http://arxiv.org/abs/1411.3858
Mrk 1388 has an unusual Seyfert nucleus that shows narrow emission-line components without broad ones, but shows a strong featureless continuum and strong iron-forbidden high-ionization emission lines. The apparent coexistence of type-1/2 characteristics is potentially attributed to a heavily obscured broad-line region or to an intermediate-mass black hole with a broad-line component intrinsically narrower than those of typical narrow-line Seyfert 1 (NLS1) galaxies. Our observation using very-long-baseline interferometry (VLBI) reveals high-brightness radio emission from nonthermal jets from an active galactic nucleus (AGN) with a significant radio luminosity. Furthermore, we investigate the radial profile of the host galaxy using a Hubble Space Telescope (HST) image, which shows a Sersic index suggestive of a pseudobulge. Using the VLBI and HST results, which are essentially not affected by dust extinction, three individual methods provide similar estimates for the black hole mass: (0.76–5.4)x10^6 M_sun, 1.5×10^6 M_sun, and 4.1×10^6 M_sun. These masses are in a range that is preferential for typical NLS1 galaxies rather than for intermediate-mass black holes. Based on the estimated masses, the full width at half maximum $FWHM(H_\beta)$ of approximately 1200–1700 km/s should have been seen. The scenario of a heavily absorbed NLS1 nucleus can explain the peculiarities previously observed.
A. Doi
Mon, 17 Nov 14
36/52
Comments: 6 pages, 3 figures, 2 tables, accepted for publication in PASJ
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