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In this recent press release,
"Chandra turns up the heat in the Milky Way center"
http://www1.msfc.nasa.gov/news/news/releases/2004/04-169.html
it is described the observation of heated gas at a temperature of 100 million K at the center of the Milky Way. It seams to be still an open question which source could had heated the gas to such a high temperature. But there is also still another mystery: the gas seams to be continuously regenerated, since due to its high temperature the whole gas cloud should had escaped gravity within a small fraction of the lifetime of the galaxy.
The intracluster gas is postulated to contain a significant fraction (apart of baryons in galaxies) of the baryonic mass in galaxy clusters. As far as I know, two theories are postulated to explain its origin: (a) the intracluster gas was already there before galaxy formation (primordial gas) and was then compressed into the potential wells of galaxy clusters recently, during cluster formation, or (b) the intracluster gas contains mainly already processed gas, which escaped from galaxies.
The option (a) is supported by the evidence of clusters with an extremely large intracluster gas mass (up to six times the stellar mass of galaxies) and, as fas as I know, with the models of biased galaxy formation, which postulate that the efficiency of galaxy formation was not high. The option (b) is supported by the observation of high metallicities in the intracluster gas.
Probably, the truth lies somewhere in the middle between (a) and (b).
But, my questions now. Both hypothesis assume different heating mechanisms of the gas, but it seams that both mechanisms (or both sets of mechanisms) lead to the same temperature (between 10^7 and 10^8 K). Is this correct? Or is the gas ejected by galaxies colder and additionally heated afterwards e.g. due to compression by falling into the potential well? If not, how is such a coincidence possible? On the other hand, which fraction of the intracluster gas could have been originated in galaxies? Could such an observation (as mentioned above) be relevant for testing theories of the formation and origin of the intracluster gas?
"Chandra turns up the heat in the Milky Way center"
http://www1.msfc.nasa.gov/news/news/releases/2004/04-169.html
it is described the observation of heated gas at a temperature of 100 million K at the center of the Milky Way. It seams to be still an open question which source could had heated the gas to such a high temperature. But there is also still another mystery: the gas seams to be continuously regenerated, since due to its high temperature the whole gas cloud should had escaped gravity within a small fraction of the lifetime of the galaxy.
The intracluster gas is postulated to contain a significant fraction (apart of baryons in galaxies) of the baryonic mass in galaxy clusters. As far as I know, two theories are postulated to explain its origin: (a) the intracluster gas was already there before galaxy formation (primordial gas) and was then compressed into the potential wells of galaxy clusters recently, during cluster formation, or (b) the intracluster gas contains mainly already processed gas, which escaped from galaxies.
The option (a) is supported by the evidence of clusters with an extremely large intracluster gas mass (up to six times the stellar mass of galaxies) and, as fas as I know, with the models of biased galaxy formation, which postulate that the efficiency of galaxy formation was not high. The option (b) is supported by the observation of high metallicities in the intracluster gas.
Probably, the truth lies somewhere in the middle between (a) and (b).
But, my questions now. Both hypothesis assume different heating mechanisms of the gas, but it seams that both mechanisms (or both sets of mechanisms) lead to the same temperature (between 10^7 and 10^8 K). Is this correct? Or is the gas ejected by galaxies colder and additionally heated afterwards e.g. due to compression by falling into the potential well? If not, how is such a coincidence possible? On the other hand, which fraction of the intracluster gas could have been originated in galaxies? Could such an observation (as mentioned above) be relevant for testing theories of the formation and origin of the intracluster gas?