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NOEMA observations support a recoiling black hole in 3C 186

Castignani, G. and Meyer, E. and Chiaberge, M. and Combes, F. and Morishita, T. and Decarli, R. and Capetti, A. and Dotti, M. and Tremblay, G. R. and Norman, C. A. (2022) NOEMA observations support a recoiling black hole in 3C 186. Astronomy and Astrophysics, 661 . Art. No. L2. ISSN 0004-6361. doi:10.1051/0004-6361/202243309.

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3C 186 is a powerful radio-loud quasar (a quasi-stellar object) at the center of a cool-core cluster at z = 1.06. Previous studies have reported evidence for a projected spatial offset of ∼1″ between the isophotal center of the galaxy and the point-source quasi-stellar object (QSO) as well as a spectral shift of ∼2000 km s⁻¹ between the narrow and broad line region of the system. In this work we report high-resolution molecular gas CO(4→3) observations of the system taken with the NOEMA interferometer. We clearly detect a large reservoir of molecular gas, M_(H2) ∼ 8 × 10¹⁰ M⊙, that is co-spatial with the host galaxy and likely associated with a rotating disk-like structure. We firmly confirm both the spatial offset of the galaxy’s gas reservoir with respect to the continuum emission of the QSO and the spectral offset with respect to the redshift of the broad line region. Our morphological and kinematical analysis confirms that the most likely scenario to explain the 3C 186 system is that the QSO is a kicked super-massive black hole (SMBH), which we believe may have resulted from a strong gravitational wave recoil as two SMBHs coalesced after the merger of their host galaxies.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Castignani, G.0000-0001-6831-0687
Chiaberge, M.0000-0003-1564-3802
Combes, F.0000-0003-2658-7893
Morishita, T.0000-0002-8512-1404
Decarli, R.0000-0002-2662-8803
Dotti, M.0000-0002-1683-5198
Norman, C. A.0000-0002-5222-5717
Additional Information:© G. Castignani et al. 2022. Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. This article is published in open access under the Subscribe-to-Open model. Subscribe to A&A to support open access publication. Received 11 February 2022; Accepted 12 April 2022; Published online 10 May 2022. We thank the anonymous referee for helpful comments which contributed to improve the paper. This work is based on observations carried out under project number W20CO with the IRAM NOEMA Interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain). GC thanks Melanie Krips and all IRAM staff for the observations and help concerning the data reduction. GC acknowledges the support from the grant ASI n.2018-23-HH.0. The authors thank Bryan Hilbert and Erini Lambrides for helpful discussion. The imaging data of HST/ACS F606W in Fig. 1 was taken in the HST GO-15254 program and processed in Morishita et al. (2022).
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Institut national des sciences de l'Univers (INSU)UNSPECIFIED
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Instituto Geográfico Nacional (IGN)UNSPECIFIED
Agenzia Spaziale Italiana (ASI)2018-23-HH.0
Subject Keywords:galaxies: active – quasars: individual: 3C186 – galaxies: jets – gravitational waves – galaxies: ISM – galaxies: star formation
Record Number:CaltechAUTHORS:20220624-707449000
Persistent URL:
Official Citation:NOEMA observations support a recoiling black hole in 3C 186. G. Castignani, E. Meyer, M. Chiaberge, F. Combes, T. Morishita, R. Decarli, A. Capetti, M. Dotti, G. R. Tremblay and C. A. Norman. A&A, 661 (2022) L2; DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:115267
Deposited By: Tony Diaz
Deposited On:24 Jun 2022 22:16
Last Modified:28 Jun 2022 19:12

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