Water masers in Compton-thick AGN I. Detailed study of the new water megamaser in IRAS15480-0344

摘要: A relationship between the water maser detection rate and large nuclear column densities in AGN has often been cited literature. Indeed, detailed studies of luminous masers, typically associated with activity, allow us to investigate innermost regions AGN, an impact on still debated Unified Model for this class objects.We have recently entertained a search emission well-defined sample Compton-thick aimed at investigating, firm statistical bases, aforementioned relationship. While survey is ongoing, matter forthcoming publication, new detected lenticular (field) S0 galaxy IRAS15480-0344, whose origin, accretion disc or outflow/jet, needs be assessed. Multi-epoch single-dish observations VLBI measurements were performed distribution, spatial extension, variability order infer main characteristics megamaser. The IRAS15480-0344 reported: megamaser total isotropic luminosity ~200 Lsun profile composed two features, broad line full width half maximum (FWHM) linewidth ~90 km/s narrow (FWHM<1 km/s) one. We follow-up Very Long Baseline Array (VLBA) confidently only component, which coincident radio continuum Large 8.4 GHz. weak feature also velocity range located 15 pc north-west respect stronger component. Neither spot compact sources derived from same VLBA dataset. [Abridged]