Discovery of a very luminous megamaser during a radio flare in the Seyfert 2 galaxy Mrk 348
Heino Falcke1, Christian Henkel1, Alison Peck1, Yoshiaki Hagiwara1, M. Almudena Prieto2, Jack F. Gallimore3
1Max-Planck-Institut für Radioastronomie, Auf den Hüugel 69, D-53121 Bonn, Germany (hfalcke@mpifr-bonn.mpg.de)2European Southern Observatory, Karl-Schwarzschild-Straße 2, 85740 Garching, Germany
3National Radio Astronomy Observatory, 520 Edgemont Rd., Charlottesville, VA 22903-2475, USA
Astronomy & Astrophysics Letters (2000), Vol. 358, p. L17
Abstract:
We report the detection of a new H2O megamaser in the Seyfert 2 galaxy Mrk~348 with the MPIfR 100 m telescope in Effelsberg. With an apparent isotropic luminosity of L H2O ~ 420 Lo the maser is the third most luminous maser discovered so far. The detected line is unusually broad (Delta v ~ 130 km s-1), is redshifted by ~130 km s-1 from the systemic velocity, and is asymmetric with a pronounced blue wing. While evidence for obscuring material towards the nucleus of this galaxy was found earlier, this detection is the first direct observation of molecular material in the vicinity of the AGN. We also searched for absorption from ammonia (NH3) and cyclopropenylidene (C3H2) against the bright radio nucleus. The H2O line was only marginally detected in archival data indicating that the maser flared recently in conjunction with a huge radio continuum flare. Continuum and line flux density increased by a factor of three, suggesting an unsaturated maser. The radio continuum flare has made Mrk 348 the most radio luminous megamaser galaxy known. It is pointed out that megamaser galaxies contain a rather large fraction of galaxies with prominent radio cores and it is speculated that the flare in the maser emission in Mrk 348 is related to the flare in the nuclear jet.
Paper: Available in PostScript and (AAS)LaTex. Please send an email request to hfalcke@mpifr-bonn.mpg.de for a preprint.
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Questions: Heino Falcke, hfalcke@mpifr-bonn.mpg.de