A systematic observational study of radio properties of H2O megamaser Seyfert-2 galaxies

TL;DR

This study systematically compares radio properties of H2O megamaser Seyfert-2 galaxies with non-masing ones, finding higher radio luminosities in maser hosts but similar spectral indices, using multi-band observations from the Effelsberg telescope.

Contribution

It provides a comprehensive multi-frequency radio analysis of H2O megamaser Seyfert-2 galaxies with improved data quality and observational consistency, confirming previous luminosity findings.

Findings

Maser galaxies have 2-3 times higher radio luminosity than non-masing ones.

No significant difference in spectral indices between the two groups.

Radio luminosity exceeds 10^29 erg s^-1 Hz^-1 in many maser hosts.

Abstract

A systematic study is performed on radio properties of H$_{2}$O megamaser host Seyfert 2 galaxies, through multi-band radio continuum observations (at 11cm, 6.0 cm, 3.6 cm, 2.0 cm and 1.3 cm) with the Effelsberg 100-m radio telescope within a total time duration of four days. For comparison, a control Seyfert 2 galaxy sample without detected maser emission was also observed. Spectral indices were determined for those sources for which measurements exist at two adjacent bands assuming a power-law dependence S$_\nu \propto \nu^{-\alpha}$, where S is the flux density and $\nu$ is the frequency. Comparisons of the radio continuum properties between megamaser and non-masing Seyfert 2s show no difference in spectral indices. However, a difference in radio luminosity is statistically significant, i.e. the maser galaxies tend to have higher radio luminosities by a factor of 2 to 3 than the non-masing ones, commonly reaching values above a critical threshold of 10$^{29}$ ergs$^{-1}$Hz$^{-1}$. This result confirms an earlier conclusion by Zhang et al. (2012), but is based on superior data with respect to the time interval within which the data were obtained, with respect to the observational facility (only one telescope used), the number of frequency bands.