A Runaway Black Hole in COSMOS: Gravitational Wave or Slingshot Recoil?

F. Civano; M. Elvis; G. Lanzuisi; K. Jahnke; G. Zamorani; L. Blecha; A. Bongiorno; M. Brusa; A. Comastri; H. Hao; A. Leauthaud; A. Loeb; M. Mignoli; V. Mainieri; E. Piconcelli; M. Salvato; N. Scoville; J. Trump; C. Vignali; T. Aldcroft; M. Bolzonella; E. Bressert; A. Finoguenov; A. Fruscione; A. M. Koekemoer; N. Cappelluti; F. Fiore; S. Giodini; R. Gilli; C. D. Impey; S. J. Lilly; E. Lusso; S. Puccetti; J. D. Silverman; H. Aussel; P. Capak; D. Frayer; E. Le Floc'h; H. J. McCracken; D. B. Sanders; D. Schiminovich; Y. Taniguchi

doi:10.1088/0004-637x/717/1/209

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arXiv · 1003.0020

A Runaway Black Hole in COSMOS: Gravitational Wave or Slingshot Recoil?

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Abstract

We present a detailed study of a peculiar source in the COSMOS survey at z=0.359. Source CXOCJ100043.1+020637 (CID-42) presents two compact optical sources embedded in the same galaxy. The distance between the 2, measured in the HST/ACS image, is 0.495" that, at the redshift of the source, corresponds to a projected separation of 2.46 kpc. A large (~1200 km/s) velocity offset between the narrow and broad components of Hbeta 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 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 data show that the absorption line is variable in energy by 500 eV over 4 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 occur in the same source is unlikely to be a coincidence. We envisage two possible explanations: (1) a gravitational wave recoiling black hole (BH), caught 1-10 Myr after merging, (2) a Type 1/ Type 2 system in the same galaxy where the Type 1 is recoiling due to slingshot effect produced by a triple BH system. The first possibility gives us a candidate gravitational waves 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 AGN.

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F. Civano, M. Elvis, G. Lanzuisi, K. Jahnke, G. Zamorani, L. Blecha, A. Bongiorno, M. Brusa, A. Comastri, H. Hao, A. Leauthaud, A. Loeb, M. Mignoli, V. Mainieri, E. Piconcelli, M. Salvato, N. Scoville, J. Trump, C. Vignali, T. Aldcroft, M. Bolzonella, E. Bressert, A. Finoguenov, A. Fruscione, A. M. Koekemoer, N. Cappelluti, F. Fiore, S. Giodini, R. Gilli, C. D. Impey, S. J. Lilly, E. Lusso, S. Puccetti, J. D. Silverman, H. Aussel, P. Capak, D. Frayer, E. Le Floc'h, H. J. McCracken, D. B. Sanders, D. Schiminovich, Y. Taniguchi. 2010-02-27. A Runaway Black Hole in COSMOS: Gravitational Wave or Slingshot Recoil?. https://doi.org/10.1088/0004-637x%2F717%2F1%2F209

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