Publication Date:
2016-04-05
Description:
We present deep new Gran Telescopio Canarias (GTC) narrow-band images and William Herschel Telescope (WHT) long-slit spectroscopy of the merging system Mrk273 that show a spectacular extended halo of warm ionized gas out to a radius of ~45 kpc from the system nucleus. Outside of the immediate nuclear regions ( r 〉 6 kpc), there is no evidence for kinematic disturbance in the ionized gas: in the extended regions covered by our spectroscopic slits the emission lines are relatively narrow (full width at half-maximum, FWHM 350 km s –1 ) and velocity shifts small (| V | 250 km s –1 ). This is despite the presence of powerful near-nuclear outflows (FWHM 〉 1000 km s –1 ; | V | 〉 400 km s –1 ; r 〈 6 kpc). Diagnostic ratio plots are fully consistent with Seyfert 2 photoionization to the NE of the nuclear region, however to the SW the plots are more consistent with low-velocity radiative shock models. The kinematics of the ionized gas, combined with the fact that the main structures are aligned with low-surface-brightness tidal continuum features, are consistent with the idea that the ionized halo represents tidal debris left over from a possible triple-merger event, rather than a reservoir of outflowing gas.
Print ISSN:
1745-3925
Electronic ISSN:
1745-3933
Topics:
Physics
