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Number of galaxies by type, today

  1. Aug 24, 2008 #1
    I'm looking for reliable informations about the % numbers of galaxies in the whole visible universe, by Hubble type (S, SB, S0, E, Irr), for a T0 time slice (i.e. today).

    Of course, looking far away into space means we're also looking far away into the past, so distant galactic populations (by type) isn't the same over there, as what we find over here. For consistency, I want to know the best (i.e. most accurate) % evaluation of galaxies at our universal epoch.

    On my side, I was able to estimate the following % numbers, and I need a confirmation :

    For all galaxies located at a distance < 100 MLY (about 2100 galaxies) :
    Irr : ~ 20%
    E : ~ 10%
    S0 : ~ 20%
    S : ~ 20%
    SB : ~ 30%

    So can I assume that these percentages are the same everywhere (at the same universal time) ?

    Any data on this ?
  2. jcsd
  3. Aug 24, 2008 #2


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    Wiki says there are 80 billion galaxies


    This may all so interest you

  4. Aug 24, 2008 #3


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  5. Aug 24, 2008 #4
    Thanks for the relpy. But apparently, there isn't much info about galactic types (E, S0, S, SB, Irr) and population today from your links.
  6. Aug 24, 2008 #5

    Vanadium 50

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    It's probably the best one can do. Looking out, we see (obviously) younger galaxies, so we would have to somehow model their evolution. But worse, we see a biased sample - we see bright galaxies. So we would have to correct twice - and what are these corrections based on? Right - nearby galaxies. So you might as well save yourself the trouble and just look at near galaxies from the get-go.
  7. Aug 25, 2008 #6


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    Discerning the morphology of galaxies beyond Z~1 is problematic. As noted by other posters, large, bright galaxies dominate the population of those observable - which obviously skews the sample. LEDA has the most complete listing available. It is interesting to extrapolate the sample population based on local distributions, but, clearly unreliable. It is highly probable young, small, irregular galaxies were extremely abundant in the early universe.
    Last edited: Aug 25, 2008
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