No Detectable One-halo Galactic Conformity Signal with Halo-mass Estimates Consistent with Weak-lensing Constraints
Abstract
One-halo galactic conformity is the tendency for satellites in halos with quenched centrals to have lower star-formation activity than those in halos with star-forming centrals at fixed halo mass. It is an important probe of the galaxy--halo connection and halo-wide quenching processes that may couple central and satellite evolution. However, its existence remains controversial, because conformity must be measured at fixed halo mass, while halo masses are difficult to estimate accurately. In this Letter, we measure one-halo conformity in SDSS using five stellar-mass-complete samples and three halo-mass estimates: an ML estimate whose star-forming and quenched stellar mass--halo mass relations (SHMRs) agree with independent weak-lensing constraints, and two conventional abundance-matching (AM) estimates. We quantify conformity as the difference in median log(sSFR) between satellites of star-forming and quenched centrals, using both satellite-level and halo-level statistics. The two AM estimates produce strong positive conformity signals, consistent with previous AM-based measurements, but these signals are not reproduced with the ML halo masses. For the halo-level statistic, the representative AM-based signals are +0.38±0.04 dex and +0.23±0.04 dex for the luminosity-ranking and mass-ranking AM halo masses, detected relative to no conformity at about 10σ and 6σ, respectively. In contrast, the ML result is consistent with no conformity, +0.00±0.03 dex; the satellite-level statistic gives a similar result. Thus, with halo-mass estimates consistent with weak-lensing constraints, we find no detectable one-halo conformity signal in the present SDSS sample, suggesting that the strong AM-based signal is largely driven by halo-mass estimation biases.
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BibTeX
@misc{zhao2026detectable,
title = {{No Detectable One-halo Galactic Conformity Signal with Halo-mass Estimates Consistent with Weak-lensing Constraints}},
author = {Dingyi Zhao and Yingjie Peng and Luis C. Ho and Houjun Mo and Cheqiu Lyu and Kai Wang and Yijun Wang and Tao Wang and Jing Dou and Zeyu Gao and Qiusheng Gu and Yukun Liu and Roberto Maiolino and Alvio Renzini and Bitao Wang and Yu-Chen Wang and Bingxiao Xu and Feng Yuan and Kunyao Zhao and Xingye Zhu},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.11313},
eprint = {2609.11313},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.11313},
}
RIS
TY - UNPB
TI - No Detectable One-halo Galactic Conformity Signal with Halo-mass Estimates Consistent with Weak-lensing Constraints
AU - Dingyi Zhao
AU - Yingjie Peng
AU - Luis C. Ho
AU - Houjun Mo
AU - Cheqiu Lyu
AU - Kai Wang
AU - Yijun Wang
AU - Tao Wang
AU - Jing Dou
AU - Zeyu Gao
AU - Qiusheng Gu
AU - Yukun Liu
AU - Roberto Maiolino
AU - Alvio Renzini
AU - Bitao Wang
AU - Yu-Chen Wang
AU - Bingxiao Xu
AU - Feng Yuan
AU - Kunyao Zhao
AU - Xingye Zhu
PY - 2026
DA - 2026/09/10
PB - arXiv
DO - 10.48550/arxiv.2609.11313
UR - https://arxiv.org/abs/2609.11313
AB - One-halo galactic conformity is the tendency for satellites in halos with quenched centrals to have lower star-formation activity than those in halos with star-forming centrals at fixed halo mass. It is an important probe of the galaxy--halo connection and halo-wide quenching processes that may couple central and satellite evolution. However, its existence remains controversial, because conformity must be measured at fixed halo mass, while halo masses are difficult to estimate accurately. In this Letter, we measure one-halo conformity in SDSS using five stellar-mass-complete samples and three halo-mass estimates: an ML estimate whose star-forming and quenched stellar mass--halo mass relations (SHMRs) agree with independent weak-lensing constraints, and two conventional abundance-matching (AM) estimates. We quantify conformity as the difference in median log(sSFR) between satellites of star-forming and quenched centrals, using both satellite-level and halo-level statistics. The two AM estimates produce strong positive conformity signals, consistent with previous AM-based measurements, but these signals are not reproduced with the ML halo masses. For the halo-level statistic, the representative AM-based signals are +0.38±0.04 dex and +0.23±0.04 dex for the luminosity-ranking and mass-ranking AM halo masses, detected relative to no conformity at about 10σ and 6σ, respectively. In contrast, the ML result is consistent with no conformity, +0.00±0.03 dex; the satellite-level statistic gives a similar result. Thus, with halo-mass estimates consistent with weak-lensing constraints, we find no detectable one-halo conformity signal in the present SDSS sample, suggesting that the strong AM-based signal is largely driven by halo-mass estimation biases.
ER -