Galaxies water masers

Water masers are also found in galaxies and star forming galaxies. 

Walsh et al., 2008, [353] used Mopra Observations to map two one square degree regions along the galactic plane to find water masers. Young stellar objects (YSOs) were studied in the outer Galaxy by detection of water masers (Mochizuki, Hachisuka and Umemoto, 2009 [233]). 

Water masers in a galaxy provide proxies for identifying star forming regions and are therefore of particular interest. 

GHz water masers were found in four nearby galaxies. The locations of these water masers coincides with ultradense H-II regions. These regions correspond also to bright 24 pm emission areas (see Darling, Brogan and Johnson, 2009 [93] and 2008 [92]). 

Using the Expanded Very Large Array, Edmonds et al., 2008 [113] have conducted a search for 22.2 GHz H2O megamaser emission in the strongly lensed sub mm galaxy, SMM J16359 -I- 6612 at z = 2.517. They did not detect any water maser emission but were able to set an upper limit on the luminosity of any water maser present (LH20 5305 L ). 

Fig. 7.16 An artist conception of water maser emission in the accretion disk of the accretion disk and radio jet around the black hole in the heart of the Seyfert galaxy NGC 4258. This accretion disk material lies within a few tenths of a parsec from a supermassive black hole. The disk is warped, rotating differentially according to Kepler s laws. The inset at the bottom of the graphic is a radio spectrum (intensity as a function of frequency or velocity) of the water maser emission. The white glints on the disk surface show the locations of regions where maser emission has been detected. Image courtesy of NRAO/AUl and Artist John Kagaya (Hoshi No Techou)...

Braatz, J.A., Gugliucci, N.E. The discovery of water maser emission from eight nearby galaxies. Astrophys. J. 678, 96-101 (2008)... 

Darling, J., Brogan, C., Johnson, K. Ubiquitous water masers in nearby star-forming galaxies. Astrophys. J. Lett. 685, L39-L42 (2008)... 

Mochizuki, N., Hachisuka, K., Umemoto, T Survey of Outer galaxy molecular lines associated with water masers. In Hagiwara, Y, Fomalont, E., Tsuboi, M., Yasuhiro, M. (eds.) Astronomical Society of the Pacific Conference Series, vol. 402, p. 384 (2009)... 

Water has been detected almost everywhere on extreme and exotic places in the universe in 5000 K hot sunspots as well as in cold molecular interstellar clouds. Extreme bright sources can be explained by a MASER mechanism that is based on water molecules. They indicate regions where stars are formed and they can be even detected in galaxies that are at a distance of several 100 million light years. 

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