Cosmological constraints on the magnification bias on submillimetre galaxies after largescale bias corrections
Abstract
Context. The study of the magnification bias produced on highredshift submillimetre galaxies by foreground galaxies through the analysis of the crosscorrelation function was recently demonstrated as an interesting independent alternative to the weaklensing shear as a cosmological probe.
Aims: In the case of the proposed observable, most of the cosmological constraints mainly depend on the largest angular separation measurements. Therefore, we aim to study and correct the main largescale biases that affect foreground and background galaxy samples to produce a robust estimation of the crosscorrelation function. Then we analyse the corrected signal to derive updated cosmological constraints.
Methods: We measured the largescale, biascorrected crosscorrelation functions using a background sample of HATLAS galaxies with photometric redshifts > 1.2 and two different foreground samples (GAMA galaxies with spectroscopic redshifts or SDSS galaxies with photometric ones, both in the range 0.2 < z < 0.8). These measurements are modelled using the traditional halo model description that depends on both halo occupation distribution and cosmological parameters. We then estimated these parameters by performing a Markov chain Monte Carlo under multiple scenarios to study the performance of this observable and how to improve its results.
Results: After the largescale bias corrections, we obtain only minor improvements with respect to the previous magnification bias results, mainly confirming their conclusions: a lower bound on Ω_{m} > 0.22 at 95% CL and an upper bound σ_{8} < 0.97 at 95% CL (results from the z_{spec} sample). Neither the much higher surface density of the foreground photometric sample nor the assumption of Gaussian priors for the remaining unconstrained parameters significantly improve the derived constraints. However, by combining both foreground samples into a simplified tomographic analysis, we were able to obtain interesting constraints on the Ω_{m}  σ_{8} plane as follows: Ω_{m} = 0.50_{0.20}^{+0.14} and σ_{8} = 0.75_{0.10}^{+0.07} at 68% CL.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 February 2021
 DOI:
 10.1051/00046361/202039043
 Bibcode:
 2021A&A...646A.152G
 Keywords:

 galaxies: highredshift;
 submillimeter: galaxies;
 gravitational lensing: weak;
 cosmological parameters