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Water maser emission from X-ray-heated circumnuclear gas in active galaxiesWe have modeled the physical and chemical conditions present within dense circumnuclear gas that is irradiated by X-rays from an active galactic nucleus. Over a wide range of X-ray fluxes and gas pressures, the effects of X-ray heating give rise to a molecular layer at temperatures of 400-1000 K within which the water abundance is large. The physical conditions within this molecular layer naturally give rise to collisionally pumped maser emission in the 6(sub 16) - 5(sub 23) 22 GHz transition of ortho-water, with predicted maser luminosities of 10(exp 2 +/- 0.5) solar luminosity per sq. pc of illuminated area. Given plausible assumptions about the geometry of the source and about the degree to which the maser emission is anisotropic, such surface luminosities are sufficient to explain the large apparent luminosities observed in water maser sources that are associated with active galactic nuclei.
Document ID
19950036361
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Neufeld, David A.
(Johns Hopkins Univ. Baltimore, MD, United States)
Maloney, Philip R.
(Univ. of Colorado, Boulder, CO United States)
Conger, Sarah
(Johns Hopkins Univ. Baltimore, MD, United States)
Date Acquired
August 16, 2013
Publication Date
December 1, 1994
Publication Information
Publication: Astrophysical Journal, Part 2 - Letters
Volume: 436
Issue: 2
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
95A67960
Funding Number(s)
CONTRACT_GRANT: NAGW-766
CONTRACT_GRANT: NAGW-3147
Distribution Limits
Public
Copyright
Other

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