Emission Line Ratios for the Circumgalactic Medium and the “Bimodal” Nature of Galaxies
AffiliationUniv Arizona, Steward Observ
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PublisherIOP PUBLISHING LTD
CitationHuanian Zhang et al 2018 ApJL 866 L4
JournalASTROPHYSICAL JOURNAL LETTERS
Rights© 2018. The American Astronomical Society. All rights reserved.
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at email@example.com.
AbstractWe find significantly different diagnostic emission line ratios for the circumgalactic gas associated with galaxies of stellar masses above and below 10(10.4)M(circle dot) 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] lambda 5007, H alpha, and [N II] lambda 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.
VersionFinal published version
SponsorsNSF [AST-1311326]; 2018 Alfred P. Sloan Research Fellowship; Alfred P. Sloan Foundation; National Science Foundation; U.S. Department of Energy Office of Science; University of Arizona; Brazilian Participation Group; Brookhaven National Laboratory; Carnegie Mellon University; University of Florida; French Participation Group; German Participation Group; Harvard University; Instituto de Astrofisica de Canarias; Michigan State/Notre Dame/JINA Participation Group; Johns Hopkins University; Lawrence Berkeley National Laboratory; Max Planck Institute for Astrophysics; Max Planck Institute for Extraterrestrial Physics; New Mexico State University; New York University; Ohio State University; Pennsylvania State University; University of Portsmouth; Princeton University; Spanish Participation Group; University of Tokyo; University of Utah; Vanderbilt University; University of Virginia; University of Washington; Yale University