Spectroscopic Characterization of redMaPPer Galaxy Clusters with DESI

ABSTRACT Optical galaxy cluster identification algorithms such as redMaPPer promise to enable an array of astrophysical and cosmological studies, but suffer from biases whereby galaxies in front of and behind a galaxy cluster are mistakenly associated with the primary cluster halo. These projection effects caused by irreducible photometric redshift uncertainty must be quantified to facilitate the use of optical cluster catalogues. We present measurements of galaxy cluster projection effects and velocity dispersion using spectroscopy from the Dark Energy Spectroscopic Instrument. Our findings are as follows: we confirm that the fraction of redMaPPer putative member galaxies mistakenly associated with cluster haloes is richness dependent, being more than twice as large at low richness than high richness; we present the first spectroscopic evidence of an increase in projection effects with increasing redshift, by as much as 25 per cent from $z\sim 0.1$ to $z\sim 0.2$; moreover, we find qualitative evidence for luminosity dependence in projection effects, with fainter galaxies being more commonly far behind clusters than their bright counterparts; finally, we fit the scaling relation between measured mean spectroscopic richness and velocity dispersion, finding an implied linear scaling between spectroscopic richness and halo mass. We discuss further directions for the application of spectroscopic data sets to improve use of optically selected clusters to test cosmological models.

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Publication Details

Journal
Monthly Notices of the Royal Astronomical Society
Published
2025-10-22
DOI
https://doi.org/10.1093/mnras/staf1831
Citations
1
Primary Topic
Nanocluster Synthesis and Applications
Type
article
Field-Weighted Citation Impact
0.52

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article

Spectroscopic Characterization of redMaPPer Galaxy Clusters with DESI

D. Gruen, J. Myles, D. Bianchi, B A Weaver et al.
1 citations
Monthly Notices of the Royal Astronomical Society
Nanocluster Synthesis and Applications
0.52
article

Spectroscopic Characterization of redMaPPer Galaxy Clusters with DESI

D. Gruen, J. Myles, D. Bianchi, B A Weaver, José Aguilar, Anthony Kremin, Peter Doel, Shaojun Fu, J. Silber, J. E. Forero-Romero, Steven P. Ahlen, R. Kehoe, John Moustakas, G Gutierrez, T Jeltema, O. Lahav, R. Miquel, T. Kisner, M Schubnell, Marc Manera, T. Claybaugh
article en
1 citations

Abstract

ABSTRACT Optical galaxy cluster identification algorithms such as redMaPPer promise to enable an array of astrophysical and cosmological studies, but suffer from biases whereby galaxies in front of and behind a galaxy cluster are mistakenly associated with the primary cluster halo. These projection effects caused by irreducible photometric redshift uncertainty must be quantified to facilitate the use of optical cluster catalogues. We present measurements of galaxy cluster projection effects and velocity dispersion using spectroscopy from the Dark Energy Spectroscopic Instrument. Our findings are as follows: we confirm that the fraction of redMaPPer putative member galaxies mistakenly associated with cluster haloes is richness dependent, being more than twice as large at low richness than high richness; we present the first spectroscopic evidence of an increase in projection effects with increasing redshift, by as much as 25 per cent from $z\sim 0.1$ to $z\sim 0.2$; moreover, we find qualitative evidence for luminosity dependence in projection effects, with fainter galaxies being more commonly far behind clusters than their bright counterparts; finally, we fit the scaling relation between measured mean spectroscopic richness and velocity dispersion, finding an implied linear scaling between spectroscopic richness and halo mass. We discuss further directions for the application of spectroscopic data sets to improve use of optically selected clusters to test cosmological models.

Monthly Notices of the Royal Astronomical SocietyVol. 544(2)
Boston University (US), Institució Catalana de Recerca i Estudis Avançats (ES), Universidad Complutense de Madrid (ES), Universitat Autònoma de Barcelona (ES), Centre National de la Recherche Scientifique (FR), Fermi National Accelerator Laboratory (US), Institute of Space Sciences (ES), Lawrence Berkeley National Laboratory (US), State Street (United States) (US), Universidad de Los Andes (CO), The University of Texas at Dallas (US), University of Pittsburgh (US), Southern Methodist University (US), University of California, Santa Cruz (US), Institute for High Energy Physics (ES), University of Milan (IT), Princeton University (US), University of California, Irvine (US), Commissariat à l'Énergie Atomique et aux Énergies Alternatives (FR), Université Paris-Saclay (FR), University of Michigan (US), SLAC National Accelerator Laboratory (US), Brera Astronomical Observatory (IT), Sejong University (KR), Sorbonne Université (FR), Institut d'Estudis Espacials de Catalunya (ES), Excellence Cluster Origins (DE), Laboratoire de Physique Nucléaire et de Hautes Énergies (FR), CEA Paris-Saclay (FR), Institut National de Physique Nucléaire et de Physique des Particules (FR), Community Science and Data Center (US), NSF NOIRLab (US), Universidad de Los Andes (BO), Instituto de Astrofísica de Andalucía (ES), Institut de Recherche sur les Lois Fondamentales de l'Univers (FR), Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (ES), University College London (GB), University of Virginia (US), The Ohio State University (US), University of Portsmouth (GB), Ludwig-Maximilians-Universität München (DE), Universidad Nacional Autónoma de México (MX), Siena College (US), University of California, Berkeley (US), Universitat Politècnica de Catalunya (ES), Stanford University (US)
National Science Foundation, U.S. Department of Energy, Alfred P. Sloan Foundation, Gordon and Betty Moore Foundation, Brinson Foundation, University of Utah, Ministerio de Ciencia e Innovación, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Office of Science, Science and Technology Facilities Council, Division of Astronomical Sciences
Openalex Percentile: Top 37%
Nanocluster Synthesis and Applications
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