Dark Energy Survey Year 3 results: Cosmological constraints from galaxy clustering and galaxy-galaxy lensing using the MagLim lens sample

Abstract

The cosmological information extracted from photometric surveys is most robust when multiple probes of the large scale structure of the universe are used. Two of the most sensitive probes are the clustering of galaxies and the tangential shear of background galaxy shapes produced by those foreground galaxies, so-called galaxy-galaxy lensing. Combining the measurements of these two two-point functions leads to cosmological constraints that are independent of the way galaxies trace matter (the galaxy bias factor). The optimal choice of foreground, or lens, galaxies is governed by the joint, but conflicting requirements to obtain accurate redshift information and large statistics. We present cosmological results from the full 5000 deg 2 of the Dark Energy Survey first three years of observations (Y3) combining those two-point functions, using for the first time a magnitude-limited lens sample (MAGLIM) of 11 million galaxies especially selected to optimize such combination, and 100 million background shapes. We consider two cosmological models, flat ΛCDM and wCDM, and marginalized over 25 astrophysical and systematic nuisance parameters. In ΛCDM we obtain for the matter density Ωm = 0.320 +0.041 −0.034 and for the clustering amplitude S8 ≡ σ8(Ωm/0.3) 0.5 = 0.778 +0.037 −0.031 , at 68% C.L. The latter is only 1σ smaller than the prediction in this model informed by measurements of the cosmic microwave background by the Planck satellite.In wCDM we find Ωm = 0.32 +0.044 −0.046 , S8 = 0.777 +0.049 −0.051 , and dark energy equation of state w = −1.031 +0.218 −0.379 . We find that including smaller scales while marginalizing over non-linear galaxy bias improves the constraining power in the Ωm − S8 plane by 31% and in the Ωm − w plane by 41% while yielding consistent cosmological parameters from those in the linear bias case. These results are combined with those from cosmic shear in a companion paper to present full DES-Y3 constraints from the three two-point functions (3 × 2pt).

Testing modified gravity with 21 cm intensity mapping, HI galaxy, cosmic microwave background, optical galaxy, weak lensing, galaxy clustering, type Ia supernovae and gravitational wave surveys

“…The above all probes can present strong constraints on MG at small scales, however, the constraints become weaker at large scales. At current stage, the observations of large scale structure of the universe such as cosmic microwave background (CMB) [1], weak lensing (WL) [10][11][12], galaxy clustering (GC) and galaxygalaxy lensing surveys [12,13] just can provide limited constraining power for typical MG parameters independently [14]. As a consequence, so far, combining them together to give a relatively tight constraint on MG is the best choice [15][16][17].…”

Model-independent constraints on clustering and growth of cosmic structures from BOSS DR12 galaxies in harmonic space

“…During the last couple of decades the physical picture of the cosmos has been set by the combination of the cosmic microwave background temperature and polarisation measurements [1] and large-scale structure probes. Among the most widely studied of these probes are the clustering of galaxies [2][3][4][5][6][7][8][9][10][11] and cosmic shear [12][13][14][15][16].…”

Galaxy cluster strong lensing cosmography: cosmological constraints from a sample of regular galaxy clusters

“…some properties related to structure formation, for instance the sub-halo population in galaxy clusters (Grillo et al 2015;Carlsten et al 2020;Meneghetti et al 2020) and the inner slope of dark matter halos (Sand et al 2004;Gnedin et al 2004;Newman et al 2011Newman et al , 2013bGnedin et al 2011;Martizzi et al 2012;Schaller et al 2015), when comparing simulations with observations. These issues motivate further tests on the ΛCDM model, both at small and large scales, and play an essential role in the concept and design of cosmological observations and projects, such as the Baryon Oscillation Spectroscopic Survey (Dawson et al 2013), the Dark Energy Survey (Abbott et al 2018;DES Collaboration et al 2021;Porredon et al 2021), the Kilo-Degree Survey (van Uitert et al 2018;Joudaki et al 2018) and the Planck satellite (Planck Collaboration et al 2020), to mention a few.…”