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Monday.
1210.6980
Finding {\eta} Car analogs in nearby galaxies using Spitzer: I. candidate selection
Khan, Stanek, Kochanek
Late-stage evolution of the most massive stars is controlled by the effects of mass loss, which may be dominated by poorly understood eruptive mass ejections. Understanding this population is challenging, because no other examples other than eta Car have been clearly identified in MW or other galaxies. User Spitzer image of 7 nearby (<= 4 Mpc) galaxies to search for such analogs. Find 34 candidates with a flat or rising MIR SED distribution towards longer MIR wavelengths that emit 1e5 Lsun in the IRAC bands (3.6 to 8.0 um) and are not known to be BG sources. Based on expected number of BG sources, expect that follow-up observations will show that most of these candidates are not dust enshrouded massive stars, with an expectation of only 6 pm 6 surviving candidates. Since we can detect true analogs of eta Car for roughly 200 years post-eruption, this implies that the rate of eruptions like eta Car is less than the ccSN [?] rate. It is possible, however, that every M>40 Msun star undergoes such eruptions given initial results. In Paper II, characterize the candidates through further analysis and follow-up observations, and there is no barrier to increasing the galaxy sample by an order of magnitude.
1210.6988
Dwarf galaxies with ionizing radiation feedback. II: spatially-resolved star formation relation
Kim, Krumholz, ... Abel et al
Spatially-resolved SF relation in high-resolution (3.8 pc) galactic-disk simulation. New stellar feedback includes: ionizing radiation, SNe explosions, solve the radiative transfer equation (not subgrid model). Photoheating by stellar radiation stabilizes gas against Jeans fragmentation, reducing the SFR. Self-consistently calculate the location of ionized gas---for the first time, able to make spatially resolved mock observations of SF tracers, such as Halpha emission. Can also observe how stellar feedback manifests itself in the correlation between ionized and molecular gas. Apply this technique to the disk in a galactic halo of 2.3e11 Msun, find that correlation between SFR density (estimated from mock H-alpha emission) and molecular hydrogen density shows large scatter, especially at high resolutions of <~75 pc that are comparable to the size of GMCs. This is because an aperture of GMC size captures only particular stages of GMC evolution. By examining the evolving environment around star clusters, demonstrate that the breakdown of the traditional SF laws of the Kennicutt-Schmidt type at small scales results from a combination of stars drifting from their birthplaces, and molecular clouds being dispersed via ionizing radiation and supernova feedback.
1210.6990
Evolution of star formation and gas
Scoville
Review of SF in local and high-z universe, most material from 20 years ago. Develop intuitive model for the evolution of galaxy mass and luminosity functions of the early Universe. Develop model for dust heating and radiative transfer to elucidate the observed IR emissions.
1210.7029
Pulsars as excellent probes for the magnetic structure in our Milky Way
Han
Many probes for B-fields of the MW; conclude that pulsars are the best probes. B-field strength and directions can be derived from their dispersion and rotation measures. B-field structures such as field reversals between the arms and interarm regions can be well revealed from the distribution of RM data. RM and DM can provide field strengths on large scales and small scales. RMs of extragalactic radio sources can be used as the indication of B-field directions in the spiral tangential regions, and can be used as probes for the B-fields in the regions farther away than pulsars when their median RMs are compared with pulsar RMs.
1210.7100
The duty cycle of radio-mode feedback in complete samples of clusters
Birzan et al
Results imply that the duty cycle of AGN outbursts (generating x-ray bubbles) with the potential to heat the gas significantly in cooling flow clusters is at least 60 per cent and could approach 100 per cent.
1210.7231
A measurement of the cosmic microwave background damping tail from the 2500-square-degree SPT-SZ survey
Story et al
SPT-SZ survey CMB temperature power spectrum over 650 < ell < 3000. Fit SPT bandpowers, combined with WMAP7 with a 6 parameter LCDM cosmological model, and find that the two datasets are consistent and well fit by the model. Adding SPT measurements significantly improves LCDM parameter constraints: sound horizon theta_s by x2.7. Impact of gravitational lensing on CMB detected with 8 sigma [!]. Amplitude of lensing spectrum consistent with LCDM. Constrain mean curvature of the observable universe with CMB data alone to be Omega_K=-0.003 pm 0.015. ns = 0.96 pm 0.01. CMB damping tail breaks the degeneracy between r and ns in large-scale CMB measurements, leading to an upper limit of r<0.18 (95% CL) in LCDM+r model. ...
Sunday.
1210.6347
Modeling mid-infrared diagnostics of obscured quasars and starbursts
Snyder, Hayward, ..., Hernquist, Hopkins, et al
Connection between MIR flux and AGN using radiative transfer calculations of SBs in hydrosims. Study quantities as a function of time, viewing angle, dust model, AGN spectrum, and AGN strength in merger simulations. In obscured SB: begins SF dominated with significant PAH emission, and ends with a 1e9 yr period of red NIR colors. Dust obscuration of AGN coalescence (i.e., when it's most luminous), dust obscures the NIR AGN signature, reduces the relative emission from PAHs, and ehnahces the 9.7 um absorption by silicates grains. Imply none of these indicators can unambiguously estimate the AGN luminosity fraction in all cases. A combination of extinction feature at 9.7 um, the PAH strength, and a NR slope an simultaneously constrain the AGN fraction and dust grain distribution for a wide range of obscuration. James Webb ST can do this, and may estimate the AGN power as tightly as the hard X-ray flux alone---can provide X-checkk and constraint for large samples of distant ULIRGs.
1210.6354
Lensing noise in mm-wave Galaxy cluster surveys
Hezaveh et al
How gravitational lensing affects SZ cluster number counts, due to its effects of DSFGs (dusty SF galaxies, due to its detection frequency range) and CMB. For a single-frequency 150 GHz survey, lensing of DSFGs leads to both a 10% increase in detected cluster number counts (due to a 50% increase in the variance of the DSFG background, and hence an increased Eddington bias), as well as to a rare (2% of the clusters) "filling-in" of SZ cluster signals by bright strongly lensed background sources. Lensing of the CMB leads to a 55% reduction in CMB power at the location of massive galaxy clusters in a spatially-matched single-frequency filter, leading to a net decrease in detected cluster number counts. Find that the increase in DSFG power and decrease in CMB power due to lensing at cluster locations largely cancel, such that the net effect on cluster number counts for current SZ surveys is sub-dominant to Poisson errors.
* eddington bias: statistical fluctuation in the measurement from one bin into the other, typically seen when detection distribution functions overlap.
* malmquist bias: detection bias, as seen in "luminosity-limited" samples (counter with "volume-limited" samples)
Saturday. Missed about 2 whole weeks of astro-ph.
1210.6650
Dark energy simulations
Baldi
Discuss range of scenarios for the cosmic acceleration that have been successfully investigated by means of dedicated N-body simulations, with broad summary of the main results. Focus on few selected studies that have lead to significant advancements; provide a comprehensive list of references for a larger number of related works. Mainly focus on outcomes of various simulations studies.
1210.6651
Retarded Green's function of a Vainshtein system and Galileon waves
Chu, Trodden
Galileon: in extra-dimensional modified gravity models (e.g., DGP theory), the scalar field (that can be interpreted as describing the bending of the brane in the extra dimension) in the decoupling limit (a constant strength of self-interaction of the scalar field, while gravitational interaction strength is taken to infinity) obeys the galilean symmetry---hence they are called Galileons. It is a new 4-d scalar field theory that has nice properties: only 5 terms in the scalar field; equations of motion are only second order in time; a range of energy scales over which the Galileon terms are important---quantum mechanical effects irrelevant; Galileon terms are unrenormalized (no quantum corrections from other Galileon terms).
1210.6652
A new approach to simulating collisionless dark matter fluids
Hahn, Abel, Kaehler
Tetrahedral tesselation of 6-d phase space, using piecewise linear approximation of phase space distribution function, rather than particle discretisation. Modify by using pseudo-particles that approximate the masses of tetrahedral cells up to quadrupolar order as the location for cloud-in-cell (CIC) deposit instead of the particles locations themselves (i.e., standard CIC deposit). Give improved stability and more accurate dynamics of collisionless DM fluid at high force and low mass resolution.
1210.6694
The DEEP2 galaxy redshift survey: clustering dependence on galaxy stellar mass and star formation rate at z~1
Mostek, Coil, Cooper, Davis, Newman, Weiner
Strong positive correlation between M* and clustering amplitude (at z~1) on 1-10 Mpc/h scales for blue, SF galaxies with 9.5< log(M*/Msun) < 11 and no dependence for red, quiescent galaxies with 10.5 < log(M*/Msun) < 11.5. Cluster amplitude increases strongly with increasing SFR and decreasing sSFR. For red galaxies, there is no significant correlation between clustering amplitude either SFR or sSFR. Blue galaxies with high SFR or low sSFR are as clustered on large scales as red galaxies. Find that the clustering trend observed with SFR can be explained mostly, but not entirely, by the correlation between stellar mass and clustering amplitude for blue galaxies. These results not consistent with the high sSFR population being dominated by major mergers. Measure clustering amplitude on small scales (<0.3 Mpc/h) and find an enhanced clustering signal relative to the best-fit large-scale power law for red galaxies with high stellar mass, blue galaxies with high SFR, and both red and blue galaxies with high sSFR. The increased small-scale clustering for galaxies with high sSFRs is likely linked to triggered SF in interacting galaxies. These measurements provide strong constraints on galaxy evolution and halo occupation distribution models at z~1.
1210.6706
Quantifying properties of ICM inhomogeneities
Zhuravleva et al
Distribution of gas properties in a given radial shell can be well described by a log-normal PSF and tail: former corresponding to a nearly hydrostatic bulk component (~99% of the volume), while the tail corresponds to high density inhomogeneities; separation of diffuse and clumpy components of ICM. Inhomogeneity exists even in relaxed clusters.
Thursday.
1210.6354
Lensing noise in mm-wave galaxy cluster surveys
Hezaveh, ... Holder, et al
How lensing by clusters can affect dusty SF galaxies (DSFGs) and CMB, and implications for SZ cluster surveys. At the location of galaxy clusters, GL modifies PDF of BG flux of DSFG as well as the CMB. Find that in a 150 GHz survey, lensing of DSFGs leads to both a slight increase (~10%) in detected cluster number counts (due to a a ~50% increase in the variance of the DSFG background, and hence an Eddington bias), as well as to a rare (occurring in ~2% of clusters) "filling-in" of SZ cluster signals by bright strongly lensed background sources. Lensing of the CMB leads to a ~55% reduction in CMB power at the location of massive galaxy clusters in a spatially-matched single-frequency filter, leading to a net decrease in detected cluster number counts. Find: increase in DSFG power and decrease in CMB power due to lensing at cluster locations largely cancel, such that the net effect on cluster number counts for current SZ surveys is sub-dominant to Poisson errors.
1210.6446
Precise measurement of the radial baryon acoustic oscillation scales in galaxy redshift surveys
Sanchez et al
Using radial scale of BAO in deep galaxy surveys. Method: empirical parameterization of the radial 2pt correlation function, which provides a robust and precise extraction of the sound horizon scale. Moreover, it uses data from galaxy surveys that is fully cosmology independent and therefore, unbiased. A study of the main systematic errors and the validation of the method in simulations also presented, showing the measurement is limited only by cosmic variance. Study full information contained in BAO, obtaining the combination of radial and angular determinations is a sensitive probe of cosmological parameters, able to set constraints on DE w/o combining with any other probe.
1210.6563
Replacing standard galaxy profiles with mixtures of gaussians
Hogg, Lang
Exponential, deVaucouleurs, and Sersic profiles: simple and successful models of 2d images of galaxies. Numerical issues: pixel rendering and convolution (or correlation) of the models with the PSF, which are slow, and easy to get slightly wrong at small radii. These models can be approximated to arbitrary accuracy with a mixture (linear superposition) of 2d Gaussians (MoGs), which are fast to render and fast to affine-transform [dilation, rotation, translation, reflection. things that preserve straight lines. "affinity" transformation]. A MoG model for pixel-convolved PSF: the convolved, affine-transformed galaxy models are themselves MoGs, and very fast to compute, integrate, and render precisely. Present worked examples that can be directly used in image fitting. MoG profiles can be swapped in to replace the standard models in any image-fitting code. Sped up model fitting by order of magnitude; make any code faster at essentially no cost in precision.
1210.6362
Identifying elusive electromagnetic counterparts to gravitational wave mergers:an end-to-end simulation
Nissanke et al
NS-NS binary mergers can be detected out to 400/750 Mpc distance with 3/5 detector GW networks. NS-BH mergers can be detected a factor of 1.5 further out. Localization uncertainty for NS-BH mergers are 50-170 sq deg (or 6-65 sq deg) for 3 (5) GW network detectors. Quantify fractions of optical counterparts detectable by different size telescopes. Present 5 case studies to illustrate diversity of challenges in secure identification of EM counterpart at low and high galactic latitudes.
1210.6368
Our astrochemical heritage
Caselli, Ceccarelli
Chemical composition of meteorites, comets and other small bodies of the solar system, potentially linked to the first phases of SS formation. Observed chemical composition in the pre-stellar core, protostellar envelope and protostellar envelope and protoplanetary disk phases, including the processes that lead to them. Draw together pieces from the idfferent objects and phases to understand whether and how much we inherited chemically from the time of the Sun's birth.
Monday. Missed Friday and Saturday, then the whole week at Pitt and Penn. Missed Monday and Tuesday again, now it's Wednesday.
1210.6046
The space motion of Leo I the mass of the Milky Way's dark matter halo
Boylan-Kolchin, et al
HST measurement of position and velocity (proper motion) of Leo I, compare with sims, find MW mass to be > 1e12 Msun.
1210. 6049
Effect of our galaxy's motion on weak lensing measurements of shear and convergence
Mertens, Yoho, Starkman
Shear and convergence affected by Lorentz boost induced by MW's motion. No ellipticity is induced to the first order in beta=v/c, the image is magnified. Affects convergence at 10% level, most notable for low multipoles in the convergence power spectrum C_kappa_kappa, and for surveys with large sky coverage like LSST. Experiments which image only small fractions of the sky and convergence power spectrum determinations at l>5 can safely neglect the boost effect to first order in beta.
1210.6232
Measurement errors and scaling relations in astrophysics: a reviewAndreon et al
Estimate model parameters or predict an observationally expensive quantity using trends between object values---review most common methods used in astronomy for regressing one quantity against another. Awkward features: heteroscedastic (point-dependent) errors, intrinsic scatter, non-ignorable data collection and selection effects, data structure and non-uniform population (Malmquist bias), non-Gaussian data, outliers and mixtures of regressions. Outline how least square fits, weighted least squares methods, Maximum Likelihood, survival analysis, and Bayesian methods applied in astrophysics literature when one or more of these features is present. In particular we concentrate on errors-in-variables regression and advocate Bayesian techniques.
Wednesday. And Thursday.
1210.2391
Evidence for grain growth in molecular clouds: a Bayesian examination of the extinction law in Perseus
Foster, et al
Find strong correlation between the extinction (Av) and the slope of the extinction law (parameterized by Rv). Most extinction comes from Perseus molecular cloud. Interpret results as grain growth at moderate optical depths. For increasing column density from Av=2mag to 10 mag, the extinction law changes from Rv=3 (diffuse) to 5 (dense). Relationship similar for two regions in the study--dust grain growth must be a fairly universal process.
1210.2392
The behaviour of shape and velocity anisotropy in dark matter haloes
Sparre, Hansen
DM haloes are triaxial, and the velocity anisotropy beta is largest along the major axis, and smallest along the minor axis. For each simulated halo, 48 different cones, and compute the velocity anisotropy profiles. Find: elongated haloes can have very distinct velocity anisotropies. 3 different categories in behavior, in beta profiles. Spherically averaged profiles often obey a linear relation between beta and the logarithmic density slope in the inner part of the haloes, but this relation not necessarily obeyed when properties are calculated in cones.
1210.2405
Extended photometry for the DEEP2 galaxy redshift survey: a testbed for photometric redshift experiments
Matthews, Newman, Coil, Cooper, Gwyn
DEEP2 with ugriz photometry (CFHTLS and SDSS) cross-matched, used to predict DEEP2 BRI photometry. Included improved astrometry tied to SDSS (not USNO-A2.0). 27k objects, 64% which have r>23. Generate catalog used for testbed for future photo-z studies for LSST and DES.
1210.2413
The Baryon acoustic oscillation broadband and broad-beam array: design overview and sensitivity forecasts
Pober, Parsons, ... McDonald, McQuinn, Aguirre, et al
21 cm power spectrum for 0.5<z<1.5: BAOBAB array. Will fully correlate dual-polarization antenna tiles over 600-900 MHz with a frequency resolution of 300 kHz and system temperature of 50K. Present calculations of the power spectrum sensitivity for various array sizes, with 35-element array measuring the cosmic neutral hydrogen fraction as a function of z, and a 132-element system detecting the BAO features in the power spectrum, yielding a 1.8% error on the z~1 distance scale; constraining DE EoS over 0.5<z<1.5 (unprecedented).
1210.2432
The challenge of large and empty voids in SDSS DR7 redshift survey
Tavasoli, Vasei, Mohayaee
Generate catalogues of voids from Millennium I Simulation mock data, representing SDSS DR7. Find: voids tend to be spherical, both in sims and observation. Void number and total volume slightly larger in the simulation than in observation. Large voids are less abundant in the simulation, and the total luminosity of the galaxies contained in a void with a given radius is on average higher than observed by SDSS DR7 survey. Expect actual discrepancy to be larger, because sigma_8 < 0.9, the value used in Millennium I sim. Discrepancy probably due to failure of SAM, which fails to reduce the small-scale power of LCDM and fails to produce sufficient power in large scales [i think that's what they're saying].
1210.2446
The weight of emptiness: the gravitational lensing signal of stacked voids
Krause, Chang, Dore, Umetsu
As the title says. With shear and magnification. Stacking helps with statistical precision, even with miscentering and projection effects. DETF stage IV surveys (Euclid, LSST) can detect void lensing signal with sufficient precision from stacking abundant medium-sized voids, thus providing direct constraints on the matter density profile of voids independent of assumptions on galaxy bias.
1210.2471
Exoplanet detection methods
Wright, Gaudi
Review of various methods of detecting exoplanets: radial velocities, astrometry, direct imaging, transits, and gravitational microlensing. Basic observable phenomena, physical properties of planets and host stars that can be derived. General experimental requirements. Compare methods, stress complementarity. History of exoplanet detections (briefly).
1210.2480
Constraining the substructure of dark matter haloes with galaxy-galaxy lensing
Li, Mo, Yang, van den Bosch
GG lensing signal around satellite galaxies in different host haloes, and located at different halo-centric distances. Use MCMC to explore the potential constraints on the mass and density profile of subhaloes associated with satellite galaxies (SDSS and LSST-like). Results: SDSS can only set a loose constraint on the mean mass of sub haloes. With LSST-like surveys, both the mean mass and the density profile of subhaloes can be well constrained.
1210.2496
GENJI programme: Gamma-ray emitting notable AGN monitoring by Japanese VLBI
Nagai et al
Monitoring program of gamma-ray bright AGNs with VERA, at 22 GHz (radio). Investigate the radio time variation of the core and possible ejection of new radio component, motion of jest, and the relation with the emission at other wavelengths especially in gamma-rays. Currently 8 AGNs monitored, once every 2 weeks. Trace trend of radio time variation on shorter timescale than conventional VLBI monitoring program me, and to provide complimentary data with them (eg MOJAVE). Quick followups.
1210.2518
Probing the early universe with the CMB scalar, vector and tensor bispectrum
Shiraichi
PhD thesis.
1210.2521
GOODS-Herschel: radio-excess signature of hidden AGN activity in distant star-forming galaxies
Del Moro et al
As the title says.
1210.2532
Simulated histories of reionization with merger tree of HII regions
Chardin, Aubert
As the title says. From the merger tree of ionized patches, one can track the individual evolution of the regions (size), or properties of the percolation process (look at formation rate, frequency of mergers, and number of individual HII regions).
1210.2578
Galaxies going MAD: the galaxy-finder comparison project
Knebe, .. Behroozi, ... et al
Object finders for simulations: comparison pojrect for DM field haloes, and DM subhaloes previously reported. Baryonic physics in sims also. Report: comparison codes as applied to CLUES (constrained local universe simulation) of the formation of the Local Group which has most of the formation physics. Compare properties of 3 main galaxies in simulation (MW, M31, M33 representation) and their satellite populations for a variety of halo finders ranging from phase-space to velocity-space to spherical over density-based codes. Better agreement amongst codes than the other comparison projects, for total, dark and stellar components of objects. But for diffuse gas content, there is great disparity, specially for low-mass satellite galaxies, due to differences in the treatment of the thermal energy during the unbinding procedure. Handling of gas in halo finders must be carefully dealt with, treatment may depend on the problem being studied.
1210.2649
Clustering of far-infrared galaxies in the AKARI All-sky survey
Pollo, et al
Preliminary study, systematics (difference between north and south hemisphere) found.
1210.2692
A close-pair analysis of damp mergers at intermediate redshifts
Chou, Bridge, Abraham
Study kinematics of ~2800 0.1<z<1.2 galaxy pairs from CFHTLS field. Find: 1/5 likely to share DM halo. Red-red pairs almost absent, suggesting that damp mergers are rare at z~0.5. Support models with a short merging timescale (<0.5 Gyr) in which SF is enhanced in the early phase of mergers, but quenched in the late phase. Hot halo models may explain this behaviour, but only if virial shocks that heat gas are inefficient until major mergers are nearly complete.
1210.2696
Interpolating point spread function anisotropy
Gentile, Courbin, Meylan
Modeling of the PSF shape and its spatial variation across the instrument crucial. Reliable interpolation scheme mandatory, typically use low-order bivariate polynomials. Study 4 other classical spatial interpolation methods based on splines (B-splines), inverse distance weighting (IDW), radial basis functions (RBF) and ordinary Kriging (OK). Tested on GREAT10 star challenge, compared with PolyFit. RBF is the clear winner, followed by IDW and OK. PolyFit and B-splines are largely behind, especially in fields with (ground-based) turbulent PSFs. In fields with non-turbulent PSFs, all interpolators reach a variance on PSF systematics better than 1e-7 upper bound expected by future space-based surveys, with the local interpolators performing better than the global (PolyFit & spline) ones.
Tuesday. 71 abstracts. Twice as many as yesterday.
1210.1849
Conserved actions, maximum entropy and dark matter haloes
Pontzen, Governato
Use maximum entropy arguments to derive the phase space distribution of a virialized DM halo, giving an improved representation of the end product of violent relaxation. Incorporate physically motivated dynamical constraints which prevent arbitrary redistribution of energy. Compare predictions with 3 high-res DM sims of varying mass; accurately predicts numerical distribution function, producing an excellent match for the vast majority of particles. Remaining particles constitute the central cusp of the halo (<4% of the dark matter), which can be accounted for within the presented framework once the short dynamical timescales of the centre are taken into account.
1210.1850
TA-DA: a tool for astrophysical data analysis
Da Rio, Robberto
A new software aimed at greatly simplifying and improving the analysis of stellar photometric data in comparison with theoretical models, and allow the derivation of stellar parameters from multi-band photometry. An IDL widget-based application.
1210.1851
General formula for the running of fNL
Byrnes, Gong
Compute scale dependence of fNL for multi-field inflation model, allowing for an arbitrary field space metric. Find: curved field space metric provides another source of scale dependence, which arises from the field-space Riemann curvature tensor and its derivatives. May be observable in the future if the amplitude of fNL is not too far from the current observational bounds.
1210.1868
Gravitational lenses in the dark Universe
Freitas, Goncalves, Oliveira
How different cosmological models of the Universe affect the probability that a BG source has multiple images related by an angular distance theta_E of the line of sight---the optical depth of gravitational lensing. examine cosmological models for different values of the density parameter Omega_i (i) CDM, (ii) LCDM, (iii) BE condensate DM model, (iv) Chaplygin gas model, (v) the viscous fluid cosmological model and (vi) holographic DE model. The dependence of the energy-matter content of the universe profoundly alters the frequency of multiple quasar image.
1210.1886
A survey for the missing hydrogen in high redshift radio sources
Currean, Whiting, Sadler, Bignell
At low z, 40% detection rate of 21cm absorption; but for hosts of z>1 radio galaxies and quasars, remarkably unsuccessful. High-z selection bias suggested, where the optically brightest objects (UV-luminous in rest frame) are seen, where the gas is ionized by AGN; infer that there must be a population of fainter objects in which H is not ionized, and which exhibit a similar detection rate at lower z. Take a survey of z>2 radio sources selected by optical faintness. No detection in any of the 8 sources for which usable data were obtained! Analysis of SED show ionizing photon rates can be determined for 3 of these, all of which suggest that the objects are above the highest luminosity of a current 21-cm detection. Possibly: selection biases the sample towards sources which are very steep in the radio band [?]--then the sources may have very extended emission, which would have the effect of reducing the coverage by putative absorbing gas.
1210.2058
Neutrino Astronomy - A review of future experiments
Karle
Current experiments: 10 GeV to 1e9 GeV, but the sensitivity for future IceCube experiments will increase in both directions: down to few/few tens of GeV to measure neutrino mass hierarchy; in the central range of classical optical neutrino telescopes, next generation detectors in Mediterranean and Lake Baikal; radio detectors in ice is among the most promising technologies to increase exposure at 1e9 GeV by more than an order of mag compared to IceCube.
1210.2127
Stellar populations
Peletier
Lectures from a 2011 winter school ("secular evolution of galaxies"). Stellar populations intimately connected to understanding the formation and evolution of galaxies. Information of stellar populations come from integrated light. Stellar evolution theory + local observations are used as building blocks to analyze these integrated stellar populations.
1210.2130
The WiggleZ dark energy survey: final data release and cosmological results
Parkinson, .. Blake, .. et al
Cosmological results from WiggleZ Dark Energy Survey. Use power spectra at z=0.22, 0.41, 0.60, and 0.78, combined with other cosmological datasets. Limiting factor: theoretical modeling of the power spectrum, including non-inearities, galaxy bias, and z-space distortions. Assess several different methods for modeling the theoretical PS, testing against simulations (GiggleZ); 6 cosmological parameters and 5 supplementary. Combine with CMB, results consistent with LCDM concordance cosmology, with measurement of the matter density of Omega_m=0.29pm0.016 and sigma8=0.81-0.84. Find no evidence for any of the extension parameters being inconsistent with their LCDM model values. Used CosmoMC. Released data and random catalogues used to construct the BAO correlation function.
1210.2131
Simultaneous constraints on the number and mass of relativistic species
Riemer-Sorensen, Parkinson, Davis, Blake
Evidence for >3 neutrino species from particle physics and cosmology. Effects of neutrino mass and number of species can in principle be disentangled for fixed cosmological parameters, but correlation must be included in the analysis.
1210.2136
Observational constraints on cosmic neutrinos and dark energy revisited
Wang, ... et al
Combine WMAP (CMB), CFHTLS (WL), SDSS+WiggleZ (BAO), H0 observations, Union2.1 (SNIa), and the HST prior, impose constraints on the sum of neutrino masses, the effective number of neutrino species, and w, individually and collectively. Find: tight upper limit on mnu can be extracted from the full data combination if n_eff and w are fixed, but severly weakened if allowed to vary. Previous reports on m_nu upper bounds robust? Best-fit values from the generalized constraint: m_nu=0.556 pm 0.25 eV, n_eff=3.8pm0.4, and w=-1.058pm0.088 at 68% confidence level: firm lower limit on total neutrino mass, extra light degree of freedom, supports Lambda. WL constraint helpful when w=-1 is of little help, once w is freed [?]. H0 dataset is advantageous over SNIa when w is fixed, in constraining n_eff. As long as w is included as a free parameter, it is still the standardizable candles of SNIa that play the most dominant role in parameter constraints [of neutrinos?].
1210.2191
Calibrating Milky Way dust extinction using cosmological sources
Mortsell
Correlation between dust column density inferred from IR data and the observed colors of celectial objects at cosmological distances with small color dispersion, constrain the properties of MW dust. Results from colors of quasars, BCGs and LRGs are broadly consistent, indicating a proportionality constant between the reddening E(B-V)=A_B-A_V and the dust column density D^T MJy/sr of p=E(B-V)/D^T=0.02 and a reddening parameter R_V=A_V/E(B-V)=3 with fractional uncertainties of the order 10%. The data does not provide any evidence for spatial variations in the dust properties, except for a possible hint of scatter in the dust extinction properties at the longest optical wavelengths.
1210.2194
Neutrino masses and cosmological parameters from a Euclid-like survey: Markov Chain Monte Carlo forecasts including theoretical errors
Audren, Lesgourgues, Bird, Haehnelt, Viel
Forecasts of accuracy to determine parameters of minimal cosmological model and total neutrino mass based on combined mock data for a future Euclid-like galaxy survey and Planck. (i) Spec-z survey and (ii) cosmic shear survey considered. Use MCMC, assume two sets of theoretical errors. The first error is meant to account for uncertainties in the modeling of the effect of neutrinos on the NL galaxy PS, and assume thsi error to be fully correlated in Fourier space. The second error is meant to parameterize the overall residual uncertainties in modelling the NL galaxy PS at small scales, and is conservatively assumed to be uncorrelated and to increase with the ratio of a given scale to the scale of NL. It hence increases with wavenumber and decreases with redshift. With these two assumptions for the errors and assuming further conservatively that the uncorrelated error rises above 2% at k=0.4 h/Mpc and z=0.5, we find that a future Euclid-like cosmic shear/galaxy survey achieves a 1-sigma error on Mnu close to 32/25 meV, sufficient for detecting the total neutrino mass with good significance. If the residual uncorrelated errors indeed rises rapidly towards smaller scales in the NL regime as we have assumed here, then the data on NL scales does not increase the sensitivity to the total neutrino mass. ....
1210.2250
Residual foreground contamination in the WMAP data and bias in non-Gaussianity estimation
Chingangbam, Park
Analyze whether there is FG contamination in the cleaned WMAP7 data for Q, V and W. A major fraction of the observed non-Gaussian deviation comes from residual FG contamination, as seen from added estimated contaminant fraction to simulated Gaussian CMB maps. Compute non-Gaussian deviations of Minkowski Functionals after applying the point sources mask of Schodeller+ and find a decrease in the overall amplitudes of the deviations which is consistent with a decrease in the level of contamination.
1210.2362
Cosmic evolution of star-formation enhancement in close major-merger galaxy pairs since z=1
Xu, ... Cooray, ... et al
See SF enhancement induced by gg interaction, by comparing IR luminosities to well-matched control samples. SFG in SFG+SFG pairs in 0.6<z<1 are consistent with no SF enhancement. SFGs in S+S pairs in a lower redshift bin of 0.2<z<0.6 show marginal evidence for a weak SF enhancement. Significant and strong sSFR enhancement shown by SFGs in local sample of S+S pairs (prior results). Results reveal a trend for SF enhancement in S+S pairs to decrease with increasing redshift. Between z=0 and z=1, this decline of interaction-induced SF enhancement occurs in parallel with the dramatic increase (~10x) of the sSFR of single SFGs. Both can be explained by the higher gas fraction in higher z disks. SFGs in mixed pairs (S+E pairs) do not show any significant SF enhancement at any z. The difference between SFGs in S+S pairs and in S+E pairs suggests a modulation of the sSFR by the inter-galactic medium IGM in the DM Hosting hosting these pairs.
Monday.
1210.1574
Detection of a virial shock around the Coma galaxy cluster
Keschet, Kushnir, Loeb, Waxman
Clusters are thought to grow by accreting mass from their surroundings through large-scale virial shocks. This should appear as gamma-ray, hard X-ray, and radio ring, elongated twoards the large-scale filmanets feeding the cluster, coincident with a cutoff in the thermal SZ signal. Report the discovery of ~5Mpc diameter gamma-ray ring around Coma, elongated towards the large scale filament connecting Coma and Abell 1367. The gamma-ray ring correlates both with a synchrotron signal and with the SZ cutoff. Signatures agree with analytic and numerical predictions, if shock deposits a few percent of the thermal energy in relativistic electrons over a Hubble time, and ~1% of the energy in B-fields. The implied inverse-Compton and synchrotron cumulative emission from similar shocks dominates the diffuse extragalactic gamma-ray and low frequency radio backgrounds. Results reveal the prolate structure of the hot gas in Coma, the feeding pattern of the cluster, and properties of the surrounding large scale voids and filaments. The anticipated detection of such shocks around other clusters would provide a powerful new cosmological probe [of what?].
1210.1576
Cosmic emulation: the concentration-mass relation for wCDM universes
Kwan, Bhattacharya, Heitmann, Habib
A cosmic emulator fo the c-M relation as a function of cosmological parameters for wCDM models, constructed from 37 individual models, with 3 nested N-body gravity-only simulations carried out for each model. Mass range: 2e12 Msun < M <1e15 Msun, with 0<z<1. Concentration varies from 2 to 8, distribution at fixed mass is Gaussian (sigma of ~1/3 of mean), almost independent of cosmology, mass and redshift over the ranges probed by the simulations. Compare results from emulator with previous analytic fits for c-M relation, and find that they underestimate the halo concentration at high masses. Sigma8 and omega_m influence the c-M relation considerably, and w has a substantial effect as well. Concentration of lower-mass haloes is more sensitive to changes in cosmological parameters are compared to cluster mass haloes.
1210.1644
The 3.3 micron PAH emission as a star formation rate indicator
Kim, et al
PAH emission features dominate the MIR spectra of SF galaxies, can be used to calibrate SFR and diagnise ionized stats of grains. The 3.3 micron PAH feature not studied as much as other PAH features, since it is weaker than others and reside outside of Spitzer capability. Use AKARI, compare sample with literature samples. Low res spectra of 20 flux-limited galaxies with mixed SED classes, 3/20 galaxies has 3.3 micron detection, which correlate with the IR luminosities of SF galaxies, but with larger scatter (1.5 dex). Correlation breaks down at the domain of ULIRGs.
1210.1802
High resolution studies of massive primordial haloes
Latif, Schleicher, Schmidt, Niemeyer
Atomic cooling haloes with T_vir > 1e4 K are the most plausible sites for the formation of the first galaxies. Study the implications of gravity driven turbulence in protogalactic haloes. High-res cosmological simulations using AMR Enzo with subgrid-scale turbulence model to study the role of unresolved turbulence. Even the highest resolution employed provides no convergence. Taking into account unresolved turbulence significantly influeneces the morphology of a halo; quantify the properties of the high-density clumps in the halo These clumps are gravitationally unbound with T>6000K and densities of 1e-12 g/cm^3. The clumps with SGS turbulence are denser and more massive compared with their counterparts in the standard simulation setup that ignores unresolved turbulence.
Friday (already).
1210.1208
2D stellar population and gas kinematics of the inner 1.5 kpc of the post-starburst quasar SDSS J0210-0903
Sanmartim et al
Post-starburst quasars (PSQs): evolution of massive galaxies in which the SF has been recently quenched due to the feedback of the nuclear activity. Test this scenario with a resolved stellar population; also study emitting gas kinematics. Old stars dominate the luminosity in the inner 0.3 kpc, while at ~0.8kpc, the stellar population is dominated by both intermediate age and young ionizing stars. The gas emission-line ratios are typical of Seyfert nuclei in the inner 0.3kpc, where an outflow is observed. Beyond this region, the line ratios are typical of LINERs, and may result from the combination of diluted radiation from the nucleus and ionization from young stars. Gas kinematics show combination of rotation in the plane of the galaxy and outflows (max blueshift of -670 km/s). Mass outflow rate estimated at 0.3-1.1 Msun/yr; power outflow of dE/dt~1.4-5.0e40 erg/s, two orders of magnitude higher than the nuclear accretion rate of 8.7e-3 Msun/yr, thus being the result of mass loading of the nuclear outflow by circumnuclear galactic gas. Observations support an evolutionary scenario in which the feeding of gas to the nuclear region has triggered a circumnuclear starburst 100's Myr ago, followed by the triggering of the nuclear activity, producing the observed gas out flow which may have quenched further star formation in the inner 0.3 kpc.
1210.1211
Recent advances on IMF research
Kroupa
Work on brown dwarfs, massive stars and the IMF in general. Stellar IMF described by an invariant two-part power law in present-day SF events within the local group of galaxies, nearly identical in shape to the pre-stellar core mass function. The majority of brown dwarfs follow a separate IMF. IMFs may have been top heavy depending on the SFR density. The IGIMF then ranges from bottom heavy at low galaxy-wide star formation rates to being top-heavy in galaxy-scale star bursts.
1210.1213
Column density distribution and cosmological mass density of neutral gas: Sloan digital sky survey-III data release 9
Noterdaeme et al
Survey results from DLAs in z>2 quasar spectra. 12k systems wit log N(HI)>=20, half have >=20.3. Largest DLA sample compiled, 7x larger than SDSS II. Probe N(HI) distribution at <z>=2.5. Distribution extends beyond 1e22 cm^-2 with a moderate slope of index ~ -3.5. Result matches the opacity-corrected distribution observed at z=0. Cosmological mass density of neutral gas in DLAs is found to be Omega_g_DLA~1e-3, evolving only mildly over the past 12 Byrs.
1210.1253
Temperature, abundance, and mass density profiling of the Perseus galaxy cluster
Geringer, et al (text overlap with 1008.2393 by other authors)
Temperature and abundance radial profile maps: lack of homogeneity within Perseus cluster. Over-densities of X-ray emission detected, evidence that the baryon fraction exceeds the universal average. Cannot verify clumping in these regions, that would explain over-abundance of x-rya emission. Remove contamination from foregrounds, including telescope, local sources (solar wind), AGN background, MW dust and stars.
1210.1294
The shortest known period star orbiting our Galaxy's supermassive black hole
Meyer et al
As the title says. Science paper.
1210.1333
Finite, intense accretion bursts from tidal disruption of stars on bound orbits
Hayasaki, Stone, Loeb
Accretion processes for tidally disrupted stars approaching SMBH on bound orbits, with 3d SPH with a pseudo-Newtonian potential. Critical value of the orbital eccentricity below which all the stelar debris remains bound to the BH. Stellar mass accreting at once onto BH cause a significant deviation from t^-5/3 mass fallback rate, when star in eccentric orbit. If several crossings, dissipation of orbital energy in shocks, allowing for rapid circularization of the debris streams and formation of the accretion disk. Shows: GR precession is crucial for accretion disk formation via circularization of stellar debris from stars on moderately eccentric orbits.
1210.1418
The Hungaria asteroids: resonances, close encounters and impacts with terrestrial planets
Galiazzo, Bazso, Dvorak
Family consists of >8k members with semi-major axes between 1.78 and 2.03 AU, a source of NE asteroids. Relatively small <1km diameter, inclinations of ~20 deg. Mainly perturbed by Jupiter and Mars, ejected because of mean motion adn secular resonances with these planets and then become Mars-crossers, later may cross Earth and Venus. Analyse close encounters and possible impacts with these planets. Compute the effect of possible impacts with terrestrial planets.
1210.1445
A study of simulated histories of reionization with merger trees of HII regions
Chardin, et al
As the title says.
1210.1450
The mid-term and log-term solar quasi-periodic cycles and the possible relationship with planetary motions
Tan, Cheng
A serios of solar quasi-periodic cycles with multi-timescales are registered with sunspot number and microwave emission at 2.8 GHz. ...
1210.1483
Excursion set peaks: a self-consisten model of dark halo abundances and clustering
Paranjape, Sheth, Desjaques
How to extend excursion set peaks framework so that its predictions of DH abundances and clustering can be compared directly with simulations. These extensions include: a halo mass definition which uses the TopHat filter in real space; The mean dependence of the critical density for collapse delta_c on halo mass m; and the scatter around this mean value. All three of these are motivated by the physics of triaxial rather than spherical collapse. A comparison of the resulting mass function with N-body results shows that, if one uses delta_c(m) and its scatter as determined from simulations, then all 3 are necessary ingredients for obtaining 10% accuracy. Same model is in good agreement with N-body results for linear halo bias, especially at the high mass end where the traditional peak-background split argument applied to the mass function fit is known to under-predict the measured bias by ~10%. In the excursion set language, our model is about walks centered on special positions (peaks) in the initial conditions. Discuss what it implies for the usual calculation in which all walks contribute to the statistics.
1210.1492
Witnessing galaxy clusters: from maturity to childhood
Ascaso
Cluster observation techniques, review cluster samples, relevance for cosmological and galaxy evolution constraints, refer to cluster science predictions for the next generation survey.
1210.1183
Do intergalactic magnetic fields imply an open universe?
Barrow, Tsagas, Yamamoto
Existence of B-fields in the universe today (that require primordial seeding) may provide strong evidence that the universe is marginally open and not marginally closed. (Prifmordial B-field cannot survive closed or flat universes.)
Thursday.
1210.0530
Best practices for scientific computing
Aruliah et al
As the title says. Worth mentioning in JC.
1210.0899
Observational limits on the gas mass of a z=4.9 galaxy
Livermore, ... Bower, ... Richard, et al
A 22x magnified galaxy, CO(5-4) emission targeted. Gas mass at 1e9Msun, gas fraction (gas/(gas+star)) = 0.6. Difficult to observe molecular gas in this epoch. Without lensing, it will be tough to get gas mass.
1210.0903
A general theory of turbulent fragmentation
Hopkins
An analytic framework to understand fragmentation in turbulent, self-gravitating media. Fully time-dependent gravo-turbulent fragmentation & collapse. Turbulent systems are always gravitationally unstable (probabilistically). Fragmentation mass spectra, size/mass relations, correlation functions, range of scales over which fragmentation occurs, and time-dependent rates of fragmentation are predictable; depends on bulk turbulent properties. Generalize to include rotation, complicated EoS, collapsing/expanding background, B-fields, intermittency, and non-normal statistics. Fragmentation is suppressed with 'stiffer' EoS or different driving mechanisms. Suppression appears at an 'effective sonic scale' where Mach(R,rho)~1. Gas becomes stable below this scale for polytropic gamma>4/3, but fragmentation still occurs on larger scales. The scale-free nature of turbulence and gravity generically drives mass spectra and correlation functions towards universal shapes, with weak dependence on many properties of the media. Correlated fluctuation structures, non-Gaussian density distributions, and intermittency have surprisingly small effects on the fragmentation process. This is because fragmentation cascades on small scales are 'frozen in' when large-scale modes push the 'parent' region above the collapse threshold; though they collapse, their statistics are only weakly modified by the collapse process. With thermal support, structure develops 'top-down' in time via fragmentation cascades; but strong rotational support reverses this to 'bottom-up' growth via mergers & introduces a maximal instability scale distinct from the Toomre scale.
1210.0932
Lunar accretion from a Roche-interior fluid disk
Salmon, Canup
Hybrid numerical approach to simulate the formation of the Moon from an impact-generated disk. Fluid model for the disk inside the Roche limit, and an N-body code to describe accretion outside the Roche limit. The inner disk spreads due to a thermally regulated viscosity, material is delivered across the Roche limit and accretes into moonlets that are added to the N-body sim. The final state of the Moon's growth is controlled by the slow spreading of the inner disk, resulting in a total lunar accretion timescale of ~100 years (not a few months, as in N-body only sims). Proposed: inner disk may compositionally equilibriate with the Earth through diffusive mixing, which offers a potential explanation for the identical oxygen isotope compositions of the Earth and Moon; but the mass fraction of the final Moon derived from the inner disk is limited by resonant torques bewteen the disk and exterior growing moons. Initial disks containing <2.5 lunar masses find final moon with mass >0.8 M_L contains <60% material derived from the inner disk, with this material preferentially delivered to the Moon at the end of its accretion.
1210.1025
The evolution of active galactic nuclei and their spins
Volonteri et al
Find: typical spin and radiative efficiency of MBHs decrease with cosmic time because of the higher incidence of stochastic processes in gas-rich galaxies and MBH-MBH mergers in gas-poor galaxies. At z=0 the spin distribution in gas-poor galaxies peaks at spins 0.4-0.8, and is not mass dependent. MBHs in gas-rich galaxies have a more complex evolution, with low-mass MBHs at low redshift having low spins, and spins increasing at larger masses and redshifts. Find: z>1 MBH spins are on average highest in high luminosity AGN, while at lower redshifts these differences disappear.
1210.1035
The evolving interstellar medium of star forming galaxies since z=2 as probed by their infrared spectral energy distributions
Magdis, et al
Derive Mdust from MIR to millimeter wavelength stacked ensembles at 0.5<z<2 in MS galaxies, which obey a tight correlation between SFR and M*. For star bursting galaxies that falls outside that relation. Exploit correlation of gas to dust mass with metallicity, and use these measurements to constrain the gas conent, CO-to-H2 conversion factors, and SFE of these galaxies. SFE lower at higher z, while a_co higher, compared to local MS galaxies with equivalent high IR luminosities. Variation of sSFR=SFR/M* are driven by varying gas fractions. For massive galaxies, show that the hardness of the radiation field <U> and the primary parameter defining the shape of the SED is equivalent to SFE/Z. For MS galaxies, measure <U>, showing that it does not depend significantly on either the stellar mass or the sSFR. Show that <U> = LIR/Mdust does evolve, with MS galaxies having harder radiation fields, and thus warmer temperatures as redshift increases from z=0 to 2; can be understood based on z evolution of M*-Z and SFR-M* relations. Motivate the construction of a universal set of SED templates for MS galaxies which vary as a function of z with only one parameter, <U>.
1210.1093
The origin of the chemical elements in cluster cores
de Plaa
ICM has metal lines from C to Zn within 0.1-10keV. Abundance of 11 elements studied; most elements formed in SNIa or II (core collapse) which have very different chemical yields. Massive stars and AGB stars contribute by providing most of the C and N in the ICM. Feedback processes suppress SF in cluster core; element abundances directly probe the SFH of the majority of stars formed between z=2 and 3. Spatial distribution in the core and evolution with z provide information about how these elements are transported from the member galaxies to the ICM.
1210.1114
Heliophysics gleaned from seismology
Gough
Heliophysical inferences drawn from seismology briefly described. Use of simple formulae, to answer specific questions about physics.
