MID-INFRARED SPECTROSCOPY OF OPTICALLY FAINT EXTRAGALACTIC 70 {mu}M SOURCES

Journal Article · Sun May 10 04:00:00 EDT 2009 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/696/2/2044; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21300626

Farrah, D ^[1]; Weedman, D; Houck, J ^[2]; Lonsdale, C J ^[3]; Polletta, M ^[4]; Rowan-Robinson, M ^[5]; Smith, H E ^[6]

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1. Astronomy Center, University of Sussex, Falmer, Brighton BN1 9RH (United Kingdom)
2. Astronomy Department, Cornell University, Ithaca, NY 14853 (United States)
3. ALMA Science Center, National Radio Astronomy Observatory, Edgemont Rd., Charlottesville, VA 22904 (United States)
4. INAF-ISAF Milano, via E. Bassini, Milan 20133 (Italy)
5. Astrophysics Group, Imperial College, London SW7 2BW (United Kingdom)
6. Center for Astrophysics and Space Sciences, University of California at San Diego, La Jolla, CA 92093 (United States)

We present mid-infrared (mid-IR) spectra of 16 optically faint sources with 70 {mu}m fluxes in the range 19 mJy <f {sub {nu}}(70 {mu}m) < 38 mJy. The sample spans a redshift range of 0.35 < z < 1.9, with most lying between 0.8 < z < 1.6, and has IR luminosities of 10{sup 12}-10{sup 13} L {sub sun}. 10 of the 16 objects show prominent polycyclic aromatic hydrocarbon (PAH) emission features; four of 16 show weak PAHs and strong silicate absorption, and two objects have no discernable spectral features. Compared to samples with f {sub {nu}}(24 {mu}m) > 10 mJy, the 70 {mu}m sample has steeper IR continua and higher luminosities. The PAH-dominated sources are among the brightest starbursts seen at any redshift, and reside in a redshift range where other selection methods turn up relatively few sources. The absorbed sources are at higher redshifts and have higher luminosities than the PAH-dominated sources, and may show weaker luminosity evolution. We conclude that a 70 {mu}m selection extending to {approx}20 mJy, in combination with selections at mid-IR and far-IR wavelengths, is necessary to obtain a complete picture of the evolution of IR-luminous galaxies over 0 < z < 2.

• OSTI ID: 21300626
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 696; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
99 GENERAL AND MISCELLANEOUS
ABSORPTION
ABSORPTION SPECTROSCOPY
EMISSION
GALAXIES
INFRARED SPECTRA
LUMINOSITY
POLYCYCLIC AROMATIC HYDROCARBONS
RED SHIFT
SILICATES