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Title: The diffuse galactic far-ultraviolet sky

Abstract

We present an all-sky map of the diffuse Galactic far ultraviolet (1344-1786 Å) background using Galaxy Evolution Explorer data, covering 65% of the sky with 11.79 arcmin{sup 2} pixels. We investigate the dependence of the background on Galactic coordinates, finding that a standard cosecant model of intensity is not a valid fit. Furthermore, we compare our map to Galactic all-sky maps of 100 μm emission, N {sub H} {sub I} column, and Hα intensity. We measure a consistent low level far-UV (FUV) intensity at zero points for other Galactic quantities, indicating a 300 photons cm{sup –2} s{sup –1} sr{sup –1} Å{sup –1} non-scattered isotropic component to the diffuse FUV. There is also a linear relationship between FUV and 100 μm emission below 100 μm values of 8 MJy sr{sup –1}. We find a similar linear relationship between FUV and N {sub H} {sub I} below 10{sup 21} cm{sup –2}. The relationship between FUV and Hα intensity has no such constant cutoff. For all Galactic quantities, the slope of the linear portion of the relationship decreases with Galactic latitude. A modified cosecant model, taking into account dust scattering asymmetry and albedo, is able to accurately fit the diffuse FUV at latitudesmore » above 20°. The best fit model indicates an albedo, a, of 0.62 ± 0.04 and a scattering asymmetry function, g, of 0.78 ± 0.05. Deviations from the model fit may indicate regions of excess FUV emission from fluorescence or shock fronts, while low latitude regions with depressed FUV emission are likely the result of self-shielding dusty clouds.« less

Authors:
;  [1];  [2]
  1. Department of Astronomy, Columbia University, 550 W 120th St, New York, NY 10025 (United States)
  2. Carnegie Institution of Science, 813 Santa Barbara Street, Pasadena, CA 91101,USA (United States)
Publication Date:
OSTI Identifier:
22348394
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 779; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ALBEDO; ASYMMETRY; COMPARATIVE EVALUATIONS; DUSTS; EVOLUTION; FAR ULTRAVIOLET RADIATION; FLUORESCENCE; GALAXIES; SCATTERING; SELF-SHIELDING; SKY

Citation Formats

Hamden, Erika T., Schiminovich, David, and Seibert, Mark. The diffuse galactic far-ultraviolet sky. United States: N. p., 2013. Web. doi:10.1088/0004-637X/779/2/180.
Hamden, Erika T., Schiminovich, David, & Seibert, Mark. The diffuse galactic far-ultraviolet sky. United States. https://doi.org/10.1088/0004-637X/779/2/180
Hamden, Erika T., Schiminovich, David, and Seibert, Mark. 2013. "The diffuse galactic far-ultraviolet sky". United States. https://doi.org/10.1088/0004-637X/779/2/180.
@article{osti_22348394,
title = {The diffuse galactic far-ultraviolet sky},
author = {Hamden, Erika T. and Schiminovich, David and Seibert, Mark},
abstractNote = {We present an all-sky map of the diffuse Galactic far ultraviolet (1344-1786 Å) background using Galaxy Evolution Explorer data, covering 65% of the sky with 11.79 arcmin{sup 2} pixels. We investigate the dependence of the background on Galactic coordinates, finding that a standard cosecant model of intensity is not a valid fit. Furthermore, we compare our map to Galactic all-sky maps of 100 μm emission, N {sub H} {sub I} column, and Hα intensity. We measure a consistent low level far-UV (FUV) intensity at zero points for other Galactic quantities, indicating a 300 photons cm{sup –2} s{sup –1} sr{sup –1} Å{sup –1} non-scattered isotropic component to the diffuse FUV. There is also a linear relationship between FUV and 100 μm emission below 100 μm values of 8 MJy sr{sup –1}. We find a similar linear relationship between FUV and N {sub H} {sub I} below 10{sup 21} cm{sup –2}. The relationship between FUV and Hα intensity has no such constant cutoff. For all Galactic quantities, the slope of the linear portion of the relationship decreases with Galactic latitude. A modified cosecant model, taking into account dust scattering asymmetry and albedo, is able to accurately fit the diffuse FUV at latitudes above 20°. The best fit model indicates an albedo, a, of 0.62 ± 0.04 and a scattering asymmetry function, g, of 0.78 ± 0.05. Deviations from the model fit may indicate regions of excess FUV emission from fluorescence or shock fronts, while low latitude regions with depressed FUV emission are likely the result of self-shielding dusty clouds.},
doi = {10.1088/0004-637X/779/2/180},
url = {https://www.osti.gov/biblio/22348394}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 779,
place = {United States},
year = {Fri Dec 20 00:00:00 EST 2013},
month = {Fri Dec 20 00:00:00 EST 2013}
}