Giant Elliptical Galaxy Stuns Astronomers
Oct 26th, 2012
By Natali Anderson
A multinational team of astronomers using the Advanced Camera for Surveys and the Wide Field Camera 3 aboard NASA’s Hubble Space Telescope has captured a remarkable image of an elliptical galaxy known as 2MASX J17222717+3207571.
The galaxy 2MASX J17222717+3207571, also known as A2261-BCG (short for Abell 2261 Brightest Cluster Galaxy), is about ten times the diameter of the Milky Way Galaxy, and located 3 billion light-years away.
The new observations reveal that the galaxy’s core, measuring about 10 000 light-years, is the largest yet seen.
The team has proposed two scenarios for the galaxy’s puffy core. One idea is that a pair of merging black holes gravitationally stirred up and scattered the stars. These black holes collectively could have been as massive as several billion suns. One of the black holes would be native to the galaxy, while the second could have been added from a smaller galaxy that was gobbled up by the massive elliptical.
Another idea is that the black hole merger created gravity waves, which are ripples in the fabric of space. According to the theory of general relativity, a pair of merging black holes produces ripples of gravity that radiate away. If the black holes are of unequal mass, then some of the energy may radiate more strongly in one direction, providing the equivalent of a rocket thrust. The imbalance of forces would have ejected the merged black hole from the center at speeds of millions of kilometers per hour, resulting in the rarity of a galaxy without a central black hole.
“When I first saw the image of this galaxy, I knew right away that it was unusual,” said Dr Marc Postman of the Space Telescope Science Institute in Baltimore, lead author of the study published in the Astrophysical Journal (arXiv.org version).
By combining the power of the NASA/ESA Hubble Space Telescope, NASA’s Spitzer Space Telescope and one of nature’s zoom lenses, astronomers have found what is probably the most distant galaxy yet seen in the Universe. The object offers a peek back into a time when the Universe was only 3 percent of its present age of 13.7 billion years: here.
- Stirred, Not Shaken. Black Hole Antics Puff Up Whopper of a Galaxy (universetoday.com)
- Monster Galaxy’s Core Is Biggest Ever Seen (space.com)
- Monster galaxy may have been stirred up by black-hole mischief (eurekalert.org)