Day 636

Wednesday.

1404.5299
A simple technique for predicting high-redshift galaxy evolution
Behroozi, Silk

Show that the ratio of galaxies' sSFRs to their host halos' specific mass accretion rates (SMARs) strongly constrains how the galaxies' stellar masses, sSFRs and those halo masses evolve over cosmic time.  This evolutionary constraint provides a simple way to probe z>8 galaxy populations without direct observations.  Tests of the method with galaxy properties at z=4 successfully reproduce the known evolution of the stellar mass-halo mass (SMHM) relation, galaxy sSFRs, and the cosmic SFR at z<4, the median galaxy mass at fixed halo mass increases strongly at z>4.  Show that this result is closely linked to the flattening in galaxy sSFRs at z>2 compared to halo specific mass accretion rates; expect that average galaxy sSFRs at fixed stellar mass will continue their mild evolution to z~15.  The expected cosmic SFR shows no breaks or features at z>8.5; this constrains both reionization and the possibility of a steep falloff in the CSFR at z=9-10.  Finally, make predictions for the JWST, which should be able to observe one galaxy with M*>1e8 Msun per 1e3 Mpc^3 at z=9.6 and one such galaxy per 1e4 Mpc^3 at z=15.
1404.5301
The properties of the cool circumgalactic gas probed with the SDSS, WISE and GALEX surveys
Lan, Ménard, Zhu

Explore the distribution of cool (~1e4K) gas around galaxies and its dependence on galaxy properties.  Cross-correlate 50k MgII absorbers with millions of sources from SDSS (optical), WISE (IR) and GALEX (UV) surveys, effectively extract about 2k galaxy-absorber paris at z~0.5 and probe relations between absorption strength and galaxy type, impact parameter and azimuthal angle.  Find that cool gas traced by MgII absorbers exists around both SF and passive galaxies with a similar incidence rate on scales greater tan 100 kpc but each galaxy type exhibits a different behavior on smaller scales: MgII EW does not correlate with the presence of passive galaxies whereas stronger MgII absorbers tend to be found in the vicinity of SF galaxies.  This effect is preferentially seen along the minor axis of these galaxies, suggesting that some of the gas is associated with outflowing material.  In contrast, the distribution of cool gas around passive galaxies is consistent with being isotropic on the same scales.  Quantify the average excess MgII EW as a function of galaxy properties and find propto SFR^0.6, sSFR^0.4 and M*^0.4 for SF galaxies.  This work demonstrates that the dichotomy between SF and passive galaxies is reflected in the CGM traced by low-ionized gas.  Also measure the covering fraction of MgII absorption and find it to be about 2-10x higher for SF galaxies than passive ones within 50 kpc.  Estimate the amount of neutral gas in the halo of M*~1e10.8 Msun galaxies to be a few x1e9 Msun for both types of galaxies.  Find that correlations between absorbers and sources detected in the UV and IR lead to physical trends consistent with those measured in the optical.

1404.5312
Constraining galaxy cluster temperatures and redshifts with eROSITA survey data
Borm, Reiprich, Mohammed, Lovisari

The upcoming eROSITA mission will exploit cluster mass function dependence on the DE by detecting roughly 100k clusters of galaxies in X-rays.  For a precise cosmological analysis, the various galaxy cluster properties need to be measured with high precision and accuracy.  To predict these characteristics of eROSITA galaxy clusters and to optimize optical follow-up observations, estimate the precision and the accuracy with which eROSITA will be able to determine galaxy cluster temperatures and redshifts from X-ray spectra.  Additionally, present the total number of clusters for which these two properties will be available from the eROSITA survey directly.  During its four years of all-sky surveys, eROSITA will determine cluster temperatures with relative uncertainties of Delta(T)/T<10% at the 68% CL for clusters up to z~0.16 which corresponds to ~1670 new clusters with precise properties.  Z information itself will become available with a precision of Delta(z)/(1+z)<10% for clusters up to z~0.45.  Additionally, estimate how the number of clusters with precise properties increases with a deepening of the exposure.  Furthermore, the biases in the best-fit temperatures as well as in the estimated uncertainties are quantified and shown to be negligible in the relevant parameter range in general.  For the remaining parameter sets, provide correction functions and factors.  The eROSITA survey will increase the number of galaxy clusters with precise temperature measurements by a factor of 5-10.  Thus the instrument present itself as a powerful tool for the determination of tight constraints on the cosmological parameters.

1404.5469
CFHTLenS: cosmological constraints from a combination of cosmic shear two-point and three-point correlations
Fu, Kilbinger, … et al

Higher-order, non-Gaussian aspects of the LSS carry valuable information on structure formation and cosmology, which is complementary to second-order statistics.  In this work, measure second-and third-order WL aperture-mass moments from CFHTLenS and combine those with CMB anisotropy probes.  The third moment is measured with a significance of 2 sigma.  The combined constraint on Sigma_8=sigma_8(Omega_m/0.27)^a is improved by 10%, in comparison to 2nd order only, and the allowed ranges for Omega_m and sigma_8 are substantially reduced.  Including general triangles of the lensing bispectrum yields tighter constraints compared to probing mainly equilateral triangles.  Second and third-order CFHTLenS lensing measurements improve Planck CMB constraints on Omega_m and sigma_8 by 26% for flat LCDM.  For a model with free curvature, the joint CFHTLenS-Planck result is Omega_m=0.28pm0.02 (68% CL), which is an improvement of 43% compared to Planck alone.  Test how results are potentially subject to 3 astrophysical sources of contamination: source-lens clustering, the IA of galaxy shapes, and baryonic effects.  Explore future limitations of the cosmological use of 3rd-order WL, such as the NL model and the Gaussianity of the likelihood function.

1404.5589
Model-independent measurements of cosmic expansion and growth at z=0.57 using the anisotropic clustering of CMASS galaxies from the Sloan Digital Sky Survey Data Release 9
Wang

Analyze 2DCF of CMASS galaxy sample from SDSS DR9 of the BOSS data.  Modeling the 2DCF fully including NL effects and RSD in the scale of 30-120 Mpc/h, find H(0.57)r_s(z_d)/c = 0.0444pm0.0019, D_A(0.57)/r_s(z_d)=9.01pm0.23, and f_g(0.57) sigma_8(0.57)=0.474pm0.075, where r_s(z_d) is the sound horizon at the drag epoch computed using a simple integral, and f_g(z) is the growth rate at redshift z, and sigma_8(z) represents the matter power spectrum normalization on 8 Mpc/h scale at z.  Find that the scales larger than 120 Mpc/h are dominated by noise in the 2DCF analysis, and that they inclusion of scales 30-40 Mpc/h significantly tightens the RSD measurement.  Measurements are consistent with previous results using the same data, but have significantly better precision since they use all information from the 2DCF in the scale range of 30-120 Mpc/h.  Measurements have been marginalized over sufficiently wide priors for the relevant parameters; they can be combined with other data to probe DE and gravity.