Most Distant Galaxy Ever, Found Using Keck

[wonderboy]

http://www.theguardian.com/science/2013 ... -factory#_

[Ann]

Interesting! Thanks for posting this, Wonderboy!

From my complete amateur perspective, it doesn't seem so strange that this galaxy was furiously churning out stars. After all, the universe must have been tremendously rich in gas so early in its history. Bear in mind that it must already have contained all the matter that it was ever going to get, but most of its baryonic matter was "free gas", not gas locked up in stars. Also, because the universe was so small back then, the gas must have been so fantastically concentrated compared with what it is now. In short, the gas supply must have been a true bonanza for a gas-hungry and gas-guzzling young galaxy back then!

I find it fascinating and rather strange that the early galaxy was so metal-rich. You would expect those early galaxies to be extremely metal-poor. But if several generations of very short-lived extremely massive stars had already exploded in this galaxy, enriching it with metals, that might explain the metal content.

Ann

[BDanielMayfield]

I found this very interesting too, and I was surprised as well by the metal content for such an infant galaxy.

I agree with all you wrote Ann except for this:

... it must already have contained all the matter that it was ever going to get ...

I think that it’s very likely and maybe even certain that this galaxy continued to draw in more material in the form of gas and other dwarf and larger galaxies that would have been gravitationally attracted to it. By now, seeing as how it got such an early start, it could be a truly enormous galactic specimen.

[Chris Peterson]

I agree with all you wrote Ann except for this:

... it must already have contained all the matter that it was ever going to get ...

I think that it’s very likely and maybe even certain that this galaxy continued to draw in more material in the form of gas and other dwarf and larger galaxies that would have been gravitationally attracted to it. By now, seeing as how it got such an early start, it could be a truly enormous galactic specimen.

I think she was referring to the Universe, not the galaxy.

[Ann]

Chris wrote:

I think she was referring to the Universe, not the galaxy.

I was.

Ann

[ErnieM]

The zoomed panel on this Hubble image highlights the galaxy known as z8_GND_5296, which was recently confirmed to be the most distant galaxy known, hailing from only 700 million years after the Big Bang. Credit: V. Tilvi (Texas A&M), S. Finkelstein (UT Austin), the CANDELS team, and HST/NASA

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By using data collected by the Hubble Space Telescope and observations from the Keck I telescope at the Keck Observatory in Hawaii, astronomers have now confirmed that the galaxy designated z8_GND_5296 formed within 700 million years after the beginning of the universe, making it the oldest and most distant galaxy ever verified.

Because the galaxy is so far from Earth, scientists were able to observe z8_GND_5296 as it would have appeared about 13.1 billion years ago.

Space is very big and there are huge amount of tiny specs in the night sky. How do NASA scientists decided on picking this particular tiny spot. Do they follow a specific set of criteria or they simply got lucky?

Why no mention of "gravitational lensing" in this story. If gravitational lensing was not involved, does this mean Hubble can see this far back, only 700 million years after the Big Bang? If so, how much further can Hubble see? Then again, another few million years in astonomical terms is inconsequntial?

[Chris Peterson]

Space is very big and there are huge amount of tiny specs in the night sky. How do NASA scientists decided on picking this particular tiny spot. Do they follow a specific set of criteria or they simply got lucky?

You'd have to look at the observing time request to see exactly why this area was chosen. But most likely it was "luck" (even if this was a survey project). A lot of information is pulled from images that were intended for other projects, as well.

The structure of the Universe is extremely uniform, so there are no apparent preferential directions to look for very distant objects. You just have to scan a lot of the sky.

Why no mention of "gravitational lensing" in this story. If gravitational lensing was not involved, does this mean Hubble can see this far back, only 700 million years after the Big Bang? If so, how much further can Hubble see? Then again, another few million years in astonomical terms is inconsequntial?

The limitations on the HST (or any astronomical camera) are based on the photon flux that can be detected, not the distance. Every optical telescope is capable of seeing to the edge of the optical universe, which represents photons emitted when the Universe was 377,000 years old. Of course, they would have to have been very energetic photons, as the redshift is so great (z > 1000). We see those photons at microwave wavelengths, as the cosmic microwave background.

Given a bright enough source, and one which emitted photons that would redshift into the optical regime, the HST has no distance limits (except the recombination wall at 377,000 years). In reality, the limits are probably not far from what we currently see, with redshifts around 12, corresponding to an age of a few hundred million years. Much further back and there may not have been any bright objects, or any that existed will be shifted to wavelengths longer than optical cameras can detect. Older sources may be better seen with radio telescopes, for instance.

[cosmo_uk]

As Chris says this was from a deep survey CANDELS I think. So basically they image the sky in many different filters and then look for faint galaxies with certain properties ie brighter in some filters than others. In this case they were probably looking for 'drop outs' galaxies that have a break in their spectral shape such that they are undetected in a 'blue' (which for high redshift objects could actually be quite red) filter but appear in redder filters. They then have a candidate list to follow up in detail with ground based telescopes (Keck in this case) to confirm these spectral features.

[BDanielMayfield]

Chris wrote:

I think she was referring to the Universe, not the galaxy.

I was.

Ann

Sorry, Ann. I thought it odd that you would say that this galaxy would never receive more material, given your astronomical savvy, but I had taken your statement out of context. In the future I will attempt to read people’s comments more carefully before responding.

Yes, we now know that the universe is not producing new mater now, and it hasn’t received any new matter since the beginning. But this wasn’t always widely believed. The old Steady State model of cosmology had the universe receiving new mater continuously, but that theory has been thoroughly disproved by the discovery of the leftover heat from the Big Bang.

[bystander]

Galaxy Found in Hubble Survey Has Farthest Confirmed Distance
NASA | STScI | HubbleSite | 2013 Oct 23

This image from the Hubble Space Telescope CANDELS survey highlights the most distant galaxy in the universe with a definitively measured distance, dubbed z8_GND_5296. The galaxy's red color alerted astronomers that it was likely extremely far away, and thus seen at an early time after the Big Bang. A team of astronomers measured the exact distance using the Keck I telescope with the new MOSFIRE spectrograph. They found that this galaxy is seen at about 700 million years after the Big Bang, when the universe was just 5 percent of its current age of 13.8 billion years.

Credit: NASA, ESA, V. Tilvi (Texas A&M University), S. Finkelstein (University of Texas, Austin), and C. Papovich (Texas A&M University)

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[url=http://mcdonaldobservatory.org/news/gallery/artists-rendition-galaxy-z8gnd5296][b][i]Artist's Rendition of Galaxy z8_GND_5296[/i][/b][/url] [b][i]Credit: V. Tilvi, S.L. Finkelstein, C. Papovich, and the Hubble Heritage Team[/i][/b]

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Texas Astronomer Discovers Most Distant Known Galaxy
MacDonald Observatory | University of Texas | 2013 Oct 23

UT, Texas A&M Astronomers Discover Universe's Most Distant Galaxy
Texas A&M University | 2013 Oct 23

A galaxy rapidly forming stars 700 million years after
the Big Bang at redshift 7.51 - S. L. Finkelstein et al

• Nature 502(7472) 524 (24 Oct 2013) DOI: 10.1038/nature12657
  arXiv.org > astro-ph > arXiv:1310.6031 > 22 Oct 2013

• An artist's rendition of the newly discovered most distant galaxy z8_GND_5296. (The galaxy looks red in the actual Hubble Space Telescope image because the collective blue light from stars get shifted toward redder colors due to the expansion of the universe and its large distance from Earth.)

[Chris Peterson]

An artist's rendition of the newly discovered most distant galaxy z8_GND_5296. (The galaxy looks red in the actual Hubble Space Telescope image because the collective blue light from stars get shifted toward redder colors due to the expansion of the universe and its large distance from Earth.)

They could be a little more clear about the effects of redshift with these very distant galaxies. We're not seeing any emitted blue light. What we're seeing with these apparently red galaxies is light emitted around 70 nm - extreme UV. The blue light shown in the artist rendering would be recorded by us at around 4 um - middle or thermal infrared.

[geckzilla]

I really wish the artist had not opted for the random sparkly appearance for the stars. Well, anyway, maybe if I am going to be critical I should try an artistic representation of this sort myself sometime.

[Chris Peterson]

I really wish the artist had not opted for the random sparkly appearance for the stars. Well, anyway, maybe if I am going to be critical I should try an artistic representation of this sort myself sometime.

It seems like a sort of silly thing to generate an "artistic representation" of in the first place. It's a galaxy. We have thousands of photographic examples of actual galaxies which are probably more representative of the visible-light appearance of this distant galaxy than any imagined image.

[geckzilla]

I think that's actually what was done for this image. It looks like a picture of an actual galaxy which has been fitted to be similar to the shape of the distant galaxy. It's just that then the sparkles were also applied.