Further multiwavelength observations of the SSA 22 Lyα-emitting blob

S. C. Chapman, D. Scott, Rogier Windhorst, D. T. Frayer, C. Borys, G. F. Lewis, R. J. Ivision

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71 Scopus citations


We present new follow-up observations of the submillimeter luminous Lyα-emitting object in the SSA 22 z = 3.09 galaxy overdensity, referred to as "blob 1" by Steidel and coworkers. In particular, we discuss high-resolution Hubble Space Telescope (HST) optical imaging, Owens Valley Radio Observatory (OVRO) spectral imaging, Keck spectroscopy, Very Large Array (VLA) 20 cm radio continuum imaging, and Chandra X-ray observations. We also present a more complete analysis of the existing James Clerk Maxwell Telescope (JCMT) submillimeter data. We detect several optical continuum components that may be associated with the core of the submillimeter-emitting region. A radio source at the position of one of the HST components [α (J2000) = 22 h17m25s.94, δ(J2000) = +00° 12′38″.9] identifies it as the likely counterpart to the submillimeter source. We also tentatively detect the CO(4-3) molecular line centered on the radio position. We use the CO(4-3) intensity to estimate a limit on the gas mass for the system. The optical morphology of sources within the Lyα cloud appears to be filamentary, while the optical source identified with the radio source has a dense knot that may be an active galactic nucleus (AGN) or compact starburst. We obtain a Keck Low-Resolution Imaging Spectrograph (LRIS) spectrum of this object, despite its faintness (R = 26.8). The spectrum reveals weak Lyα emission but no other obvious features, suggesting that the source is not an energetic AGN (or that it is extremely obscured). We use nondetections in deep Chandra X-ray images to constrain the nature of the blob. Although conclusive evidence regarding the nature of the object remains hard to obtain at this redshift, the evidence presented here is at least consistent with a dust-obscured AGN surrounded by a starburst situated at the heart of this giant Lyα cloud.

Original languageEnglish (US)
Pages (from-to)85-91
Number of pages7
JournalAstrophysical Journal
Issue number1 I
StatePublished - May 1 2004


  • Cosmology: observations
  • Galaxies: evolution
  • Galaxies: formation
  • Galaxies: high-redshift
  • Galaxies: starburst

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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