Astrophys. J., 708, 1528-1536 (2010/January-2)
On the nuclear obscuration of H2 O maser galaxies.
ZHANG J.S., HENKEL C., GUO Q., WANG H.G. and FAN J.H.
Abstract (from CDS):
To shed light onto the circumnuclear environment of 22 GHz (λ ∼ 1.3 cm) H2 O maser galaxies, we have analyzed some of their multiwavelength properties, including the far-infrared luminosity (FIR), the luminosity of the [OIII] λ5007 emission line, the nuclear X-ray luminosity, and the equivalent width (EW) of the neutral iron Kα emission line (EW (Kα)). Our statistical analysis includes a total of 85 sources, most of them harboring an active galactic nucleus (AGN). There are strong anticorrelations between EW (Kα) and two "optical thickness parameters," i.e., the ratios of the X-ray luminosity versus the presumably more isotropically radiated [OIII] and FIR luminosities. Based on these anticorrelations, a set of quantitative criteria, EW (Kα)>300 eV, L2–10keV < 2L[OIII], and LFIR>600 L_2-10 keV_ can be established for Compton-thick nuclear regions. Eighteen H2 O maser galaxies belong to this category. There are no obvious correlations between the EW (Kα), the [OIII] luminosity, and the isotropic H2 O maser luminosity. When comparing samples of Seyfert 2s with and without detected H2 O maser lines, there seem to exist differences in EW (Kα) and the fraction of Compton-thick nuclei. This should be studied further. For AGN masers alone, there is no obvious correlation between FIR and H2 O maser luminosities. However, including masers associated with star-forming regions, a linear correlation is revealed. Overall, the extragalactic FIR-H2 O data agree with the corresponding relation for Galactic maser sources, extrapolated by several orders of magnitude to higher luminosities.
galaxies: active - galaxies: Compton - galaxies: nuclei - masers - X-rays: galaxies
In table 1: J0804+3607 is not identified.
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