2018/09/24 by Huanian Zhang, Huanian 华年 Zhang 张, Dennis Zaritsky +2
Physics and Astronomy · #Accretion (finance) #Active galactic nucleus #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Emission spectrum #Galaxies: Formation, Evolution, Phenomena #Galaxy #Line (geometry) #Quasar #Sky #Spectral line #astro-ph.GA
paper · pdf · doi:10.3847/2041-8213/aae37e
5 pages, 3 figures, accepted by ApJL
arxiv created 2018/09/24 · openalex publication_date 2018/10/04 · arxiv updated 2018/10/17 · openalex created_date 2019/06/27 · openalex updated_date 2026/08/06
Abstract We find significantly different diagnostic emission line ratios for the circumgalactic gas associated with galaxies of stellar masses above and below 10 10.4 M ⊙ using Sloan Digital Sky Survey spectroscopy. Specifically, in a sample of 17,393 galaxies, intersected by 18,535 lines of sight at projected radii between 10 and 50 kpc, we stack measured fluxes for nebular strong emission lines, [O iii ] λ 5007, H α , and [N ii ] λ 6583, and find that the gas surrounding the lower-mass galaxies exhibits similar line ratios to those of gas ionized by star formation and that surrounding the higher-mass galaxies similar to those of gas ionized by active galactic nucleus or shocks. This finding highlights yet another characteristic of galaxies that is distinctly different above and below this stellar mass threshold, but one that is more closely connected to the gas accretion behavior hypothesized to be responsible for this dichotomy.