How Do High Redshift Galaxies Differ from Low Redshift Galaxies?

[skydivephil]

How do high red shift galaxies differ from low red shift galaxies? Dow e see significant differences? if so what ?

 

[marcus]

Several galaxies have been confirmed at z=8.2-8.5. They would be smaller and bluer (with new stars). You probably wouldn't see spiral structure---more like just blobs. The blue-ish new-ish starlight would be shifted into the infrared by the time we get it. I don't know a lot about this and would happily defer to anyone who shows up with more expert information. Here is some general audience reporting about that recent z=10 find:

The most recent (claimed) observation of a z=10 galaxy is, I guess, still not completely certain. There is a paper by Bowens and Illingworth and others about it:
http://arxiv.org/abs/0912.4263
It is designated UDFj-39546284

==quote from Msnbc==
"Our previous searches had found 47 galaxies at somewhat later times, when the universe was about 650 million years old. However, we could only find one galaxy candidate just 170 million years earlier," Garth Illingworth of the University of California at Santa Cruz, a leader of the research team, said today in a news release. "The universe was changing very quickly in a short amount of time."
Among the galaxies used for comparison were the previous "farthest galaxy" and two others dating to around the same time period. The distances for super-faraway galaxies are usually expressed in terms of their redshift factor, or "z." The higher the number, the more distant the galaxy. The three comparison galaxies were at redshift 8.2 or more. The team involved in last October's research report said that UDFy-38135539 was at redshift 8.55. UDFj had a redshift factor of 10.3, Illingworth and his colleagues reported.
The researchers said the galaxy candidate was less than 1 percent the size of our own Milky Way galaxy. They also said there was a 20 percent chance that the object is "a contaminant or is spurious." It's possible that an anomaly is making the galaxy look older than it really is. There's even a remote possibility that the galaxy doesn't exist at all.
==endquote==

http://cosmiclog.msnbc.msn.com/_news/2011/01/26/5920882-hubble-spots-farthest-galaxy-again

==quote from Deseret News blog==

The galaxy, designated UDFj-39546284, is so small and faint that the orbiting observatory had to collect light from the region for 87 hours. For most of that time, when exposures were made with ordinary light, it didn't show up at all. It was visible only in the 41 hours of exposures taken with a camera sensitive to far-infrared rays. The images were taken in the summers of 2009 and 2010 and combined into a single view.

NASA experts said the galaxy is a mere 1 percent of the size of our Milky Way. It's a compact object that would look blue with new stars, if its light hadn't been red-shifted during the journey to Earth.
==endquote==

 

[Chronos]

Extreme redshift galaxies generally fall under the category 'irregular'. They were too young to have time enough to evolve structures like spiral arms.