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ToSeek
2004-Aug-23, 04:30 PM
A galaxy's fatal plunge (http://www.spaceflightnow.com/news/n0408/22chandra/)


These images offer a dramatic look at C153, a galaxy being ripped apart as it races at 4.5 million miles per hour through a distant cluster of galaxies. The infalling galaxy's gas is being stripped by the pressure of 20-million-degree Celsius gas that permeates the cluster.

ngc3314
2004-Aug-23, 06:05 PM
A galaxy's fatal plunge (http://www.spaceflightnow.com/news/n0408/22chandra/)


These images offer a dramatic look at C153, a galaxy being ripped apart as it races at 4.5 million miles per hour through a distant cluster of galaxies. The infalling galaxy's gas is being stripped by the pressure of 20-million-degree Celsius gas that permeates the cluster.

Well, it's about time spaceflightnow caught that! The images did show up as a press release in January. Much more information may be seen at http://www.astr.ua.edu/keel/c153. I was trying to get some spectra; information on the stripped gas from Kitt Peak last week (as well as with a more suitable instrument last month, which was lost to typical weather). Trying to unscramble the spectrum was an interesting software challenge - I could just hear C153 laughing at me across 3 billion light-years. But one of the programmers pointed out that, based on the results of the analysis, I was entitled to a few chuckles, since I'm here at z=0 and C153 was thoroughly shredded long ago...

This is a good place to pay tribute to coworker Michael Ledlow, who died suddenly last June at age 39. Mike, clusters just aren't the same without you...

Manchurian Taikonaut
2005-Feb-03, 08:50 AM
X-ray scope Locates Missing Matter



NASA's Chandra X-ray Observatory has discovered two huge intergalactic clouds of diffuse hot gas. These clouds are the best evidence yet that a vast cosmic web of hot gas contains the long-sought missing matter - about half of the atoms and ions in the Universe.

Various measurements give a good estimate of the mass-density of the baryons - the neutrons and protons that make up the nuclei of atoms and ions - in the Universe 10 billion years ago. However, sometime during the last 10 billion years a large fraction of the baryons, commonly referred to as "ordinary matter" to distinguish them from dark matter and dark energy, have gone missing.


http://chandra.harvard.edu/press

"An inventory of all the baryons in stars and gas inside and outside of galaxies accounts for just over half the baryons that existed shortly after the Big Bang," explained Fabrizio Nicastro of the Harvard-Smithsonian Center for Astrophysics, and lead author of a paper in the 3 February 2005 issue of Nature describing the recent research. "Now we have found the likely hiding place of the missing baryons."

Nicastro and colleagues did not just stumble upon the missing baryons - they went looking for them. Computer simulations of the formation of galaxies and galaxy clusters indicated that the missing baryons might be contained in an extremely diffuse web-like system of gas clouds from which galaxies and clusters of galaxies formed.

These clouds have defied detection because of their predicted temperature range of a few hundred thousand to a million degrees Celsius, and their extremely low density. Evidence for this warm-hot intergalactic matter (WHIM) had been detected around our Galaxy, or in the Local Group of galaxies, but the lack of definitive evidence for WHIM outside our immediate cosmic neighborhood made any estimates of the universal mass-density of baryons unreliable....


....discovery of much more distant clouds came when the team took advantage of the historic X-ray brightening of the quasar-like galaxy Mkn 421
...

:D