A close look at the dwarf AGN of NGC4395: optical and near-IR integral field spectroscopy

Intermediate-mass black holes (10(3) - 10(5) M-circle dot) 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 nearinfrared integral field spectroscopy of the inner similar to 50 pc of the dwarf galaxy NGC4395, known to harbour an AGN. NGC4395 is an ideal candidate to investigate the nature of dwarf AGN, as it is nearby (d approximate to 4.4Mpc) enough to allow a close look at its nucleus. The optical data were obtained with the Gemini GMOS-IFU covering the 4500-7300 angstrom 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 similar to 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 x 10(5) M-circle dot inside a radius of 10 pc. From the H alpha broad-line component, we estimate the AGN bolometric luminosity as L-bol = (9.9 +/- 1.4) x 10(40) erg s(-1) and a mass M-BH = (2.5(-0.8)(+1.0)) x 10(5) M-circle dot for the central black hole. The mean surface mass densities for the ionized and molecular gas are in the ranges (1-2) M-circle dot pc(-2) and (1-4) x 10(-3) M-circle dot pc(-2) and the average ratio between ionized and hot molecular gas masses is similar to 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 approximate to 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.