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Isophotal analysis of M87, using data from the Advanced Camera for Surveys, reveals a projected displacement of 6.8 ± 0.8 pc (∼ 0. ′′ 1) between the nuclear point source (presumed to be the location of the supermassive black hole, SMBH) and the photo-center of the galaxy. The displacement is along a position angle of 307 ± 17 • and is consistent with the jet axis. This suggests the active SMBH in M87 does not currently reside at the galaxy center of mass, but is displaced in the counter-jet direction. Possible explanations for the displacement include orbital motion of an SMBH binary, gravitational perturbations due to massive objects (e.g., globular clusters), acceleration by an asymmetric or intrinsically one-sided jet, and gravitational recoil resulting from the coalescence of an SMBH binary. The displacement direction favors the latter two mechanisms. However, jet asymmetry is only viable, at the observed accretion rate, for a jet age of >0.1 Gyr and if the galaxy restoring force is negligible. This could be the case in the low density core of M87. A moderate recoil ∼1 Myr ago might explain the disturbed nature of the nuclear gas disk, could be aligned with the jet axis, and can produce the observed offset. Alternatively, the displacement could be due to residual oscillations resulting from a large recoil that occurred in the aftermath of a major merger ≤1 Gyr ago.

Magain et al. argued that the host galaxy of the quasar in HE0450−2958 is substantially underluminous given the quasar brightness. Using kinematical information from the spectra of the quasar and the companion galaxy, an ultraluminous infrared galaxy, we test the hypothesis that the black hole powering the quasar was ejected from the companion galaxy during a merger. We argue that the ejection model is unlikely, since the kick velocity required to remove the black hole from the galaxy is ≳500 km s−1, inconsistent with the presence of narrow emission‐line gas at the same redshift as the quasar nucleus. We also show that the quasar in HE0450−2958 has the spectral characteristics of a narrow‐line Seyfert 1 galaxy and calculate a mass for its black hole that is roughly an order of magnitude smaller than that estimated by Magain et al. The predicted luminosity of the host galaxy is then consistent with the upper limits inferred by those authors.

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In order to identify the dominant nuclear outflow mechanisms in Active Galactic Nuclei, we have undertaken deep, high resolution observations of two compact radio sources (PKS 1549-79 and PKS 1345+12) with the Advanced Camera for Surveys (ACS) aboard the Hubble Space Telescope. Not only are these targets known to have powerful emission line outflows, but they also contain all the potential drivers for the outflows: relativistic jets, quasar nuclei and starbursts. ACS allows the compact nature (<0.15") of these radio sources to be optically resolved for the first time. Through comparison with existing radio maps we have seen consistency in the nuclear position angles of both the optical emission line and radio data. There is no evidence for bi-conical emission line features on the large-scale and there is a divergance in the relative position angles of the optical and radio structure. This enables us to exclude starburst driven outflows. However, we are unable to clearly distinguish between radiative AGN wind driven outflows and outflows powered by relativistic radio jets. The small scale bi-conical features, indicative of such mechanisms could be below the resolution limit of ACS, especially if aligned close to the line of sight. In addition, there may be offsets between the radio and optical nuclei induced by heavy dust obscuration, nebular continuum or scattered light from the AGN.Comment: 9 pages, 8 figures, emulateapj, ApJ Accepte