Day 764

Wednesday.

1410.3468
An exploration of galaxy-galaxy lensing and galaxy clustering in the Millennium-XL simulation
Marian, Smith, Angulo

The combination of gg lensing and galaxy clustering data has the potential to simultaneously constrain both the cosmological galaxy formation models.  However, to fully exploit this potential one needs to understand the signals as well as their joint covariance matrix.  In this paper, perform a comprehensive exploration of these ingredients, through a combination of analytic and numerical approaches.  First, derive analytic expressions for the projected galaxy correlation function and stacked tangential shear profile and their respective covariances.  Second, measure these quantitates from mock galaxy catalogues derived from the Millennium-XXL simulation and SAM of galaxy formation.  Find that on large scales (R>10 Mpc), the galaxy bias is roughly linear and deterministic.  On smaller scales (R<5Mpc) the bias is a complicated function of scale and luminosity, determined by the different spatial distribution and abundance of satellite galaxies present when different magnitude cuts are applied, as well as by the dependence of the mass of haloes hosting the central galaxies on magnitude.  The theoretical model for the covariances provides a reasonably good description of the measured ones on small and large scales.  However, on intermediate scales (1<R<10 Mpc), the predicted errors are ~2-3x smaller, suggesting that the inclusion of higher-order, non-Gaussian terms in the covariance will be required for further improvements.  Importantly, both the theoretical and numerical methods show that the gg lensing and clustering signals are not independent from each other, but have a non-hero cross-covariance matrix with significant bin-to-bin correlation.  Future surveys aiming to combine these probes must take this into account in order to obtain unbiased and realistic constraints.

1410.3489
The clustering of halo masses of star forming galaxies at z<1
Dolley, ... Kochanek, et al

Clustering measurements and halo masses of SF galaxies at 0.2<z<1.0.  After excluding AGN, construct a sample of 22k 24um sources selected from 8.42 sq deg of Spityer MIPS AGN and Galaxy Evolution Survey of Boötes.  MIR imaging allows observation of galaxies with the highest SFRs, less biased by dust obscuration afflicting the optical bands.  Find that the galaxies with the highest SFRs have optical colors which are redder than typical blue cloud galaxies, with many residing within the green valley.  At z>0.4, the sample is dominated by LIRGs, >1e11 Lsun) and is comprised entirely of LIRGs and ULRIGS (>1e12 Lsun) at z>0.6.  Observe weak clustering of r_0=3-6 Mpc/h for almost all of the SF samples.  Find that the clustering and halo mass depend on L at all redshifts, where galaxies with higher L (hence higher SFRs) have stronger clustering.  Galaxies with the highest SFRs at each z typically reside within DM haloes of M~1e12.9 Msun/h.  This is consistent with a transitional halo mass, above which SF is largely truncated, although cannot exclude that ULIRGs reside within higher mass haloes.  By modeling the clustering evolution of haloes, connect the SF galaxy samples to their local descendants.  Most SF galaxies at z<1.0 are the progenitors of L<2.5 L* blue galaxies in the local universe, but SF galaxies with the highest SFRs (>1e11.7 Lsun) at 0.6<z<1.0 are the progenitors of early-type galaxies in denser group environments.