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Title: THE NATURE OF THE SECOND PARAMETER IN THE IRX-{beta} RELATION FOR LOCAL GALAXIES

Abstract

We present an analysis of 98 galaxies of low-dust content, selected from the Spitzer Local Volume Legacy survey, aimed at examining the relation between the ultraviolet (UV) color and dust attenuation in normal star-forming galaxies. The IRX-{beta} diagram relates the total dust attenuation in a galaxy, traced by the far-IR (FIR) to UV ratio, to the observed UV color, indicated by {beta}. Previous research has indicated that while starburst galaxies exhibit a relatively tight IRX-{beta} relation, normal star-forming galaxies do not, and have a much larger spread in the total-IR to far-UV (FUV) luminosity for a fixed UV color. We examine the role that the age of the stellar population plays as the ''second parameter'' responsible for the observed deviation and spread of star-forming galaxies from the starburst relation. We model the FUV to FIR spectral energy distribution of each galaxy according to two broad bins of star formation history (SFH): constant and instantaneous burst. We find clear trends between stellar population mean age estimators (extinction-corrected FUV/NIR, U - B, and EW(H{alpha})) and the UV color {beta}; the trends are mostly driven by the galaxies best-described by instantaneous burst populations. We also find a significant correlation between {beta} and themore » mean age directly determined from the best-fit instantaneous models. As already indicated by other authors, the UV attenuation in star-forming galaxies may not be recovered with the UV color alone and is highly influenced by the stellar population's mean age and SFH. Overall, the scatter in the IRX-{beta} diagram is better correlated with {beta} than with the perpendicular distance, d{sub p}.« less

Authors:
; ;  [1];  [2]
  1. Astronomy Department, University of Massachusetts, Amherst, MA 01003 (United States)
  2. STScI, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
Publication Date:
OSTI Identifier:
22130944
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 773; 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; COLOR; CORRELATIONS; ENERGY SPECTRA; FIRS; GEOPHYSICAL SURVEYS; POPULATIONS; PUBLIC OPINION; STARS; ULTRAVIOLET RADIATION

Citation Formats

Grasha, Kathryn, Calzetti, Daniela, Andrews, Jennifer E., Lee, Janice C., and Dale, Daniel A., E-mail: kgrasha@astro.umass.edu. THE NATURE OF THE SECOND PARAMETER IN THE IRX-{beta} RELATION FOR LOCAL GALAXIES. United States: N. p., 2013. Web. doi:10.1088/0004-637X/773/2/174.
Grasha, Kathryn, Calzetti, Daniela, Andrews, Jennifer E., Lee, Janice C., & Dale, Daniel A., E-mail: kgrasha@astro.umass.edu. THE NATURE OF THE SECOND PARAMETER IN THE IRX-{beta} RELATION FOR LOCAL GALAXIES. United States. https://doi.org/10.1088/0004-637X/773/2/174
Grasha, Kathryn, Calzetti, Daniela, Andrews, Jennifer E., Lee, Janice C., and Dale, Daniel A., E-mail: kgrasha@astro.umass.edu. 2013. "THE NATURE OF THE SECOND PARAMETER IN THE IRX-{beta} RELATION FOR LOCAL GALAXIES". United States. https://doi.org/10.1088/0004-637X/773/2/174.
@article{osti_22130944,
title = {THE NATURE OF THE SECOND PARAMETER IN THE IRX-{beta} RELATION FOR LOCAL GALAXIES},
author = {Grasha, Kathryn and Calzetti, Daniela and Andrews, Jennifer E. and Lee, Janice C. and Dale, Daniel A., E-mail: kgrasha@astro.umass.edu},
abstractNote = {We present an analysis of 98 galaxies of low-dust content, selected from the Spitzer Local Volume Legacy survey, aimed at examining the relation between the ultraviolet (UV) color and dust attenuation in normal star-forming galaxies. The IRX-{beta} diagram relates the total dust attenuation in a galaxy, traced by the far-IR (FIR) to UV ratio, to the observed UV color, indicated by {beta}. Previous research has indicated that while starburst galaxies exhibit a relatively tight IRX-{beta} relation, normal star-forming galaxies do not, and have a much larger spread in the total-IR to far-UV (FUV) luminosity for a fixed UV color. We examine the role that the age of the stellar population plays as the ''second parameter'' responsible for the observed deviation and spread of star-forming galaxies from the starburst relation. We model the FUV to FIR spectral energy distribution of each galaxy according to two broad bins of star formation history (SFH): constant and instantaneous burst. We find clear trends between stellar population mean age estimators (extinction-corrected FUV/NIR, U - B, and EW(H{alpha})) and the UV color {beta}; the trends are mostly driven by the galaxies best-described by instantaneous burst populations. We also find a significant correlation between {beta} and the mean age directly determined from the best-fit instantaneous models. As already indicated by other authors, the UV attenuation in star-forming galaxies may not be recovered with the UV color alone and is highly influenced by the stellar population's mean age and SFH. Overall, the scatter in the IRX-{beta} diagram is better correlated with {beta} than with the perpendicular distance, d{sub p}.},
doi = {10.1088/0004-637X/773/2/174},
url = {https://www.osti.gov/biblio/22130944}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 773,
place = {United States},
year = {Tue Aug 20 00:00:00 EDT 2013},
month = {Tue Aug 20 00:00:00 EDT 2013}
}