Integral Field Spectrography of the double AGN merging system Markarian 463

Abstract

A b s t r a c t . Markarian 463, a system of 2 interacting/merging galaxies (E and W) has been observed with SILFID at C F H T in sub-arcsec resolution conditions. We found that both nuclei are AGNs, with the W component being a Sy 2 or LINER and the E component, hitherto known to be a "hidden" Seyfert 1, having essentially Sy 2 characteristics. The bipolar collimated emission originating from the E nucleus is a conspicuous feature in the [OIII]SOOT and Ha reconstructed images, as well as in the V -R color map. In velocity maps some previously undetected kinematical features are detected, most notably a sharp velocity gradient (more than 300 km « _ 1 ) within 2" NE of the E nucleus. In addition, in the direct imaging mode a bright optical jet extending ~ 1.2" S from the E nucleus and a fuzzy blue component 0.8" W of the W nucleus were seen. Both were also discovered on HST images. Detailed ionization maps reveal individual regions with distinct physical conditions, which constrain the mechanism(s) responsible for the ionization of the gas. I n t r o d u c t i o n : T h e M r k 4 6 3 s y s t e mAlthough the origin of nuclear activity in galaxies is still not fully understood, most observational data can be reproduced by the black hole -accretion disk model. In this model of AGN, galaxy interaction and merging is a n efficient mechanism for fuelling the central black hole, with gas supplied by the host galaxy, the interacting companion, or both (Roos 1981, Norman andSilk 1983). In order to further investigate how interaction and merging of galaxies can trigger their nuclear activity, we selected a sample of active galaxies with disturbed morphologies and/or multiple nuclei. Mrk 463 was one of the systems we observed in bidimensional spectroscopy as well as in direct imaging mode.Optically, Mrk 463 is a complex system containing two central condensations, the E and W nuclei, separated by ~ 4" (~ 4 Kpc for z~ 0.05), embedded in a common diffuse body with prominent tidal tails. The E nucleus shows a typical Seyfert 2 spectrum (strong, blue-asymmetric, broad-based lines) but polarization studies have shown clear signatures of a "hidden" Seyfert 1 nucleus Goodrich, 1987 and1990;Mazzarella et al. 1991). Hutchings and Neff (1989) discovered a linear [OHI] 5 oo7 feature centered on this nucleus, extending ~ 20" in the N-S direction. It is associated with a similar radio structure Ulvestad 1988, Mazzarella et al. 1991). Recently, a one-sided linear 229 terms of use, available at https://www.cambridge.org/core/terms. https://doi