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It's Journal Club time again...

The way Journal Club works around here is by a roster - everyone gets a date and has to pick a paper on whatever the topic is at the time, with topics usually lasting for three weeks. It's my turn again this week, and the topic at the moment is masers. I'm first up in this topic and I've picked a paper from Nature that I read recently anyway as part of researching the News*. Yes, I'm lazy. The advantage of this is that not only is is a short paper, but there is also a handy press release, and my script from the January issue, so the talk was already half written before I started. This turned out to be a very good thing given how much other stuff is going on at the moment. The next two weeks are going to be manic. Here's the story...

Observations made using the 100-m Effelsberg telescope in Germany have detected the presense of water vapour in a galaxy at a record ditancefrom the Earth. The study used an effect known as gravitational lensing to search for radio emission in the quasar MG J0414+0534, located at a redshift of 2.64, a light-travel time of 11.1 billion years. The previous record for the detection of water was at a redshift of 0.66 corresponding to a light-travel time of just 6 billion years. The astronomers were looking for water masers - radiation beamed and amplified in as imilar way to light in a laser, but at microwave wavelengths instead. Masers occur naturally in regions of dense gas in areas of high star formation or around supermassive black holes in active galaxies as highly energetic megamasers. The water maser found in J0414 has a luminosity equivalent to 10,000 times the luminosity of the Sun, making it more powerful than most water masers seen in nearby galaxies, but without the effects of gravitational lensing an observation of 580 days would have been required, rather than the 14 hours that were used. In looking for distant regions of water the group selected a distant quasar where a foreground galaxy was along the same line of sight, acting like a magnifying glass, allowing sensitive observations out to much greater distances than is normally possible. The presence of a water maser in the first gravitationally lensed object observed by the group implies that water may have been mush more abundant in the early universe than first thought, pointed out by John McKean, a co-author of the discovery paper published in Nature during December 2008.

Posted by Megan on Sunday 22nd Mar 2009 (10:58 UTC) | Add a comment | Permalink


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