The gravitational lensing imprints of DES Y3 superstructures on the CMB: a matched filtering approach

• Published in: Monthly notices of the Royal Astronomical Society 2024-10, Vol.534 (3), p.2328-2343
• Main Authors: Demirbozan, U, Nadathur, S, Ferrero, I, Fosalba, P, Kovács, A, Miquel, R, Davies, C T, Pandey, S, Adamow, M, Bechtol, K, Drlica-Wagner, A, Gruendl, R A, Hartley, W G, Pieres, A, Ross, A J, Rykoff, E S, Sheldon, E, Yanny, B, Abbott, T M C, Aguena, M, Allam, S, Alves, O, Bacon, D, Bertin, E, Bocquet, S, Brooks, D, Rosell, A Carnero, Carretero, J, Cawthon, R, da Costa, L N, Pereira, M E S, De Vicente, J, Desai, S, Doel, P, Everett, S, Flaugher, B, Friedel, D, Frieman, J, Gatti, M, Gaztanaga, E, Giannini, G, Gutierrez, G, Hinton, S R, Hollowood, D L, James, D J, Jeffrey, N, Kuehn, K, Lahav, O, Lee, S, Marshall, J L, Mena-Fernández, J, Mohr, J J, Myles, J, Ogando, R L C, Malagón, A A Plazas, Roodman, A, Sanchez, E, Sevilla-Noarbe, I, Smith, M, Soares-Santos, M, Suchyta, E, Swanson, M E C, Tarle, G, Weaverdyck, N, Weller, J, Wiseman, P
• Format: Article
• Language: English
• Subjects: ASTRONOMY AND ASTROPHYSICS; cosmic background radiation; cosmological parameters; cosmology: observations; gravitational lensing: weak; large-scale structure of Universe
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stae2206

Low-density cosmic voids gravitationally lens the cosmic microwave background (CMB), leaving a negative imprint on the CMB convergence $\kappa$. This effect provides insight into the distribution of matter within voids, and can also be used to study the growth of structure. We measure this lensing imprint by cross-correlating the Planck CMB lensing convergence map with voids identified in the Dark Energy Survey Year 3 (DES Y3) data set, covering approximately 4200 deg$^2$ of the sky. We use two distinct void-finding algorithms: a 2D void-finder that operates on the projected galaxy density field in thin redshift shells, and a new code, Voxel, which operates on the full 3D map of galaxy positions. We employ an optimal matched filtering method for cross-correlation, using the Marenostrum Institut de Ciències de l’Espai N-body simulation both to establish the template for the matched filter and to calibrate detection significances. Using the DES Y3 photometric luminous red galaxy sample, we measure $A_\kappa$, the amplitude of the observed lensing signal relative to the simulation template, obtaining $A_\kappa = 1.03 \pm 0.22$ ($4.6\sigma$ significance) for Voxel and $A_\kappa = 1.02 \pm 0.17$ ($5.9\sigma$ significance) for 2D voids, both consistent with Lambda cold dark matter expectations. We additionally invert the 2D void-finding process to identify superclusters in the projected density field, for which we measure $A_\kappa = 0.87 \pm 0.15$ ($5.9\sigma$ significance). The leading source of noise in our measurements is Planck noise, implying that data from the Atacama Cosmology Telescope, South Pole Telescope and CMB-S4 will increase sensitivity and allow for more precise measurements.