Day 766

Friday.

1410.4270
Galaxy alignment on large and small scales
Kang, et al

On small scales satellite galaxies have a tendency to distribute along the major axis of the central galaxy, with dependence on galaxy properties that both red satellites and centrals have stronger alignment than their blue counterparts.  On large scales, it is found that the major axes of LRGs have correlation up to 30 Mpc/h. Using hydro-dynamical sim with SF, investigate the origin of galaxy alignment on different scales.  Found that most red satellite galaxies stay in the inner region of DM halo inside which the shape of the central galaxy is well aligned with the DM distribution.  Red centrals have stronger alignment than blue ones as they live in massive haloes and the central galaxy-halo alignment increases with halo mass.  On large scales, the alignment of LRGs is also from the galaxy-halo shape correlation, but with some extent of mis-alignment.  The massive haloes have stronger alignment than haloes in filament which connect massive haloes.  This is contrary to the naive expectation that cosmic filament is the cause of halo alignment.

1410.4502
Cross-correlation between the CMB lensing potential measured by Planck and high-z sub-mm galaxies detected by the Herschel-ATLAS survey
Bianchini, et al

Correlation between CMB lensing from Planck and z>1.5 galaxies from Herschel-ATLAS covering 600 sq deg.  20sigma correlation found, substantially stronger than expected.  The result was checked by performing a number of null tests.  The galaxy bias parameter, b, derived from a joint analysis of the cross-power spectrum and of the auto-power spectrum of the galaxy density contrast is found to be b=2.8, consistent with earlier estimates of H-ATLAS galaxies at similar redshifts.  On the other hand, the amplitude of the cross-correlation is found to be a factor 1.6 higher than expected from the standard model and also found by cross-correlation analysis with other tracers of the LSS.  The enhancement due to lensing magnification can account for only a fraction of the excess X-correlation signal.  Suggest that most of it may be due to an incomplete removal of the contamination of the CIB, that includes the H-ATLAS sources that are being X-correlated with.  In any case, the highly significant detection reported here using a catalog covering only 1.5% of the sky demonstrates the potential of CMB lensing correlations with sub-mm surveys.