APEC Seminar (Astronomy - Particle Physics - Experimental Physics - Cosmology)

Speaker: Alex Krolewski (Berkeley/Perimeter)
Title: CMB lensing tomography to redshift 2 with galaxies from the unWISE catalog
Date (JST): Thu, Oct 01, 2020, 11:00 - 12:00
Place: Zoom
Related File: 2580.pdf
Abstract: CMB lensing tomography has the potential to map the amplitude and growth of structure over cosmic time, provide stringent tests of gravity, and break important degeneracies between cosmological parameters. I use the unWISE photometric galaxy catalog to create three samples at median redshifts z~0.6, 1.1, and 1.5, and cross-correlate them with the most recent Planck CMB lensing maps. The resulting significance of ~80 at 100 < ell < 1000 is the highest significance detection to date of CMB lensing cross-correlation. The redshift distribution of the two-band unWISE galaxies is a major source of systematic error. I primarily use cross-correlations with BOSS galaxies and quasars and eBOSS quasars to measure the redshift distribution, supplemented with cross-matching to deep COSMOS photometric redshifts. I demonstrate how to propagate the uncertainty in the redshift distribution to the modeling of the signal, and perform a number of null tests. Finally, I discuss the cosmological implications of this measurement and lessons learned for CMB lensing cross-correlations with future photometric surveys.