Cross-correlation between Planck CMB lensing potential and galaxy catalogues from HELP

Abstract

ABSTRACT We present the study of cross-correlation between Cosmic Microwave Background (CMB) gravitational lensing potential map released by the Planck collaboration and photometric redshift galaxy catalogues from the Herschel Extragalactic Legacy Project (HELP), divided into four sky patches: NGP, Herschel Stripe-82, and two halves of SGP field, covering in total ∼660 deg2 of the sky. We estimate the galaxy linear bias parameter, b0, from joint analysis of cross-power spectrum and galaxy autopower spectrum using Maximum Likelihood Estimation technique to obtain values ranging from 0.70 ± 0.01 for SGP Part-2 to 1.02 ± 0.02 for SGP Part-1 field. We also estimate the amplitude of cross-correlation and find the values spanning from 0.67 ± 0.18 for SGP Part-2 to 0.80 ± 0.23 for SGP Part-1 field, respectively. For NGP and SGP Part-1 fields, the amplitude is consistent with the expected value for the standard cosmological model within $\sim 1\, \sigma$, while for Herschel Stripe-82 and SGP Part-2, we find the amplitude to be smaller than expected with $\sim 1.5\, \sigma$ and $\sim 2\, \sigma$ deviation, respectively. We perform several tests on various systematic errors to study the reason for the deviation, however, value of the amplitude turns out to be robust with respect to these errors. The only significant change in the amplitude is observed when we replace the minimum-variance CMB lensing map, used in the baseline analysis, by the lensing map derived from the CMB temperature map with deprojected thermal Sunyaev–Zeldovich signal.