ESO galaxy hunters come up trumps
Searching the skies with quasars
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Galaxy-hunting astronomers at the European Southern Observatory (ESO) have turned up 14 previously undiscovered starburst galaxies, thanks to a new searching technique.
A starburst galaxy is one in the throes of rapid star formation. The team says some of the galaxies are spawning new stars at a rate of 20 suns per day.
Newly Found Galaxies (SINFONI/VLT)
To find the galaxies, the team went looking armed with a catalogue of quasars. A quasar is an extremely bright and distant object. Observed from Earth, sometimes their emissions seems to dip, suggesting that something rather large has blocked our direct line of sight, albeit briefly, and absorbed some of the quasar's radiation.
The team scanned the catalogues looking for dipping quasars. Twenty quasars with these dips in brightness made it onto a shortlist for further investigation. Of these, 14 turned out to have galaxies between us and them.
But that further investigation is no mean feat. "The difficulty in actually spotting and seeing these galaxies stems from the fact that the glare of the quasar is too strong compared to the dim light of the galaxy," says Nicolas Bouché of the Max Planck Institute for Extraterrestrial Physics, in Germany.
To untangle the light of the quasar from the light of the galaxy, the team used the ESO's VLT and SINFONI. SINFONI is an infrared integral field spectrometer that "simultaneously delivers very sharp images and highly resolved colour information (spectra) of an object on the sky", the team explains.
"This high detection rate alone is a very exciting result," says Bouché. "But, these are not just ordinary galaxies: they are most notable ones, actively forming a lot of new stars and qualifying as 'starburst galaxies'."
The team says the high detection rate is particularly exciting because it suggests SINFONI will be a very useful tool in locating new galaxies to study. For now though, the researchers plan to use SINFONI to probe deeper into the galaxies they have already found, rather than casting their net wider in the hope of catching other specimens.
The work is published in the Astrophysical Journal The SINFONI Mg II Program for Line Emitters (SIMPLE): discovering starbursts near QSO sightlines, N. Bouché et al. ®
COMMENTS
Wot???
This story is incomprehensible, quite apart from "a quasar is an extremely bright and distant object".
A quasar is a an object of small angular diameter which has not been shown to have an evident structure, and characterised by very high red shift. It is only an inference that it is distant, and not a conclusive one. If you believe it is distant, then it necessarily follows it has to be bright. But this seems irrelevant to the story.
First, what are these guys looking for? Quasars with brightness variation? Galaxies with quasars behind them? Galaxies with signs of high rate of star formation? What was their objective, or are they just filling the time between coffee breaks?
Second, on what basis do they ascribe their results to the galaxy rather than the quasar?
Third, are they inferring a galaxy from alleged evidence of star formation, or alleged star formation because they see a galaxy?
Third, can it be so simple to infer from intensity of an infra-red spectrometer measurement to something being warm. Phew wot a scorcher - got to be some hot new stars in there? (Copyright, The Sun).
Fourth, what is this kind of reporting about? Hello, ESO guys, we know you're there - because we've thrown lots of taxpayers money at you. Did you some pretty pictures for us while we weren't looking?
Close at hand in images of elsewhere
The quasars are far away: the starburst galaxies are not so far though (being inbetween us and the quasars). From other reports, the starburst episodes in question are only about 6 billion light years distant so are significantly more recent than, say, the age of the Milky Way, let alone the universe. Sorry I haven't programmed 'units' with Bulgarian airbags or other Reg-enhanced units yet.
For comparison, the oldest detected non-quasar galaxies are IIRC in the area of 12 billion light years away.
The term "Milky Way" here refers to our galaxy and not to any form of confection ...
Another new unit of measurement for Vulture Central?
20 Suns per day? So the equivalent of 0.833 Suns per hour or 0.0138 Suns per minute or 0.0002314 Suns per second.
I propose this to be added to the new measurements system, as upon review there are no measurements for the passage or duration of time.
Example:
As he sat at his work terminal calculating the difference between hours, minutes and seconds for the new measurement system, he realised he had effectively wasted (constructively of course...) 7 minutes of his day, or 0.0966 Suns.
Any takers?
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