Millimetric Observations of the Center of M81 : A Starved Nucleus with Intraday Variability

Abstract

The central kiloparsec of M81 has been observed in the CO(J=1-0) line and the 3 mm continuum at 100 pc resolution in an attempt to probe molecular gas, and to search for the nuclear inner Lindblad resonance (NILR), around the low-luminosity AGN M81*. We found the following. (1) Molecular gas in the central kpc is mainly on a ``pseudoring'' or a spiral arm at a radius of about 500 pc. (2) The region within ~300 pc from the nucleus is mostly devoid of molecular gas except for diffuse one; in particular, there is neither a giant molecular cloud that is now accreting on the nucleus nor a conspicuous gas feature that can be identified as an NILR. (3) The 3 mm continuum emission shows significant intraday variation, suggesting an emitting region of ~100 AU. (4) The 3-sigma upper limit for CO absorption toward the continuum source is tau_CO(0->1) dV < 0.1 for a linewidth of 10 km/s. The dearth of accreting molecular gas in the vicinity of the nucleus may explain the low luminosity of M81*.

25 pages, 8 figures (2 of them bitmapped), to appear in AJ (Sept. 2001), for full ps file see http://th.nao.ac.jp/~wada/m81/

References in corpus (6)

• Bar-driven Transport of Molecular Gas to Galactic Centers and Its Consequences
• The Narrow-Line Regions of LINERs as Resolved with the Hubble Space Telescope
• A Stationary Core with a One-sided Jet in the Center of M81
• Gas Dynamics in the LINER Galaxy NGC 5005: Episodic Fueling of a Nuclear Disk
• Discovery of Radio Outbursts in the Active Nucleus of M81
• Long-Term Variability of the Low-Luminosity Active Galactic Nucleus of M81

Cited by in corpus (15)

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• A high-frequency radio survey of low-luminosity active galactic nuclei
• Millimeter-band variability of the radio-quiet nucleus of NGC7469
• Millimeter Radio Continuum Emissions as the Activity of Super Massive Black Holes in Nearby Early-Type Galaxies and Low-Luminosity Active Galactic Nuclei
• The resolved scaling relations in DustPedia: Zooming in on the local Universe
• High-resolution, 3D radiative transfer modelling. II. The early-type spiral galaxy M81
• Molecular clouds in the center of M81
• The millimetre variability of M81* -- Multi-epoch dual frequency mm-observations of the nucleus of M81
• Radio jet precession in M81*
• Nuclear Radio Jet from a Low-Luminosity Active Galactic Nucleus in NGC 4258
• The JCMT Nearby Galaxies Legacy Survey VI: The distribution of gas and star formation in M81
• The nature of the variable millimetre-selected AGN in the Brightest Cluster Galaxy of Abell 851
• The role of young and evolved stars in the heating of dust in local galaxies