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9 Gy old galaxy?

by marcus
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Mar3-05, 10:03 AM
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title: "Galaxies break new records"

Last year Roser Pello's team at the Pyrennees Observatory thought they had found a 10 billion year old galaxy IIRC, but this was later challenged [CORRECTION: hellfire reminded me that Roser thought she had found one at z=10, it wasnt 10 billion LY but z=10 which is much more remarkable]

now according to a news item some people at European Southern say they'v found one 9 billion years old. I am not sure this makes sense or that I understand correctly. It looks to me that they are claiming redshift 1.4, which would not be record-breaking. Am I missing something?

"Christopher Mullis of the University of Michigan and co-workers at the European Southern Observatory (ESO) discovered the distant cluster by sifting through old images from the XMM-Newton satellite. They looked for large X-ray sources that had not been studied before and then took a series of follow-up images of 30 candidate galaxies at optical wavelengths with ESO's Very Large Telescope (VLT) in Chile. One of these galaxies - now named XMMU J2235.3-2557 - had a redshift of 1.4, which means that it is nine billion light years away and must have formed when the universe was less than a third of its present age. Moreover, the spherical shape of the cluster implies that it has a well-organised and mature structure (Astrophysical Journal to be published)."

Here is the technical article mentioned in the article

here is a webpage with more info and some pictures
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Mar3-05, 10:32 AM
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Roser Pello's galaxy (or protogalaxy) was postulated to be located at z = 10, which means it supposed to be more than 13 Gyr old. This 9 Gyr old galaxy (at 9 GLyr of light travel distance) is located at z = 1.4 within a galaxy cluster. As far as I know, it is believed that galaxy clusters began forming at z = 2. Thus, this is actually a far cluster, but I think it is not the farthest cluster discovered till now (the paper claims that it is the "the most distant X-ray-selected cluster found to date").
Mar3-05, 10:47 AM
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Hellfire, thanks for jogging my memory about that Roser Pello thing.
It was the z=10 that was so astonishing there.
this z= 1.4 is not all that much----9 billion LY. according to the usual assumptions

Here is another related article where the claim is z > 2

Spectroscopic Redshifts to z > 2 for Optically Obscured Sources Discovered with the Spitzer Space Telescope
J. R. Houck, B. T. Soifer, D. Weedman, al
Accepted for publication on 7 Feb 2005 in ApJL. 7 pages 2 figures

"We have surveyed a field covering 9.0 degrees^2 within the NOAO Deep Wide-Field Survey region in Bootes with the Multiband Imaging Photometer on the Spitzer Space Telescope (SST) to a limiting 24 um flux density of 0.3 mJy. Thirty one sources from this survey with F(24um) > 0.75 mJy which are optically very faint (R > 24.5 mag) have been observed with the low-resolution modules of the Infrared Spectrograph on SST. Redshifts derived primarily from strong silicate absorption features are reported here for 17 of these sources; 10 of these are optically invisible (R > 26 mag), with no counterpart in B_W, R, or I. The observed redshifts for 16 sources are 1.7 < z < 2.8. These represent a newly discovered population of highly obscured sources at high redshift with extreme infrared to optical ratios. Using IRS spectra of local galaxies as templates, we find that a majority of the sources have mid-infrared spectral shapes most similar to ultraluminous infrared galaxies powered primarily by AGN. Assuming the same templates also apply at longer wavelengths, bolometric luminosities exceed 10^13 L(solar)."

Mar3-05, 11:26 AM
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9 Gy old galaxy?

Quote Quote by marcus
Assuming the same templates also apply at longer wavelengths, bolometric luminosities exceed 10^13 L(solar)."
Huh? Luminosity of over 10 Trillion suns?
Mar3-05, 12:54 PM
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but I think it is not the farthest cluster discovered till now
You're true, the article of marcus is wrong. The most distant galaxy cluster known was discovered a few days ago, and existed 1 billion years after Big Bang (see the news of 17 february of this article)
See also
Ok, introducing an age at redshift equal to 1 billion year in the Cosmology calculator
This implies for this cluster a redshift of z=5.8
That is, a comoving radial distance of 27.1 Gly

It would be nice to know when exactly formed the first galaxy cluster

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