraints on their multiwave length luminosities and colors; review high-z galaxy stellar content, SF history; interstellar contents (dust, gas, heavy elements); structural and dynamical properties. Conclude by listing some of the most pressing and open questions regarding the physics of high-z galaxies.
* what are the most pressing and open questions of high-z galaxies???
1107.5045
Too small to succeed? Lighting up massive dark matter subaloes of the MW
Di Cintio, Knebe, Libeskind, Yepes, Gottloeber, Hoffman
Simulation of the Local Group (using CLUES--Constrained local universe simulations): used to investigate the recently highlighted problem of the most massive dark subhalos of MW too dense to host bright satellites. Baryonic processes leave a twofold effect on the relation between the peak of the rotation curve, and its position (Vmax and Rmax). Those with large baryon fraction undergo baryonic contraction, decreasing in Rmax while Vmax unchanged. Those with smaller baryion fraction undergo decrease in Vmax (possibly due to outflow of material). Problem cannot be solved by simply investigating baryonic processes.
* Does CLUES simulate gas and DM separately? It must. That info should be in the abstract.
* not sure what the point was the abstract was.
1107.5256
Extreme emission line galaxies in CANDELS: Broad-band selected, star-bursting dwarf galaxies at z>1
van der Wel et al
* EELG: extreme emission line galaxies -- my guess is that these are typically vigorously star-forming galaxies w/o much dust. I could be wrong.
* CANDELS: Cosmic assembly near-IR deep extragalactic legacy survey
Found a bunch (69 candidates) of EELG at z=1.6-1.8 in CANDELS, rest-frame equivalent widths of 1000A. These are dwarf galaxies with 10e8 Msun stellar mass, undergoing enormous starburst phase (15My\
r). Burst may cause outflows strong enough to produce cored DM profiles in low-mass galaxies. Such galaxies have SFR and comoving number density (3.7e-4 Mpc^{-3}) that can, in ~4Gyr, produce much of the stellar mass density that is presently contained in 10e8-10e9 Msun dwarf galaxies. Strong indication that many or even most of the stars in present-day dwarf galaxies formed in strong, short-lived bursts, mostly at z>1.
* The last conclusion seem to be bit of a jump.
1107.4631
A more general model for the intrinsic scatter in SNIa distance moduli
Marriner, Bernstein, Kessler, Lampeitl, Miquel, Mosher, Nichol, Sako, Schneider, Smith
* SALT2 model parameters alpha and beta
Better way to determine the aforementioned parameters, using covariance matrix instead of a single parameter to describe the intrinsic scatters. Beta is larger, and the uncertainty larger than conventional method (of course). Beta: value expected for extinction by the type of dust found in the MW. Modeling the distribution of SNIa in color show strong evidence that variation in color is a significant contributor to the scatter of SNIa around their standard candle magnitude.
1107.5060
Physical properties of galaxies from z=2-4
Shapley
Census of the method used to find distant galaxies and the empirical constraints on their multiwave length luminosities and colors; review high-z galaxy stellar content, SF history; interstellar contents (dust, gas, heavy elements); structural and dynamical properties. Conclude by listing some of the most pressing and open questions regarding the physics of high-z galaxies.
* what are the most pressing and open questions of high-z galaxies???
1107.5045
Too small to succeed? Lighting up massive dark matter subaloes of the MW
Di Cintio, Knebe, Libeskind, Yepes, Gottloeber, Hoffman
Simulation of the Local Group (using CLUES--Constrained local universe simulations): used to investigate the recently highlighted problem of the most massive dark subhalos of MW too dense to host bright satellites. Baryonic processes leave a twofold effect on the relation between the peak of the rotation curve, and its position (Vmax and Rmax). Those with large baryon fraction undergo baryonic contraction, decreasing in Rmax while Vmax unchanged. Those with smaller baryion fraction undergo decrease in Vmax (possibly due to outflow of material). Problem cannot be solved by simply investigating baryonic processes.
* Does CLUES simulate gas and DM separately? It must. That info should be in the abstract.
* not sure what the point was the abstract was.
1107.5256
Extreme emission line galaxies in CANDELS: Broad-band selected, star-bursting dwarf galaxies at z>1
van der Wel et al
* EELG: extreme emission line galaxies -- my guess is that these are typically vigorously star-forming galaxies w/o much dust. I could be wrong.
* CANDELS: Cosmic assembly near-IR deep extragalactic legacy survey
Found a bunch (69 candidates) of EELG at z=1.6-1.8 in CANDELS, rest-frame equivalent widths of 1000A. These are dwarf galaxies with 10e8 Msun stellar mass, undergoing enormous starburst phase (15My\
r). Burst may cause outflows strong enough to produce cored DM profiles in low-mass galaxies. Such galaxies have SFR and comoving number density (3.7e-4 Mpc^{-3}) that can, in ~4Gyr, produce much of the stellar mass density that is presently contained in 10e8-10e9 Msun dwarf galaxies. Strong indication that many or even most of the stars in present-day dwarf galaxies formed in strong, short-lived bursts, mostly at z>1.
* The last conclusion seem to be bit of a jump.
Thursday, July 28, 2011
Day 51
Thursday. Packed my stuff all morning; it's now 3pm and I'm finally ready for work. Tomorrow is travel and Hot Springs! I'll be Home Saturday.
Friday. Only read one abstract yesterday, but didn't write the summary. Continuing with writing on the train, on my way to Busan on KTX, with free WiFi.
1107.4372
The Demographics of broad-line quasars in the mass-luminosity plane. I. Testing FWHM-based virial black hole masses
Shen, Kelly
Use 58k uniformly selected quasars from SDSS DR7 at z~0.4-5 to jointly constrain the LF and BHMF via description of underlying active BHMF and Eddington ratio distribution to match the observed distribution in the quasar mass-luminosity plane. Systematics considered: selection effect of the sample flux limit, statistical scatter between true BH masses and FWHM-based single-epoch virial mass estimates, potential luminosity-dependent biases of these mass estimates. LF is tightly constrained, and makes reasonable predictions 3 mags fainter than the SDSS flux limit, but the BHMF is unconstrained at z>0.7 because of the unknown dependencies/biases of the BH mass obtained from estimators, and the scarcity of the high-z objects (but some bias estimated--estimated mass probably biased high by a factor of few at z > 0.7). Some evidence of "downsizing" in BHMF. BH mass density in broad-line quasars insignificant compare to the total BH mass density at all times. No strong BH mass dependence on mean Eddington ratio, but evidence for increased mean Eddington ratio (at fixed BH mass) with redshift.
* what is "downsizing"? I always ask and hear the answer, and I always forget.
* what is the mass-luminosity plane for quasars?
Friday. Only read one abstract yesterday, but didn't write the summary. Continuing with writing on the train, on my way to Busan on KTX, with free WiFi.
1107.4372
The Demographics of broad-line quasars in the mass-luminosity plane. I. Testing FWHM-based virial black hole masses
Shen, Kelly
Use 58k uniformly selected quasars from SDSS DR7 at z~0.4-5 to jointly constrain the LF and BHMF via description of underlying active BHMF and Eddington ratio distribution to match the observed distribution in the quasar mass-luminosity plane. Systematics considered: selection effect of the sample flux limit, statistical scatter between true BH masses and FWHM-based single-epoch virial mass estimates, potential luminosity-dependent biases of these mass estimates. LF is tightly constrained, and makes reasonable predictions 3 mags fainter than the SDSS flux limit, but the BHMF is unconstrained at z>0.7 because of the unknown dependencies/biases of the BH mass obtained from estimators, and the scarcity of the high-z objects (but some bias estimated--estimated mass probably biased high by a factor of few at z > 0.7). Some evidence of "downsizing" in BHMF. BH mass density in broad-line quasars insignificant compare to the total BH mass density at all times. No strong BH mass dependence on mean Eddington ratio, but evidence for increased mean Eddington ratio (at fixed BH mass) with redshift.
* what is "downsizing"? I always ask and hear the answer, and I always forget.
* what is the mass-luminosity plane for quasars?
Tuesday, July 26, 2011
Day 50
Wednesday. SCAMP going slower than expected, but hope to get some good info from Gary today. I don't want to slack off on day 50!
1107.4095
Long-term evolution of massive black hole binaries. IV. Mergers of galaxies with collisionally relaxed nuclei
Gualandris, Merritt
N-body simulation of two galaxies with collisionally-relaxed (MBH+star) cores, to study the distribution of "stellar-mass BHs" (?) after the merger. There are 4 mass groups representing old stellar populations. Merger assumption: 1:3 mass ratio, two different orbits. During merger, initial mass distribution erased, large cores are carved out in the stellar distribution (several times the radius of influence of the massive BH). Follow for 3 central relaxation times after coalescence of the massive binary: standard and top-heavy mass functions are considered. Cores persist; the distribution of stellar-mass BHs evolves against this fixed BG. After 3 relaxation times, it still looks different from the relaxed, multi-mass models often assumed to describe distribution of stars and stellar remnants near massive BH; e.g. density of stellar BH much smaller in the models.
* EMRI problem: "Extreme mass ratio inspiral"
* Bahcall-Wolf cusps: density cusp around a massive object (BH)
* I want to know if the consider DM and stellar mass separately (both are non-interacting particles); what they probably do is assign certain DM particles as stars (and paint them in 4 different colors, depending on their initial position).
1107.4095
Long-term evolution of massive black hole binaries. IV. Mergers of galaxies with collisionally relaxed nuclei
Gualandris, Merritt
N-body simulation of two galaxies with collisionally-relaxed (MBH+star) cores, to study the distribution of "stellar-mass BHs" (?) after the merger. There are 4 mass groups representing old stellar populations. Merger assumption: 1:3 mass ratio, two different orbits. During merger, initial mass distribution erased, large cores are carved out in the stellar distribution (several times the radius of influence of the massive BH). Follow for 3 central relaxation times after coalescence of the massive binary: standard and top-heavy mass functions are considered. Cores persist; the distribution of stellar-mass BHs evolves against this fixed BG. After 3 relaxation times, it still looks different from the relaxed, multi-mass models often assumed to describe distribution of stars and stellar remnants near massive BH; e.g. density of stellar BH much smaller in the models.
* EMRI problem: "Extreme mass ratio inspiral"
* Bahcall-Wolf cusps: density cusp around a massive object (BH)
* I want to know if the consider DM and stellar mass separately (both are non-interacting particles); what they probably do is assign certain DM particles as stars (and paint them in 4 different colors, depending on their initial position).
Monday, July 25, 2011
Day 49
Tuesday. Slacking off on the astroph. Must ... turn ... brain ... on ... I want to generate an MEF so that I can to get SExtractor working with it, then with SCAMP. Then report to Gary!
1107.4629
Precision simulation of ground-based lensing data using observations from space
Mandelbaum, Hirata, Leauthaud, Massey, Rhodes
SHERA (SHEar Reconvolution Analysis) simulates ground-based data, starting from space-based images from COSMOS (CTE-corrected images used), and taking into account the HST PSF. Optionally apply weak lensing shear. Allows for a precise, realistic assessment of systematic errors due to the method of data processing, given user-suppled observational conditions and real galaxy morphologies. Can also test error estimates and parameter degeneracies. Software publicly released.
* Good job Rachel!
1107.4629
Precision simulation of ground-based lensing data using observations from space
Mandelbaum, Hirata, Leauthaud, Massey, Rhodes
SHERA (SHEar Reconvolution Analysis) simulates ground-based data, starting from space-based images from COSMOS (CTE-corrected images used), and taking into account the HST PSF. Optionally apply weak lensing shear. Allows for a precise, realistic assessment of systematic errors due to the method of data processing, given user-suppled observational conditions and real galaxy morphologies. Can also test error estimates and parameter degeneracies. Software publicly released.
* Good job Rachel!
Thursday, July 21, 2011
Day 48
Friday. Hopefully have recovered from the all-nighter Wed-Thu. Took all day to deal with German visa yesterday; today I hope to get the GGLens code running again, with the correct binning.
1103.2016
Toward physical cosmology: focus on inhomogeneous geometry and its non-perturbative effects
Buchert
He wants to construct a physical, fully relativistic cosmology, including influence of inhomogeneities on the effective evolution history of the universe. Backreaction terms: influence of inhomogeneities in the effective evolution of the Universe; can be expressed through spatially averaged geometrical invariants; can be interpreted as energies of an emerging scalar field ("morphon"). Propose a strategy of phenomenological scalar field models can be traced back to inhomoegenous geometrical properites of space and its embedding into spacetime.
* Interesting theory on DM, DE and Inflation. It is a review article.
* Interesting theory on DM, DE and Inflation. It is a review article.
Day 47
Thursday. Stupidly, I stayed up till 5am this morning to work and play (starting with a Euclid telecon that started midnight...). Woke up at 10am for another telecon with Rachel.
1106.5507
Galaxy bias and non-linear structure formation in general relativity
Baldauf, Seljak, Senatore, Zaldarriaga
* 48 pages! 4 figures.
Non-Gaussianity in the initial conditions can show up as scale dependent bias at the largest scales--must include GR effects. Provide GR generalization of the bias, valid for both Gaussian and non-Gaussian initial conditions. Small-scale collapse in the Fermi frame (locally almost flat), while long-wavelength modes are in the quasi linear regime, and are encoded in the mapping from the cosmological frame to the local frame. The long-wavelength modes in linear bias, the dynamics is encoded in the local curvature of the universe---allows for GR generalization of bias in Newtonian settings. Bias due to non-Gaussianties doesn't need to vanish at Hubble scales or larger. For non-G of the local kind, the bias goes to a constant. Application: not necessary to perform large N-body sims to extract information on long-wavelength modes: Simply add long-wavelength modes by adding curvature to the simulation and rescaling the coordinates.
* General-relativistic generalization of the galaxy bias (eech).
1106.5508
ELMAG: a Monte Carlo simulation of EM cascades on the extragalactic BG light and in magnetic fields
Kachelriess, Ostapchenko, Tomas
Extragalactic background light (EBL) interacting with high-energy photon/electron cascades, simulated by MC. Pair production, inverse Compton scattering, synchrotron losses, deflections of charged component in extragalactic magnetic field (EGMF) included. Weighted sampling employed. Simulation provides the energy, observation angle, and the time delay of secondary cascade particles. Possible applications: TeV blazars and influence of EGMF on their spectra; calculating contribution from UHCR to dark matter to diffuse extragalactic gamma-ray BG. Derives limits on the EGMF.
1106.5646
Pulse profile stability of the Crab pulsar
Jain, Paul
Use RXTE archival data over the last decade, in soft (2-20keV) and hard (30-100keV) X-ray, to study the stability of the Crab pulsar pulse profile. Check separation, intensity and widths of two peaks. No significant time dependency found in the pulse shape; stable for the past 10 years. Some description of the two peak types.
* what was that about?
1106.5508
ELMAG: a Monte Carlo simulation of EM cascades on the extragalactic BG light and in magnetic fields
Kachelriess, Ostapchenko, Tomas
Extragalactic background light (EBL) interacting with high-energy photon/electron cascades, simulated by MC. Pair production, inverse Compton scattering, synchrotron losses, deflections of charged component in extragalactic magnetic field (EGMF) included. Weighted sampling employed. Simulation provides the energy, observation angle, and the time delay of secondary cascade particles. Possible applications: TeV blazars and influence of EGMF on their spectra; calculating contribution from UHCR to dark matter to diffuse extragalactic gamma-ray BG. Derives limits on the EGMF.
1106.5646
Pulse profile stability of the Crab pulsar
Jain, Paul
Use RXTE archival data over the last decade, in soft (2-20keV) and hard (30-100keV) X-ray, to study the stability of the Crab pulsar pulse profile. Check separation, intensity and widths of two peaks. No significant time dependency found in the pulse shape; stable for the past 10 years. Some description of the two peak types.
* what was that about?
Tuesday, July 19, 2011
Day 46
Wednesday. Did get SExtractor to work yesterday, now onto SCAMP. But before that, I gotta make some plots with GGLens.
1107.0009
Confronting 2D delayed-detonation models with light curves and spectra of Type Ia supernovae
Blondin, Kasen, Roepke, Kirshner, Mandel
Compare theoretical SNIa explosions with 251 SNe lightcurves and 2231 (low dispersion) spectra, and data from literature. Use commonly used data analysis software (MLCS2k2, SALT2, SNooPy, SNID) to assess how well the models match the data. Models that fare well lie systematically on the observed width-luminosity relation. Reject six high-ly asymmetric ignition conditions and a large amount (>1 M_sun) of synthesized 56Ni that yield poor matches to observed SNIa spectra. Models have general difficulty to match the U-band flux at early times (caused by hot ionized ejecta that affect the subsequent redistribution of flux at longer wavelengths). Examine ways in which the asymptotic kinetic energy of the explosion affects both the predicted velocity and velocity gradient in the SiII and CaII lines. Models with asymmetric distribution of 56Ni are found to result in a larger variation of photometric and spectroscopic properties with viewing angle, regardless of the initial ignition setup. Discuss whether highly anisotropic conditions are ruled out (well, are they?), and how detailed comparison between models and data (light curves and spectra) can lead to better understanding of SN Ia explosion mechanisms.
* Well, how well the the anisotropic conditions constrained?
1107.2665
Toward early-warning detection of gravitational waves from compact binary coalescence
Cannon et al
Rapid detection of compact binary coalescence with a network of advanced gravitational wave detectors will offer unique opportunities--e.g., to observe EM counterpart. Demonstrate computationally practical filtering strategy that can do early warning.
* how do they do it?
1107.2651
Spatially-resolved spectroscopy of SDSS J0952+2552: a confirmed dual AGN
* I read this one.
You can find dual AGNs from double-peaked narrow OIII emission lines, but they need to be confirmed both by image (AO at Keck) and spectra. This one is confirmed AGN, type 1 and 2 pair, separated by 4.8kpc.
1107.3151
Segue 3: An old, extremely low luminosity star cluster in the milky way's halo
Fadely, Willman, Geha, Walsh, Munoz, Jerjen, Vargas, Da Costa
Kinematic and photometric properties of Segue 3, a MW companion, with Keck/DEIMOS spetroscopy and Magellan/IMACS g/r band imaging. Structure and stellar population of Segue 3 studied w/ ML method. Half-light radius is 2.1pc (26"\pm5") and M_V = 0.0\pm0.8 mag--the least luminous old stellar system known. Consistent with single stellar population, 12.0Gyr and [Fe/H] = -1.7. Determine 32 stars associated with Segue 3 via LOS velocities from spectra + photometry; stars w/in 3 half-light radii have velocity dispersion of 1.2 km/s (whoa! that's low); spread in [Fe/H] of < 0.3dex. Segue 3 is likely and old, faint stellar cluster which contains no significant dark matter. Find tentative evidence of mass loss through 11 candidate members outside 3 half-light radii (expected). Interpretation outside this radii is complicated by the coincidence with a previously known halo substructure, may contaminate member sample.
1106.5494
The cosmological impact of luminous TeV blasars I: Implications of plasma instabilities for the intergalactic magnetic field and extragalactic gamma-ray background
Broderick, Chang, Pfrommer
* inverse Compton: photon gains energy upon interaction with (high-kinetic energy) matter.
Inverse Compton cascades initiated by high (>100GeV) energy gamma rays enhance GeV emission of bright, TeV sources; however, this is not seen in bright TeV blazars, and that's used to constrain the intergalactic magnetic field (IGMF); limits on unresolved extragalactic gamma-ray background (EGRB) by Fermi is used to argue against a large number of such objects at high-z. But plasma-beam instabilities (?) --the "oblique" instability--present a plausible mechanism by which the energy of the produced (presumably particle) pair can be dissipated locally, heating the IGM. These instabilities grow on timescales shorter than inv-Comp cooling rate, so they suppress cascades. This is an obstacle in trying to limit the IGMF from the lack of discernible GeV bump in TeV sources; also weakens the Fermi limits upon the evolution of blazar populations (why?). Specifically, construct TeV-blazar luminosity function from these objects, and find that it is very well described by the quasar luminosity function at z~0.1, shifted to lower luminosity and number densities, suggesting that both classes of sources are regulated by similar processes. Extending this relationship to higher redshifts show that the magnitude and shape of EGRB above 10GeV is naturally reproduced with this rapidly evolving TeV-blazar luminosity function.
* subtle points being made.
1106.5493
Dark Matter and synchrotron emission from galactic center radio fliaments
Linden, Hooper, Yusef-Zadeh
Non-thermal radio filaments trance magnetic field lines, has hard synchrotron emission spectra. Origin of filaments not understood. Light DM particle (5-10GeV) annihilation matches the intensity, spectral shape, and flux variation of NRFs. NRF explanation also covers excess gamma-ray emission from Galactic center by Fermi-LAT, as well as direct detection from CoGeNT and DAMA/LIBRA.
* I'm curious bout the NRF, but also about the origin of the magnetic field lines.
1107.0009
Confronting 2D delayed-detonation models with light curves and spectra of Type Ia supernovae
Blondin, Kasen, Roepke, Kirshner, Mandel
Compare theoretical SNIa explosions with 251 SNe lightcurves and 2231 (low dispersion) spectra, and data from literature. Use commonly used data analysis software (MLCS2k2, SALT2, SNooPy, SNID) to assess how well the models match the data. Models that fare well lie systematically on the observed width-luminosity relation. Reject six high-ly asymmetric ignition conditions and a large amount (>1 M_sun) of synthesized 56Ni that yield poor matches to observed SNIa spectra. Models have general difficulty to match the U-band flux at early times (caused by hot ionized ejecta that affect the subsequent redistribution of flux at longer wavelengths). Examine ways in which the asymptotic kinetic energy of the explosion affects both the predicted velocity and velocity gradient in the SiII and CaII lines. Models with asymmetric distribution of 56Ni are found to result in a larger variation of photometric and spectroscopic properties with viewing angle, regardless of the initial ignition setup. Discuss whether highly anisotropic conditions are ruled out (well, are they?), and how detailed comparison between models and data (light curves and spectra) can lead to better understanding of SN Ia explosion mechanisms.
* Well, how well the the anisotropic conditions constrained?
1107.2665
Toward early-warning detection of gravitational waves from compact binary coalescence
Cannon et al
Rapid detection of compact binary coalescence with a network of advanced gravitational wave detectors will offer unique opportunities--e.g., to observe EM counterpart. Demonstrate computationally practical filtering strategy that can do early warning.
* how do they do it?
1107.2651
Spatially-resolved spectroscopy of SDSS J0952+2552: a confirmed dual AGN
* I read this one.
You can find dual AGNs from double-peaked narrow OIII emission lines, but they need to be confirmed both by image (AO at Keck) and spectra. This one is confirmed AGN, type 1 and 2 pair, separated by 4.8kpc.
1107.3151
Segue 3: An old, extremely low luminosity star cluster in the milky way's halo
Fadely, Willman, Geha, Walsh, Munoz, Jerjen, Vargas, Da Costa
Kinematic and photometric properties of Segue 3, a MW companion, with Keck/DEIMOS spetroscopy and Magellan/IMACS g/r band imaging. Structure and stellar population of Segue 3 studied w/ ML method. Half-light radius is 2.1pc (26"\pm5") and M_V = 0.0\pm0.8 mag--the least luminous old stellar system known. Consistent with single stellar population, 12.0Gyr and [Fe/H] = -1.7. Determine 32 stars associated with Segue 3 via LOS velocities from spectra + photometry; stars w/in 3 half-light radii have velocity dispersion of 1.2 km/s (whoa! that's low); spread in [Fe/H] of < 0.3dex. Segue 3 is likely and old, faint stellar cluster which contains no significant dark matter. Find tentative evidence of mass loss through 11 candidate members outside 3 half-light radii (expected). Interpretation outside this radii is complicated by the coincidence with a previously known halo substructure, may contaminate member sample.
1106.5494
The cosmological impact of luminous TeV blasars I: Implications of plasma instabilities for the intergalactic magnetic field and extragalactic gamma-ray background
Broderick, Chang, Pfrommer
* inverse Compton: photon gains energy upon interaction with (high-kinetic energy) matter.
Inverse Compton cascades initiated by high (>100GeV) energy gamma rays enhance GeV emission of bright, TeV sources; however, this is not seen in bright TeV blazars, and that's used to constrain the intergalactic magnetic field (IGMF); limits on unresolved extragalactic gamma-ray background (EGRB) by Fermi is used to argue against a large number of such objects at high-z. But plasma-beam instabilities (?) --the "oblique" instability--present a plausible mechanism by which the energy of the produced (presumably particle) pair can be dissipated locally, heating the IGM. These instabilities grow on timescales shorter than inv-Comp cooling rate, so they suppress cascades. This is an obstacle in trying to limit the IGMF from the lack of discernible GeV bump in TeV sources; also weakens the Fermi limits upon the evolution of blazar populations (why?). Specifically, construct TeV-blazar luminosity function from these objects, and find that it is very well described by the quasar luminosity function at z~0.1, shifted to lower luminosity and number densities, suggesting that both classes of sources are regulated by similar processes. Extending this relationship to higher redshifts show that the magnitude and shape of EGRB above 10GeV is naturally reproduced with this rapidly evolving TeV-blazar luminosity function.
* subtle points being made.
1106.5493
Dark Matter and synchrotron emission from galactic center radio fliaments
Linden, Hooper, Yusef-Zadeh
Non-thermal radio filaments trance magnetic field lines, has hard synchrotron emission spectra. Origin of filaments not understood. Light DM particle (5-10GeV) annihilation matches the intensity, spectral shape, and flux variation of NRFs. NRF explanation also covers excess gamma-ray emission from Galactic center by Fermi-LAT, as well as direct detection from CoGeNT and DAMA/LIBRA.
* I'm curious bout the NRF, but also about the origin of the magnetic field lines.
Monday, July 18, 2011
Day 45
Tuesday. Couldn't get Source Extractor to run properly. Feel like an idiot.
1107.1966
A new catalogue of polar-ring galaxies selected from the SDSS
Moiseev, Smirnova, Smirnova, Reshetnikov
* galaxies with polar rings?
Polar rings in galaxies can be used to study formation and evolution of galaxies, and study the properties of dark halos. Present new catalog of polar ring galaxies (PRGs) based on Galaxy Zoo. Previous: ~24, this catalog from SDSS: 70 galaxies as "best candidates", 115 good PRG candidates; 53 classified as PRG-related; 37 galaxies with their polar rings almost face-on. Sloan PRG's are on average fainter and located further away than the old (Whitmore-based) catalog (from 1990), but also includes nearby candidates. Spectroscopic observations of six galaxies: polar ring confirmed in 5, while the last one appeared to be a projection of two galaxies. Added 10 galaxies to the kinematically-confirmed PRGs.
* ooh, pretty pictures.
* ooh, pretty pictures.
1107.2067
Variability of the SiO thermal line emission toward the young L1448-mm outflow
Jiminez-Serra, Martin-Pintado, Winters, Rodriguez-Franco, Caselli
* C-shocks: no info
* what an awful first sentence of an abstract. I don't understand what's going on or what they're going to talk about. What outflow? Where?
* situation does not improve half-way through the abstract. What condensation?
Narrow SiO thermal emission towards young outflows has been proposed to be a signature of the magnetic precursor of C-shocks. Some study on some object. Something about a jet. Speculate something about the SiO features associated with the precursor of C-shocks appearing at the interface of the new SiO components seen at intermediate velocities.
* I still don't understand what the subject is about. Can't tell if this is about a star or a galaxy or what. And it's been accepted by ApJ. What a dorkus referee.
* first line of the intro: "Variability is a common phenomena in the evolution of very young stars." Aaaah, so we're talking about stars! Still not clear what a C-shock is. Dorks.
* I'm probably in a bad mood today.
1103.3505
Bias in low-multipole CMB reconstructions
Copi, Huterer, Schwarz, Starkman
Low l multipoles are hampered by cosmic variance and our Galaxy. Reconstruction of full sky from partial sky is biased due to leakage of info from obscured region to the used region. Using the unobscured region without reconstructing is the most robust way to measure the true CMB sky. For noise-free data, the usual optimal, unbiased estimator can be employed without smoothing, avoiding the leakage problem. But real data with noise and residual foregrounds yields highly biased reconstructions.
1107.0682
Violation of the rotational invariance in the CMB bispectrum
Shiraishi, Yokoyama
* I've read this one before, it's about some theoretical cr.. stuff.
quantum fluctuations of a vector field can imprint on CMB as rotational invariance in the CMB bispectrum.
1107.2920
Starspots, spin-orbit misalignment, and active latitudes in the HAT-P-11 exoplanetary system
Sanchis-Ojeda, Winn
* Rossiter-McLaughlin effect: a spectroscopic phenomenon observed when an eclipsing binary's exoplanet/secondary star transits across the face of the parent/primary star.
Observed 26 transits of super-Neptune exoplanet, where they also expect starspots rotating at the "active latitude", causing some anomaly when the planet transits across the spots. Rossiter-McLaughlin effect also observed, find two solutions for the stellar obliquity (psi) and active latitude (l). Future observations should reveal changes in the preferred phases of spot-crossing anomalies.
1107.3120
AzTEC 1.1 mm images of 16 radio galaxies at 0.5<z<5.2 and a quasar at z=6.3
Humphrey et al
Observed 16 radio galaxies at high z + a radio-quiet quasar at z=6.3 at 1.1mm, more than doubling the number of high-z radio galaxies imaged at millimeter/sub-millimeter wavelengths. 11 of the active galaxies show mm counterpart signals (probably). The other 6 have one more more likely associated mm source. Thus, powerful radio-loud galaxies at high-z are beacons for finding luminous mm/sub-mm galaxies at high-z.
Combine with Spitzer, examine the mid-infrared colors of sample. Those with 1.1 mm counterpart are consistent with dusty starbursts, and are bluer than high-z Spitzer-selected active galaxes. Additionally, find arcs of 200-500 kpc apparently associated with 3 of the radio galaxies.
1107.3137
An HST/WFC3-IR morphological survey of galaxies at z=1.5-3.6: I. Survey description and morphological properties of star forming galaxies
Law, Steidel, Shapley, Nagy, Reddy, Erb
Study rest-frame optical morphologies of star-forming galaxies at z=1.5-3.6 with HST. 42 orbits, F160W (why in blue?), 65 arcmin^2, 27.9 AB mag (5 sigma, 0.2" radius aperture). M* ranges from 1e9 to 1e11 M_sun, 306 SF galaxies, half-light radii range of 0.7-3.0kpc. A stellar mass-radius relation described at z~3. Distribution of axis rations strongly inconsistent with a population of inclined exponential disks--better reproduced by triaxial stellar systems with c/a and b/a ratio of 0.3 and 0.7, respectively. Rest-UV and Rest-optical morphologies are generally similar for subset of HST imaging data; differences are pronounced at higher masses of M* > 3e10 M_sun. Gas-phase kinematics related to morphological maturity of the system and degree of rotational support; larger galaxies and more disk-like kinematics have a large quantity of gas at the systemic redshift that produces interstellar absorption lines whose centroids are systematically less blueshifted than in their smaller-dispersion counterparts. (what?) Discuss galaxy morphology in the context of merger fraction constraints: morphologically-identified mergers/non-mergers generally have insignificant differences in terms of physical observables such as stellar mass, SFR, and gas-phase kinematics.
* I guess I don't really understand what they mean when they say "gas-phase kinematics".
* And that sentence about gas-phase kinematics and morphological maturity is confusing as hell. I still don't get what they're trying to say.
0903.2732
F(R) cosmology in presence of a phantom fluid and its scalar-tensor counterpart: towards a unified precision model of the universe evolution
Elizalde, Saez-Gomez
Phantom fluid introduced in an f(R) model. Dark fluid gives rise to deceleration in early universe; today they add to the effective cosmological constant; later, produces transition toa "phantom era" (whoa) which may already have observable consequences. Dark fluid dominates at Rip time. Dark fluid with phantom behavior gives rise to super-accelerated phase. F(R) model can be constructed from a phantom model in a scalar-tensor theory.
* what are the observable consequences? That should be in the abstract.
1102.5363
The effect of helium sedimentation on galaxy cluster masses and scaling relations
Bulbul, Hasler, Bonamente, Joy, Marrone, Miller, Mroczkowski
Inner regions of galaxy clusters may have an enhanced He abundance due to sedimentation, which may affect the cluster mass estimates. Chandra observation of 8 relaxed galaxy clusters, investigate upper limits to the effect of He sedimentation to the relation Y_X vs M_500 and Y_X-M_2500. Calculate gas mass and total mass in two limits: un-enhanced abundance distribution and radial distribution of He sedimentation over 11 Gyrs. The sedimentation model produces a negligible increase in the gas mass within r<r500 (1.3%) and a 10% decrease in the total mass w/in r<r500. Stronger effect at smaller radii due to larger variance in He abundance in the inner region. Slope of the Y_X-M500 scaling relation is not significantly affected with He sedimentation.
* if He sedimentation is true, then mass estimates of M500 can be off by up to +10%, but the Y_X-M500 relation slope doesn't change much.
1107.2564
Testing the WMAP cosmology via Planck radio catalogues
Whitbourn, Shankes, Sawangwit
* I read this one before
Beam profile affects CMB experiments, but some discrepancies in WMAP and Planck observed in galaxy cluster SZ effects can't seem to be fixed.
1107.3160
Astroinformatics of galaxies and quasars: a new general method for photometric redshifts estimation
Laurino, D'Abrusco, Longo, Riccio
Weak Gated Experts (WGE) method: combination of data mining techiniques to determine photo-z. Sigma of 0.02 in (presumably the MAIN) galaxy; WGE also provides accuracy estimates. Works for quasars too.
* I still believe in the scientifically-based method of template fitting, not "informatics".
1106.3182
Enhanced sensitivity to dark matter self-annihilations in the sun using Neurtrino Spectral information
Rott, Tanaka, Itow
Self-annihilating DM particles captured gravitationally in the sun can generate observable neutrino signals. Detect spin-dependent scattering of WIMPs with nucleons in the Sun. Describe how to convert neutrino fluxes to WIMP-nucleon cross section (how?). Sensitive to low mass WIMPs; best results obtained with e- neutrino channel.
* how?
1107.3131
Requiem for an FCHAMP?
Langacker, Steigman
* whoa, Langacker!
FCHAMP: fractionally charged massive particles; appear in extension of the std model with superstring constructions. Lightest FCHAMP should be in existence today due to its stability. Massively charged particles behave like baryons, affects primordial nucleosynthesis and CMB anisotropies; measurements limit the FCHAMP relic density. Accelerator searches also constrain. FCHAMP can combine with alpha particles and protons, forming a tighly bound, positively charged states. ... I lost interest in this abstract.
* Do they mean electrical charge? In which case, I think the photons can see it (it's observable, not a dark form of matter)?
1107.2934
The baryonic Tully-Fisher relation of gas rich galaxies as a test of LCDM and MOND
McGaugh
Baryonic Tully-Fisher relation (BTFR): empirical realtion between garyonic mass and rotation velocity in disk galaxies; can test LCDM galaxy formation models, and MOND. Uses gas mass instead of stellar mass. ... galaxies that have experiences the least star formation have been most impacted by feedback.
* am I getting lazy, or are these abstracts not interesting?
1107.2944
Renegade subhaloes in the local group
Knebe, Libeskind, Doumler, Yepes, Cottloeber, Hoffman
Renegade subhalos: subhaloes that change their affiliation from one of the two prominent hosts to the other (e.g., from Milky way to Andromeda; LMC and SMC spawed near Andromeda?). N-body simulation suggest that the renegade subhaloes appear to be flying past one host before being pulled into the other. Merger not required to trigger such an event. Simulated Local Group facilitate such behavior. Small fraction of the full z=0 subhalo populations are renegades--intrinsically difficult to distinguish them despite clear differences in velocity, radial distribution, shape and spin-parameter distributions.
* first line of the intro: "Variability is a common phenomena in the evolution of very young stars." Aaaah, so we're talking about stars! Still not clear what a C-shock is. Dorks.
* I'm probably in a bad mood today.
1103.3505
Bias in low-multipole CMB reconstructions
Copi, Huterer, Schwarz, Starkman
Low l multipoles are hampered by cosmic variance and our Galaxy. Reconstruction of full sky from partial sky is biased due to leakage of info from obscured region to the used region. Using the unobscured region without reconstructing is the most robust way to measure the true CMB sky. For noise-free data, the usual optimal, unbiased estimator can be employed without smoothing, avoiding the leakage problem. But real data with noise and residual foregrounds yields highly biased reconstructions.
1107.0682
Violation of the rotational invariance in the CMB bispectrum
Shiraishi, Yokoyama
* I've read this one before, it's about some theoretical cr.. stuff.
quantum fluctuations of a vector field can imprint on CMB as rotational invariance in the CMB bispectrum.
1107.2920
Starspots, spin-orbit misalignment, and active latitudes in the HAT-P-11 exoplanetary system
Sanchis-Ojeda, Winn
* Rossiter-McLaughlin effect: a spectroscopic phenomenon observed when an eclipsing binary's exoplanet/secondary star transits across the face of the parent/primary star.
Observed 26 transits of super-Neptune exoplanet, where they also expect starspots rotating at the "active latitude", causing some anomaly when the planet transits across the spots. Rossiter-McLaughlin effect also observed, find two solutions for the stellar obliquity (psi) and active latitude (l). Future observations should reveal changes in the preferred phases of spot-crossing anomalies.
1107.3120
AzTEC 1.1 mm images of 16 radio galaxies at 0.5<z<5.2 and a quasar at z=6.3
Humphrey et al
Observed 16 radio galaxies at high z + a radio-quiet quasar at z=6.3 at 1.1mm, more than doubling the number of high-z radio galaxies imaged at millimeter/sub-millimeter wavelengths. 11 of the active galaxies show mm counterpart signals (probably). The other 6 have one more more likely associated mm source. Thus, powerful radio-loud galaxies at high-z are beacons for finding luminous mm/sub-mm galaxies at high-z.
Combine with Spitzer, examine the mid-infrared colors of sample. Those with 1.1 mm counterpart are consistent with dusty starbursts, and are bluer than high-z Spitzer-selected active galaxes. Additionally, find arcs of 200-500 kpc apparently associated with 3 of the radio galaxies.
1107.3137
An HST/WFC3-IR morphological survey of galaxies at z=1.5-3.6: I. Survey description and morphological properties of star forming galaxies
Law, Steidel, Shapley, Nagy, Reddy, Erb
Study rest-frame optical morphologies of star-forming galaxies at z=1.5-3.6 with HST. 42 orbits, F160W (why in blue?), 65 arcmin^2, 27.9 AB mag (5 sigma, 0.2" radius aperture). M* ranges from 1e9 to 1e11 M_sun, 306 SF galaxies, half-light radii range of 0.7-3.0kpc. A stellar mass-radius relation described at z~3. Distribution of axis rations strongly inconsistent with a population of inclined exponential disks--better reproduced by triaxial stellar systems with c/a and b/a ratio of 0.3 and 0.7, respectively. Rest-UV and Rest-optical morphologies are generally similar for subset of HST imaging data; differences are pronounced at higher masses of M* > 3e10 M_sun. Gas-phase kinematics related to morphological maturity of the system and degree of rotational support; larger galaxies and more disk-like kinematics have a large quantity of gas at the systemic redshift that produces interstellar absorption lines whose centroids are systematically less blueshifted than in their smaller-dispersion counterparts. (what?) Discuss galaxy morphology in the context of merger fraction constraints: morphologically-identified mergers/non-mergers generally have insignificant differences in terms of physical observables such as stellar mass, SFR, and gas-phase kinematics.
* I guess I don't really understand what they mean when they say "gas-phase kinematics".
* And that sentence about gas-phase kinematics and morphological maturity is confusing as hell. I still don't get what they're trying to say.
0903.2732
F(R) cosmology in presence of a phantom fluid and its scalar-tensor counterpart: towards a unified precision model of the universe evolution
Elizalde, Saez-Gomez
Phantom fluid introduced in an f(R) model. Dark fluid gives rise to deceleration in early universe; today they add to the effective cosmological constant; later, produces transition toa "phantom era" (whoa) which may already have observable consequences. Dark fluid dominates at Rip time. Dark fluid with phantom behavior gives rise to super-accelerated phase. F(R) model can be constructed from a phantom model in a scalar-tensor theory.
* what are the observable consequences? That should be in the abstract.
1102.5363
The effect of helium sedimentation on galaxy cluster masses and scaling relations
Bulbul, Hasler, Bonamente, Joy, Marrone, Miller, Mroczkowski
Inner regions of galaxy clusters may have an enhanced He abundance due to sedimentation, which may affect the cluster mass estimates. Chandra observation of 8 relaxed galaxy clusters, investigate upper limits to the effect of He sedimentation to the relation Y_X vs M_500 and Y_X-M_2500. Calculate gas mass and total mass in two limits: un-enhanced abundance distribution and radial distribution of He sedimentation over 11 Gyrs. The sedimentation model produces a negligible increase in the gas mass within r<r500 (1.3%) and a 10% decrease in the total mass w/in r<r500. Stronger effect at smaller radii due to larger variance in He abundance in the inner region. Slope of the Y_X-M500 scaling relation is not significantly affected with He sedimentation.
* if He sedimentation is true, then mass estimates of M500 can be off by up to +10%, but the Y_X-M500 relation slope doesn't change much.
1107.2564
Testing the WMAP cosmology via Planck radio catalogues
Whitbourn, Shankes, Sawangwit
* I read this one before
Beam profile affects CMB experiments, but some discrepancies in WMAP and Planck observed in galaxy cluster SZ effects can't seem to be fixed.
1107.3160
Astroinformatics of galaxies and quasars: a new general method for photometric redshifts estimation
Laurino, D'Abrusco, Longo, Riccio
Weak Gated Experts (WGE) method: combination of data mining techiniques to determine photo-z. Sigma of 0.02 in (presumably the MAIN) galaxy; WGE also provides accuracy estimates. Works for quasars too.
* I still believe in the scientifically-based method of template fitting, not "informatics".
1106.3182
Enhanced sensitivity to dark matter self-annihilations in the sun using Neurtrino Spectral information
Rott, Tanaka, Itow
Self-annihilating DM particles captured gravitationally in the sun can generate observable neutrino signals. Detect spin-dependent scattering of WIMPs with nucleons in the Sun. Describe how to convert neutrino fluxes to WIMP-nucleon cross section (how?). Sensitive to low mass WIMPs; best results obtained with e- neutrino channel.
* how?
1107.3131
Requiem for an FCHAMP?
Langacker, Steigman
* whoa, Langacker!
FCHAMP: fractionally charged massive particles; appear in extension of the std model with superstring constructions. Lightest FCHAMP should be in existence today due to its stability. Massively charged particles behave like baryons, affects primordial nucleosynthesis and CMB anisotropies; measurements limit the FCHAMP relic density. Accelerator searches also constrain. FCHAMP can combine with alpha particles and protons, forming a tighly bound, positively charged states. ... I lost interest in this abstract.
* Do they mean electrical charge? In which case, I think the photons can see it (it's observable, not a dark form of matter)?
1107.2934
The baryonic Tully-Fisher relation of gas rich galaxies as a test of LCDM and MOND
McGaugh
Baryonic Tully-Fisher relation (BTFR): empirical realtion between garyonic mass and rotation velocity in disk galaxies; can test LCDM galaxy formation models, and MOND. Uses gas mass instead of stellar mass. ... galaxies that have experiences the least star formation have been most impacted by feedback.
* am I getting lazy, or are these abstracts not interesting?
1107.2944
Renegade subhaloes in the local group
Knebe, Libeskind, Doumler, Yepes, Cottloeber, Hoffman
Renegade subhalos: subhaloes that change their affiliation from one of the two prominent hosts to the other (e.g., from Milky way to Andromeda; LMC and SMC spawed near Andromeda?). N-body simulation suggest that the renegade subhaloes appear to be flying past one host before being pulled into the other. Merger not required to trigger such an event. Simulated Local Group facilitate such behavior. Small fraction of the full z=0 subhalo populations are renegades--intrinsically difficult to distinguish them despite clear differences in velocity, radial distribution, shape and spin-parameter distributions.
Sunday, July 17, 2011
Day 44
Welp, I really need to run SExtractor today. It's Monday.
1107.1863
Non-Gaussian extrema counts for CMB maps
Pogosyan, Pichon, Gay
Assuming isotropic random field, and its gradient and invariants of the Hessian, calculate 2d differential extrema counts as a function of the excursion set threshold derived from the full moments expansion of the random field (like BBKS?). It's a geometrical analysis of weakly non-G CMB maps: An analytic expressions for these counts are given to second order in the non-G correction; can be calculated to arbitrary order using Monte Carlo method. Demonstrate with matching count estimators on "Planck" data.
Day 43
Sunday. Need to run SExtractor today.
1107.2904
Extending the effective-one-body Hamiltonian of BH binaries to include next-to-next-to-leading spin-orbit couplings
Barausse, Buonanno
* can't they think of a better title?
* effective one body approach: two body problem of m1 and m2 reduced to one body of mass mu = (m1 m2)/(m1+m2).
* Kerr metric: geometry of spacetime around a rotating massive body, which should exhibit frame dragging. Frame dragging predicts that objects coming close to a rotating mass will be entrained to participate in its rotation, because of the curvature of spacetime associated with rotating bodies. At close enough distances, all objects (even light itself) must rotate with the body (the ergosphere).
Effective one body approach to two compact binaries of masses m1 and m2, spins S1 and S2, mapped into the dynamics of one test particle mu and spin S* moving in a deformed Kerr metric with mass M=m1+m2 and spin S_kerr. Compute (1) spin-spin coupling, (2) spin-orbit couplings, and (3) all spin-orbit couplings in the test-particle limit. Go to higher-order terms ("next-to-next-to..."). Some new classifications depending on equatorial orbis.
1101.2215
SED fitting with MCMC: Metholodogy and application to z=3.1 Lyman-alpha emitting galaxies
Acquaviva, Gawiser, Guaita
GalMC: MCMC algorithm to fit age, stellar mass, dust reddening, metallicity, redshift, and SFR. Efficiency in MCMC is better than grid by x100 for a 3d parameter space, and increases with number of dimensions. Use GalMC to Lyman-alpha emitters (LAE) at z=3.1. Age=0.67Gyr and stellar mass 3.2e9 M_sun if detected in IRAC 3.6 micron band, and 0.06Gyr with stellar mass 2e8 M_sun if not (stacked SED results); both consistent with absence of dust. SFH neither exponential nor constant preferred. Constraint on the metallicity found for the first time (Z<Z_sun).
1104.4500
Generalized slow roll for non-canonical kinetic terms
Hu
Generalized slow-roll approach for calculating power spectrum (where the slow roll parameters are neither small nor slowly varying) can be readily extended to models with non-canonical kinetic terms in the inflaton action. Ex: rapid sound speed variations in DBI models with features in the warp factor, affecting the power spectrum shape. Single source function for deviations athat is simply related to the power spectrum exists: empirical constraints on this source function can be readily interpreted in the context of features in the inflaton potential or sound speed.
1107.2904
Extending the effective-one-body Hamiltonian of BH binaries to include next-to-next-to-leading spin-orbit couplings
Barausse, Buonanno
* can't they think of a better title?
* effective one body approach: two body problem of m1 and m2 reduced to one body of mass mu = (m1 m2)/(m1+m2).
* Kerr metric: geometry of spacetime around a rotating massive body, which should exhibit frame dragging. Frame dragging predicts that objects coming close to a rotating mass will be entrained to participate in its rotation, because of the curvature of spacetime associated with rotating bodies. At close enough distances, all objects (even light itself) must rotate with the body (the ergosphere).
Effective one body approach to two compact binaries of masses m1 and m2, spins S1 and S2, mapped into the dynamics of one test particle mu and spin S* moving in a deformed Kerr metric with mass M=m1+m2 and spin S_kerr. Compute (1) spin-spin coupling, (2) spin-orbit couplings, and (3) all spin-orbit couplings in the test-particle limit. Go to higher-order terms ("next-to-next-to..."). Some new classifications depending on equatorial orbis.
1101.2215
SED fitting with MCMC: Metholodogy and application to z=3.1 Lyman-alpha emitting galaxies
Acquaviva, Gawiser, Guaita
GalMC: MCMC algorithm to fit age, stellar mass, dust reddening, metallicity, redshift, and SFR. Efficiency in MCMC is better than grid by x100 for a 3d parameter space, and increases with number of dimensions. Use GalMC to Lyman-alpha emitters (LAE) at z=3.1. Age=0.67Gyr and stellar mass 3.2e9 M_sun if detected in IRAC 3.6 micron band, and 0.06Gyr with stellar mass 2e8 M_sun if not (stacked SED results); both consistent with absence of dust. SFH neither exponential nor constant preferred. Constraint on the metallicity found for the first time (Z<Z_sun).
1104.4500
Generalized slow roll for non-canonical kinetic terms
Hu
Generalized slow-roll approach for calculating power spectrum (where the slow roll parameters are neither small nor slowly varying) can be readily extended to models with non-canonical kinetic terms in the inflaton action. Ex: rapid sound speed variations in DBI models with features in the warp factor, affecting the power spectrum shape. Single source function for deviations athat is simply related to the power spectrum exists: empirical constraints on this source function can be readily interpreted in the context of features in the inflaton potential or sound speed.
Saturday, July 16, 2011
Day 42
Saturday 3pm. Finally finished new binning code for GGLens. Will go running in the gym (it's raining) after I finish this astro-ph thing.
1107.2651
Spatially-resolved spectroscopy of SDSS J0952+2552: a confirmed dual AGN
McGurk, Max, Rosario, Shields, Smith, Wright
This object is a double AGN, as suspected from SDSS spectra of OIII doublet, and confirmed by Keck 2 laser AO spatially-resolved spectroscopy. They are nucleus of galaxies separated by 1", and the two AGNs are separated by 4.8 kpc. The double OIII lines confirm AGN photoionization characteristics. Unique opportunity to study galaxy mergers and their effect on BH growth.
1107.2654
Testin the WMAP cosmology via Planck radio catalogues
Whibourn, Shanks, Sawangwit
WMAP CMB power specrum is highly sensitive to the beam profile. Use Planck early data release to further test WMAP beam profiles; QVW appear wider than expected compared to Jupiter beam, from direct radio source profile normalization, using Planck fluxes, or using NVSS source catalogues. WMAP source fluxs and that of Planck show a non-linear relation. Applying this non-linear relation to the Jupiter beam profile results in an excellent fit to the observed radio source profile. The stacked SZ decrement profile of ~160 cluster still has a problem, so this problem is not entirely due to the beam profile. Beam profile systematics can have significant effects on both the amplitude and position of the first acoustic peak---a wider beam can move the position of the first peak to significantly larger wavenumbers.
* sounds like a good study on CMB beam systematics.
1107.2673
On the prior dependence of constraints on the tensor-to-scalar ratio
Cortez, Liddle, Parkinson
Cosmic tensor perturbation constraints has prior dependence, which is studied here. Common prior: single-field inflationary consistency equation, which relates the tensor spectral index nT to the tensor-to-scalar ratio r. Dropping it leads to significantly different constraints on nT and on the upper limit of r on scales 0.01<k<0.05 Mpc^{-1} by a factor of >10. Even with consistency equation adopted, dependence on pivot scale exists. Determine the optimal scale for constraining the tensor amplitude.
* what are the "consistency relations?"
1107.2163
Higgs-Dilaton cosmology: from the early to the late universe
Garcia-Bellido, Rubio, Shaposhnikov, Zenhäusern
* Dilaon: a hypothetical partical of scalar field phi that always comes with gravity. Generated by promoting Planck mass (assumed to be a constant) to a dynamic field.
* Higgs: hypothetical massive elementary particle predicted from the Standard Model of particle physics.
Minimal scale-invariant extension of the SM, combined with Unimodular Gravity: has inflationary stage related to the SM Higgs field, but a late period of DE domination, associated with an almost massless dilaton. Derive relation between tilt (n_s) and the present value of w. Find bounds for scalar tilt n_s < 0.97, associated running ln n_s/ d ln k ~0, and scalar-to-tensor ratio r < 0.0033, which can be tested by Planck. Model predicts w>-1. The relation between n_s and w (or: omega_DE^0) allows bounds on n_s to constrain omega_DE.
1107.2651
Spatially-resolved spectroscopy of SDSS J0952+2552: a confirmed dual AGN
McGurk, Max, Rosario, Shields, Smith, Wright
This object is a double AGN, as suspected from SDSS spectra of OIII doublet, and confirmed by Keck 2 laser AO spatially-resolved spectroscopy. They are nucleus of galaxies separated by 1", and the two AGNs are separated by 4.8 kpc. The double OIII lines confirm AGN photoionization characteristics. Unique opportunity to study galaxy mergers and their effect on BH growth.
1107.2654
Testin the WMAP cosmology via Planck radio catalogues
Whibourn, Shanks, Sawangwit
WMAP CMB power specrum is highly sensitive to the beam profile. Use Planck early data release to further test WMAP beam profiles; QVW appear wider than expected compared to Jupiter beam, from direct radio source profile normalization, using Planck fluxes, or using NVSS source catalogues. WMAP source fluxs and that of Planck show a non-linear relation. Applying this non-linear relation to the Jupiter beam profile results in an excellent fit to the observed radio source profile. The stacked SZ decrement profile of ~160 cluster still has a problem, so this problem is not entirely due to the beam profile. Beam profile systematics can have significant effects on both the amplitude and position of the first acoustic peak---a wider beam can move the position of the first peak to significantly larger wavenumbers.
* sounds like a good study on CMB beam systematics.
1107.2673
On the prior dependence of constraints on the tensor-to-scalar ratio
Cortez, Liddle, Parkinson
Cosmic tensor perturbation constraints has prior dependence, which is studied here. Common prior: single-field inflationary consistency equation, which relates the tensor spectral index nT to the tensor-to-scalar ratio r. Dropping it leads to significantly different constraints on nT and on the upper limit of r on scales 0.01<k<0.05 Mpc^{-1} by a factor of >10. Even with consistency equation adopted, dependence on pivot scale exists. Determine the optimal scale for constraining the tensor amplitude.
* what are the "consistency relations?"
1107.2163
Higgs-Dilaton cosmology: from the early to the late universe
Garcia-Bellido, Rubio, Shaposhnikov, Zenhäusern
* Dilaon: a hypothetical partical of scalar field phi that always comes with gravity. Generated by promoting Planck mass (assumed to be a constant) to a dynamic field.
* Higgs: hypothetical massive elementary particle predicted from the Standard Model of particle physics.
Minimal scale-invariant extension of the SM, combined with Unimodular Gravity: has inflationary stage related to the SM Higgs field, but a late period of DE domination, associated with an almost massless dilaton. Derive relation between tilt (n_s) and the present value of w. Find bounds for scalar tilt n_s < 0.97, associated running ln n_s/ d ln k ~0, and scalar-to-tensor ratio r < 0.0033, which can be tested by Planck. Model predicts w>-1. The relation between n_s and w (or: omega_DE^0) allows bounds on n_s to constrain omega_DE.
Thursday, July 14, 2011
Day 41
Friday. Gotta plan the outing tonight. Gotta finish coding the binning fix, and get the gglens code going for the weekend!
1107.2145
Supernova 2000cb: high-energy version of SN 1987A
Utrobin, Chugai
* SNe type IIP: Type II SN are sub-divided into two classes, depending on the shape of the light curve. The light curve for a Type II-L supernovae shows a stead (linear) decline following the peak brightness. Type II-P supernova has a distinctive flat streach during the decline. For type IIL, expulsion of most of the hydrogen envelope of the progenitor star causes the lightcurve shape; for type IIP, due to the change in the opacity of the exterior layer. Shock wave ionizes the hydrogen in the outer envelope, resulting in a significant increase in opacity, preventing the photons from escaping, until the hydrogen cools enough to recombine and become transparent.
Use hydro simulations of the SNe to compare 1987A and 2000cb (IIP SNe from blue supergiants) to describe light curve and spectroscopic data. Assume 35 R_sun, 22.3 M_sun ejecta, 4.4e51 erg energy, Ni 56 mass of 0.083 M_sun; estimated progenitor mass: 24-28 M_sun. Dome-like light curves are entirely powered by radioactive decay, unlike normal type IIP supernovae, where the plateau is dominated by the internal energy deposited after the shock wave propagation through the pre-supernova. Find signatures of explosion asymmetry in the photospheric and nebular spectra. "The explosion energy of SN 2000cb is higher by a factor of three compared to SN 1987A, which poses a serious problem for explosion mechanisms of type IIP supernovae."
* that last sentence is not clear at all what they mean. What serious problem? It sounds more like a classification problem than a type IIP explosion mechanism problem to me. Why is the factor of three a problem?
1107.2145
Supernova 2000cb: high-energy version of SN 1987A
Utrobin, Chugai
* SNe type IIP: Type II SN are sub-divided into two classes, depending on the shape of the light curve. The light curve for a Type II-L supernovae shows a stead (linear) decline following the peak brightness. Type II-P supernova has a distinctive flat streach during the decline. For type IIL, expulsion of most of the hydrogen envelope of the progenitor star causes the lightcurve shape; for type IIP, due to the change in the opacity of the exterior layer. Shock wave ionizes the hydrogen in the outer envelope, resulting in a significant increase in opacity, preventing the photons from escaping, until the hydrogen cools enough to recombine and become transparent.
Use hydro simulations of the SNe to compare 1987A and 2000cb (IIP SNe from blue supergiants) to describe light curve and spectroscopic data. Assume 35 R_sun, 22.3 M_sun ejecta, 4.4e51 erg energy, Ni 56 mass of 0.083 M_sun; estimated progenitor mass: 24-28 M_sun. Dome-like light curves are entirely powered by radioactive decay, unlike normal type IIP supernovae, where the plateau is dominated by the internal energy deposited after the shock wave propagation through the pre-supernova. Find signatures of explosion asymmetry in the photospheric and nebular spectra. "The explosion energy of SN 2000cb is higher by a factor of three compared to SN 1987A, which poses a serious problem for explosion mechanisms of type IIP supernovae."
* that last sentence is not clear at all what they mean. What serious problem? It sounds more like a classification problem than a type IIP explosion mechanism problem to me. Why is the factor of three a problem?
Day 40
Still Thursday. Two more days of work this week, but it felt like Friday yesterday. Arman cooked a very nice dinner for all of us (Teppei, Hayin, Fred, me) last night.
INPA LBL
DeepCore and beyond - a phase approach toward precision megaton neutrino detectors
Darren Grant
* atmospheric neutrinos: produced in the collision of primarily cosmic rays (typically protons) with nuclei (N, O, etc) in the upper atmosphere. This creates a shower of hadrons, mostly pions, which decay into a muon and muon anti-neutrino. The muons decay to an electron, muon neutrino, and an electron anti-neutrino: 2 to 1 muon to electron neutrino ratio produced (some modification necessary).
* atmospheric neutrino detection: Super-K detects atmospheric neutrinos interaction with H and O in the 22.5 kT mass of water, reactions "fully contained" in the detector volume. Neutrino flavor tagged by detecting and identifying the final state lepton (muon or electron). Low energy (E < 1 GeV) neutrinos typically react by quasi-elastic scattering, with only the lepton visible. At higher energies, the final state muon or electrons is often accompanied by a pion or numerous hadrons (deep inelastic scattering). To properly associate the event with the neutrino type, select events with a single Cherenkov ring. "Partially contained" events are usually (98%) muons, since only muons have such great penetrating power. Muon ring sharp, electron ring more fuzzy (due to e- shower).
* evidence of neutrino oscillations in atmospheric neutrinos: (1) predicted muon/electron neutrino ratio has anomaly, (2) up-down asymmetry in high-E muon neutrinos, when we expect the high-E CR flux distribution to be symmetric (low-E CR's are affected by earth's magnetic field), (3) upward-going muons: the rate of low and high-E events were in poor agreement with the standard prediction, but in good agreement with a hypothesis of neutrino oscillations.
DeepCore: low energy extension to the IceCube Neutrino Observatory, fiducial volume up to 35 MT, energy threshold as low as 10GeV. Use of IceCube array as the active veto for cosmic ray muons to achieve a pure neutrino sample. New physics: atmospheric neutrino oscillations, indirect DM searches.
Possible to achieve lower detector energy thresholds and higher precision measurements in deep ice with more "infill". Two-phase approach of infill considered. First: similar to DeepCore, 10MT wth <1GeV sensitivity--improved sensitivity for indirect WIMP searches, atmospheric neutrinos, Galactic center point sources, proton decay searches. Second: few MT fiducial with 10 MeV threshold for large-scale physics program that includes proton decay, SNe neutrinos, and future long-baseline efforts.
Current status of DeepCore, 1st year data, simulation results, feasibility sutides for new arrays.
1107.2401
Interaction between dark matter sub-halos & galactic gaseous disk
Kannan, Maccio, Pasquali, Moster, Walter
Origin of observed holes and shells in H I distribution of galaxies: Intraction of DM sub-halos with gas disk (an idea). High-resolution hydro sims show pure DM sub-halos impacting galactic disk cannot produce holes, but result in high density regions in the disk. Sub-halos containing a small amount of gas (few percent gas mass fraction) can displace the gas in disk and form holes and shells. Size and lifetime dependent on density, halo gas mass, impact velocity. 1e8 M_sun can create a kpc scale hole. Also register an increased SFR at the rim of the hole, as also seen in observations. Number of predicted holes falls short compared to observations. DM halo impact is not the major channel through wich holes are formed.
1107.2516
Real-time, fast radio transient searches with GPU de-dispersion
Magro, Karastergiou, Salvini, Mort, Dulwich, Adami
Identification and discovery of fast radio transients throught blind-search surveys requires a large amount of processing power, ~O(N^3). GPUs can be used for fast transient discorvy in real-time.
1107.2542
An effective theory of accelerated expansion
Jiminez, Talavera, Verde
Effective theory of inflation and DE. How many (free) parameters are needed to broadly capture the physics of a theory describine cosmic acceleration? What are the physical interpretation of the parameters? There are 5 independent parameters, one can be constrained via general relativity tests; the other 4 by observing H(z). Need accurate measurement for H(z).
* Interesting-sounding paper.
1010.5250
The signatures of large-scale temperature and intensity fluctaions in the lyman-alpha forest
McQuinn, Hernquist, Lidz, Zaldarriaga
Reionization processes produce large-scale temperature fluctations in the intergalactic medium. Study consequences of inhomogeneous heating for the Ly-alpha forest--it's subtle, and doesn't show up in usual statisitcs. But earlier analysis were not sensitive to 3d modes with >30 comoving Mpc/h wavelengths, scales where temperature fluctuations are likely to be largest. Find physically motivated temperature models can alter 3D power specrum of the Ly-alpha forest at order unity level at k<0.1 Mpc^{-1}, easily detectable with BOSS. Fluctuation in the intensity of the UV BG can also alter P_F significantly. Can constrain models for the sources of the ionizing background. At higher z, potentially detect the thermal imprint of hydrogen reionization.
1103.5378
The flare-energy distributions generated by kink-unstable ensembles of zero-net-current coronal loops
Bareford, Browning, Van der Linden
* nano-flares can heat the corona to a million degrees K.
1106.5790
Stable heating of cluster cooling flows by CR streaming
Fujita, Ohira
* CR from AGN produces Alfven waves instability that heat the cooling flow in clusters.
1107.2155
The XENON 100 Dark Matter experiment
XENON100 collaboration
* time projection chamber: particle detected invented by Nygren at LBL. Consists of a gas-filled cylindrical chamber with multi-wire proportional chambers (MWPC) as endplates. Electric field along the cylinder radial direction, magnetic field along the cylinder axis. z coordinage determined by measuring the drift time from the ionization event to the MWPC at the end. Anode wires in the azimuthal direction, which provides information on the radial coordinate r.
Liquid Xe in a TPC to measure Xe nuclear recoils from WIMPs. Detector design, performance results from commissioning and first science runs. 62kg for LXe, surrounded by 99kg of LXe veto, instrumented by PMTs inside the liquid or Xe gas. LXe target in low-radioactivity stainless steel vessel, embedded in a pasive radiation shield. Installed in Gran Sasso (underground); has 100 live-days DM search. Design goal: detect WIMP-nucleon scattering of sigma=2e-45 cm^2 for a 100 GeV WIMP.
1107.2213
Weak lensing tomography with orthognal polynomials
Schaefer, Heisenberg
WL shear tomography with LOS weighting with a set of special orthogonal polynomials (TaRDiS). Each polynomial projects out statistically independent information; combination of multiple polynomials lifts degeneracies. Assumption of a reference cosmology is needed for the construction of the polynomials (!).
* It's like tomography, except that it doesn't use a top-hat. It uses TaRDiS polynomials.
1107.2258
Beyond Einstein: Cosmologcal test of model independent modified gravity
Thomas
Add Galaxy cluters to the observables and examine whether they can improve the constraints on the modified gravity parameters: Planck CMB, SZ cluster, DES WL survey. Cluster counts improves the constraints.
1107.2112
Symmetryon cosmology
Hinterbichler, Khoury, Levy, Matas
Symmetron: scalar field in the dark sector, where coupling to matter depends on the ambient matter density. Decoubled and screened in regions of high density (satisfies local constraint on gravity), but couples with gravitational strength in regions of low density. Derive the cosmological expansion history in the presence of a symmetron field, through inflation, radiation, and matter-dominated epochs. The scalar field reaches symmetry-breaking vacuum by the present epoch. Still needs cosmological constant to drive late-time cosmic acceleration.
1107.2316
Odyssey 2: A mission toward Neptune and Triton to test GR
Lenoir, et al
* Eddington parameter: "gamma", which is a straightforward paramaeterization of the amount of deflection of light bya gravitational source; equal to 1 for GR. Best constrained of the 10 post-Newtonian parameters.
Odyssey 2 proposed for M3 mission for Cosmic Vision 2015-2025. Aims at Neptune and Triton. Two sets of objectives: (1) perform a set of gravitation experiments at the Solar system scale; measure the Eddington parameter; investigate the navigation anomalies during fly-bys. These require Electrostatic accelerometer with a rotating stage, radio-science, and laser ranging. (2) enhance our knowledge of Neptune and Triton. Need: camera, spectrometer, dust and particle etectors, magnetometer. Obtain: gravity field, atmosphere and magnetosphere of the two bodies, surface geology of Triton, nature of planetary rings around Neptune.
1107.1714
Impacts of Dark Stars on Reionization and signatures in the CMB
Scott, Venkatesan, Roebber, Gondolo, Pierpaoli, Holder
Possible impacts of dark stars in reionization and CMB: if dark stars capture large amounts of dark matter via nuclear scattering, reionzation can be substantially delayed, decreasing integrated optical depth to last scattering. These effects can be constrained from WMAP7 data, but are degenerate with astrophysical uncertainties.
1107.1716
Do baryons trace dark matter in the early universe?
Grin, Dore, Kamionkowski
BBN and galaxy clusters allows compensated isocurvature perturbations to be as large as ~10%. They can modulate the power spectrum of CMB fluctuations. Observable in B modes in CMB polarization. Calculate the magnitude of this effect, describe the observability.
* any two-field inflationary picture would generically produce some iso-curvature; above scenario just happened to be poorly constrained. Can use CMB to learn more (don't need 21cm). Considers the case where the dominant perturbations are still adiabatic.
1107.1789
Cosmology today-a brief review
Cervantes-Cota, Smoot
Breif review of the standard model of cosmology. FRW at different epochs, comological lengths, physical processes necessary to understand the early and very early universe, and observations of it.
1107.1916
Where will supersymmetric DM first be seen?
Gao, Frenk, Jenkins, Springel, White
If dark matter consists of supersymmetric particles, then annihilation signals should come rom haloes. More signals from nearby rich clusters, just as clean as local dSph's. Signal mostly from subhalos. Fermi may be able to resolve them. Promising clusters: Coma and Fornax, but need better detection algorithms, since the signal is expected to be weak.
1107.1715
Global fits to the cMSSM including the first LHC and XENON100 data
Bertone, Cerdeno, Fornasa, Ruiz de Austri, Strege, Trotta
cMSSM: constrained minimal supersymmetric standard model, constrained using ATLAS, CMS at LHC, and XENON100. Conseequences for neutralino DM studied, rules out Focus Point region, from particle astrophysics.
1107.1477
Herschel detects a massive dust reservoir in Supernova 1987A
Matsuura et al
Far IR and submillimiter observations of SN 1987A in LMC. Observations show presence of a population of cold dust grains radiating at 17-23K at 220 L_sun; SED and intensity implies dust mass of 0.4-0.7 M_sun. This must be the SN ejecta, which requires efficient precipitation of all refractory material into dust. Implies SNe can produce the large dust masses detected in young galaxies at very high z.
INPA LBL
DeepCore and beyond - a phase approach toward precision megaton neutrino detectors
Darren Grant
* atmospheric neutrinos: produced in the collision of primarily cosmic rays (typically protons) with nuclei (N, O, etc) in the upper atmosphere. This creates a shower of hadrons, mostly pions, which decay into a muon and muon anti-neutrino. The muons decay to an electron, muon neutrino, and an electron anti-neutrino: 2 to 1 muon to electron neutrino ratio produced (some modification necessary).
* atmospheric neutrino detection: Super-K detects atmospheric neutrinos interaction with H and O in the 22.5 kT mass of water, reactions "fully contained" in the detector volume. Neutrino flavor tagged by detecting and identifying the final state lepton (muon or electron). Low energy (E < 1 GeV) neutrinos typically react by quasi-elastic scattering, with only the lepton visible. At higher energies, the final state muon or electrons is often accompanied by a pion or numerous hadrons (deep inelastic scattering). To properly associate the event with the neutrino type, select events with a single Cherenkov ring. "Partially contained" events are usually (98%) muons, since only muons have such great penetrating power. Muon ring sharp, electron ring more fuzzy (due to e- shower).
* evidence of neutrino oscillations in atmospheric neutrinos: (1) predicted muon/electron neutrino ratio has anomaly, (2) up-down asymmetry in high-E muon neutrinos, when we expect the high-E CR flux distribution to be symmetric (low-E CR's are affected by earth's magnetic field), (3) upward-going muons: the rate of low and high-E events were in poor agreement with the standard prediction, but in good agreement with a hypothesis of neutrino oscillations.
DeepCore: low energy extension to the IceCube Neutrino Observatory, fiducial volume up to 35 MT, energy threshold as low as 10GeV. Use of IceCube array as the active veto for cosmic ray muons to achieve a pure neutrino sample. New physics: atmospheric neutrino oscillations, indirect DM searches.
Possible to achieve lower detector energy thresholds and higher precision measurements in deep ice with more "infill". Two-phase approach of infill considered. First: similar to DeepCore, 10MT wth <1GeV sensitivity--improved sensitivity for indirect WIMP searches, atmospheric neutrinos, Galactic center point sources, proton decay searches. Second: few MT fiducial with 10 MeV threshold for large-scale physics program that includes proton decay, SNe neutrinos, and future long-baseline efforts.
Current status of DeepCore, 1st year data, simulation results, feasibility sutides for new arrays.
1107.2401
Interaction between dark matter sub-halos & galactic gaseous disk
Kannan, Maccio, Pasquali, Moster, Walter
Origin of observed holes and shells in H I distribution of galaxies: Intraction of DM sub-halos with gas disk (an idea). High-resolution hydro sims show pure DM sub-halos impacting galactic disk cannot produce holes, but result in high density regions in the disk. Sub-halos containing a small amount of gas (few percent gas mass fraction) can displace the gas in disk and form holes and shells. Size and lifetime dependent on density, halo gas mass, impact velocity. 1e8 M_sun can create a kpc scale hole. Also register an increased SFR at the rim of the hole, as also seen in observations. Number of predicted holes falls short compared to observations. DM halo impact is not the major channel through wich holes are formed.
1107.2516
Real-time, fast radio transient searches with GPU de-dispersion
Magro, Karastergiou, Salvini, Mort, Dulwich, Adami
Identification and discovery of fast radio transients throught blind-search surveys requires a large amount of processing power, ~O(N^3). GPUs can be used for fast transient discorvy in real-time.
1107.2542
An effective theory of accelerated expansion
Jiminez, Talavera, Verde
Effective theory of inflation and DE. How many (free) parameters are needed to broadly capture the physics of a theory describine cosmic acceleration? What are the physical interpretation of the parameters? There are 5 independent parameters, one can be constrained via general relativity tests; the other 4 by observing H(z). Need accurate measurement for H(z).
* Interesting-sounding paper.
1010.5250
The signatures of large-scale temperature and intensity fluctaions in the lyman-alpha forest
McQuinn, Hernquist, Lidz, Zaldarriaga
Reionization processes produce large-scale temperature fluctations in the intergalactic medium. Study consequences of inhomogeneous heating for the Ly-alpha forest--it's subtle, and doesn't show up in usual statisitcs. But earlier analysis were not sensitive to 3d modes with >30 comoving Mpc/h wavelengths, scales where temperature fluctuations are likely to be largest. Find physically motivated temperature models can alter 3D power specrum of the Ly-alpha forest at order unity level at k<0.1 Mpc^{-1}, easily detectable with BOSS. Fluctuation in the intensity of the UV BG can also alter P_F significantly. Can constrain models for the sources of the ionizing background. At higher z, potentially detect the thermal imprint of hydrogen reionization.
1103.5378
The flare-energy distributions generated by kink-unstable ensembles of zero-net-current coronal loops
Bareford, Browning, Van der Linden
* nano-flares can heat the corona to a million degrees K.
1106.5790
Stable heating of cluster cooling flows by CR streaming
Fujita, Ohira
* CR from AGN produces Alfven waves instability that heat the cooling flow in clusters.
1107.2155
The XENON 100 Dark Matter experiment
XENON100 collaboration
* time projection chamber: particle detected invented by Nygren at LBL. Consists of a gas-filled cylindrical chamber with multi-wire proportional chambers (MWPC) as endplates. Electric field along the cylinder radial direction, magnetic field along the cylinder axis. z coordinage determined by measuring the drift time from the ionization event to the MWPC at the end. Anode wires in the azimuthal direction, which provides information on the radial coordinate r.
Liquid Xe in a TPC to measure Xe nuclear recoils from WIMPs. Detector design, performance results from commissioning and first science runs. 62kg for LXe, surrounded by 99kg of LXe veto, instrumented by PMTs inside the liquid or Xe gas. LXe target in low-radioactivity stainless steel vessel, embedded in a pasive radiation shield. Installed in Gran Sasso (underground); has 100 live-days DM search. Design goal: detect WIMP-nucleon scattering of sigma=2e-45 cm^2 for a 100 GeV WIMP.
1107.2213
Weak lensing tomography with orthognal polynomials
Schaefer, Heisenberg
WL shear tomography with LOS weighting with a set of special orthogonal polynomials (TaRDiS). Each polynomial projects out statistically independent information; combination of multiple polynomials lifts degeneracies. Assumption of a reference cosmology is needed for the construction of the polynomials (!).
* It's like tomography, except that it doesn't use a top-hat. It uses TaRDiS polynomials.
1107.2258
Beyond Einstein: Cosmologcal test of model independent modified gravity
Thomas
Add Galaxy cluters to the observables and examine whether they can improve the constraints on the modified gravity parameters: Planck CMB, SZ cluster, DES WL survey. Cluster counts improves the constraints.
1107.2112
Symmetryon cosmology
Hinterbichler, Khoury, Levy, Matas
Symmetron: scalar field in the dark sector, where coupling to matter depends on the ambient matter density. Decoubled and screened in regions of high density (satisfies local constraint on gravity), but couples with gravitational strength in regions of low density. Derive the cosmological expansion history in the presence of a symmetron field, through inflation, radiation, and matter-dominated epochs. The scalar field reaches symmetry-breaking vacuum by the present epoch. Still needs cosmological constant to drive late-time cosmic acceleration.
1107.2316
Odyssey 2: A mission toward Neptune and Triton to test GR
Lenoir, et al
* Eddington parameter: "gamma", which is a straightforward paramaeterization of the amount of deflection of light bya gravitational source; equal to 1 for GR. Best constrained of the 10 post-Newtonian parameters.
Odyssey 2 proposed for M3 mission for Cosmic Vision 2015-2025. Aims at Neptune and Triton. Two sets of objectives: (1) perform a set of gravitation experiments at the Solar system scale; measure the Eddington parameter; investigate the navigation anomalies during fly-bys. These require Electrostatic accelerometer with a rotating stage, radio-science, and laser ranging. (2) enhance our knowledge of Neptune and Triton. Need: camera, spectrometer, dust and particle etectors, magnetometer. Obtain: gravity field, atmosphere and magnetosphere of the two bodies, surface geology of Triton, nature of planetary rings around Neptune.
1107.1714
Impacts of Dark Stars on Reionization and signatures in the CMB
Scott, Venkatesan, Roebber, Gondolo, Pierpaoli, Holder
Possible impacts of dark stars in reionization and CMB: if dark stars capture large amounts of dark matter via nuclear scattering, reionzation can be substantially delayed, decreasing integrated optical depth to last scattering. These effects can be constrained from WMAP7 data, but are degenerate with astrophysical uncertainties.
1107.1716
Do baryons trace dark matter in the early universe?
Grin, Dore, Kamionkowski
BBN and galaxy clusters allows compensated isocurvature perturbations to be as large as ~10%. They can modulate the power spectrum of CMB fluctuations. Observable in B modes in CMB polarization. Calculate the magnitude of this effect, describe the observability.
* any two-field inflationary picture would generically produce some iso-curvature; above scenario just happened to be poorly constrained. Can use CMB to learn more (don't need 21cm). Considers the case where the dominant perturbations are still adiabatic.
1107.1789
Cosmology today-a brief review
Cervantes-Cota, Smoot
Breif review of the standard model of cosmology. FRW at different epochs, comological lengths, physical processes necessary to understand the early and very early universe, and observations of it.
1107.1916
Where will supersymmetric DM first be seen?
Gao, Frenk, Jenkins, Springel, White
If dark matter consists of supersymmetric particles, then annihilation signals should come rom haloes. More signals from nearby rich clusters, just as clean as local dSph's. Signal mostly from subhalos. Fermi may be able to resolve them. Promising clusters: Coma and Fornax, but need better detection algorithms, since the signal is expected to be weak.
1107.1715
Global fits to the cMSSM including the first LHC and XENON100 data
Bertone, Cerdeno, Fornasa, Ruiz de Austri, Strege, Trotta
cMSSM: constrained minimal supersymmetric standard model, constrained using ATLAS, CMS at LHC, and XENON100. Conseequences for neutralino DM studied, rules out Focus Point region, from particle astrophysics.
1107.1477
Herschel detects a massive dust reservoir in Supernova 1987A
Matsuura et al
Far IR and submillimiter observations of SN 1987A in LMC. Observations show presence of a population of cold dust grains radiating at 17-23K at 220 L_sun; SED and intensity implies dust mass of 0.4-0.7 M_sun. This must be the SN ejecta, which requires efficient precipitation of all refractory material into dust. Implies SNe can produce the large dust masses detected in young galaxies at very high z.
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