Day 903

Wednesday.


1506.02671
Imprint of inflation on galaxy shape correlations
Schmidt, Chisari, Dvorkin

Show that intrinsic (not lensing-induced) correlations between galaxy shapes offer a new probe of primordial non-Gaussianity and inflationary physics which is complementary to galaxy number counts.  Specifically, intrinsic assignment correlations are sensitive to an anisotropic squeezed limit bispectrum of the primordial perturbations.  Such a feature arises in solid inflation, as well as more broadly in the presence of light higher spin fields during inflation (as pointed out recently by Arkani-Hamed and Maldacena).  Present a derivation of the all-sky 2pt correlations of intrinsic shapes and number counts in the presence of non-Gausiannity with general angular dependence, and show that a quadrupolar (spin-2) anisotropy leads to the analog in galaxy shapes of the well-known scale-dependent bias induced in number counts by isotropic (spin-0) non-G.  Moreover, in presence of non-zero anisotropic non-G, the quadruple of galaxy shapes becomes sensitive to far super horizon modes.  These effects come about because long-wavelength modes induce a local anisotropy in the initial PS, with which galaxies will correlate.  Forecast that future imaging surveys could provide constraints on the amplitude of anisotropic non-Gaussianity that are comparable to those from the CMB.  These are complementary as they probe different physical scales.  The constraints, however, depend on the sensitivity of galaxy shapes to the ICs which are only roughly estimated from observed tidal alignments.


1506.02720
High resolution imaging and spectroscopy of the gravitational lens SDSJ1206+4332: a natural coronagraph at $z=1.789$ and a standard ruler at $z=0.745$
Agnello, ... Suyu, Treu, Fassnacht, .. .Bradac, et al

Present spectroscopy and laser guide star adaptive optics (LGSAO) images of the double imaged lensed quasar SDSS J1206+4332.  Revise the deflector redshift proposed previously to z_d=0.745, and measure for the first time its velocity dispersion sigma=(290±30) km/s.  The LGSAO data show the lensed quasar host galaxy stretching over the astroid caustic thus forming an extra pair of merging images, which was previously thought to be an unrelated galaxy in seeing limited data.  Owing to the peculiar geometry, the lens acts as a natural coronagraph on the broad-one region of the quasar so that only narrow [OIII] emission is found in the fold arc.  Use the data to reconstruct the source structure and deflector potential, including nearby potential perturbers.  Reconstruct the PSF from the quasar images themselves, since no additional point source is present in the field of view.  From gravitational lensing and stellar dynamics, find the slope of the total mass density profile to be gamma'=-log rho/log r = 1.93±0.09.  Discuss the potential of this system for measuring time delay distance (and thus H0 and other cosmo params), r as a standard ruler, in combination with the time delay published by the COSMOGRAIL collaboration.  Conclude that this system is very promising for cosmography.  However, in order to achieve competitive precision and accuracy, and independent characterization of the PSF is needed.  Spatially resolved kinematics of the deflector would reduce the uncertainties further.  Both are within the reach of current observational facilities.