Spitzer observations of extended Lyman-α clouds in the SSA22 field

T. M.A. Webb, T. Yamada, J. S. Huang, M. L.N. Ashby, Y. Matsuda, E. Egami, M. Gonzalez, T. Hayashimo

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42 Citations (Scopus)


We present the results of a Spitzer IRAC and MIPS 24 μm study of extended Lyman-α clouds (or Lyman-α Blobs, LABs) within the SSA22 filamentary structure at z = 3.09. We detect 6/26 LABs in all IRAC filters, four of which are also detected at 24 μm, and find good correspondence with the 850 μm measurements of Geach et al. An analysis of the rest-frame ultraviolet, optical, near- and mid-infrared colors reveals that these six systems exhibit signs of nuclear activity (active galactic nucleus (AGN)) and/or extreme star formation. Notably, they have properties that bridge galaxies dominated by star formation (Lyman-break galaxies (LBGs)) and those with AGNs (LBGs classified as QSOs). The LAB systems not detected in all four IRAC bands, on the other hand, are, as a group, consistent with pure star-forming systems, similar to the majority of the LBGs within the filament. These results indicate that the galaxies within LABs do not comprise a homogeneous population, though they are also consistent with scenarios in which the gas halos are ionized through a common mechanism such as galaxy-scale winds driven by the galaxies within them, or gravitational heating of the collapsing cloud itself.

Original languageEnglish
Pages (from-to)1561-1570
Number of pages10
JournalAstrophysical Journal
Issue number2
Publication statusPublished - 2009 Feb 20


  • dust, extinction
  • galaxies: active
  • galaxies: formation
  • galaxies: high-redshift
  • galaxies: starburst
  • infrared: galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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