TY - JOUR
T1 - Emission Line Ratios for the Circumgalactic Medium and the "bimodal" Nature of Galaxies
AU - Zhang, Huanian
AU - Zaritsky, Dennis
AU - Werk, Jessica
AU - Behroozi, Peter
N1 - Funding Information:
D.Z. and H.Z. acknowledge financial support from NSF grant AST-1311326. J.W. acknowledges support from a 2018 Alfred P. Sloan Research Fellowship. The authors gratefully acknowledge the SDSS-III team for providing a valuable resource to the community. Funding for SDSS-III has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, and the U.S. Department of Energy Office of Science. The SDSS-III web site ishttp://www.sdss3.org/.
Publisher Copyright:
© 2018. The American Astronomical Society. All rights reserved.
PY - 2018/10/10
Y1 - 2018/10/10
N2 - We find significantly different diagnostic emission line ratios for the circumgalactic gas associated with galaxies of stellar masses above and below 1010.4 M o 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] λ5007, Hα, and [N ii] λ6583, 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.
AB - We find significantly different diagnostic emission line ratios for the circumgalactic gas associated with galaxies of stellar masses above and below 1010.4 M o 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] λ5007, Hα, and [N ii] λ6583, 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.
KW - galaxies: halos
KW - galaxies: kinematics and dynamics
KW - galaxies: structure
KW - intergalactic medium
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U2 - 10.3847/2041-8213/aae37e
DO - 10.3847/2041-8213/aae37e
M3 - Article
AN - SCOPUS:85055214087
SN - 2041-8205
VL - 866
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 1
M1 - L4
ER -