Cosmological constraints with the sub-millimetre galaxies Magnification Bias after large scale bias corrections. (arXiv:2007.15134v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Gonzalez_Nuevo_J/0/1/0/all/0/1">J. Gonzalez-Nuevo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cueli_M/0/1/0/all/0/1">M. M. Cueli</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bonavera_L/0/1/0/all/0/1">L. Bonavera</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lapi_A/0/1/0/all/0/1">A. Lapi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Migliaccio_M/0/1/0/all/0/1">M. Migliaccio</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Argueso_F/0/1/0/all/0/1">F. Arg&#xfc;eso</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Toffolatti_L/0/1/0/all/0/1">L. Toffolatti</a>

The study of the magnification bias produced on high z sub-mm galaxies by
foreground galaxies through the analysis of the cross-correlation function was
recently demonstrated as an interesting independent alternative to the weak
lensing shear as a cosmological probe. In the case of the proposed observable,
most of the cosmological constraints depends mainly on the largest angular
separation measurements. Therefore, we aim at studying and correcting the main
large scale biases that affect foreground and background galaxy samples in
order to produce a robust estimation of the cross-correlation function (CCF).
Then we analyse the corrected signal in order to derive updated cosmological
constraints. The large scale bias corrected CCFs are measured using a
background sample of H-ATLAS galaxies with photometric redshift > 1.2 and two
different foreground samples (GAMA galaxies with spectroscopic redshift or SDSS
galaxies with photometric ones, both in the range 0.2 < z < 0.8). They are
modelled using the traditional halo model description that depends on both HOD
and cosmological parameters. These parameters are then estimated by performing
a MCMC under different scenarios to study the performance of this observable
and the way to further improve its results. After the large scale bias
corrections, we get only minor improvements with respect to the Bonavera et al.
2020 results, mainly confirming their conclusions: a lower bound on $Omega_m >
0.22$ at $95%$ C.L. and an upper bound $sigma_8 < 0.97$ at $95%$ C.L.
(results from the $z_{spec}$ sample). However, by combining both foreground
samples into a simplified tomographic analysis, we were able to obtain
interesting constraints on the $Omega_m$-$sigma_8$ plane: $Omega_m= 0.42_{-
0.14}^{+ 0.08}$ and $sigma_8= 0.81_{- 0.09}^{+ 0.09}$ at 68% CL.

The study of the magnification bias produced on high z sub-mm galaxies by
foreground galaxies through the analysis of the cross-correlation function was
recently demonstrated as an interesting independent alternative to the weak
lensing shear as a cosmological probe. In the case of the proposed observable,
most of the cosmological constraints depends mainly on the largest angular
separation measurements. Therefore, we aim at studying and correcting the main
large scale biases that affect foreground and background galaxy samples in
order to produce a robust estimation of the cross-correlation function (CCF).
Then we analyse the corrected signal in order to derive updated cosmological
constraints. The large scale bias corrected CCFs are measured using a
background sample of H-ATLAS galaxies with photometric redshift > 1.2 and two
different foreground samples (GAMA galaxies with spectroscopic redshift or SDSS
galaxies with photometric ones, both in the range 0.2 < z < 0.8). They are
modelled using the traditional halo model description that depends on both HOD
and cosmological parameters. These parameters are then estimated by performing
a MCMC under different scenarios to study the performance of this observable
and the way to further improve its results. After the large scale bias
corrections, we get only minor improvements with respect to the Bonavera et al.
2020 results, mainly confirming their conclusions: a lower bound on $Omega_m >
0.22$ at $95%$ C.L. and an upper bound $sigma_8 < 0.97$ at $95%$ C.L.
(results from the $z_{spec}$ sample). However, by combining both foreground
samples into a simplified tomographic analysis, we were able to obtain
interesting constraints on the $Omega_m$-$sigma_8$ plane: $Omega_m= 0.42_{-
0.14}^{+ 0.08}$ and $sigma_8= 0.81_{- 0.09}^{+ 0.09}$ at 68% CL.

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