Even central galaxies feel their environment: cosmic siphoning of cool gas accretion
Abstract
Identifying the key processes regulating cool gas accretion in galaxies is essential for understanding the baryon cycle within galactic ecosystems. Recent studies indicate that the most fundamental internal process is likely the competition between halos and central black holes. This is revealed through a universal relation between increasing black hole masses and decreasing cool gas fraction (μHI ≡ MHI/M⋆ ∝ MBH−0.6). Here we further explore the primary external effects on cool gas accretion in central galaxies. We find that galaxies deviating significantly from the μHI−MBH relation are overwhelmingly isolated central galaxies without substantial satellites. These isolated, gas-poor centrals exhibit systematically higher black-hole-to-stellar-mass ratios and more prominent bulges. At larger scales, they are preferentially located near massive neighboring halos. We suggest that this may reflect a ``cosmic siphoning" scenario, replenished by their satellites and by gas flowing along the cosmic web. This model naturally explains the prevalence of gas-poor isolated central galaxies near massive halos. It complements internal regulation by supermassive black holes and suggests a cosmic 'rich get richer' scenario.
Related
- The Role of Environment in Shaping the Assembly Timelines of Massive Quiescent Galaxies at Cosmic Noon
- Tracing the Cosmic web across Cosmic time through SKA observations of radio galaxies
- Internal structure, not environment, shapes metallicity gradients in low-mass galaxies from MaNGA
- Ten years since the NGC 6334I-MM1 accretion outburst: the impact on its environment
- Ten years since the NGC 6334I-MM1 accretion outburst: the impact on its environment
BibTeX
@misc{xu2026even,
title = {{Even central galaxies feel their environment: cosmic siphoning of cool gas accretion}},
author = {Ke Xu and Tao Wang},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2607.13961},
eprint = {2607.13961},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.13961},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Even central galaxies feel their environment: cosmic siphoning of cool gas accretion
AU - Ke Xu
AU - Tao Wang
PY - 2026
DA - 2026/10/23
PB - arXiv
DO - 10.48550/arxiv.2607.13961
UR - https://arxiv.org/abs/2607.13961
AB - Identifying the key processes regulating cool gas accretion in galaxies is essential for understanding the baryon cycle within galactic ecosystems. Recent studies indicate that the most fundamental internal process is likely the competition between halos and central black holes. This is revealed through a universal relation between increasing black hole masses and decreasing cool gas fraction (μ_HI ≡ M_HI/M_⋆ ∝ M_BH^−0.6). Here we further explore the primary external effects on cool gas accretion in central galaxies. We find that galaxies deviating significantly from the μ_HI−M_BH relation are overwhelmingly isolated central galaxies without substantial satellites. These isolated, gas-poor centrals exhibit systematically higher black-hole-to-stellar-mass ratios and more prominent bulges. At larger scales, they are preferentially located near massive neighboring halos. We suggest that this may reflect a ``cosmic siphoning" scenario, replenished by their satellites and by gas flowing along the cosmic web. This model naturally explains the prevalence of gas-poor isolated central galaxies near massive halos. It complements internal regulation by supermassive black holes and suggests a cosmic 'rich get richer' scenario.
ER -