Model-Independent Measurement of Baryon Gas Fractions through Galaxy-Galaxy Lensing and the Kinematic Sunyaev-Zel'dovich Effect
Year: 2026
Type: preprint
Abstract: Baryon feedback is a leading source of systematic uncertainty for cosmology from weak lensing, but measurements of the gas distribution around galaxies have largely relied on parametric profile models or simulation-calibrated frameworks. We present model independent measurements of the radial gas fraction profile around galaxies, combining galaxy-galaxy lensing and kinematic Sunyaev-Zel'dovich (kSZ) effect. We introduce a method that applies the same radial $ΔΣ$ aperture filter to both the galaxy-galaxy lensing shear field and the velocity-weighted kSZ temperature maps; their ratio directly yields $ΔΣ$ filtered gas fraction $f_{\rm gas}(R)$, the ratio of ionized gas to total matter as a function of projected radius. We apply this approach to DESI DR2 Bright Galaxy Survey (BGS, $\bar{z} \approx 0.26$) and Luminous Red Galaxy (LRG, $0.4 < z < 1.1$) samples, using ACT DR6 component-separated CMB maps for kSZ, and the HSC Year 3 shear catalog for weak lensing. After correcting for ACT beam suppression using a simulation-calibrated compensation factor, we detect baryon depletion relative to the cosmic mean baryon fraction at SNR = 17.2 (BGS) and SNR = 13.8 (LRG bin 1). Comparison with six hydrodynamical simulations from the Illustris, IllustrisTNG, SIMBA, and FLAMINGO suites shows that the fiducial FLAMINGO run most closely tracks the observed radial gas distribution in both samples, with Illustris-1 and TNG300-1 bracketing the data from below and above at small radii. We find a mild discrepancy between the kSZ measurements in the South and North Galactic Caps in one LRG redshift bin, which may indicate residual systematics. We show that the ratio is robust to splits by stellar mass and to the removal of close pairs. These results establish $ΔΣ$ filtering of kSZ versus weak lensing signal as a model-independent probe of the baryon distribution around galaxies.
Source: arXiv (Cornell University)
Authors: Liu, R. Henry, Seljak, Uroš, Ferraro, Simone, Hadzhiyska, Boryana, Qu, Frank J., Guachalla, Bernardita Ried, Schaan, Emmanuel, Aguilar, Jessica Nicole, Ahlen, Steven, Lizancos, Anton Baleato, Beutler, Florian, Bianchi, Davide, Brooks, David, Rosell, Aurelio Carnero, Castander, Francisco Javier, Claybaugh, Todd, Cuceu, Andrei, de la Macorra, Axel, Forero-Romero, Jaime E., Gaztañaga, Enrique, Gontcho, Satya Gontcho A, Gutierrez, Gaston, Honscheid, Klaus, Huterer, Dragan, Ishak, Mustapha, Juneau, Stephanie, Karim, Tanveer, Kirkby, David, Kremin, Anthony, Lahav, Ofer, Landriau, Martin, Guillou, Laurent Le, Lokken, Martine, Manera, Marc, Meisner, Aaron, Miquel, Ramon, Moustakas, John, Nadathur, Seshadri, Newman, Jeffrey A., Noriega, Hernan Enrique, Percival, Will, Pérez-Ràfols, Ignasi, Prada, Francisco, Ravoux, Corentin, Rossi, Graziano, Samushia, Lado, Sanchez, Eusebio, Saulder, Christoph, Schlegel, David, Schubnell, Michael, Seo, Hee-Jong, Siudek, Małgorzata, Tarlé, Gregory, Weaver, Benjamin Alan, Zhou, Rongpu
Institutions: Lawrence Berkeley National Laboratory, University of California, Berkeley, University of Cambridge, SLAC National Accelerator Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Boston University, University of Edinburgh, University of Milan, Brera Astronomical Observatory, University College London, Universidad de La Laguna, Instituto de Astrofísica de Canarias, Institute of Space Sciences, Institut d'Estudis Espacials de Catalunya, Universidad Nacional Autónoma de México, Universidad de Los Andes, Royal Observatory, Fermi National Accelerator Laboratory, University of Michigan, Centre National de la Recherche Scientifique, The University of Texas at Dallas, University of Toronto, University of California, Irvine, Sorbonne Université, Laboratoire de Physique Nucléaire et de Hautes Énergies, Institut National de Physique Nucléaire et de Physique des Particules, NSF NOIRLab, University of Pittsburgh, Institute for High Energy Physics, Barcelona Institute of Science and Technology, Universitat Autònoma de Barcelona, Institució Catalana de Recerca i Estudis Avançats, University of Portsmouth, Universitat Politècnica de Catalunya, Instituto de Astrofísica de Andalucía, Université Clermont Auvergne, Laboratoire de Physique de Clermont Auvergne, Sejong University, Kansas State University, Evgeni Kharadze Georgian National Astrophysical Observatory, Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, Max Planck Institute for Extraterrestrial Physics, Ohio University
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, U.S. Department of Energy, Gordon and Betty Moore Foundation, Ministerio de Ciencia, Innovación y Universidades, Ministry of Education, Culture, Sports, Science and Technology, Cabinet Office, Government of Japan, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Toray Science Foundation, Office of Science, Natural Sciences and Engineering Research Council of Canada, Science and Technology Facilities Council, Japan Society for the Promotion of Science, Japan Science and Technology Agency, Division of Astronomical Sciences
OpenAlex ID: W7214015293