The Discovery of Five New H 2O Megamasers in Active Galaxies
Abstract
H_2_O megamasers with (isotropic) luminosities between 60 and 200 L_sun_ (H_0_ = 75 km s^-1^ Mpc^-1^)have been detected in the Seyfert 2 galaxies Mrk 1, Mrk 1210, and NGC 5506 and in the LINERs NGC 1052 and NGC 2639. No megamasers have been found in Seyfert 1's. The galaxies have redshifts between 1500 and 4800 km s^-1^ and are the most distant H_2_O sources reported to date. NGC 1052 is also the first elliptical galaxy known to contain an H_2_O maser. The intensity distribution of an H_2_O five-point map obtained toward NGC 5506 shows that the H_2_O emission is pointlike compared to the 40" telescope beam. The lack of CO emission in NGC 1052 implies a conservative lower limit to the H_2_O brightness temperature of 1000 K, thus ruling out a thermal origin for the H_2_O emission. The success of this survey relative to other recent searches makes it evident that H_2_O megamasers are preferentially found in galaxies with active nuclei.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- December 1994
- DOI:
- 10.1086/187692
- Bibcode:
- 1994ApJ...437L..99B
- Keywords:
-
- Active Galactic Nuclei;
- Elliptical Galaxies;
- Interstellar Masers;
- Seyfert Galaxies;
- Water Masers;
- Brightness Temperature;
- Carbon Monoxide;
- Emission Spectra;
- Interstellar Matter;
- Radio Astronomy;
- Stellar Luminosity;
- Space Sciences (General);
- GALAXIES: ACTIVE;
- GALAXIES: NUCLEI;
- GALAXIES: SEYFERT;
- ISM: MOLECULES;
- MASERS;
- RADIO LINES: GALAXIES