MOOOAAR PAPERS ! Congratulations Robert Minchin and Olivia Keenan. And me, too... :)
We looked at some isolated galaxies in case they weren't actually isolated, but it turns out that they were. Oh well, never mind.
Maybe I'll do less pithy analysis when I have time...
http://arxiv.org/abs/1510.08715
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What is it about dwarf companions that make them objects of study?
ReplyDeleteAnthony Shaw In this context, it's all about the numbers. There are ~30 known dwarf satellites of the Milky Way, but these isolated galaxies have only about one each. Models of galaxy formation typically predict many hundreds of dwarf companions.
ReplyDeleteOne possibility is that some of the dwarfs never accrete enough gas to form stars. Maybe star formation is triggered in the Milky Way satellites by the other galaxies in the Local Group (Andromeda and Triangulum). These isolated galaxies don't have any giant neighbours, so maybe their dwarf companions haven't been detected by optical searches because their gas has just been sitting there all this time doing bugger all.
It turns out that this is not the case - the isolated galaxies not only lack optically bright companions, but they have hardly any gas-rich, optically dark companions too. So it seems that galaxy formation really works differently in different environments, although as to exactly what the differences are and why they occur is anyone's guess.
Is this what you are using? I'm reading its main purpose is for discovering pulsars.
ReplyDeletehttps://en.m.wikipedia.org/wiki/PALFA_Survey
Yes, we use ALFA - but pulsar discoveries are [massive sarcasm] just an unfortunate side-effect [/massive sarcasm]. Actually it's used for lots of different studies, of which HI is probably the main purpose in terms of number of surveys.
ReplyDeletehttp://www.naic.edu/alfa/surveydata.shtml
Number of currently ongoing surveys will be different though since most of the HI surveys have finished collecting data.
Photo of said receiver here : http://4.bp.blogspot.com/-2cxqY8VG66w/ThWoJgImnYI/AAAAAAAAAfc/soaGsjRMao0/s1600/IMG_0723.JPG
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