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Article Dans Une Revue The Astrophysical Journal Année : 2008

The Nature of Star Formation in Distant Ultraluminous Infrared Galaxies Selected in a Remarkably Narrow Redshift Range

D. Farrah
  • Fonction : Auteur
C. J. Lonsdale
  • Fonction : Auteur
D. W. Weedman
  • Fonction : Auteur
H. W. W. Spoon
  • Fonction : Auteur
M. Rowan-Robinson
  • Fonction : Auteur
S. Oliver
  • Fonction : Auteur
J. R. Houck
  • Fonction : Auteur
H. E. Smith
  • Fonction : Auteur

Résumé

We present mid-infrared spectra of 32 high-redshift ultraluminous infrared galaxies, selected via the stellar photospheric feature at rest-frame 1.6 μm, and an observed-frame 24 μm flux of >500 μJy. Nearly all the sample reside in a redshift range of langle zrangle = 1.71 +/- 0.15 and have rest-frame 1-1000 μm luminosities of 1012.9-1013.8 L. Most of the spectra exhibit prominent polycyclic aromatic hydrocarbon emission features and weak silicate absorption, consistent with a starburst origin for the IR emission. Our selection method appears to be a straightforward and efficient way of finding distant, IR-luminous, star-forming galaxies in narrow redshift ranges. There is, however, evidence that the mid-IR spectra of our sample differ systematically from those of local ULIRGs; our sample have comparable PAH equivalent widths but weaker apparent silicate absorption, and (possibly) enhanced PAH 6.2 μm/7.7 μm and 6.2 μm/11.2 μm flux ratios. Furthermore, the composite mid-IR spectrum of our sample is almost identical to that of local starbursts with IR luminosities of 1010-1011 L, rather than that of local ULIRGs. These differences are consistent with a reduced dust column, which can plausibly be obtained via some combination of (1) star formation that is extended over spatial scales of 1-4 kpc and (2) star formation in unusually gas-rich regions.

Dates et versions

hal-03646467 , version 1 (19-04-2022)

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Citer

D. Farrah, C. J. Lonsdale, D. W. Weedman, H. W. W. Spoon, M. Rowan-Robinson, et al.. The Nature of Star Formation in Distant Ultraluminous Infrared Galaxies Selected in a Remarkably Narrow Redshift Range. The Astrophysical Journal, 2008, 677, pp.957-969. ⟨10.1086/529485⟩. ⟨hal-03646467⟩
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