Thursday, still behind. Friday.
1301.3131
Explaining the observed velocity dispersion of dwarf galaxies by baryonic mass loss during the first collapse
Gritschneder, Lin
Dwarf galaxies are the building blocks of larger galaxies, formed relatively early (when BG density was high); they are expected to retain their integrity as satellite galaxies when they merge to form larger entities. Many dSphs are found in the galactic halo around the MW, but their phase space density (velocity dispersion) appears to be significantly smaller than that expected for satellite dwarf galaxies in the LCDM scenario. In order to account for this discrepancy, consider the possibility that they may have lost a significant fraction of their baryonic matter content during the first infall at the Hubble expansion turnaround. Such ass loss arises naturally due to the feedback by relatively massive stars which formed in their centers briefly before the maximum contraction. Show with N-body sims that the timely loss of a significant fraction of the dSphs initial baryonic matter content can have profound effects on their asymptotic half-mass radius, velocity dispersion, phase-space density, and the mass fraction between residual baryonic and dark matter.
1301.3132
Relativistic effects in galaxy clustering in a parameterized post-Friedmann universe
Lombriser, Yoo, Koyama
Signatures of quintessence and modified gravity theories in galaxy clustering within a parameterized post-Friedmann framework. Effects in the linear Post-Friedmann perturbations,; relativistic effects in galaxy clustering. Quantify the impact of modified gravity and DE models on galaxy clustering from velocity-to-matter density ratio F, the velocity contribution R, and the potential contribution P; give an estimate of their detectability in future galaxy surveys. The relativistic correction contains additional information on gravity and DE which needs to be taken in to account in consistent horizon-scale tests of departures from LCDM using the galaxy-density field.
1301.3157
Mass assembly in quiescent and star-forming galaxies since z=4 from UltraVISTA
Ilbert, McCracken, Le Fevre, Capak, ... Mellier et al
Estimate galaxy stellar mass function and stellar mass density for SF and quiescent galaxies with 0.2<z<4, using 30-band photos. 220k galaxies UltraVISTA DR1. Compare with 10.8k specs from zCOSMOS, pretty good precision. Derive stellar mass function and correct for the Eddington bias; find mass-dependent evolution of the global and SF populations, with the low-mass end of the mass functions evolving more rapidly than the high-mass end. THis mass-dependent evolution is a direct consequence of the SF being "quenched" in galaxies more massive than M>1e10.8 Msun, while the rapid evolution at the low mass end is explained by the evolution of the specific SFR. By deriving the global stelar mass density, show that galaxies grow in mass twice as quickly at 1<z<4 than at 0.1<z<1. Also confirm that global stellar mass density is lower by 0.2-0.3 dex than the cosmic SFR integrated over cosmic time [why would that be?]. For the mass function of the quiescent galaxies, do not find any significant evolution of the high-mass end at z<1, while observing a clear flattening of the faint-end slope. From z=3 to z=1, the density of quiescent galaxies increase over the entire mass range. Their comoving stellar mass density increases by 1.5 between z=3 and z=1 and by less than 0.2 dex at z<1. Finally, compare results with the semi-analytical model and find that they overestimate the density of low mass quiescent galaxies by an order of magnitude.
1301.3164
SYNMAG photometry: a fast tool for catalog-level matched colors of extended sources
Bundy, Hogg, et al
Aperture magnitudes are the most widely tabulated flux measurements in survey catalogs, producing synthetic aperture magnitudes (SYNMAGs) enables very fast matched photometry at the catalog level, without reprocessing imaging data. Code public.
1301.3255
Nonlinearities in modified gravity cosmology. II. impacts of modified gravity on the halo properties
Zhang, et al
DM halos essential in understanding NL evolution. Use N-body sims to see modified gravity effects on halo mass function, concentration and bias; model the impact of mod. grab. by a single parameter zeta, which determines the enhancement of particle acceleration wrt GR. Results demonstrate that the halo mass function and/or the concentration are snesitive to the nature of gravity.
1301.3301
Evolution of hierarchical clustering in the CFHTLS-Wide since z~1
Wolk, McCracken, ... Kilbinger, Mellier, Ilbert, et al
Measurements of higher order clustering of galaxies from CFHTLS Wide survey. 0.2<z<1, volume limited, over the 4 independent fields of CFHTLS; use counts-in-cells to measure variance and hierarchical moments as a function of z and angular scale. Test for robustness, field-to-field scatter in good agreement with analytical predictions. Suggest hierarchical moments increase with z. At large scales, measurements are fully consistent with perturbation theory predictions for standard LCDM with simple linear bias.
1301.3456
Fitting methods for Baryon Acoustic Oscillations in the Lyman-{\alpha} forest fluctuations in BOSS data release 9
Kirkby, Margala, Slosar, et al
Describe fitting methods developed to analyze fluctuations in Ly-a forest for BAO measurements. Based on models of 3d correlation function in physical coordinate space; includes effects of z-space distortions, anisotropic NL broadening, broadband distortions. Allow for independent scale factors along and perpendicular to the LoS to minimize dependence on assumed fiducial cosmology, and to obtain separate measurements of the BAO angular and relative velocity scales. Fitting software and the input files to reproduce results publicly available.
1301.3459
Measurement of Baryon Acoustic Oscillations in the Lyman-alpha forest fluctuations in BOSS data release 9
Slosar, Irsic, Kirkby, Bailey, ... et al
Measure the position of BAO feature in Ly-a forest at z=2.4. Assess bias in method, stability of the error covariance matrix and possible systematic effects. Errors become significantly non-G for deviations over 3 std dev from best fit value. Give tighter constraints than previous BAO analysis, providing a consistency test of the std cosmological model in a new z regime.
1301.3131
Explaining the observed velocity dispersion of dwarf galaxies by baryonic mass loss during the first collapse
Gritschneder, Lin
Dwarf galaxies are the building blocks of larger galaxies, formed relatively early (when BG density was high); they are expected to retain their integrity as satellite galaxies when they merge to form larger entities. Many dSphs are found in the galactic halo around the MW, but their phase space density (velocity dispersion) appears to be significantly smaller than that expected for satellite dwarf galaxies in the LCDM scenario. In order to account for this discrepancy, consider the possibility that they may have lost a significant fraction of their baryonic matter content during the first infall at the Hubble expansion turnaround. Such ass loss arises naturally due to the feedback by relatively massive stars which formed in their centers briefly before the maximum contraction. Show with N-body sims that the timely loss of a significant fraction of the dSphs initial baryonic matter content can have profound effects on their asymptotic half-mass radius, velocity dispersion, phase-space density, and the mass fraction between residual baryonic and dark matter.
1301.3132
Relativistic effects in galaxy clustering in a parameterized post-Friedmann universe
Lombriser, Yoo, Koyama
Signatures of quintessence and modified gravity theories in galaxy clustering within a parameterized post-Friedmann framework. Effects in the linear Post-Friedmann perturbations,; relativistic effects in galaxy clustering. Quantify the impact of modified gravity and DE models on galaxy clustering from velocity-to-matter density ratio F, the velocity contribution R, and the potential contribution P; give an estimate of their detectability in future galaxy surveys. The relativistic correction contains additional information on gravity and DE which needs to be taken in to account in consistent horizon-scale tests of departures from LCDM using the galaxy-density field.
1301.3157
Mass assembly in quiescent and star-forming galaxies since z=4 from UltraVISTA
Ilbert, McCracken, Le Fevre, Capak, ... Mellier et al
Estimate galaxy stellar mass function and stellar mass density for SF and quiescent galaxies with 0.2<z<4, using 30-band photos. 220k galaxies UltraVISTA DR1. Compare with 10.8k specs from zCOSMOS, pretty good precision. Derive stellar mass function and correct for the Eddington bias; find mass-dependent evolution of the global and SF populations, with the low-mass end of the mass functions evolving more rapidly than the high-mass end. THis mass-dependent evolution is a direct consequence of the SF being "quenched" in galaxies more massive than M>1e10.8 Msun, while the rapid evolution at the low mass end is explained by the evolution of the specific SFR. By deriving the global stelar mass density, show that galaxies grow in mass twice as quickly at 1<z<4 than at 0.1<z<1. Also confirm that global stellar mass density is lower by 0.2-0.3 dex than the cosmic SFR integrated over cosmic time [why would that be?]. For the mass function of the quiescent galaxies, do not find any significant evolution of the high-mass end at z<1, while observing a clear flattening of the faint-end slope. From z=3 to z=1, the density of quiescent galaxies increase over the entire mass range. Their comoving stellar mass density increases by 1.5 between z=3 and z=1 and by less than 0.2 dex at z<1. Finally, compare results with the semi-analytical model and find that they overestimate the density of low mass quiescent galaxies by an order of magnitude.
1301.3164
SYNMAG photometry: a fast tool for catalog-level matched colors of extended sources
Bundy, Hogg, et al
Aperture magnitudes are the most widely tabulated flux measurements in survey catalogs, producing synthetic aperture magnitudes (SYNMAGs) enables very fast matched photometry at the catalog level, without reprocessing imaging data. Code public.
1301.3255
Nonlinearities in modified gravity cosmology. II. impacts of modified gravity on the halo properties
Zhang, et al
DM halos essential in understanding NL evolution. Use N-body sims to see modified gravity effects on halo mass function, concentration and bias; model the impact of mod. grab. by a single parameter zeta, which determines the enhancement of particle acceleration wrt GR. Results demonstrate that the halo mass function and/or the concentration are snesitive to the nature of gravity.
1301.3301
Evolution of hierarchical clustering in the CFHTLS-Wide since z~1
Wolk, McCracken, ... Kilbinger, Mellier, Ilbert, et al
Measurements of higher order clustering of galaxies from CFHTLS Wide survey. 0.2<z<1, volume limited, over the 4 independent fields of CFHTLS; use counts-in-cells to measure variance and hierarchical moments as a function of z and angular scale. Test for robustness, field-to-field scatter in good agreement with analytical predictions. Suggest hierarchical moments increase with z. At large scales, measurements are fully consistent with perturbation theory predictions for standard LCDM with simple linear bias.
1301.3456
Fitting methods for Baryon Acoustic Oscillations in the Lyman-{\alpha} forest fluctuations in BOSS data release 9
Kirkby, Margala, Slosar, et al
Describe fitting methods developed to analyze fluctuations in Ly-a forest for BAO measurements. Based on models of 3d correlation function in physical coordinate space; includes effects of z-space distortions, anisotropic NL broadening, broadband distortions. Allow for independent scale factors along and perpendicular to the LoS to minimize dependence on assumed fiducial cosmology, and to obtain separate measurements of the BAO angular and relative velocity scales. Fitting software and the input files to reproduce results publicly available.
1301.3459
Measurement of Baryon Acoustic Oscillations in the Lyman-alpha forest fluctuations in BOSS data release 9
Slosar, Irsic, Kirkby, Bailey, ... et al
Measure the position of BAO feature in Ly-a forest at z=2.4. Assess bias in method, stability of the error covariance matrix and possible systematic effects. Errors become significantly non-G for deviations over 3 std dev from best fit value. Give tighter constraints than previous BAO analysis, providing a consistency test of the std cosmological model in a new z regime.
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