Spectropolarimetric evidence for a kicked supermassive black hole in the quasar E1821+643
Robinson, A.; Young, S.; Axon, D.J.; Kharb, P.; Smith, J.E.
Citation: Robinson , A , Young , S , Axon , D J , Kharb , P & Smith , J E 2010 , ' Spectropolarimetric evidence for a kicked supermassive black hole in the quasar E1821+643 ' Astrophysical Journal Letters , vol 717 , no. 2 , pp. L122-L126 .
We report spectropolarimetric observations of the quasar E1821+643 (z = 0.297), which suggest that it may be an example of gravitational recoil due to anisotropic emission of gravitational waves following the merger of a supermassive black hole (SMBH) binary. In total flux, the broad Balmer lines are redshifted by approximate to 1000 km s(-1) relative to the narrow lines and have highly red asymmetric profiles, whereas in polarized flux the broad Ha line exhibits a blueshift of similar magnitude and a strong blue asymmetry. We show that these observations are consistent with a scattering model in which the broad-line region has two components, moving with different bulk velocities away from the observer and toward a scattering region at rest in the host galaxy. If the high-velocity system is identified as gas bound to the SMBH, this implies that the SMBH is itself moving with a velocity similar to 2100 km s(-1) relative to the host galaxy. We discuss some implications of the recoil hypothesis and also briefly consider whether our observations can be explained in terms of scattering of broad-line emission originating from the active component of an SMBH binary, or from an outflowing wind.
Original article can be found at: http://iopscience.iop.org/2041-8205 Copyright American Astronomical Society [Full text of this article is not available in the UHRA]