Speaker
Description
As they travel through the Universe, a small fraction of cosmic microwave background (CMB) photons scatter off free electrons from the gaseous halos of moving galaxies leaving a temperature signal: the kinematic Sunyaev-Zel'dovich effect (kSZ). In this work, we precisely measure this effect with velocity stacking to infer gas profiles around galaxies and their dependence on galaxy properties, an important input for galaxy formation models. We use spectroscopically confirmed luminous red galaxies from the Dark Energy Spectroscopic Instrument (DESI) Y1, which overlap with the Atacama Cosmology Telescope (ACT) Data Release 6 temperature maps over more than 4,000 square degrees. The kSZ effect is measured with high significance (SNR~10), allowing us to explore its evolution with various parameters. We find no trend with redshift, but clear trends with stellar mass and absolute magnitude in g, r, and z bands. Our results suggest that the gas is much more extended than the dark matter and that there is a significant amount of additional energy injection compared to cosmological hydrodynamical simulations. Additionally, we present the first estimate of the kSZ signal from the DESI Y1 bright galaxy sample and emission-line galaxies, whose features match qualitative expectations. We also confirm the consistency of a previous photometric kSZ measurement using DESI luminous red galaxies, which, while offering comparable statistical power, may be subject to more complex systematic effects, thereby increasing confidence in those results. Finally, we provide an SNR forecast for stacking kSZ measurements in future experiments with the latest ACT maps, such as DESI Y3 and the Rubin Observatory Legacy Survey of Space and Time, with the latter reaching an SNR of ~50. We expect our results will substantially reduce baryonic uncertainties in cosmological lensing analyses and hydrodynamical simulations.
| Would you be interested in presenting a poster if the conference is oversubcribed? | Yes |
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