2020/11/05 by Glenn G. Kacprzak, Nikole M. Nielsen, Hasti Nateghi +6
Environmental Science · Medicine · Physics and Astronomy · #Absorption (acoustics) #Astronomy #Astrophysics #Emission spectrum #Equivalent width #Galaxies: Formation, Evolution, Phenomena #Galaxy #Medicine #Metallicity #Physics #Plant Water Relations and Carbon Dynamics #Population #Quasar #Spectral line #Star formation #Stellar, planetary, and galactic studies #astro-ph.GA
paper · pdf · doi:10.1093/mnras/staa3461
14 pages, 9 figures, 2 tables. Accepted to MNRAS on November 4, 2020
arxiv created 2020/11/05 · openalex publication_date 2020/11/06 · arxiv updated 2020/11/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
ABSTRACT The relationship between a galaxy’s properties and its circumgalactic medium (CGM) provides a unique view of how galaxies evolve. We present an interesting edge-on (i = 86°) disc galaxy (G1547) where the CGM is probed by a background quasar at a distance of 84 kpc and within 10° of the galaxy major axis. G1547 does not have any detectable CGM absorption down to stringent limits, covering H i (EWr <0.02 Å, log(N(H i)/cm−2) < 12.6) and a range of low and high ionization absorption lines (O i, C ii, N ii, Si ii, C iii, N iii, Si iii, C iv, Si iv, N v, and O vi). This system is rare, given the covering fraction of 1.00-0.04+0.00 for sub-L* galaxies within 50–100 kpc of quasar sightlines. G1547 has a low star formation rate (SFR, 1.1 M⊙ yr−1), specific SFR (sSFR, 1.5 × 10−10 yr−1), and ΣSFR (0.06 M⊙ yr−1 kpc−2) and does not exhibit active galactic nucleus or star-formation-driven outflows. Compared to the general population of galaxies, G1547 is in the green valley and has an above average metallicity with a negative gradient. When compared to other H i absorption-selected galaxies, we find that quiescent galaxies with log(sSFR/yr−1) < −11 have a low probability (4/12) of possessing detectable H i in their CGM, while all galaxies (40/40) with log(sSFR/yr−1) > −11 have H i absorption. We conclude that sSFR is a good indicator of the presence of H i CGM. Interestingly however, G1547 is the only galaxy with log(sSFR/yr−1) > −11 that has no detectable CGM. Given the properties of G1547, and its absent CGM, it is plausible that G1547 is undergoing quenching due to a lack of accreting fuel for star formation, with an estimated quenching time-scale of 4 ± 1 Gyr. G1547 provides a unique perspective into the external mechanisms that could explain the migration of galaxies into the green valley.