A search for water maser emission in nearby low-luminosity QSO host galaxies

TL;DR

This study searched for water maser emission in 17 nearby low-luminosity QSO host galaxies but detected none, providing upper limits and discussing the rarity of such masers in Seyfert 1 galaxies.

Contribution

First systematic search for water masers in low-luminosity QSO hosts, establishing upper limits and analyzing factors affecting maser detection in these galaxies.

Findings

No water maser emission detected in the sample.

Upper limits of 27 to 60 mJy set for maser flux density.

Detection probability highest at a viewing angle of about 6 degrees.

Abstract

A sample of nearby galaxies hosting low-luminosity type 1 quasi-stellar objects (QSOs), previously studied in CO and HI emission lines, has been searched for maser emission. Using the Effelsberg 100-m telescope, we observed 17 sources with redshifts of z<0.06 and {\delta}>-30{\deg} for emission in the 22 GHz water vapor maser transition. The sample objects have been drawn from a wide-angle survey for optically bright QSOs (Hamburg /ESO survey, HES). No host galaxies from the sample have been detected in the water maser emission line. In this paper we review the discussion on the reasons for water megamasers being rarely found in Seyfert 1 galaxies. Eight of them are bulge dominated and probably of elliptical type (E/S0), whereas 6 have spiral geometry. Three of the objects seem to be in a phase of merging/interaction. We found 3{\sigma} upper limits for the flux density of 27 to 60 mJy at spectral resolutions of ~0.43 km/s. We furthermore find that the viewing angle to the line of sight to the galaxy, under which the probability to detect megamaser emission is highest, is about 6{\deg}.