Star formation powers optical line emission from the CGM
Abstract
Using integral field spectroscopy, we explore the disk-halo interface, or the inner circumgalactic medium (CGM), of individual galaxies by constructing and analyzing emission-line maps for a large sample (72) of normal, low-redshift galaxies spanning three orders of magnitude in stellar mass and four orders in star formation rate (SFR). We find a steep turnover occurring at (1−2) Re in the Hα, [O {\small II}], and [O {\small III}] line emission radial profiles. Beyond this radius, the slope of the line emission radial profiles becomes shallower as the SFR of the central galaxy decreases, which might reflect the strength of the feedback processes. The line emission fluxes at large radius ((5−10) Re or ∼ (0.1−0.25)rvir) correlate with the galaxy's SFR, but not with its stellar mass. These findings suggest that ionizing photons escaping from star-forming regions in the central galaxy account for the observed emission line fluxes from the inner CGM, with escape fractions inferred from the [O {\small III}] and [O {\small II}] ratio. Different state-of-the-art theoretical models do not agree on the predicted dependence of cool gas on the SFR of the central galaxies, highlighting the importance of CGM emission line measurements to distinguish between different subgrid models for star formation and feedback processes.
Related
- The JWST Emission Line Survey (JELS): A narrow-band determination of the Hα Luminosity Function and Cosmic Star Formation into the Epoch of Reionization
- J-PAS: Exploring the connection between local environment and the triggering of bursty star formation in Extreme Emission Line Galaxies
- Evolutionary Map of the Universe (EMU): Selection of active galactic nuclei and star-formation emission with machine-learning techniques
- A Direct DESI--SDSS Two-Fibre Test of Aperture Bias in Optical Emission-Line Diagnostics
- Evolutionary Map of the Universe (EMU): Selection of active galactic nuclei and star-formation emission with machine-learning techniques
BibTeX
@misc{zhang2026star,
title = {{Star formation powers optical line emission from the CGM}},
author = {Huanian Zhang and Lizhi Xie and Zhijie Qu and Dennis Zaritsky and Luis C. Ho and Min Bao and Fabio Fontanot and Michaela Hirschmann and Chenxu Liu and Gabriella De Lucia and Enci Wang and Haoyan Zheng},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2607.18385},
eprint = {2607.18385},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.18385},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Star formation powers optical line emission from the CGM
AU - Huanian Zhang
AU - Lizhi Xie
AU - Zhijie Qu
AU - Dennis Zaritsky
AU - Luis C. Ho
AU - Min Bao
AU - Fabio Fontanot
AU - Michaela Hirschmann
AU - Chenxu Liu
AU - Gabriella De Lucia
AU - Enci Wang
AU - Haoyan Zheng
PY - 2026
DA - 2026/10/09
PB - arXiv
DO - 10.48550/arxiv.2607.18385
UR - https://arxiv.org/abs/2607.18385
AB - Using integral field spectroscopy, we explore the disk-halo interface, or the inner circumgalactic medium (CGM), of individual galaxies by constructing and analyzing emission-line maps for a large sample (72) of normal, low-redshift galaxies spanning three orders of magnitude in stellar mass and four orders in star formation rate (SFR). We find a steep turnover occurring at (1−2) R_e in the Hα, [O {\small II}], and [O {\small III}] line emission radial profiles. Beyond this radius, the slope of the line emission radial profiles becomes shallower as the SFR of the central galaxy decreases, which might reflect the strength of the feedback processes. The line emission fluxes at large radius ((5−10) R_e or ∼ (0.1−0.25)r_vir) correlate with the galaxy's SFR, but not with its stellar mass. These findings suggest that ionizing photons escaping from star-forming regions in the central galaxy account for the observed emission line fluxes from the inner CGM, with escape fractions inferred from the [O {\small III}] and [O {\small II}] ratio. Different state-of-the-art theoretical models do not agree on the predicted dependence of cool gas on the SFR of the central galaxies, highlighting the importance of CGM emission line measurements to distinguish between different subgrid models for star formation and feedback processes.
ER -