Kavli Affiliate: Jing Wang
| First 5 Authors: Sijia Li, Sijia Li, , ,
| Summary:
The interstellar medium (ISM) in high-redshift galaxies exhibits
significantly higher electron densities ($n_rm e$) than in the local
universe. To investigate the origin of this trend, we analyze a sample of 9590
centrally star-forming galaxies with stellar masses greater than
$10^9,M_odot$ at redshifts $0.01 < z < 0.04$, selected from the Dark Energy
Spectroscopic Instrument (DESI) Data Release 1. We derive electron densities
from the [S II] $lambdalambda6716,6731$ doublet, measuring values of $n_rm
e = 30$-$400~rm cm^-3$ at $z approx 0$. We find a tight correlation
between $n_rm e$ and the star formation rate surface density ($Sigma_rm
SFR$), which is well described by a broken power law. Above a threshold of
$log(Sigma_rm SFR / M_odot,rm yr^-1,kpc^-2) ge -1.46$, the
relation follows $n_rm e = (233 pm 13),Sigma_rm SFR^0.49 pm 0.02$.
Below this threshold, $n_rm e$ remains approximately constant at $44 pm
3~rm cm^-3$. Remarkably, this relation remains consistent with
measurements of galaxies at $z = 0.9$-$10.2$. By converting the observed
redshift evolution of $Sigma_rm SFR$ into $n_rm e$ evolution through our
$n_rm e$-$Sigma_rm SFR$ relation, we obtain $n_rm e =
40(1+z)^1.4~rm cm^-3$, consistent with previous direct observations. The
$n_rm e$-$Sigma_rm SFR$ relation likely arises because the high
$Sigma_rm SFR$, fueled by dense cold gas or elevated efficiency, enhances
radiative and mechanical feedback and produces dense ionized gas whose electron
densities are further regulated by ambient pressure. We conclude that the
redshift evolution of $n_rm e$ primarily reflects the evolution of cold gas
density and star formation activity over cosmic time.
| Search Query: ArXiv Query: search_query=au:”Jing Wang”&id_list=&start=0&max_results=3