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| Yousuf Khan... |
 Posted: Fri Oct 23, 2009 1:29 am |
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The galaxy cluster, known as JKCS041, beats the previous record holder
by about a billion light years.
Yousuf Khan
Most distant galaxy cluster yet discovered | Machines Like Us
"The most distant galaxy cluster yet has been discovered by combining
data from NASA's Chandra X-ray Observatory and optical and infrared
telescopes. The cluster is located about 10.2 billion light years away,
and is observed as it was when the Universe was only about a quarter of
its present age."
http://machineslikeus.com/news/most-distant-galaxy-cluster-yet-discovered |
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| Dan Birchall... |
| Posted: Fri Oct 23, 2009 3:33 am |
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bbbl67 at (no spam) spammenot.yahoo.com (Yousuf Khan) wrote:
[quote]The galaxy cluster, known as JKCS041, beats the previous record holder
by about a billion light years.
Yousuf Khan
Most distant galaxy cluster yet discovered | Machines Like Us
"The most distant galaxy cluster yet has been discovered by combining
data from NASA's Chandra X-ray Observatory and optical and infrared
telescopes. The cluster is located about 10.2 billion light years away,
and is observed as it was when the Universe was only about a quarter of
its present age."
http://machineslikeus.com/news/most-distant-galaxy-cluster-yet-discovered
[/quote]
Following up,
http://chandra.harvard.edu/press/09_releases/press_102209.html
"JKCS041 was originally detected in 2006 in a survey from the United
Kingdom Infrared Telescope (UKIRT). The distance to the cluster was then
determined from optical and infrared observations from UKIRT, the
Canada-France-Hawaii telescope in Hawaii and NASA's Spitzer Space
Telescope. Infrared observations are important because the optical light
from the galaxies at large distances is shifted into infrared
wavelengths because of the expansion of the universe.
"The Chandra data were the final - but crucial - piece of evidence as
they showed that JKCS041 was, indeed, a genuine galaxy cluster. The
extended X-ray emission seen by Chandra shows that hot gas has been
detected between the galaxies, as expected for a true galaxy cluster
rather than one that has been caught in the act of forming."
Multi-wavelength astronomy for the win.
--
djb at (no spam) | Dan Birchall, Night Operation Assistant, Subaru Telescope/NAOJ.
naoj | Views I express are my own, obviously not those of my employer.
..org | I need to practice "First Responder" skills. Go hurt yourself? |
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| dlzc... |
| Posted: Fri Oct 23, 2009 8:18 am |
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Dear Yousuf Khan:
On Oct 23, 10:39 am, Yousuf Khan <bbb... at (no spam) spammenot.yahoo.com> wrote:
[quote]Dan Birchall wrote:
"The Chandra data were the final - but crucial - piece
of evidence as they showed that JKCS041 was,
indeed, a genuine galaxy cluster. The extended
X-ray emission seen by Chandra shows that hot
gas has been detected between the galaxies, as
expected for a true galaxy cluster rather than one
that has been caught in the act of forming."
Multi-wavelength astronomy for the win.
At that distance, with that red-shift, I wonder if
X-rays are still detected as X-rays?
[/quote]
*All* light is red shifted by 1+z.
At 10 billion light years, this should be a factor of ~2.5.
What I wonder is if we are missing more distant clusters, because more
distant objects are larger... hence so would be the systems. After
all the CMBR glow originated from "intercluster gas" too...
David A. Smith |
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| Yousuf Khan... |
| Posted: Fri Oct 23, 2009 11:39 am |
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Dan Birchall wrote:
[quote]"The Chandra data were the final - but crucial - piece of evidence as
they showed that JKCS041 was, indeed, a genuine galaxy cluster. The
extended X-ray emission seen by Chandra shows that hot gas has been
detected between the galaxies, as expected for a true galaxy cluster
rather than one that has been caught in the act of forming."
Multi-wavelength astronomy for the win.
[/quote]
At that distance, with that red-shift, I wonder if X-rays are still
detected as X-rays?
Yousuf Khan |
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| YKhan... |
| Posted: Fri Oct 23, 2009 9:10 pm |
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On Oct 23, 2:18 pm, dlzc <dl... at (no spam) cox.net> wrote:
[quote]*All* light is red shifted by 1+z.
At 10 billion light years, this should be a factor of ~2.5.
[/quote]
According to Wolfram Alpha, the z=1.92 at that range.
[quote]What I wonder is if we are missing more distant clusters, because more
distant objects are larger... hence so would be the systems. After
all the CMBR glow originated from "intercluster gas" too...
[/quote]
Well, sure, but at that time all of the galaxies would've been part of
one big cluster rather than several.
Yousuf Khan |
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| Steve Willner... |
| Posted: Mon Oct 26, 2009 11:52 am |
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In article <81068a25-8797-4997-ab6b-3538e07c674f at (no spam) w37g2000prg.googlegroups.com>,
dlzc <dlzc1 at (no spam) cox.net> writes:
[quote]*All* light is red shifted by 1+z.
At 10 billion light years, this should be a factor of ~2.5.
[/quote]
I couldn't find a journal article or even a preprint, but there's
more information at
http://chandra.cfa.harvard.edu/photo/2009/jkcs041/
Depending on which distance they are giving -- I'm guessing it's the
light travel time distance -- redshift should be about 1.92, as
someone else mentioned. This means the X-rays observed by Chandra
at, say, 1.5 keV were emitted at an energy of 4.5 keV or so.
[quote]What I wonder is if we are missing more distant clusters, because more
distant objects are larger... hence so would be the systems. After
all the CMBR glow originated from "intercluster gas" too...
[/quote]
Note the difference between "intracluster gas," which was observed
from JKCS 041, and "intercluster gas." No clusters existed when the
CMBR was formed, so neither term is really correct for the CMBR.
The importance of observing the intracluster hot gas is that it
establishes the existence of a genuine -- probably nearly virialized
-- cluster, not just a bunch of galaxies that happen to be near each
other in space. In other words, at least some of the galaxies have
crossed the cluster volume under the influence of the cluster's
gravitational potential. Otherwise, the gas wouldn't be heated.
As dlzc suggests, more distant clusters would be far harder to
observe because of surface brightness dimming. I'm amazed at an
X-ray observation at z=1.92. It took >75 ks, but even so....
--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123 swillner at (no spam) cfa.harvard.edu
Cambridge, MA 02138 USA |
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