New water masers in Seyfert and FIR bright galaxies. II

TL;DR

This study extends a water maser survey to lower FIR flux galaxies, confirming the correlation between FIR flux and maser detection rate, and reports two new maser detections in specific galaxies.

Contribution

It provides new maser detections in lower FIR flux galaxies, supporting the FIR-maser correlation and expanding the known maser source catalog.

Findings

Detected a megamaser in NGC613 with ~35 solar luminosities.

Detected a kilomaser in NGC520 with ~1 solar luminosity.

Confirmed the correlation between FIR flux density and maser detection rate.

Abstract

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 micron flux density > 50 Jy and a declination >-30 degrees. 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. A sample of 41 galaxies with 30 Jy < S(100 micron) < 50 Jy and Dec. > -30 degrees was observed with the 100-m telescope at Effelsberg in a search for the 22 GHz water vapor line. The average 3-sigma 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 about 0.5 solar luminosities at a distance of 25 Mpc. Two detections are reported: a megamaser with an isotropic luminosity of approximately 35 solar luminosities in the Seyfert/HII galaxy NGC613 and a kilomaser of approximately 1 solar luminosity in the merger system NGC520.[abridged]