Searches for H$_2$O Masers toward Narrow-Line Seyfert 1 galaxies

TL;DR

This study searched for water masers in 36 narrow-line Seyfert 1 galaxies but found no new sources, suggesting that higher sensitivity observations are needed to better understand their occurrence compared to other galaxy types.

Contribution

The paper provides the first systematic survey of H$_2$O masers in NLS1 galaxies, highlighting the need for more sensitive observations to determine their true detection rate.

Findings

No new water masers detected in the sample.

Detection rate in NLS1s similar to other Seyfert types.

Insufficient sensitivity likely caused non-detections.

Abstract

We present searches for 22 GHz H$_2$O masers toward 36 narrow-line Seyfert 1 galaxies (NLS1s), selected from known NLS1s with $v_{sys}$ $\lesssim$ 41000 km/s. Out of the 36 NLS1s in our sample, 11 NLS1s have been first surveyed in our observations, while the observations of other NLS1s were previously reported in literature. In our survey, no new water maser source from NLS1s was detected at 3 $\sigma$ rms level of 8.4 mJy to 144 mJy, which depends on different observing conditions or inhomogeneous sensitivities of each observation using three different telescopes. It is likely that non-detection of new masers in our NLS1 sample is primarily due to insufficient sensitivities of our observations. Including the five known NLS1 masers, the total detection rate of the H$_2$O maser in NLS1s is not remarkably different from that of type 2 Seyfert galaxies or LINERs. However, more extensive and systematic searches of NLS1 would be required for statistical discussion of the detection rate of the NLS1 maser, compared with that of type 2 Seyferts or LINERs.