Discovery of a large ∼200 kpc gaseous nebula at z ≈ 2.7 with the Spitzer Space Telescope

Arjun Dey, Chao Bian, Baruch T. Soifer, Kate Brand, Michael J.I. Brown, Frederic H. Chaffee, Emeric Le Floc'h, Grant Hill, James R. Houck, Buell T. Jannuzi, Marcia Rieke, Daniel Weedman, Mark Brodwin, Peter Eisenhardt

Research output: Contribution to journalArticlepeer-review

123 Scopus citations


We report the discovery of a very large, spatially extended Lyα-emitting nebula at z = 2.656 associated with a luminous mid-infrared source. The bright mid-infrared source (F24μm = 0.86 mJy) was first detected in observations made using the Spitzer Space Telescope. Existing broadband imaging data from the NOAO Deep Wide-Field Survey revealed the mid-infrared source to be associated with a diffuse, spatially extended, optical counterpart in the BW band. Spectroscopy and further imaging of this target reveals that the optical source is an almost purely line-emitting nebula with little, if any, detectable diffuse continuum emission. The Lyα nebula has a luminosity of LLyα ≈ 1.7 × 1044 ergs s-1 and an extent of at least 20″ (160 kpc). Its central ≈8″ shows an ordered, monotonic velocity profile; interpreted as rotation, this region encloses a mass M ≈ 6 × 1012 M. Several sources lie within the nebula. The central region of the nebula shows narrow (≈365 km s-1) emission lines of C IV and He II. The midinfrared source is a compact object lying within the nebula but offset from the center by a projected distance of ≈2″.5 (20 kpc), and likely to be an enshrouded AGN. Ayoung star-forming galaxy lies near the northern end of the nebula. We suggest that the nebula is a site of recent multiple galaxy and AGN formation, with the spatial distribution of galaxies within the nebula perhaps tracking the formation history of the system.

Original languageEnglish (US)
Pages (from-to)654-666
Number of pages13
JournalAstrophysical Journal
Issue number2 I
StatePublished - Aug 20 2005


  • Galaxies: formation
  • Galaxies: high-redshift
  • Galaxies: starburst
  • H II regions

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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