production of dust...
Gall etal
Large amounts of dust detected in sub-millimeter galaxies and quasars at high z challenges galaxy formation models, and theories of cosmic dust formation. At z>6 only stars with M > 3 Msun are sufficiently short-lived to be potential stellar sources of dust. Identify and quantify the most important stellar channels of rapid dust formation. Dust production efficiency of stars with 3>M/Msun>40 using both observed and theoretical dust yields of evolved massive stars and SNe; provide analytical expressions for the "dust production efficiencies" in various scenarios. Address the strong sensitivity of the total dust productivity to the IMF (I guess one needs more massive stars; IMF in the early, pristine universe is very likely different than the local universe anyhow). High-mass (>3Msun) asymptotic gian branch stars can be dominant dust producers if SNe only generate <~3e-3 Msun of dust; otherwise SNe dust dominate. Address challenges in inferring dust masses and star-formation rates from observation of high-z galaixes. Significant SN dust production at high-z is likely required to reproduce current dust mass estimates, possibly coupled with rapid dust grain growth in the ISM.
* SNe is likely the dust producers in the early universe (z~6), not AGB stars.
1105.0419
Evidence for dark energy from the CMB alone using the ACT lensing measurements
Sherwin, Dunkley, Das et al
* this is v3 of the paper, version accepted by PRL.
The first CMB-only measurement that favors w=-1 cosmologies, at 3.2 sigma. Demonstrate by combining CMB lensing deflection power spectrum from ACT with temperature and polarization power spectra from WMAP. Lensing data break the degeneracy of different cosmological models with similar CMB power spectra. (how come they don't mention matter growth after z~1100?) CMB-only measurement of DE confirms other measurements of DE from SNe, clusters and BAO, and demonstrates the power of CMB lensing as a new cosmological tool.
1108.0426
An analytic model for the evolution of the stellar, gas, and metal content of galaxies
Dave, Finlator, Oppenheimer
Inspired by hydrodynamic simulations (galaxies live in a slowly-evolving equilibrium between inflow, outflow and star formaton), generate an analytic formalism that describes the evolution of the stellar, gas and metal content of galaxies. This formalism broadly captures the behaviour of galaxy properties evolving in simulations. Resulting equilibrium euqations for the SFR, gas fraction and metallicity depend on 3 key free parameters that represent (1) ejective feedback, (2) preventive feedback, and (3) re-accretion of ejected material. Schematically describe how these parameters are constrained by models and observations. Galaxies perturbed off the equilibrium relations due to inflow tend to be driven back towards equilibrium; deviations in star fromation rate at a given mass is correlated with gas fraction and anti-correlated with metallicity. (? I thought high metallicity resulted in high SFR? I guess that's not true) Early: gas acucmulation epoch; quiescent star-forming galaxies expected to be in equilibrium most of the time. Equilibrium model provides a simple intuitive framework for understanding the cosmic evolution of galaxy properties; features the cycle of baryons between galaxies and surrounding gas as the driver of galaxy growth.
1108.0490
Model calculation of N2 Vegard-Kaplan band emissions in Martian dayglow
Jain, Bhardwaj
* Martian dayglow!
* Vegard-Kaplan band: no wikipedia entry...
* Mars Express: Space exploration mission conducted by ESA. Consists of 2 parts: Mars Express Orbiter and Beagle 2 (a lander, exobiology and geochemistry research). The lander failed to land safely on the Martian surface. Orbiter successfully performs scientific measurements since early 2004. 5 mission extensions granted till the end of 2014.
Develop model for N2 VK band emissions in Martian dayglow, to explain the observations by SPICAM (Spectroscopy for investigation of characteristics of the atmosphere of Mars) UV spectrograph aboard Mars Express. Steady state photoelectro fluxes and volume excitation rates calculated using some technique. Interstate cascading is important for triplet states of N2, calculate population of any three states under equilibrium considering direct excitation, cascading, and quenching. Relative population of all vibrational levels of each triplet state calculated. LOS intensitries and high-integrated overhead intensities calculated for VK, several bands of N2. Reduction in the N2 density by a factor of 3 in the Mars thermospheric general calculation model required. Constrain the N2/CO2 ratio.
INPA, LBL
Discovery of the anti-alpha particle at STAR
Hank Crawford (LBNL)
Discovery of the antimatter 4He nucleus. STAR experiment at RHIC examined 109 interactions produced by colliding beams of gold nuclei at center of mass energy of 200 GeV per nucleon pair. Analysis yields 18 clean 4He particles. International space station AMS experiment.
* STAR: Solenoidal tracker at RHIC (relativistic heavy ion collider)--at Brookhaven. Formation and characteristics of the quark-glon plasma
* AMS: Alpha magnetic spectrometer (AMS-02)--particle physics experiment module that is mounted on International space station. Measure CR (search various types of unusual matter). PI is Samuel Ting.
Seminar, UCB Astro
Magnetic activity cycles in solar-type stars: statistics and impact on precise radial velocities
Christophe Lovis
Extrasolar planet detection through radial velocity measurements relies on the stability of stellar photospheres. Characterize statistical properties of magnetic activity cycles; study their impact on spectroscopic measurement, such as radial velocities, line bisectors and line shapes. Use planet search data from 304 FGK stars over 7 years; obtain high-precision Ca II H/K chromospheric activity measurements; convert to R'HK indicies and line shape parameters. Long-time precision on S is x3 better than Mt. Wilson survey. Classify stars according to Ca II variability; identify activity cycles. about 30-50% of old soloar-type stars do not show any activity cycles (very weak); 50-70% do show activity. Non-cycling stars are only found among G dwarfs. Magnetic cycle amplitude decreases with decreasing activity level (which is measured how?). Significant fraction of stars exhibit small variations in radial velocities and line shape parameters that are correlated with activity cycles. Sensitivity of radial velocity to magnetic cycles increases for hotter stars. Late K dwarfs are nearly insensitive. Conclusion: activity cycles induce long-period, low-amplitude radial velocity variations, at levels up to 25m/s. (whoa) Caution is mandatory when searching for long-period exoplanets. These effects can be corrected to high precision by detrending the rdial velocity data using simultaneous measurements of Ca II flux and line shape parameters (because that correlates to magnetic activity).
1108.0413
A physical model of FeLoBALs: implications for quasar feedback
Faucher-Giguere, Quataert, Murray
FeLoBALs: Photoionization modeling of the low-ionization broad-absorption lines of certain quasars: reveals the number density of the wind absorbers and their distance from the central SMBH. Feedback efficiency of the quasars can be derived. Implied properties of FeLoBALs are surprising: thickness of the absorbers relative to their distance from the BH (Delta R/R) can be as small as 1e-5. Such absorbers are not likely to survive the journey from SMBH to their inferred location. The observed FeLoBAL properties are readily explained if they are formed in situ in radiative shocks produced when a quasar blast wave impacts a moderately dense interstellar clump along the LOS (differs from the thin shell approximation often assumed). Implies outflow rates, kinetic luminosities and momentum fluxes that differ correspondingly, in some cases at the order of magnitude level. Using the radiative shock model, estimate the ratio of the outflow kinetic luminosity to bolometric luminosity for 3 bright FeLoBAL quasars in the literature. Find Edot/Lbol ~ 2-5%, similar to models reproducing the M-sigma relation. Outflow properties also comparable to those inferred for molecular outflows in local ULIRGs. Suggests ACN are capable of driving such outflows.
1108.0494
Lensing clusters of galaxies in the SDSS-III
Wen, Han, Jiang
New strong-lensing clusters by visual inspection of color images. 68 new clusters show giant arcs in addition to 30 known lensing systems. 13 are "almost certain" giant tangential arcs, 22 are "probable" and 31 are "possible" lensing systems. 2 exotic systems with blue rings. Giant arcs have separations of 2" to 25" from BCG. Separation between arcs and BCG increase with cluster richness.
1108.0504
Gravitational microlensing of a reverberating quasar broad line region -- I. Method and qualitative results
Garsden, Bate, Lewis
* BELR: broad emission line region.
Quasar BELR kinematics and morphology is still under debate; two leading methods of constraining BELR properties are microlensing and reverberation mapping. Combine these two methods in Q2237+0305; look at microlensing as a change in continuum emission (flare) passes through it. Start with generic model if BELR (sphere, bicones, disk); slice in velocity and time to produce brightness profiles of BELR over the duration of the flare. Numerically microlens to determine whether microlensing of reverberation mapping provides new information. Qualitative results given in this paper; highlight some effects that can be observed. Conclusion: influence of microlensing, while not strong, can produce significant observable effects that will help in differentiating the properties of BELRs.
* The conclusion can be better described in the abstract, I think.
INPA, LBL
Discovery of the anti-alpha particle at STAR
Hank Crawford (LBNL)
Discovery of the antimatter 4He nucleus. STAR experiment at RHIC examined 109 interactions produced by colliding beams of gold nuclei at center of mass energy of 200 GeV per nucleon pair. Analysis yields 18 clean 4He particles. International space station AMS experiment.
* STAR: Solenoidal tracker at RHIC (relativistic heavy ion collider)--at Brookhaven. Formation and characteristics of the quark-glon plasma
* AMS: Alpha magnetic spectrometer (AMS-02)--particle physics experiment module that is mounted on International space station. Measure CR (search various types of unusual matter). PI is Samuel Ting.
Seminar, UCB Astro
Magnetic activity cycles in solar-type stars: statistics and impact on precise radial velocities
Christophe Lovis
Extrasolar planet detection through radial velocity measurements relies on the stability of stellar photospheres. Characterize statistical properties of magnetic activity cycles; study their impact on spectroscopic measurement, such as radial velocities, line bisectors and line shapes. Use planet search data from 304 FGK stars over 7 years; obtain high-precision Ca II H/K chromospheric activity measurements; convert to R'HK indicies and line shape parameters. Long-time precision on S is x3 better than Mt. Wilson survey. Classify stars according to Ca II variability; identify activity cycles. about 30-50% of old soloar-type stars do not show any activity cycles (very weak); 50-70% do show activity. Non-cycling stars are only found among G dwarfs. Magnetic cycle amplitude decreases with decreasing activity level (which is measured how?). Significant fraction of stars exhibit small variations in radial velocities and line shape parameters that are correlated with activity cycles. Sensitivity of radial velocity to magnetic cycles increases for hotter stars. Late K dwarfs are nearly insensitive. Conclusion: activity cycles induce long-period, low-amplitude radial velocity variations, at levels up to 25m/s. (whoa) Caution is mandatory when searching for long-period exoplanets. These effects can be corrected to high precision by detrending the rdial velocity data using simultaneous measurements of Ca II flux and line shape parameters (because that correlates to magnetic activity).
1108.0413
A physical model of FeLoBALs: implications for quasar feedback
Faucher-Giguere, Quataert, Murray
FeLoBALs: Photoionization modeling of the low-ionization broad-absorption lines of certain quasars: reveals the number density of the wind absorbers and their distance from the central SMBH. Feedback efficiency of the quasars can be derived. Implied properties of FeLoBALs are surprising: thickness of the absorbers relative to their distance from the BH (Delta R/R) can be as small as 1e-5. Such absorbers are not likely to survive the journey from SMBH to their inferred location. The observed FeLoBAL properties are readily explained if they are formed in situ in radiative shocks produced when a quasar blast wave impacts a moderately dense interstellar clump along the LOS (differs from the thin shell approximation often assumed). Implies outflow rates, kinetic luminosities and momentum fluxes that differ correspondingly, in some cases at the order of magnitude level. Using the radiative shock model, estimate the ratio of the outflow kinetic luminosity to bolometric luminosity for 3 bright FeLoBAL quasars in the literature. Find Edot/Lbol ~ 2-5%, similar to models reproducing the M-sigma relation. Outflow properties also comparable to those inferred for molecular outflows in local ULIRGs. Suggests ACN are capable of driving such outflows.
1108.0494
Lensing clusters of galaxies in the SDSS-III
Wen, Han, Jiang
New strong-lensing clusters by visual inspection of color images. 68 new clusters show giant arcs in addition to 30 known lensing systems. 13 are "almost certain" giant tangential arcs, 22 are "probable" and 31 are "possible" lensing systems. 2 exotic systems with blue rings. Giant arcs have separations of 2" to 25" from BCG. Separation between arcs and BCG increase with cluster richness.
1108.0504
Gravitational microlensing of a reverberating quasar broad line region -- I. Method and qualitative results
Garsden, Bate, Lewis
* BELR: broad emission line region.
Quasar BELR kinematics and morphology is still under debate; two leading methods of constraining BELR properties are microlensing and reverberation mapping. Combine these two methods in Q2237+0305; look at microlensing as a change in continuum emission (flare) passes through it. Start with generic model if BELR (sphere, bicones, disk); slice in velocity and time to produce brightness profiles of BELR over the duration of the flare. Numerically microlens to determine whether microlensing of reverberation mapping provides new information. Qualitative results given in this paper; highlight some effects that can be observed. Conclusion: influence of microlensing, while not strong, can produce significant observable effects that will help in differentiating the properties of BELRs.
* The conclusion can be better described in the abstract, I think.
1108.0583
Dark matter merging induced turbulence as an efficient engine for gas cooling
Prieto, Jiminez, Marti
* Burgers spectrum
Simulation of primordial baryonic gas collapsing onto a 3e7 Msun DM halo. Large scale baryonic accretion process and the merger of few 1e6 Msun DM halos is enough to create super sonic (M>10) shocks and develop turbulent environment. The post shocked regions are able to produce both H2 and HD molecules very efficiently (n_H2~1e-2 n_H and n_HD~few 1e-6 n_H), enough to cool the gas below 100k in some regions. The KE spectrum of the turbulent primordial gas is close to a Burgers spectrum (E_k ~ k^-2), solenoidal to total KE ratio is ~0.65-0.7 for a wide range of wave numbers; this value is close to 2/3, the natural equipartition energy value of a random turbulent flow. Turbulence and molecular cooling seem to work together in order to produce potential SF regions of cold and dense gas in primordial environments. Conclude: both mergers and collapse process into the main DM halo provide enough energy to develop super sonic turbulence with favor the molecular coolant formation--can create stars at high z.
* gas cooling produced from shocks in mergers! leading to SF at high z.
1108.0596
Search for non-Gaussianities in the WMAP data with the scaling index method
Rossmanith, Modest, Raeth, Banday, Gorski, Morfill
Review: study of non-Gaussianity on CMB accomplished with a measure of local type--SIM (Scaling index method). SIM able to detect structural characteristics of a given data set; used for comparing the data set with simulations as well as surrogates--full sky maps generated by randomisation of previously selected features of the original map. With this investigation, strong evidence for non-Gaussianities, as well as assymetries and local features can be detected. In combination with the surrogates approach, the SIM detected the highest significance for non-Gaussianity to date (what was it compared to?).
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