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Molecular Gas in Galactic Nuclei

Scoville, N. Z. and Yun, M. S. and Bryant, P. M. (1997) Molecular Gas in Galactic Nuclei. In: CO: Twenty-Five Years of Millimeter-Wave Spectroscopy. IAU Symposium Proceedings Series. No.170. Springer Netherlands , Dordrecht, pp. 305-313. ISBN 978-0-7923-4284-7.

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Dense molecular clouds are critical to the activity occurring in galactic nuclei. They are the active component from which starbursts arise and this dense interstellar gas may be the fuel for AGNs. In both the nearby infrared bright galaxies (e.g., M82, NGC 253, and IC342) and the ultraluminous IRAS galaxies, high resolution millimeter line mapping has shown extremely high gas surface densities in the central kpc. Often a significant fraction (> 25%) of the total molecular line emission from the galaxy arises from these central regions. New maps at resolutions down to 0.8″ of the ultraluminous IRAS galaxies reveal kinematic gradients parallel to the major axis of the CO intensity distribution, suggesting that the gas is situated in a central rotating disk. The most extreme central concentrations are seen in Arp 220 and Mrk 231 (Sey 1), which have now been mapped in both the 2.6 and 1.3 mm CO transitions. In both galaxies, the high observed CO brightness temperatures indicate large area filling factors with mean H₂ densities exceeding 10⁴cm⁻³. To produce the observed luminosities, the star formation rates must be ∼100 M⊙ yr⁻¹ within the central 500 pc radius. Estimated time scales for both the dynamical evolution and the exhaustion of the observed central ISM are typically 2 × 10⁸ years.

Item Type:Book Section
Related URLs:
URLURL TypeDescription ReadCube access
Scoville, N. Z.0000-0002-0438-3323
Yun, M. S.0000-0001-7095-7543
Additional Information:© 1997 Springer Science+Business Media Dordrecht. Our research is supported in part by NSF Grant AST 93-14079.
Funding AgencyGrant Number
NSFAST 93-14079
Subject Keywords:Spiral Galaxy; Star Formation Rate; Starburst Galaxy; Dust Lane; Dense Molecular Cloud
Series Name:IAU Symposium Proceedings Series
Issue or Number:170
Record Number:CaltechAUTHORS:20201124-070756003
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:106799
Deposited By: Tony Diaz
Deposited On:24 Nov 2020 16:48
Last Modified:16 Nov 2021 18:56

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