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The mid-infrared properties of starburst galaxies from Spitzer-IRS spectroscopy

Brandl, B. R. and Bernard-Salas, J. and Spoon, H. W. W. and Devost, D. and Sloan, G. C. and Guilles, S. and Wu, Y. and Houck, J. R. and Weedman, D. W. and Armus, L. and Appleton, P. N. and Soifer, B. T. and Charmandaris, V. and Hao, L. and Marshall, J. A. and Higdon, S. J. and Herter, T. L. (2006) The mid-infrared properties of starburst galaxies from Spitzer-IRS spectroscopy. Astrophysical Journal, 653 (2). pp. 1129-1144. ISSN 0004-637X.

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We present 5-38 μm mid-infrared spectra at a spectral resolution of R ≈ 65-130 of a large sample of 22 starburst nuclei taken with the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope. The spectra show a vast range of starburst SEDs. The silicate absorption ranges from essentially no absorption to heavily obscured systems with an optical depth of τ_(9.8 μm) ~ 5. The spectral slopes can be used to discriminate between starburst and AGN powered sources. The monochromatic continuum fluxes at 15 and 30 μm enable a remarkably accurate estimate of the total infrared luminosity of the starburst. We find that the PAH equivalent width is independent of the total starburst luminosity L_(IR) as both continuum and PAH feature scale proportionally. However, the luminosity of the 6.2 μm feature scales with L_(IR) and can be used to approximate the total infrared luminosity of the starburst. Although our starburst sample covers about a factor of 10 difference in the [Ne III]/[Ne II] ratio, we found no systematic correlation between the radiation field hardness and the PAH equivalent width or the 7.7 μm/11.3 μm PAH ratio. These results are based on spatially integrated diagnostics over an entire starburst region, and local variations may be "averaged out." It is presumably due to this effect that unresolved starburst nuclei with significantly different global properties appear spectrally as rather similar members of one class of objects.

Item Type:Article
Related URLs:
URLURL TypeDescription
Bernard-Salas, J.0000-0002-8452-8675
Spoon, H. W. W.0000-0002-8712-369X
Armus, L.0000-0003-3498-2973
Appleton, P. N.0000-0002-7607-8766
Charmandaris, V.0000-0002-2688-1956
Marshall, J. A.0000-0001-7712-8465
Higdon, S. J.0000-0002-4021-7453
Herter, T. L.0000-0002-3856-8385
Additional Information:© 2006 The American Astronomical Society. Received 2005 November 11; accepted 2006 August 31. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under NASA contract 1407. Support for this work was provided by NASA through contract 1257184 issued by JPL/Caltech.
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Subject Keywords:galaxies: starburst; infrared: galaxies
Issue or Number:2
Record Number:CaltechAUTHORS:20110217-112209402
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Official Citation:The Mid-Infrared Properties of Starburst Galaxies from Spitzer-IRS Spectroscopy B. R. Brandl, J. Bernard-Salas, H. W. W. Spoon, D. Devost, G. C. Sloan, S. Guilles, Y. Wu, J. R. Houck, D. W. Weedman, L. Armus, P. N. Appleton, B. T. Soifer, V. Charmandaris, L. Hao, J. A. Marshall, S. J. Higdon, and T. L. Herter doi: 10.1086/508849
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:22356
Deposited By: Ruth Sustaita
Deposited On:17 Feb 2011 22:15
Last Modified:04 Nov 2019 22:13

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