TY - JOUR
T1 - Emission from the Ionized Gaseous Halos of Low-redshift Galaxies and Their Neighbors
AU - Zhang, Huanian
AU - Zaritsky, Dennis
AU - Behroozi, Peter
N1 - Publisher Copyright:
© 2018. The American Astronomical Society. All rights reserved.
PY - 2018/7/1
Y1 - 2018/7/1
N2 - Using a sample of nearly half a million galaxies, intersected by over 8 million lines of sight from the Sloan Digital Sky Survey Data Release 12, we extend our previous study of the recombination radiation emitted by the gaseous halos of nearby galaxies. We identify an inflection in the radial profile of the Hα+N[ii] radial emission profile at a projected radius of ∼50 kpc and suggest that beyond this radius the emission from ionized gas in spatially correlated halos dominates the profile. We confirm that this is a viable hypothesis using results from a highly simplified theoretical treatment in which the dark matter halo distribution from cosmological simulations is straightforwardly populated with gas. Whether we fit the fraction of halo gas in a cooler (T = 12,000 K), smooth (c = 1) component (0.26 for galaxies with M∗ = 10 10.88 M o and 0.34 for those with M∗ = 10 10.88 M o) or take independent values of this fraction from published hydrodynamical simulations (0.19 and 0.38, respectively), this model successfully reproduces the radial location and amplitude of the observed inflection. We also observe that the physical nature of the gaseous halo connects to primary galaxy morphology beyond any relationship to the galaxy's stellar mass and star formation rate. We explore whether the model reproduces behavior related to the central galaxy's stellar mass, star formation rate, and morphology. We find that it is unsuccessful in reproducing the observations at this level of detail and discuss various shortcomings of our simple model that may be responsible.
AB - Using a sample of nearly half a million galaxies, intersected by over 8 million lines of sight from the Sloan Digital Sky Survey Data Release 12, we extend our previous study of the recombination radiation emitted by the gaseous halos of nearby galaxies. We identify an inflection in the radial profile of the Hα+N[ii] radial emission profile at a projected radius of ∼50 kpc and suggest that beyond this radius the emission from ionized gas in spatially correlated halos dominates the profile. We confirm that this is a viable hypothesis using results from a highly simplified theoretical treatment in which the dark matter halo distribution from cosmological simulations is straightforwardly populated with gas. Whether we fit the fraction of halo gas in a cooler (T = 12,000 K), smooth (c = 1) component (0.26 for galaxies with M∗ = 10 10.88 M o and 0.34 for those with M∗ = 10 10.88 M o) or take independent values of this fraction from published hydrodynamical simulations (0.19 and 0.38, respectively), this model successfully reproduces the radial location and amplitude of the observed inflection. We also observe that the physical nature of the gaseous halo connects to primary galaxy morphology beyond any relationship to the galaxy's stellar mass and star formation rate. We explore whether the model reproduces behavior related to the central galaxy's stellar mass, star formation rate, and morphology. We find that it is unsuccessful in reproducing the observations at this level of detail and discuss various shortcomings of our simple model that may be responsible.
KW - galaxies: halos
KW - intergalactic medium
KW - large-scale structure of universe
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U2 - 10.3847/1538-4357/aac6b7
DO - 10.3847/1538-4357/aac6b7
M3 - Article
AN - SCOPUS:85049952464
SN - 0004-637X
VL - 861
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 34
ER -