Near-IR observations of the HE0450-2958 system: discovery of a second AGN?

Abstract

The QSO HE0450-2958 was brought to the front scene by the non-detection of its host galaxy and strong upper limits on the latter's luminosity. The QSO is also a powerful infrared emitter, in gravitational interaction with a strongly distorted UltraLuminous InfraRed companion galaxy. We investigate the properties of the companion galaxy, through new near- and mid-infrared observations of the system obtained with NICMOS onboard HST, ISAAC and VISIR on the ESO VLT. The companion galaxy is found to harbour a point source revealed only in the infrared, in what appears as a hole or dark patch in the optical images. Various hypotheses on the nature of this point source are analyzed and it is found that the only plausible one is that it is a strongly reddened AGN hidden behind a thick dust cloud. The hypothesis that the QSO supermassive black hole might have been ejected from the companion galaxy in the course of a galactic collision involving 3-body black holes interaction is also reviewed, on the basis of this new insight on a definitely complex system.

8 pages, 8 figures, accepted for publication in MNRAS

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Cited by in corpus (7)

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• HST Images and KPNO Spectroscopy of the Binary Black Hole Candidate SDSS J153636.22+044127.0
• Study of a homogeneous QSO sample: relations between the QSO and its host galaxy
• GEMINI 3D spectroscopy of BAL+IR+Fe II QSOs: II. IRAS 04505-2958 an explosive QSO with hypershell and a new scenario for galaxy formation and galaxy end
• The QSO HE0450-2958: Scantily dressed or heavily robed? A normal quasar as part of an unusual ULIRG
• Further evidence for a quasar-driven jet impacting its neighbour galaxy: The saga of HE0450-2958 continues
• Deep near-infrared imaging of the HE0450-2958 system