Surprise Discovery in the Early Universe [earliest known massive cluster of galaxies]

An international team of astronomers using the world's largest X-ray and optical telescopes have spotted the most distant massive object ever detected, a cluster of galaxies 9 billion light years distant from Earth.

The cluster of galaxies is so far away that the light detected by the team is much older than the Earth itself. The galaxy cluster, if it is even still there, would be at least 11 billion years old now.

"By capturing this ancient, 9-billion-year-old light, we have a snapshot of the universe at a youthful age of less than 5 billion years, which is about 1/3 of the present age," said project leader Christopher Mullis, a research fellow in the University of Michigan's Department of Astronomy.

Schematic diagram of the distribution of known galaxy clusters in space. As Earth-bound observers look out from the bottom point toward the top of the cone, they view an increasingly distant and early universe. Distance (redshift) is marked on the right axis and the corresponding cosmic look-back time is indicated on the left axis. The newly discovered cluster at z=1.4 (labeled "XMMU J2235") illuminates a remote regime which is well beyond the horizon of previous studies (labeled "ROSAT horizon").

As exciting as it is to break a record, it's also an important cosmological finding. "Just a few years ago, astronomers did not believe structures like this even existed at such an early time," Mullis said. This galaxy cluster, which is being seen as it appeared about 2 billion years after its formation, is well-organized and "mature," he said. Although it is very far back in time, it looks as if this structure had formed in a way that is consistent with more recent structures.

"Even at this early stage in cosmic history, this appears already as a mature, fully assembled structure which implies that this is an old cluster in a young universe," said European Southern Observatory astronomer Piero Rosati, who collaborated on the study.

The record-breaking galaxy cluster was also a somewhat surprising find for the team, who were testing a new approach to hunting distant objects. "Basically we stepped up to the plate for our first time at bat with this new system, and we hit a home run," Mullis said.

Mullis and his colleagues started their search by combing through archives of old images from the European Space Agency's orbiting X-ray observatory, XMM-Newton, looking for diffuse X-ray sources that had not been previously studied. Cluster galaxies shine brightly in optical light, but they also emit strong X-ray signals resulting from very hot gas that envelopes the cluster.

The record-breaking cluster initially turned up, small but distinct, off center in an image made by another team.

The X-ray image of the distant cluster is comprised of just 280 photons---individual parcels of light---collected over a 12.5-hour exposure. By comparison, on a sunny day the human eye is flooded by about 10 quadrillion photons per second.

With this distant cluster candidate and dozens of others culled from the X-ray archive, Mullis and his team then turned to one of the world's largest optical telescopes, the European Southern Observatory's Very Large Telescope, located in the Atacama Desert, Chile. They took a series of relatively quick exposures of the candidates with red and blue filters on the telescope.

What Mullis and his Italian and German collaborators were looking for at each of the candidate spots were very red galaxies, indicating light that has traveled for an extremely long time to reach Earth. "The redder the better," Mullis said. Almost immediately, they turned up this cluster of red objects that seemed to be beyond the previous distance record.

"I spent a full day rechecking my data before I called any of the other scientists," Mullis said. "It appeared to be almost unbelievably distant."

Subsequent, more detailed measurements on 12 major galaxies in the cluster were used to confirm that they were equidistant from Earth at about 9 billion light years. The entire cluster is probably hundreds or even thousands of galaxies held together by gravity, Mullis said.

Collaborator Hans Bohringer of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany said the discovery "encourages us to search for additional distant clusters using the same efficient techniques used to locate the present cluster."

Mullis and his team are going to broaden the search to find more super-distant galaxy clusters with this new approach. They also plan to go back and take longer optical and X-ray telescope exposures of the record-setting cluster to get a better sense of its features.

"Finding it is one thing," Mullis said. "We also need to go back in there and maximize that return." With enough data on this and other super-distant massive objects, Mullis expects to find new answers to some fundamental questions of how the universe formed.

Mullis will be presenting this finding at an international astronomy conference in Hawaii focused on connecting galaxy clusters to the underlying physics of space time and gravity. The meeting is being organized by U-M physics professor Gus Evrard, and sponsored in part by the Michigan Center for Theoretical Physics.

"It's special to live in the era of human history when the terrain of the whole visible universe is being revealed," Evrard said.

A paper by Mullis and his team will also appear in an upcoming issue of The Astrophysical Journal.

More images and information is available on Christopher Mullis' dedicated web page here.

2 posted on 03/02/2005 5:12:16 PM PST by PatrickHenry (<-- Click on my name. The List-O-Links for evolution threads is at my freeper homepage.)

What I never understood about "looking back into time" when viewing distant galaxies, is that the Universe is expanding at less than light speed (c), so (assuming the Big Bang theory's contention that the Universe expanded from a single point) how could a galaxy that is 11 billion light years away still appear ancient?

It seems to me it should appear somewhat more recent.

Soo, when is the next train leaving for that galagxy? If it is not infested with dummycRATs, I wanna be there.

Incredible. Thanks for bringing this to our attention.

Also, please add me to your space items ping list.

how could a galaxy that is 11 billion light years away still appear ancient?

The light started out 11 billion years ago, and it took the light that long to get here. We're seeing what was "sent" to us 11 billion years ago. It's an old picture.

6 posted on 03/02/2005 5:32:09 PM PST by PatrickHenry (<-- Click on my name. The List-O-Links for evolution threads is at my freeper homepage.)

please add me to your space items ping list.

It's not a space list. Read the description at my homepage. Then let me know. If you want to be on a space ping list, contact KevinDavis.

8 posted on 03/02/2005 5:36:28 PM PST by PatrickHenry (<-- Click on my name. The List-O-Links for evolution threads is at my freeper homepage.)

The people who believe that God created everthing already mature would be interested in that comment.

The light started out 11 billion years ago, and it took the light that long to get here.

Ya I understand that, but 11 billion years ago, the Universe was much MUCH closer together, so wouldn't that light have reached this part of the universe earlier?

Maybe I'm not explaining my question correctly... but it seems to me that we can look 11 billion years in the past, then we should be able to also look 4 billion years in the past and see the forming of our own solar system.

The people who believe that God created everthing already mature would be interested in that comment.

Only to be shot down once they realised it's all about normalized number density, not about finding "just one".

but it seems to me that we can look 11 billion years in the past, then we should be able to also look 4 billion years in the past and see the forming of our own solar system.

We can look back 4 billion years. It's a matter of finding things that are 4 billion light years away from us, and they can be spotted by looking for objects that appear with a specific redshift. But we aren't 4 billion light years away. Someone who is that far away can see what you're talking about, just as you can see them as they were 4 billion years ago.

12 posted on 03/02/2005 6:08:16 PM PST by PatrickHenry (<-- Click on my name. The List-O-Links for evolution threads is at my freeper homepage.)

But we aren't 4 billion light years away

Well, assuming an expanding universe (and a red shift basically proves that point) we SHOULD be able to see "ourselves" somewhere between the speed of light and the speed of expansion.

And if not (which I believe to be the case) then why do we see 11B (or 15B as the limit currently is) light years back in time?

Here is one way to visualize it: imagine the formation of our solar system was a "flash and bang" event. From that event the light began traveling in all directions. In order for us to see the event now would require that our solar system traveled in excess of the speed of light in order to get outside the sphere of light spreading from the formation event.

In order for us to see the event now would require that our solar system traveled in excess of the speed of light in order to get outside the sphere of light spreading from the formation event.

Exactly!

At the moment of creation (singularity), the light reaching us would be "immediate". Now if we were expanding at say half the speed of light, the light we would see wouldn't be 11B years old, but rather 6.5B. No?

we SHOULD be able to see "ourselves" somewhere between the speed of light and the speed of expansion.

In one sense, you're right. The light from the solar system, as it was 4 billion years ago, really is "out there." Right now that light is 4 billion light years away. (Adjusted a bit for the fact that the sun has been moving during that time, but not at the speed of light.) It can be seen, but only by those who are in a position -- now -- to receive that light. For you to see that light, you'd need to go to where it is, and that doesn't seem possible.

16 posted on 03/02/2005 6:33:21 PM PST by PatrickHenry (<-- Click on my name. The List-O-Links for evolution threads is at my freeper homepage.)

I don't know how to answer that for I'm as puzzled by some aspects of the expanding Universe as you may be.

This may be the most interesting if not profound statement in the whole article.

Just a dumb query- given the Big Bang - has every bit of matter traveled at the same rate of degrading or increasing expansion? If so, either way, is the constant currently used (our light speed)- valid? Or could it be prone to variance on a scale yet unimagined?

The speed of light is believed to have been constant. There is evidence for this: The Age of the Universe and SN1987A.

The speed of the expansion, starting with the big bang, is believed to have originally been very fast, then it slowed down, and now it seems to be accelerating. There's a lot of information on the internet. Here's a starter: Big Bang.

20 posted on 03/02/2005 7:07:23 PM PST by PatrickHenry (<-- Click on my name. The List-O-Links for evolution threads is at my freeper homepage.)

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