skip to main content

Title: SERENDIPITOUS ALMA DETECTION OF A DISTANT CO-EMITTING X-RAY BRIGHT GALAXY

We report the detection of a distant star-forming galaxy, ALMA J010748.3–173028, which is identified by a 13σ emission line at 99.75 GHz (SΔv = 3.1 Jy km s{sup –1}), behind the nearby merging galaxies VV114 using the Atacama Large Millimeter/submillimeter Array (ALMA) Band 3. We also find an 880 μm counterpart with ALMA Band 7 (S {sub 880μm} = 11.2 mJy). A careful comparison of the intensities of the line and the continuum suggests that the line is a redshifted {sup 12}CO transition. A photometric redshift analysis using the infrared to radio data favors a CO redshift of z = 2.467, although z = 3.622 is acceptable. We also find a hard X-ray counterpart, suggesting the presence of a luminous (L {sub X} ∼ 10{sup 44} erg s{sup –1}) active galactic nucleus obscured by a large hydrogen column (N {sub H} ∼ 2 × 10{sup 23} cm{sup –2} if z = 2.47). A cosmological simulation shows that the chance detection rate of a CO-emitting galaxy at z > 1 with ≥1 Jy km s{sup –1} is ∼10{sup –3} per single ALMA field of view and 7.5 GHz bandwidth at 99.75 GHz. This demonstrates that ALMA has sufficient sensitivity to find an emission-line galaxy such as ALMA J010748.3–173028 even by chance, although themore » likelihood of stumbling across such a source is not high.« less
Authors:
 [1] ; ; ;  [2] ; ;  [3] ;  [4] ;  [5]
  1. Institute of Astronomy, The University of Tokyo, Mitaka, Tokyo 181-0015 (Japan)
  2. National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan)
  3. Division of Physics and Astronomy, Kyoto University, Kitashirakawa-Oiwake-Cho, Sakyo, Kyoto 606-8502 (Japan)
  4. Department of Astronomy, University of Massachusetts, 710 North Pleasant Street, Amherst, MA 01003 (United States)
  5. Joint ALMA Observatory, Alonso de Cordova 3107, Vitacura, Santiago 763 0355 (Chile)
Publication Date:
OSTI Identifier:
22364008
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 781; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CARBON MONOXIDE; COMPARATIVE EVALUATIONS; COMPUTERIZED SIMULATION; DETECTION; EMISSION SPECTRA; GALAXY NUCLEI; GHZ RANGE; HARD X RADIATION; HYDROGEN; PHOTOMETRY; QUASARS; RED SHIFT; SENSITIVITY; STARS; X-RAY GALAXIES