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Title: A RUNAWAY BLACK HOLE IN COSMOS: GRAVITATIONAL WAVE OR SLINGSHOT RECOIL?

Journal Article · · Astrophysical Journal
; ; ; ;  [1];  [2]; ; ;  [3]; ;  [4]; ;  [5];  [6];  [7];  [8]; ;  [9];  [10];  [11]
  1. Harvard Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  2. Max Planck Institut fuer Astronomie, Koenigstuhl 17, Heidelberg, D-69117 (Germany)
  3. INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, I-40127 Bologna (Italy)
  4. Astronomy Department, Harvard University, 60 Garden Street, Cambridge, MA 02138 (United States)
  5. Max Planck Institut fuer Extraterrestrische Physik Giessenbachstrasse 1, D-85748 Garching (Germany)
  6. LBNL and BCCP, University of California, Berkeley, CA 94720 (United States)
  7. European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching (Germany)
  8. INAF-Osservatorio Astronomico di Roma, via di Frascati 33, I-00040 Monteporzio Catone (Italy)
  9. California Institute of Technology, MC 105-24, 1200 East California Boulevard, Pasadena, CA 91125 (United States)
  10. Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)
  11. Dipartimento di Astronomia, Universita degli Studi di Bologna, Via Ranzani 1, I-40127 Bologna (Italy)

We present a detailed study of a peculiar source detected in the COSMOS survey at z = 0.359. Source CXOC J100043.1+020637, also known as CID-42, has two compact optical sources embedded in the same galaxy. The distance between the two, measured in the HST/ACS image, is 0.''495 {+-} 0.''005 that, at the redshift of the source, corresponds to a projected separation of 2.46 {+-} 0.02 kpc. A large ({approx}1200 km s{sup -1}) velocity offset between the narrow and broad components of H{beta} has been measured in three different optical spectra from the VLT/VIMOS and Magellan/IMACS instruments. CID-42 is also the only X-ray source in COSMOS, having in its X-ray spectra a strong redshifted broad absorption iron line and an iron emission line, drawing an inverted P-Cygni profile. The Chandra and XMM-Newton data show that the absorption line is variable in energy by {Delta}E = 500 eV over four years and that the absorber has to be highly ionized in order not to leave a signature in the soft X-ray spectrum. That these features-the morphology, the velocity offset, and the inverted P-Cygni profile-occur in the same source is unlikely to be a coincidence. We envisage two possible explanations, both exceptional, for this system: (1) a gravitational wave (GW) recoiling black hole (BH), caught 1-10 Myr after merging; or (2) a Type 1/Type 2 system in the same galaxy where the Type 1 is recoiling due to the slingshot effect produced by a triple BH system. The first possibility gives us a candidate GW recoiling BH with both spectroscopic and imaging signatures. In the second case, the X-ray absorption line can be explained as a BAL-like outflow from the foreground nucleus (a Type 2 AGN) at the rearer one (a Type 1 AGN), which illuminates the otherwise undetectable wind, giving us the first opportunity to show that fast winds are present in obscured active galactic nuclei (AGNs), and possibly universal in AGNs.

OSTI ID:
21452887
Journal Information:
Astrophysical Journal, Vol. 717, Issue 1; Other Information: DOI: 10.1088/0004-637X/717/1/209; ISSN 0004-637X
Country of Publication:
United States
Language:
English