Discover the Hubble Ultra Deep Field: Deepest Portrait of the Visible Universe

[russ_watters]

Hubble Ultra Deep Field!

Very, very, very http://www10.ksc.nasa.gov/mirrors/s.../newsdesk/archive/releases/2004/07/index.html.

Astronomers at the Space Telescope Science Institute today unveiled the deepest portrait of the visible universe ever achieved by humankind. Called the Hubble Ultra Deep Field (HUDF), the million-second-long exposure reveals the first galaxies to emerge from the so-called "dark ages," the time shortly after the big bang when the first stars reheated the cold, dark universe. The new image should offer new insights into what types of objects reheated the universe long ago.

 

[Loren Booda]

The Hubble Deep Field had been my favorite wallpaper. Thanks for helping me redesign my space with the HUDF. There's art, and apparently intelligence, as far as one can see!

 

[hedons]

Supposedly the now famous original Hubble Deep Field covered an area of sky equivalent to the size of a grain of sand held at arms distance. How small an area does this new Ultra Deep Field photo cover?

Thanks!

 

[Daaf]

I recently saw a documentary on Discovery covering the Hubble telescope. At the very end of the program they said something about the next-generation Hubble, which (if they get the thing up somehow... $-wise) will be positioned 1 000 000 kms from earth.
Sounds good! They want to look at the universe at an even earlier stage. Pictures like the one posted above make us feel good about such projects again.

 

[Phobos]

HUDF - a thing of beauty

 

[russ_watters]

Originally posted by Loren Booda
The Hubble Deep Field had been my favorite wallpaper. Thanks for helping me redesign my space with the HUDF.

I'm alrady planning the poster/collage I'm going to make of it. I'll take a large photo of the whole thing for the center and two small blowups of individual galaxies or portions of it to each side/top/bottom.

Supposedly the now famous original Hubble Deep Field covered an area of sky equivalent to the size of a grain of sand held at arms distance. How small an area does this new Ultra Deep Field photo cover?

http://www10.ksc.nasa.gov/mirrors/s...desk/archive/releases/2004/07/text/index.html

Some numbers:

-HUDF covers a field of about 1/10 the diameter of the Moon, or
roughly 1/13millionth of the sky.
-HUDF contains about 10,000 galaxies.
-The oldest objects in HUDF formed roughly 800 million
years after the Big Bang.
-Hubble received roughly 1 photon per minute from the more
distant objects in HUDF.
-The total exposure length was roughly 11 days.

 

[ranyart]

Originally posted by russ_watters
Very, very, very http://www10.ksc.nasa.gov/mirrors/s.../newsdesk/archive/releases/2004/07/index.html.

Amazing! and if one looks close, actually if one moves away from the full image to about 6ft, one can clearly see an 'S'(rotation to the left of 12:00 clock), barred shape collection of Galaxies, almost as if flying outwards from a catherine wheel firework!

Pretty awesome field!

 

[Loren Booda]

The weird thing is how many of those galaxies were just then generating life!

 

[Embermage]

Just a quick clarification: the picture shows what the universe may have looked like billions of years ago because of the speed of light and the distance it has to travel to get to the Hubble camera? So in essence, the other galaxies may be more developed now, but they don't appear so to us yet... sound right?

Thanks!

 

[Nereid]

From the press release: "The ACS uncovered galaxies that existed 800 million years after the big bang (at a redshift of 7). But the NICMOS may have spotted galaxies that lived just 400 million years after the birth of the cosmos (at a redshift of 12). Thompson must confirm the NICMOS discovery with follow-up research."

Here is an example of how this kind of follow-up has been done using large Earth-based telescopes. While the objects that Gemini looked at are not in the UDF (they're very close near by), and as the faint galaxies have already been located (on NICMOS images) the 'search' part of the GEMINI work is already done, the spectra will likely be obtained in a manner similar to that described in the link.

 

[Dagenais]

Is there anyway that scientists can discover new galaxies without having to wait billions of years for the light?

 

[Nereid]

Originally posted by Embermage
Just a quick clarification: the picture shows what the universe may have looked like billions of years ago because of the speed of light and the distance it has to travel to get to the Hubble camera? So in essence, the other galaxies may be more developed now, but they don't appear so to us yet... sound right?

Not quite.

a) the distant galaxies are much redder in the image than they would have looked if you had been there at the time

b) the image contains objects at distances from 'next door' (e.g. stars in our own Milky Way), through 'sort of close' (e.g. galaxies 'only' ~1 billion light years distant), to extremely distant galaxies. In the early days of the universe, if you were there, you'd also see nearby stars and quite a few nearby 'galaxies' (they'd look quite different), but no distant ones.

You are right in saying that we're seeing the galaxies as they were when the light we now record left the galaxies, ~ 1 billion to ~<13 billion years ago. IF we could 'see' them 'today', they'd look different (the 'nearby' ones would look similar to how they appear in the image; the distant ones, likely very different).

 

[Nereid]

Originally posted by Dagenais
Is there anyway that scientists can discover new galaxies without having to wait billions of years for the light?

Sure, if the 'new galaxies' are closer than billions of light years from us

Otherwise, no; nothing travels faster than light (neutrinos are possibly a tiny, tiny fraction slower; gravity is the same as light).

 

[Dagenais]

Otherwise, no; nothing travels faster than light

Says you. Ever heard of the Millennium Falcon? It's called hyper speed!



That sucks though. Having to wait for new discoveries, as opposed to sciences like Computers, where you don't have to wait a certain amount of time for new, important discoveries.

 

[Loren Booda]

Maybe branes will enable interdimensional travel. Therein gravity is supposed to bypass ordinary spacetime separation.

 

[russ_watters]

Originally posted by Dagenais
That sucks though. Having to wait for new discoveries, as opposed to sciences like Computers, where you don't have to wait a certain amount of time for new, important discoveries.

With 10,000 galaxies in that photo alone (remember, not all of them are 13 billion light years away - many are much closer), waiting for the light to get here is not a concern.

 

[wisp]

So how did all these galaxies form so quickly after the Big Bang?
Did the galaxies condense from BB material or was something thrown out during the BB that formed the seeds of the galaxies?

 

[Nereid]

Originally posted by Dagenais That sucks though. Having to wait for new discoveries, as opposed to sciences like Computers, where you don't have to wait a certain amount of time for new, important discoveries.

'Twas ever thus in astronomy Dagenais, whether the Crab Nebula, a supernova recorded by Chinese, Korean (and more) folk nearly 1,000 years ago, but which exploded some 6,500 years earlier; or SN1987 in the Larger Magellenic Cloud (which many PF members probably saw with their own eyes in 1987), but which exploded some ~165,000 years earlier; or http://skyandtelescope.com/news/current/article_914_1.asp, one of the brightest and nearest gamma ray bursts observed to date, on 29 March 2003 (and Finnish amateur astonomers' observations of which contributed to confirming the GRB-supernova connection), but which originated over 2 billion years ago.

Because the speed of light is finite, we have a time machine.

 

[Loren Booda]

The black body radiation is an artifact of the epoch of decoupling (~400,000 years), when hydrogen became largely un-ionized. This hydrogen condensed to form stars (~80,000,000 years), which in turn formed galaxies (<1,000,000,000 years).

Condensation of hydrogen takes place where the Jeans radius, limited by the mean free path of sound in the medium under gravity and at a given temperature, determines the expanse of gaseous agglomeration.

 

[quartodeciman]

If this view touches the very edge of the "Dark Ages", when recombination made electrons join up with nuclei, is there light (EM radiation) to be expected at an earlier time than this? Are there only neutrino and gravitational radiation to be expected from before this time?

 

[Nereid]

Originally posted by wisp
So how did all these galaxies form so quickly after the Big Bang?
Did the galaxies condense from BB material or was something thrown out during the BB that formed the seeds of the galaxies?

This is an excellent question wisp!

AFAIK, in the 'concordance model', galaxies condensed from over-(matter*) density fluctuations, which were generated by "inflation, in which quantum fluctuations are able to seed density fluctuations" (the quote is from this lecture, which PF members - esp marcus! - may find interesting).

*'matter' means both 'dark matter' and 'baryonic matter' (the stuff of which we, the Earth, gas, dust, stars, ... are made). In terms of the formation of proto-galaxies, the critical distinction between 'dark matter' and baryonic matter is that the latter can 'cool' as it collapses - when baryonic matter interacts with other baryonic matter, radiation is often generated (so, crudely speaking, gravitational potential energy can be 'lost' as radiation) - this does not happen with 'dark matter'.

 

[Nereid]

Originally posted by Loren Booda
*SNIP

Condensation of hydrogen takes place where the Jeans radius, limited by the mean free path of sound in the medium under gravity and at a given temperature, determines the expanse of gaseous agglomeration.

I'm sure many PF members and guests don't really understand this statement - would you mind explaining it in somewhat simpler terms Loren?

 

[Loren Booda]

In a material medium like gas, the speed of sound determines the extent to which heat is transmitted. Also, large clouds of gas maintain their integrity by self-gravitation.

By considering both - an excess of gravitational energy over thermal energy - one may determine the minimal initial radius of coherent star formation, the Jeans radius.

 

[ranyart]

Originally posted by wisp
So how did all these galaxies form so quickly after the Big Bang?
Did the galaxies condense from BB material or was something thrown out during the BB that formed the seeds of the galaxies?

You may want to review this recent paper:http://uk.arxiv.org/PS_cache/astro-ph/pdf/0403/0403225.pdf

 

[Dagenais]

Because the speed of light is finite, we have a time machine.

Half of that stuff might not even exist anymore.

We have to wait for the light to reach us in order to make new discoveries. That's disappointing. Time limits discoveries made.

 

[russ_watters]

Originally posted by Dagenais
Half of that stuff might not even exist anymore.

We have to wait for the light to reach us in order to make new discoveries. That's disappointing. Time limits discoveries made.

But like I said earlier, with in excess of 100 billion such discoveries available to be made, we're not going to run out any time soon.

 

[quartodeciman]

It is the faint ghostly stuff that is supposed to be primordially old in this picture, yes? The brighter and more structured objects are foreground objects whose light originates at more recent times. Please correct me if I'm wrong.

 

[Monique]

Originally posted by russ_watters
Very, very, very http://www10.ksc.nasa.gov/mirrors/s.../newsdesk/archive/releases/2004/07/index.html.

?that's an eleven and a half day exposure.. how do they do thát?

 

[Nereid]

Originally posted by Monique
?that's an eleven and a half day exposure.. how do they do thát?

Simple summary - take lots of images (http://hubble.gsfc.nasa.gov/survey/hubbledev/newscenter/newsdesk/archive/releases/2004/07/faq/index.html ) of the same patch of sky, and add them up. In fact, that's really the only way to do it; otherwise cosmic rays would be difficult to remove from the image.

 

[Nereid]

Originally posted by quartodeciman
It is the faint ghostly stuff that is supposed to be primordially old in this picture, yes? The brighter and more structured objects are foreground objects whose light originates at more recent times. Please correct me if I'm wrong.

At the 0-th order, correct.

Next level, the 'blue drop-out' objects are likely to be the really distant ones. Distant objects will be redshifted so much that rest-wavelengths blue-ward of the Lyman limit (which are expected to be absorbed by hydrogen gas near the distant object) are in the visible part of the spectrum. In fact, there will surely be some interesting astronomy to be done looking at the faint objects - which look like point sources? which are distant white dwarfs? which are quasars? etc.

Next level, take spectra of the faint objects ...

 

[monadian]

Enough analogies, what's the focal area?

With the original Deep Field, I heard that it was like looking through the eye of a needle held at arms length. For the UDF, it's like a grain of sand at arms length or looking through an 8 foot soda straw. That fine, but what portion of the sky is this equivalent to in terms of arc minutes and seconds?

I've got this data for Deep Field at home some place I think, but I can't find this info anyplace for UDF. If anybody knows, I'd sure be happy if you could share! And if you happen to know a weblink with corroborating data, that would be frosting on the cake.

Thanks fellow space junkies

 

[Loren Booda]

Have these observed structures modified Hubble's "tuning fork" or other, sequential, classifications of galaxies?

 

[Nereid]

Originally posted by monadian
With the original Deep Field, I heard that it was like looking through the eye of a needle held at arms length. For the UDF, it's like a grain of sand at arms length or looking through an 8 foot soda straw. That fine, but what portion of the sky is this equivalent to in terms of arc minutes and seconds?

I've got this data for Deep Field at home some place I think, but I can't find this info anyplace for UDF. If anybody knows, I'd sure be happy if you could share! And if you happen to know a weblink with corroborating data, that would be frosting on the cake.

Thanks fellow space junkies

Try the Fast Facts and Q&A on http://hubble.gsfc.nasa.gov/survey/hubbledev/newscenter/newsdesk/archive/releases/2004/07/fastfacts/index.html . 3 arc minutes; < 1 ten-millionth of the whole sky; I'll take a (Belgian) chocolate cake please (or a New York cheesecake with Belgian chocolate topping).

 

[Loren Booda]

Isn't Hubble's optical resolution ~.05"?

 

[Nereid]

Originally posted by Loren Booda
Isn't Hubble's optical resolution ~.05"?

From the link in my previous post:
"9) How sharp is Hubble's resolution in pinpointing far-flung galaxies in the Ultra Deep Field?

Hubble's keen vision (0.085 arc seconds.) *SNIP"

The UDF ACS image is ~3' (arc minutes) on each side; the NICMOS one ~2.4' square.