New H2O masers in Seyfert and FIR bright galaxies II. the intermediate luminosity range

被引：0

作者：

Castangia, P. ^{[1
,2
]}

Tarchi, A. ^{[2
,3
]}

Henkel, C. ^{[1
]}

Menten, K.M. ^{[1
]}

机构：

[1] Max-Planck-Insitut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany

[2] INAF, Osservatorio Astronomico di Cagliari, Loc. Poggio dei Pini, Strada 54, 09012 Capoterra (CA), Italy

[3] INAF, Istituto di Radioastronomia, via Gobetti 101, 40129 Bologna, Italy

来源：

Astronomy and Astrophysics | 2008年 / 479卷 / 01期

关键词：

Context.Recently; a relationship between the water maser detection rate and far infrared (FIR) flux density has been found as a result of a 22 GHz maser survey in a sample comprised of northern galaxies with 100 m flux density $ 50 Jy and a declination $ -30°.Aims.The survey has been extended toward galaxies with lower FIR flux densities in order to confirm this correlation and to discover additional maser sources for relevant follow-up interferometric studies.Methods.A sample of 41 galaxies with 30 Jy 50 Jy and -30$ ° was observed with the 100-m telescope at Effelsberg in a search for the 22 GHz water vapor line. The average 3 noise level of the survey is 40 mJy for a 1 km s channel; corresponding to a detection threshold for the isotropic maser luminosity of ∼0.5 at a distance of 25 Mpc.Results.Two detections are reported: a megamaser with an isotropic luminosity; of 35 in the Seyfert/Hii galaxy NGC 613 and a kilomaser with in the merger system NGC 520. The high luminosity and the presence of a Seyfert nucleus favor an association for NGC 613 with an active galactic nucleus. The kilomaser in NGC 520 was also detected with the Very Large Array; providing a position with subarcsecond accuracy. The HO emission; originating from a pc sized region with a brightness temperature K (if the observed variations are intrinsic to the masing cloud(s)); is close to one of the two radio continuum sources located in the inner parsecs of NGC 520. The maser is most likely associated with a young supernova remnant (); although an association with a low-luminosity AGN (LLAGN) cannot be ruled out. The maser detection rate; with 2 new maser sources out of 41 galaxies observed; is consistent with expectations extrapolated from the statistical properties of the $ 50 Jy sample. The HO kilomasers are subluminous; while HO megamasers tend to be superluminous with respect to the FIR luminosity of their parent galaxy; when compared with sites of massive star formation in the Milky Way. © 2008 ESO;

D O I：

暂无

中图分类号：

学科分类号：

摘要：

Journal article (JA)

引用

页码：111 / 122