51. The Atacama Cosmology Telescope: Large-scale velocity reconstruction with the kinematic Sunyaev--Zel'dovich effect and DESI LRGs
- Author
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McCarthy, Fiona, Battaglia, Nicholas, Bean, Rachel, Bond, J. Richard, Cai, Hongbo, Calabrese, Erminia, Coulton, William R., Devlin, Mark J., Dunkley, Jo, Ferraro, Simone, Gluscevic, Vera, Guan, Yilun, Hill, J. Colin, Johnson, Matthew C., Kusiak, Aleksandra, Laguë, Alex, MacCrann, Niall, Madhavacheril, Mathew S., Moodley, Kavilan, Naess, Sigurd, Qu, Frank J., Guachalla, Bernardita Ried, Sehgal, Neelima, Sherwin, Blake D., Sifón, Cristóbal, Smith, Kendrick M., Staggs, Suzanne T., van Engelen, Alexander, Vavagiakis, Eve M., and Wollack, Edward J.
- Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
The kinematic Sunyaev--Zel'dovich (kSZ) effect induces a non-zero density-density-temperature bispectrum, which we can use to reconstruct the large-scale velocity field from a combination of cosmic microwave background (CMB) and galaxy density measurements, in a procedure known as ``kSZ velocity reconstruction''. This method has been forecast to constrain large-scale modes with future galaxy and CMB surveys, improving their measurement beyond what is possible with the galaxy surveys alone. Such measurements will enable tighter constraints on large-scale signals such as primordial non-Gaussianity, deviations from homogeneity, and modified gravity. In this work, we demonstrate a statistically significant measurement of kSZ velocity reconstruction for the first time, by applying quadratic estimators to the combination of the ACT DR6 CMB+kSZ map and the DESI LRG galaxies (with photometric redshifts) in order to reconstruct the velocity field. We do so using a formalism appropriate for the 2-dimensional projected galaxy fields that we use, which naturally incorporates the curved-sky effects important on the largest scales. We find evidence for the signal by cross-correlating with an external estimate of the velocity field from the spectroscopic BOSS survey and rejecting the null (no-kSZ) hypothesis at $3.8\sigma$. Our work presents a first step towards the use of this observable for cosmological analyses., Comment: 16 pages (main)+5 pages (Appendix); 13 figures (main) + 8 figures (appendix)
- Published
- 2024