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Posted

Check out Spitzer's newest press release:

 

Four galaxies are slamming into each other and kicking up billions of stars in one of the largest cosmic smash-ups ever observed.

 

The clashing galaxies, spotted by NASA's Spitzer Space Telescope, will eventually merge into a single, behemoth galaxy up to 10 times as massive as our own Milky Way. This rare sighting provides an unprecedented look at how the most massive galaxies in the universe form.

 

"Most of the galaxy mergers we already knew about are like compact cars crashing together," said Kenneth Rines of the Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass. "What we have here is like four sand trucks smashing together, flinging sand everywhere." Rines is lead author of a new paper accepted for publication in Astrophysical Journal Letters.

 

Here's the rest: http://www.spitzer.caltech.edu/Media/releases/ssc2007-13/release.shtml

 

its really amazing to think of just how MASSIVE this stuff is...

Posted

Hi Doc and YT.

 

Doc this is very exciting and you are doing a good job digging up news that people can discuss. For my part I thank you, and hopefully others appreciate it too.

 

Sometimes the TECHNICAL JOURNAL article can give clarification and extra info, and here it is. This is what has been accepted for publication by Astrophysical journal Letters.

 

If you want the full PDF, just go here to the abstract and click on PDF. It is FREE.

 

http://arxiv.org/abs/0708.0011

 

An Extremely Massive Dry Galaxy Merger in a Moderate Redshift Cluster

Kenneth Rines (CfA), Rose Finn (Siena), Alexey Vikhlinin (CfA)

5 pages, 2 figures, to appear in ApJL

(Submitted on 31 Jul 2007)

 

"Abstract: We have identified perhaps the largest major galaxy merger ever seen. While analysing Spitzer IRAC images of CL0958+4702, an X-ray selected cluster at z=0.39, we discovered an unusual plume of stars extending $\gtrsim$110 kpc outward from the bright central galaxy (BCG). Three galaxies 1-1.5 mag fainter than the BCG lie within 17 kpc (projected) of the BCG and are probably participating in the merger. The plume is detected in all four IRAC channels and at optical wavelengths in images from the WIYN telescope; the surface brightness is remarkably high ($\mu_r\approx$24.8 mag arcsec$^{-2}$ at 50 kpc). The optical and infrared colors are consistent with those of other BCGs, suggesting that the plume is composed of old stars and negligible recent star formation (hence a "dry merger"). The luminosity in the plume is at least equivalent to a 4L^* galaxy. A diffuse halo extending 110 kpc from the BCG in one IRAC image suggests the total amount of diffuse light is L_r\sim 1.3x10^{11}h^{-2} L_sun. A Chandra observation shows an X-ray image and spectrum typical of moderate-mass clusters. We use MMT/Hectospec to measure 905 redshifts in a 1 deg^2 region around the cluster. The velocities of two of the BCG companions indicate a merger timescale for the companion galaxies of $\sim$110 Myr and $\sim$0.5-1 Gyr for the plume. We conclude that the BCG and intracluster light of CL0958 is formed by major mergers at moderate redshifts. After the major merger is complete, CL0958 will likely become a fossil cluster. "

 

All the notational garbage and $ signs will go away if you download the PDF file. It is only the abstract summary that has this unpleasant hard to read mess of symbols.

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