ON THE NUCLEAR OBSCURATION OF H{sub 2}O MASER GALAXIES

Journal Article · Sun Jan 10 00:00:00 EST 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/708/2/1528· OSTI ID:21392387

Zhang, J S; Guo, Q; Wang, H G; Fan, J H ^[1]; Henkel, C ^[2]

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1. Center for Astrophysics, GuangZhou University, GuangZhou, 510006 (China)
2. Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany)

To shed light onto the circumnuclear environment of 22 GHz ({lambda} {approx} 1.3 cm) H{sub 2}O maser galaxies, we have analyzed some of their multiwavelength properties, including the far-infrared luminosity (FIR), the luminosity of the [O{sub III}]{lambda}5007 emission line, the nuclear X-ray luminosity, and the equivalent width (EW) of the neutral iron K{alpha} emission line (EW (K{sub {alpha}})). Our statistical analysis includes a total of 85 sources, most of them harboring an active galactic nucleus (AGN). There are strong anticorrelations between EW (K{sub {alpha}}) and two 'optical thickness parameters', i.e., the ratios of the X-ray luminosity versus the presumably more isotropically radiated [O{sub III}] and FIR luminosities. Based on these anticorrelations, a set of quantitative criteria, EW (K{sub {alpha}})>300 eV, L{sub 2-10keV}<2L{sub [O{sub III}]}, and L{sub FIR}>600 L{sub 2-10{sub keV}} can be established for Compton-thick nuclear regions. Eighteen H{sub 2}O maser galaxies belong to this category. There are no obvious correlations between the EW (K{sub a}lpha), the [O{sub III}] luminosity, and the isotropic H{sub 2}O maser luminosity. When comparing samples of Seyfert 2s with and without detected H{sub 2}O maser lines, there seem to exist differences in EW (K{sub {alpha}}) and the fraction of Compton-thick nuclei. This should be studied further. For AGN masers alone, there is no obvious correlation between FIR and H{sub 2}O maser luminosities. However, including masers associated with star-forming regions, a linear correlation is revealed. Overall, the extragalactic FIR-H{sub 2}O data agree with the corresponding relation for Galactic maser sources, extrapolated by several orders of magnitude to higher luminosities.

• OSTI ID: 21392387
• Journal Information: Astrophysical Journal, Vol. 708, Issue 2; Other Information: DOI: 10.1088/0004-637X/708/2/1528; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
EV RANGE 100-1000
GALAXY NUCLEI
GHZ RANGE 01-100
IRON
LUMINOSITY
STARS
WATER
X RADIATION
X-RAY GALAXIES
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
ELECTROMAGNETIC RADIATION
ELEMENTS
ENERGY RANGE
EV RANGE
FREQUENCY RANGE
GALAXIES
GHZ RANGE
HYDROGEN COMPOUNDS
IONIZING RADIATIONS
METALS
OPTICAL PROPERTIES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RADIATIONS
TRANSITION ELEMENTS