Environmental dependence of galaxy properties in the DESI DR1 Bright Galaxy Survey: Star formation, morphology, and AGN activity at z < 0.55
Abstract
We present the environmental dependence of galaxy properties using ∼1.4 million BGS_BRIGHT galaxies in groups and clusters (log(Mh/M⊙) ≥ 12.5) from the Dark Energy Spectroscopic Instrument (DESI) Data Release 1 at 0.05 < z < 0.55. Using the magnitude-limited BGS_BRIGHT sample (r < 19.5) and the extended halo-based group catalogue, we examine how specific star formation rate (sSFR), Sersic index, and active galactic nucleus (AGN) fraction depend on halo mass across stellar masses log(M*/M⊙) = 9.0-$12.0$ and halo masses log(Mh/M⊙) = 12.5-$15.0$. The median sSFR decreases with increasing halo mass, but much of this trend is driven by the rising satellite fraction rather than stronger suppression of individual galaxies. Satellites show lower median sSFR than centrals at fixed stellar mass and halo mass, most clearly at intermediate stellar masses. The stellar mass threshold at which the environmental trend becomes apparent shifts from log(M*/M⊙) ∼ 11 at z ∼ 0.4 to ∼ 10 at z ∼ 0.1, a shift that partly tracks the survey's rising stellar-mass completeness limit. The mean Sersic index increases only weakly with halo mass (median Δlog(n) ≈ 0.05 from field to cluster at fixed stellar mass and redshift). Among emission-line-detected galaxies (S/N > 3 in all four BPT lines), the combined AGN fraction increases monotonically with stellar mass. At fixed stellar mass, the Seyfert fraction shows no significant environmental trend (consistent with flat; field-to-cluster differences ≲ 3σ in the only well-populated high-mass bin), and the LINER fraction likewise shows no clear environmental trend. The most robust outcome of this work is the relative environmental ordering of galaxy properties and its decomposition into intrinsic suppression and compositional (satellite fraction) effects.
Versions
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BibTeX
@misc{kim2026environmental,
title = {{Environmental dependence of galaxy properties in the DESI DR1 Bright Galaxy Survey: Star formation, morphology, and AGN activity at z < 0.55}},
author = {Duho Kim},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2608.01940},
eprint = {2608.01940},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.01940},
}
RIS
TY - UNPB
TI - Environmental dependence of galaxy properties in the DESI DR1 Bright Galaxy Survey: Star formation, morphology, and AGN activity at z < 0.55
AU - Duho Kim
PY - 2026
DA - 2026/08/03
PB - arXiv
DO - 10.48550/arxiv.2608.01940
UR - https://arxiv.org/abs/2608.01940
AB - We present the environmental dependence of galaxy properties using ∼1.4 million BGS_BRIGHT galaxies in groups and clusters (log(M_h/M_⊙) ≥ 12.5) from the Dark Energy Spectroscopic Instrument (DESI) Data Release 1 at 0.05 < z < 0.55. Using the magnitude-limited BGS_BRIGHT sample (r < 19.5) and the extended halo-based group catalogue, we examine how specific star formation rate (sSFR), Sersic index, and active galactic nucleus (AGN) fraction depend on halo mass across stellar masses log(M_*/M_⊙) = 9.0-$12.0$ and halo masses log(M_h/M_⊙) = 12.5-$15.0$. The median sSFR decreases with increasing halo mass, but much of this trend is driven by the rising satellite fraction rather than stronger suppression of individual galaxies. Satellites show lower median sSFR than centrals at fixed stellar mass and halo mass, most clearly at intermediate stellar masses. The stellar mass threshold at which the environmental trend becomes apparent shifts from log(M_*/M_⊙) ∼ 11 at z ∼ 0.4 to ∼ 10 at z ∼ 0.1, a shift that partly tracks the survey's rising stellar-mass completeness limit. The mean Sersic index increases only weakly with halo mass (median Δlog(n) ≈ 0.05 from field to cluster at fixed stellar mass and redshift). Among emission-line-detected galaxies (S/N > 3 in all four BPT lines), the combined AGN fraction increases monotonically with stellar mass. At fixed stellar mass, the Seyfert fraction shows no significant environmental trend (consistent with flat; field-to-cluster differences ≲ 3σ in the only well-populated high-mass bin), and the LINER fraction likewise shows no clear environmental trend. The most robust outcome of this work is the relative environmental ordering of galaxy properties and its decomposition into intrinsic suppression and compositional (satellite fraction) effects.
ER -