An Infrared view of the obscured AGN environment in NGC 4945

Abstract

NGC 4945 harbors one of the nearest active galactic nuclei (AGN), which allows reaching high spatial resolution with the current observational facilities. The Seyfert 2 nucleus is deeply obscured by an edge-on disk with $A_V\sim 14$, requiring infrared observations to study circumnuclear structures and the interstellar medium. In this work, we present an imaging and longslit spectroscopic study of the nuclear region with a spatial resolution of 6.5 pc, based on Flamingos-2 (F2) and T-ReCS data taken at the Gemini South observatory. We report sub-arcsecond photometric measurements of the nucleus in $J$, $H$ and $K_{\mathrm{s}}$ filters, and at larger apertures. We do not detect nuclear variability. The nuclear spectra confirm that even in $K$-band the AGN emission-line features are completely obscured by dust. We detect a circumnuclear disk in $K$-band as well as in the mid-infrared (MIR) $N$- and $Q_{\mathrm{a}}$-bands, with a radial scale length of $\sim$120 pc. The disk shows knots mostly in a ring-like arrangement that has been previously detected with HST Pa $\alpha$ observations, indicating that these are deeply embedded, massive young star clusters. We present here the spectrum of one of the brightest and unresolved object (R$<5$pc), which we identify as a super star cluster candidate with M${}_{K_{\mathrm{s}}}-16.6\pm 0.4$. For the circumnuclear region, a detailed rotation curve allows to measure a nuclear mass of $M=(4.4\pm 3)\times 10^6{M}_{\odot }$ within a radius of $\sim 6.5$ pc. We also report the detection of hot dust ($\sim 1000$ K) out to a nuclear distance of 80 pc measured along the semi-major axis.

14 pages

References in corpus (23)

• AGN Dusty Tori: I. Handling of Clumpy Media
• Molecular line emission in NGC1068 imaged with ALMA. I An AGN-driven outflow in the dense molecular gas
• The Evolution of Dust in the Early Universe with Applications to the Galaxy SDSS J1148+5251
• The SAURON project - VII. Integral-field absorption and emission-line kinematics of 24 spiral galaxy bulges
• Unification of the Fundamental Plane and Super-Massive Black Holes Masses
• Observational Constraints on the Feeding of Supermassive Black Holes
• The interplay between a galactic bar and a supermassive black hole: nuclear fueling in a sub-parsec resolution galaxy simulation
• Feeding versus Feedback in NGC 4151 probed with Gemini NIFS. I. Excitation
• An image of the dust sublimation region in the nucleus of NGC 1068
• A Strong Correlation between Circumnuclear Dust and Black Hole Accretion in Early-Type Galaxies
• Obscuration in AGNs: near-infrared luminosity relations and dust colors
• Shocks and angular momentum flips: a different path to feeding the nuclear regions of merging galaxies
• The accretion ratios in Seyfert 2 galaxies with and without hidden broad-line regions
• The resolved star-formation relation in nearby active galactic nuclei
• Free-free and H42alpha emission from the dusty starburst within NGC 4945 as observed by ALMA
• A new bright z=6.82 quasar discovered with VISTA: VHS J0411-0907
• Ionized Gas Outflows from the MAGNUM Survey: NGC 1365 and NGC 4945
• The AGNIFS survey: distribution and excitation of the hot molecular and ionised gas in the inner kpc of nearby AGN hosts
• ALMA resolves the remarkable molecular jet and rotating wind in the extremely radio-quiet galaxy NGC 1377
• Nuclear Spiral Shocks and Induced Gas Inflows in Weak Oval Potentials
• Imaging the AGN Torus in Cygnus
• A Near Infrared View of Nearby Galaxies: The Case of NGC 6300
• Circumnuclear rings and Lindblad resonances in spiral galaxies

Cited by in corpus (1)

• NIRDust: Probing Hot Dust Emission Around Type 2 AGN Using K-band Spectra