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Mid-Infrared Spectral Assessment of Early-type Galaxies with Star Formation

Published online by Cambridge University Press:  05 December 2011

Lerothodi L. Leeuw
Affiliation:
Physics Department, U. of Johannesburg, P.O. Box 524, Auckland Park, 2006, South Africa email: lerothodi@alum.mit.edu SETI Institute, 515 N. Whisman Avenue, Mountain View, CA 94043, USA
Jesse D. Bregman
Affiliation:
Space Science and Astrophysics Branch, NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035, USA
Jacqueline Davidson
Affiliation:
U. of Western Australia, School of Physics, 35 Stirling Hwy, Crawley, WA 6009, Australia
Pasquale Temi
Affiliation:
Space Science and Astrophysics Branch, NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035, USA
Stephen S. Im
Affiliation:
Space Science and Astrophysics Branch, NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035, USA
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Abstract

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Mid-infrared (mid-IR) spectra from ~5 to 14 μm of five, nearby (< 70 Mpc) elliptical galaxies are presented that were observed with the Infrared Spectrograph on the Spitzer Space Telescope. The sample galaxies have a main stellar component that is typical for normal, passively evolving ellipticals; however, they are rich in cold gas and dust and have morphological-merger signatures from which a time order of the galaxies since the merger or accretion events can be estimated. The presented results are significant because (1) emission due to Polycyclic Aromatic Hydrocarbons (PAHs) and associated species is detected for the first time in these galaxies and (2) the detected mid-IR spectra are independently exploited as a probe of current or recent star-formation that, in this case, is assumed to be triggered by the merger. As shown in exemplary spectra of the early-age merger NGC 3656, the strength of the PAH emission is more centrally peaked in the earlier-age mergers, suggesting that the PAH data are indeed probing star-formation that is correlated with the time since the mergers and systematically depletes the centrally located gas, becoming weaker and more flatly distributed as the merger evolves.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2011

References

Balcells, M. 1997, ApJL, 486, L87Google Scholar
Balcells, M., vanAAAAGorkom, J. H., Sancisi, R., & delAAAABurgo, C. 2001, AJ, 122, 1758Google Scholar
Bregman, J. N., Temi, P., & Bregman, J. D. 2006, ApJ, 647, 265CrossRefGoogle Scholar
Galliano, F., Madden, S. C., Tielens, A. G. G. M., Peeters, E., & Jones, A. P. 2008, ApJ, 679, 310Google Scholar
Leeuw, L. L., Davidson, J., Dowell, C. D., & Matthews, H. E. 2008, ApJ, 677, 249Google Scholar
Quillen, A. C., Bland-Hawthorn, J., Green, J. D., Smith, J. D., Prasad, D. A., Alonso-Herrero, A., Cleary, K., Brookes, M. H., & Lawrence, C. R. 2008, MNRAS, 384, 1469Google Scholar
Rothberg, B. & Joseph, R. D. 2004, AJ, 128, 2098Google Scholar
Rothberg, B. & Joseph, R. D. 2006, AJ, 132, 976 727Google Scholar
Young, L. M. 2005, ApJ, 634, 258CrossRefGoogle Scholar
Young, L. M., Bendo, G. J., & Lucero, D. M. 2009, AJ, 137, 3053CrossRefGoogle Scholar