Day 991

Monday.


1510.04696
Beyond 31 mag/arcsec^2: the low surface brightness frontier with the largest optical telescopes
Trujillo, Fliri

The detection of optical surface brightness structures in the sky with magnitudes fainter than 30 mag/arcsec^2 (3 sigma in 10x10 arcsec boxes; r-band) has remained elusive in current photometric deep surveys.  Show how present-day 10m class telescopes can provide broadband imaging 1.5-2 mag deeper than most previous results within a reasonable amount of time (i.e., <10h on sources integration).  In particular, illustrate the ability of the 10.4 Gran Telescopio de Canaries (GTC) telescope to produce imaging with a limiting surface brightness of 31.5 mag/arcsec^2 (3 sigma in 10x10 arcsec boxes; 4-band) using 8.1 hours on source.  Apply this power to explore the stellar halo of the galaxy UGC00180, a galaxy analogous to M31 located at ~150 Mpc, by obtaining a surface brightness radial profile down to mu_r~33 mag/arcsec^2.  This depth is similar to that obtained using star counts techniques of Local Group galaxies, but is achieved at a distance where this technique is unfeasible.  Find that the mass of the stellar halo of this galaxy is ~4e9 Msun, i.e., 3±1% of the total stellar mass of the whole system.  This amount of mass in the stellar halo is in agreement with current theoretical expectations for galaxies of this kind.


1510.04809
A new look at lines of sight: using Fourier methods for the wide-angle anisotropic 2-point correlation function
Slepian, Eisenstein

The anisotropic 2PCF of galaxies measures pairwise clustering as a function of the pair separation's angle to the line of sight.  The latter is often defined as either the angle bisector of the observer-galaxy-pair triangle or the vector from the observer to the separation midpoint.  Show how to accelerate either of these measurements with Fourier Transforms, using a slight generalization of the Yamamoto+2006 estimator in which each member of the pair is used successively as the line of sight.  Also present perturbation theory predictions for the generalized estimator including wide-angle corrections.