NS: Giant glowing bubbles found around Milky Way
Posted: Thu Jun 03, 2010 4:50 pm
Giant glowing bubbles found around Milky Way
New Scientist - 03 June 2010
New Scientist - 03 June 2010
IS THE Milky Way blowing giant bubbles? A pair of gamma ray bubbles, shaped like an hourglass, seem to be spewing from the black hole we think lies at the centre of our galaxy. That is according to the latest maps from the Fermi Gamma-ray Space Telescope. Its large area telescope has been scanning the whole sky every three hours since June 2008.
The source of the bubbles is a mystery but it seems unlikely that dark matter is responsible. This was what Douglas Finkbeiner of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, first suspected when he looked at the maps with his colleagues last year2.
But a new analysis with more Fermi data suggests that the gamma radiation traces out a pair of distinct bubbles that span some 65,000 light years from end to end - towering above the 2000-light-year-thick disc of the galaxy.
Such a well-defined shape is inconsistent with dark matter, which you would expect to be smoothly distributed and produce a diffuse glow, from gamma rays produced after dark matter particles meet and annihilate each other. "We are pretty sure the majority of emissions are not from dark matter," says Finkbeiner's student Meng Su.
Instead, they think the bubbles may have been blown out by the explosion of short-lived, massive stars born in a burst of new star formation about 10 million years ago. Alternatively, the bubbles may have been forged about 100,000 years ago by high-speed jets of matter created when roughly 100 suns' worth of material fell into the black hole at the centre of our galaxy1.
- Giant Gamma-ray Bubbles from Fermi-LAT: AGN Activity or Bipolar Galactic Wind? - Meng Su et al
- arXiv.org > astro-ph > arXiv:1005.5480 > 29 May 2010 (v1), 18 Oct 2010 (v3)
- The Fermi Haze: A Gamma-Ray Counterpart to the Microwave Haze - Gregory Dobler et al
- arXiv.org > astro-ph > arXiv:0910.4583 > 26 Oct 2009 (v1), 07 May 2010 (v2)