Tomography with Magnification Bias

The CCF was measured between a foreground spectroscopic sample of Galaxy And Mass Assembly galaxies and a background sample of Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) galaxies. The foreground sample was divided into four redshift bins (0.1-0.2, 0.2-0.3, 0.3-0.5, and 0.5-0.8) and the sample of H-ATLAS galaxies has photometric redshifts >1.2. The CCF was modelled using a halo model description that depends on HOD and cosmological parameters.

Then a Markov chain Monte Carlo method was used to estimate the parameters for different cases. For the {Lambda}CDM model the analysis yields a maximum posterior value at 0.26 with [0.17, 0.41] 68% C.I. for {Omega}_M_ and at 0.87 with [0.75, 1] 68% C.I. for {sigma}_8_. With our current results H_0_ is not yet constrained.

With a more general {omega}_0_CDM model, the constraints on {Omega}_M_ and {sigma}_8_ are similar, but we found a maximum posterior value for {omega}_0_ at -1 with [-1.56, -0.47] 68% C.I. In the {omega}_0_{omega}_a_CDM model, the results are -1.09 with [-1.72, -0.66] 68% C.I. for {omega}_0_ and -0.19 with [-1.88, 1.48] 68% C.I. for {omega}_a_. The results on Mmin show a trend towards higher values at higher redshift confirming recent findings.

The tomographic analysis presented in this work improves the constraints in the {sigma}_8_-{Omega}_M_ plane with respect to previous findings exploiting the magnification bias and it confirms that magnification bias results do not show the degeneracy found with cosmic shear measurements. Moreover, related to dark energy, we found a trend of higher {omega}_0_ values for lower H_0_ values.