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View Full Version : HST Imaging of a z=1.55 Old Galaxy Group



Spaceman Spiff
2002-May-17, 05:24 PM
See here for a study of a group of galaxies
at a redshift 1.5:
http://xxx.lanl.gov/abs/astro-ph/0205239

Someday soon, studies such as these and much
deeper will become commonplace. They will
have to be if we are to understand the
history and evolution of galaxies. Note
that they find that the bulk stellar
populations must be older than about 3
billion years. This leaves about 1 billion
years for those galaxies' formation, for
today's best estimates of the cosmological
parameters. No mention of a 10 billion
year old stellar population at this redshift,
though.

Note, too, that the elliptical galaxy's
surface brightness essentially scales to
what it should be, if one were to redshift
a nearby elliptical of a similar mass
(a (1+z)^4 dimming), allowing for the
expected luminosity evolution of the stellar
population, given a formation epoch at
z > 3 (probably more like z > 5).

happy reading....

John Kierein
2002-May-18, 10:54 AM
I suspect that most radio objects have large numbers of electrons associated with them that produce an intrinsic red shift from the Compton effect. Still, "very cool".