Hard X-ray Properties of Water Maser Galaxies
Abstract
The Megamaser Cosmology Project (MCP) uses VLBI observations to measure distances for a sample of galaxies showing maser emission and to derive the Hubble Constant with an accuracy of 3 %. A knowledge of the properties of known maser galaxies can lead to a better physical understanding of the maser phenomenon and the development of successful search strategies to increase source-number statistics. The hard X-ray properties of megamaser galaxies are largely unexplored. Based on 70 months of Swift/BAT survey data, we detect a substantial fraction of 40 % of the megamaser galaxy sample at energies between 14 keV and 195 keV.
From studies of the soft X-ray band (2-10 keV), a connection between X-ray absorbing column densities and the maser phenomenon have been established. Hard X-rays are virtually unaffected by absorption. We compare the hard X-ray properties of the maser sample with their radio luminosities to study relations between these emissions. The BAT spectra in a range of 20-100 keV can be described by simple power laws. For the sources in the maser sample we determined X-ray fluxes and photon indices, or alternatively upper flux limits. We present comparisons of these results with properties of non-maser sources from the BAT catalog.- Publication:
-
The X-ray Universe 2014
- Pub Date:
- July 2014
- Bibcode:
- 2014xru..confE.117L