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Title: Detection of ultraviolet halos around highly inclined galaxies

Abstract

We report the discovery of diffuse ultraviolet light around late-type galaxies out to 5-20 kpc from the midplane using Swift and GALEX images. The emission is consistent with the stellar outskirts in the early-type galaxies but not in the late-type galaxies, where the emission is quite blue and consistent with a reflection nebula powered by light escaping from the galaxy and scattering off dust in the halo. Our results agree with expectations from halo dust discovered in extinction by Ménard et al. to within a few kpc of the disk and imply a comparable amount of hot and cold gas in galaxy halos (a few× 10{sup 8} M{sub ☉} within 20 kpc) if the dust resides primarily in Mg II absorbers. The results also highlight the potential of UV photometry to study individual galaxy halos.

Authors:
;  [1]
  1. Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States)
Publication Date:
OSTI Identifier:
22365667
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 789; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; DETECTION; DUSTS; EMISSION; GALAXIES; IMAGES; NEBULAE; PHOTOMETRY; REFLECTION; SCATTERING; ULTRAVIOLET RADIATION; VISIBLE RADIATION

Citation Formats

Hodges-Kluck, Edmund, and Bregman, Joel N., E-mail: hodgeskl@umich.edu. Detection of ultraviolet halos around highly inclined galaxies. United States: N. p., 2014. Web. doi:10.1088/0004-637X/789/2/131.
Hodges-Kluck, Edmund, & Bregman, Joel N., E-mail: hodgeskl@umich.edu. Detection of ultraviolet halos around highly inclined galaxies. United States. doi:10.1088/0004-637X/789/2/131.
Hodges-Kluck, Edmund, and Bregman, Joel N., E-mail: hodgeskl@umich.edu. Thu . "Detection of ultraviolet halos around highly inclined galaxies". United States. doi:10.1088/0004-637X/789/2/131.
@article{osti_22365667,
title = {Detection of ultraviolet halos around highly inclined galaxies},
author = {Hodges-Kluck, Edmund and Bregman, Joel N., E-mail: hodgeskl@umich.edu},
abstractNote = {We report the discovery of diffuse ultraviolet light around late-type galaxies out to 5-20 kpc from the midplane using Swift and GALEX images. The emission is consistent with the stellar outskirts in the early-type galaxies but not in the late-type galaxies, where the emission is quite blue and consistent with a reflection nebula powered by light escaping from the galaxy and scattering off dust in the halo. Our results agree with expectations from halo dust discovered in extinction by Ménard et al. to within a few kpc of the disk and imply a comparable amount of hot and cold gas in galaxy halos (a few× 10{sup 8} M{sub ☉} within 20 kpc) if the dust resides primarily in Mg II absorbers. The results also highlight the potential of UV photometry to study individual galaxy halos.},
doi = {10.1088/0004-637X/789/2/131},
journal = {Astrophysical Journal},
number = 2,
volume = 789,
place = {United States},
year = {Thu Jul 10 00:00:00 EDT 2014},
month = {Thu Jul 10 00:00:00 EDT 2014}
}
  • We examine ultraviolet halos around a sample of highly inclined galaxies within 25 Mpc to measure their morphology and luminosity. Despite contamination from galactic light scattered into the wings of the point-spread function, we find that ultraviolet (UV) halos occur around each galaxy in our sample. Around most galaxies the halos form a thick, diffuse disk-like structure, but starburst galaxies with galactic superwinds have qualitatively different halos that are more extensive and have filamentary structure. The spatial coincidence of the UV halos above star-forming regions, the lack of consistent association with outflows or extraplanar ionized gas, and the strong correlationmore » between the halo and galaxy UV luminosity suggest that the UV light is an extragalactic reflection nebula. UV halos may thus represent 10{sup 6}–10{sup 7} M {sub ⊙} of dust within 2–10 kpc of the disk, whose properties may change with height in starburst galaxies.« less
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