Quote:
Originally Posted by speach
Are these two galaxies old or new? If they are old they seem to be dispersing, or if new not yet coalesced. As all galaxies seem to have black holes at their centres, again if old the BH have evaporated, if new the BH hasn't yet formed.
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Hmmm... not sure there is evidence ALL galaxies have a black hole? Certainly the vast majority of large galaxies seem to, but my understanding is that dwarf galaxies do not. And even if the MCs did, not sure that evaporation of black holes (I assume you are talking about evaporation by the Hawking radiation process) would have enough time even in the 13 billion years of the universes existence to do the job. I think I read somewhere that calculations show that solar mass black holes would still only radiate at a much lower temperature than the CMB, so would still absorb energy (and hence mass) from the CMB. The larger Black Holes found in galaxy centres would be even colder so we will have to wait until the universe is much larger and colder before they start evaporating.
Malcolm
