Bibcode
Brum, C.; Diniz, Marlon R.; Riffel, Rogemar A.; Rodríguez-Ardila, A.; Ho, Luis C.; Riffel, Rogério; Mason, Rachel; Martins, Lucimara; Petric, Andreea; Sánchez-Janssen, Rubén
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 486, Issue 1, p.691-707
Advertised on:
6
2019
Citations
20
Refereed citations
19
Description
Intermediate-mass black holes (103-105
M⊙) in the centre of dwarf galaxies are believed to be
analogous to growing active galactic nuclei (AGNs) in the early
Universe. Their characterization can provide insight about the early
galaxies. We present optical and near-infrared integral field
spectroscopy of the inner ˜50 pc of the dwarf galaxy NGC 4395,
known to harbour an AGN. NGC 4395 is an ideal candidate to investigate
the nature of dwarf AGN, as it is nearby (d ≈ 4.4 Mpc) enough to
allow a close look at its nucleus. The optical data were obtained with
the Gemini GMOS-IFU covering the 4500 -7300 Å spectral range at a
spatial resolution of 10 pc. The J and K-band spectra were obtained with
the Gemini NIFS at spatial resolutions of ˜5 pc. The gas
kinematics show a compact, rotation disc component with a projected
velocity amplitude of 25 km s^{-1}. We estimate a mass of 7.7 ×
105 M⊙ inside a radius of 10 pc. From the
Hα broad-line component, we estimate the AGN bolometric luminosity
as L_bol=(9.9± 1.4)× 10^{40} erg s-1 and a mass
M_BH=(2.5^{+1.0}_{-0.8})× 10^5 M⊙ for the central
black hole. The mean surface mass densities for the ionized and
molecular gas are in the ranges (1-2) M_{⊙} pc-2 and
(1-4) × 10-3 M⊙ pc-2 and the
average ratio between ionized and hot molecular gas masses is
˜500. The emission-line flux distributions reveal an elongated
structure at 24 pc west of the nucleus, which is blueshifted relative to
the systemic velocity of the galaxy by ≈30 km s^{-1}. We speculate
that this structure is originated by the accretion of a gas-rich small
satellite or by a low-metallicity cosmic cloud.