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

• Published in: Physical review. D 2022-11, Vol.106 (10), Article 103530
• Main Authors: Porredon, A., Crocce, M., Elvin-Poole, J., Cawthon, R., Giannini, G., De Vicente, J., Carnero Rosell, A., Ferrero, I., Krause, E., Fang, X., Prat, J., Rodriguez-Monroy, M., Pandey, S., Pocino, A., Castander, F. J., Choi, A., Amon, A., Tutusaus, I., Dodelson, S., Sevilla-Noarbe, I., Fosalba, P., Gaztanaga, E., Alarcon, A., Alves, O., Andrade-Oliveira, F., Baxter, E., Bechtol, K., Becker, M. R., Bernstein, G. M., Blazek, J., Camacho, H., Campos, A., Carrasco Kind, M., Chintalapati, P., Cordero, J., DeRose, J., Di Valentino, E., Doux, C., Eifler, T. F., Everett, S., Ferté, A., Friedrich, O., Gatti, M., Gruen, D., Harrison, I., Hartley, W. G., Herner, K., Huff, E. M., Huterer, D., Jain, B., Jarvis, M., Lee, S., Lemos, P., MacCrann, N., Mena-Fernández, J., Muir, J., Myles, J., Park, Y., Raveri, M., Rosenfeld, R., Ross, A. J., Rykoff, E. S., Samuroff, S., Sánchez, C., Sanchez, E., Sanchez, J., Sanchez Cid, D., Scolnic, D., Secco, L. F., Sheldon, E., Troja, A., Troxel, M. A., Weaverdyck, N., Yanny, B., Zuntz, J., Abbott, T. M. C., Aguena, M., Allam, S., Annis, J., Avila, S., Bacon, D., Bertin, E., Bhargava, S., Brooks, D., Buckley-Geer, E., Burke, D. L., Carretero, J., Costanzi, M., da Costa, L. N., Pereira, M. E. S., Davis, T. M., Desai, S., Diehl, H. T., Dietrich, J. P., Doel, P., Drlica-Wagner, A., Eckert, K., Evrard, A. E., Flaugher, B., Frieman, J.
• Format: Article
• Language: English
• Subjects: ASTRONOMY AND ASTROPHYSICS; cosmological parameters; cosmology; dark energy; dark matter; gravitational lenses; large scale structure of the universe; sky surveys
• ISSN: 2470-0010; 2470-0029
• DOI: 10.1103/PhysRevD.106.103530

Two of the most sensitive probes of the large scale structure of the universe 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 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 sq. deg2 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. 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. Furthermore, 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 x 2pt).