APOD: The Hubble Extreme Deep Field (2012 Oct 14)

[ErnieM]

Is this the only sweet spot Hubble is able to see galaxies as young as 13 billions years ago? Are we looking towards the direction of a long (13 billion years) elongated tapering tube of a Picard horn shaped universe? The farther we are able to see, space are more compact and dense hence the red-shifted young galaxies are much closer to each other.

[DavidLeodis]

The 'WFPC3' link in the explanation brings up information on the 'WFC3' camera of the Hubble Space Telescope in which it states "The Wide Field Camera 3 (WFC3)...installed in May 2009...replaces the Wide Field Planetary Camera 2 (WFPC2)". The Hubble NewsCenter release about the image does not mention a WFPC3 but does mention the WFC3. I would be grateful if someone could please let me know if WFC3 and WFPC3 are, or are not, alternative names (as acronyms here) for the same camera.

[500pesos]

I am a bit puzzled. If this picture shows galaxies as they were 13 billion years ago, I would expect to see mostly irregular and/or spiral galaxies. 13 billion yrs ago and, already, plenty of oval-shaped galaxies where it seems star formation has already ceaced? Weird.

[bystander]

The 'WFPC3' link in the explanation brings up information on the 'WFC3' camera of the Hubble Space Telescope in which it states "The Wide Field Camera 3 (WFC3)...installed in May 2009...replaces the Wide Field Planetary Camera 2 (WFPC2)". The Hubble NewsCenter release about the image does not mention a WFPC3 but does mention the WFC3. I would be grateful if someone could please let me know if WFC3 and WFPC3 are, or are not, alternative names (as acronyms here) for the same camera.

The WFC3 (SM4) is the replacement for the WFPC2 (SM1).

[bystander]

Is this the only sweet spot Hubble is able to see galaxies as young as 13 billions years ago? Are we looking towards the direction of a long (13 billion years) elongated tapering tube of a Picard horn shaped universe? The farther we are able to see, space are more compact and dense hence the red-shifted young galaxies are much closer to each other.

This is just one relatively "blank" spot in the sky where they chose to aim the Hubble. We could choose any other "blank" spot and get much the same results, just different galaxies. The HDF-S and HDF-N are two early results of the same type of images.

[bystander]

I am a bit puzzled. If this picture shows galaxies as they were 13 billion years ago, I would expect to see mostly irregular and/or spiral galaxies. 13 billion yrs ago and, already, plenty of oval-shaped galaxies where it seems star formation has already ceaced? Weird.

Only the faintest and reddest galaxies are over 13 billion years old. This image shows a wide range of galaxies. The larger and brighter galaxies are much closer.

The Hubble Ultra Deep Field is an image of a small area of space in the constellation of Fornax (The Furnace), created using Hubble Space Telescope data from 2003 and 2004. By collecting faint light over one million seconds of observation, the resulting image revealed thousands of galaxies, both nearby and very distant, making it the deepest image of the Universe ever taken at that time.

The new full-color XDF image is even more sensitive than the original Hubble Ultra Deep Field image, thanks to the additional observations, and contains about 5500 galaxies, even within its smaller field of view. The faintest galaxies are one ten-billionth the brightness that the unaided human eye can see'

[DavidLeodis]

The 'WFPC3' link in the explanation brings up information on the 'WFC3' camera of the Hubble Space Telescope in which it states "The Wide Field Camera 3 (WFC3)...installed in May 2009...replaces the Wide Field Planetary Camera 2 (WFPC2)". The Hubble NewsCenter release about the image does not mention a WFPC3 but does mention the WFC3. I would be grateful if someone could please let me know if WFC3 and WFPC3 are, or are not, alternative names (as acronyms here) for the same camera.

The WFC3 (SM4) is the replacement for the WFPC2 (SM1).

Thanks bystander.

I was just confused by the explanation using WFPC3 yet that link was to information on the WFC3. As I knew there had been a Wide Field Planetary Camera 2 (WFPC2) I had wondered if there had also been a Wide Field Planetary Camera 3 (WFPC3) and the explanation had, wrongly, used that acronym. It seems however that WFC3 and WFPC3 are presumably alternative acronyms for the same camera.

[EKI]

Is it a three core galaxy in the top central part of the image ??

[casusB]

so, are the distant galaxies in the image less than a billion years old? Are they metallic-poor in consequence?
Look like regular galaxies to me.
14 billion year old universe? Poppycock. Big Bang? Poppycock.

[neufer]

so, are the distant galaxies in the image less than a billion years old?

Are they metallic-poor in consequence?

Look like regular galaxies to me.

<<After the Big Bang, the universe, for a time, was remarkably homogeneous, as can be observed in the Cosmic Microwave Background or CMB (the fluctuations of which are less than one part in one hundred thousand). There was little-to-no structure in the universe, and thus no galaxies. Therefore we must ask how the smoothly distributed universe of the CMB became the clumpy universe we see today.

The most accepted theory of how these structures came to be is that all the large-scale structure of the cosmos we observe today was formed as a consequence of the growth of the primordial fluctuations, which are small changes in the density of the universe in a confined region. As the universe cooled clumps of dark matter began to condense, and within them gas began to condense. The primordial fluctuations gravitationally attracted gas and dark matter to the denser areas, and thus the seeds that would later become galaxies were formed. These structures constituted the first galaxies. At this point the universe was almost exclusively composed of hydrogen, helium, and dark matter. Soon after the first proto-galaxies formed, the hydrogen and helium gas within them began to condense and make the first stars. Thus the first galaxies were then formed. In 2007, using the Keck telescope, a team from California Institute of Technology found six star forming galaxies about 13.2 billion light years (light travel distance) away and therefore created when the universe was only 500 million years old. The discovery of a galaxy more than 13 billion years old, which existed only 480 million years after the Big Bang, was reported in January 2011.

[b][color=#0000FF]Early galaxies were small, violent & surprising metal rich.[/color][/b]

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The universe was very violent in its early epochs, and galaxies grew quickly, evolving by accretion of smaller mass galaxies. The result of this process is left imprinted on the distribution of galaxies in the nearby universe. Galaxies are not isolated objects in space; rather, galaxies are distributed in a great cosmic web of filaments throughout the universe. The locations where the filaments meet are dense clusters of galaxies that began as small fluctuations in the early universe. Hence the distribution of galaxies is closely related to the physics of the early universe.

Despite its many successes, this picture is not sufficient to explain the variety of structure we see in galaxies. Galaxies come in a variety of shapes, from round, featureless elliptical galaxies to the pancake-flat spiral galaxies.

Some notable observed features of galaxy structure (including our own Milky Way) that astronomers wish to explain with galactic formation theories include (but are certainly not limited to) the following:

• Spiral galaxies and the galactic disk are quite thin, dense, and rotate very fast. The Milky Way disk is 100 times longer than it is thick.
  
  The majority of mass in galaxies is made up of dark matter, a substance which is not directly observable, and does not interact through any means except gravity.
  
  Halo stars are typically much older and have much lower metallicities (that is to say, they are almost exclusively composed of hydrogen and helium) than disk stars.
  
  Many disk galaxies have a puffed up outer disk (often called the "thick disk") that is composed of old stars.
  
  Globular clusters are typically old and metal-poor as well, but there are a few that are not nearly as metal-poor as most, and/or have some younger stars. Some stars in globular clusters appear to be as old as the universe itself (by entirely different measurement and analysis methods).
  
  High velocity clouds, clouds of neutral hydrogen are "raining" down on the galaxy, and presumably have been from the beginning (this would be the necessary source of a gas disk from which the disk stars formed).
  
  Galaxies come in a great variety of shapes and sizes (see the Hubble Sequence), from giant, featureless blobs of old stars (called elliptical galaxies) to thin disks with gas and stars arranged in highly-ordered spirals.
  
  The majority of giant galaxies contain a supermassive black hole in their centers, ranging in mass from millions to billions of times the mass of our Sun. The black hole mass is tied to properties of its host galaxy.

Many of the properties of galaxies (including the galaxy color-magnitude diagram) indicate that there are fundamentally two types of galaxies. These groups divide into blue star-forming galaxies that are more like spiral types, and red nonstar forming galaxies that are more like elliptical galaxies.

[b][color=#0000FF]This artist’s impression shows two galaxies in the early universe. The brilliant explosion on the left is a gamma-ray burst. As the light from the burst passes through the two galaxies on the way to Earth (outside the frame to the right), some colours are absorbed by the cool gas in the galaxies, leaving characteristic dark lines in the spectrum. Careful study of these spectra [idicates] that these two galaxies are [u]remarkably rich in heavier chemical elements[/u].[/color][/b]

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The key properties of disk galaxies, which are also commonly called spiral galaxies, is that they are very thin, rotate rapidly, and often show spiral structure. One of the main challenges to galaxy formation is the great number of thin disk galaxies in the local universe. The problem is that disks are very fragile, and mergers with other galaxies can quickly destroy thin disks.

Olin Eggen, Donald Lynden-Bell, and Allan Sandage in 1962, proposed a theory that disk galaxies form through a monolithic collapse of a large gas cloud. As the cloud collapses the gas settles into a rapidly rotating disk. Known as a top-down formation scenario, this theory is quite simple yet no longer widely accepted because observations of the early universe strongly suggest that objects grow from bottom-up (i.e. smaller objects merging to form larger ones). It was first proposed by Leonard Searle and Robert Zinn that galaxies form by the coalescence of smaller progenitors. More recent theories include the clustering of dark matter halos in the bottom-up process. Essentially early on in the universe galaxies were composed mostly of gas and dark matter, and thus, there were fewer stars. As a galaxy gained mass (by accreting smaller galaxies) the dark matter stays mostly on the outer parts of the galaxy. This is because the dark matter can only interact gravitationally, and thus will not dissipate. The gas, however, can quickly contract, and as it does so it rotates faster, until the final result is a very thin, very rapidly rotating disk. Astronomers do not currently know what process stops the contraction. In fact, theories of disk galaxy formation are not successful at producing the rotation speed and size of disk galaxies. It has been suggested that the radiation from bright newly formed stars, or from an active galactic nuclei can slow the contraction of a forming disk. It has also been suggested that the dark matter halo can pull the galaxy, thus stopping disk contraction.

In recent years, a great deal of focus has been put on understanding merger events in the evolution of galaxies. Our own galaxy (the Milky Way) has a tiny satellite galaxy (the Sagittarius Dwarf Elliptical Galaxy) which is currently gradually being ripped up and "eaten" by the Milky Way. It is thought these kinds of events may be quite common in the evolution of large galaxies. The Sagittarius dwarf galaxy is orbiting our galaxy at almost a right angle to the disk. It is currently passing through the disk; stars are being stripped off of it with each pass and joining the halo of our galaxy. There are other examples of these minor accretion events, and it is likely a continual process for many galaxies. Such mergers provide "new" gas, stars, and dark matter to galaxies. Evidence for this process is often observable as warps or streams coming out of galaxies.

The Lambda-CDM model of galaxy formation underestimates the number of thin disk galaxies in the universe. The reason is that these galaxy formation models predict a large number of mergers. If disk galaxies merge with another galaxy of comparable mass (at least 15 percent of its mass) the merger will likely destroy, or at a minimum greatly disrupt the disk, yet the resulting galaxy is not expected to be a disk galaxy. While this remains an unsolved problem for astronomers, it does not necessarily mean that the Lambda-CDM model is completely wrong, but rather that it requires further refinement to accurately reproduce the population of galaxies in the universe.>>

[Chris Peterson]

so, are the distant galaxies in the image less than a billion years old? Are they metallic-poor in consequence?
Look like regular galaxies to me.

And just how does a "regular" galaxy look compared with a metal-poor one?

14 billion year old universe? Poppycock. Big Bang? Poppycock.

Perhaps you could post a list of your peer-reviewed papers providing more illumination on your Poppycock Theory.

[BMAONE23]

Perhaps what is needed is another copy of the image with a rollover giving the various distances to some of the galaxies like different colored circles for varying distances, this would stop confusion with the misinterpretation of the text implying that all the galaxies in the image are 13GLY away. Anyone up for the task?

[Chris Peterson]

Perhaps what is needed is another copy of the image with a rollover giving the various distances to some of the galaxies like different colored circles for varying distances, this would stop confusion with the misinterpretation of the text implying that all the galaxies in the image are 13GLY away. Anyone up for the task?

Determining the redshift means placing a spectroscopic instrument on different galaxies- something that I doubt has been done for many of those showing in this image. And tracking down the handful that have been measured and finding them in this image sounds like quite a lot of effort.

[BDanielMayfield]

This image compares the angular size of the XDF field to the angular size of the full Moon. The XDF is a very small fraction of sky area, but it provides a "core sample" of the heavens by penetrating deep into space over a sightline of over 13 billion light-years. Several thousand galaxies are contained within this small field of view. At an angular diameter of one-half degree, the Moon spans an area of sky only one-half the width of a finger held at arm's length.

Source: http://hubblesite.org/newscenter/archiv ... 7/image/c/

Truly amazing, and gets things into perspective about the vastness of our Universe!

Very true starchaser. Thanks for providing the moon for comparison here. There have been many interesting comments about colors and such, but to me the fantastic thing about this apod is the shear number of galaxies packed into such a tiny area of sky. What does this imply about the total number of galaxies inside our temporal event horizon? Pondering this led me to the following:

I believe there are about 41,255 square degrees in the entire celestial sphere. Since there are 60^2 arc minutes per degree^2, there are about 148,518,000 arcmin^2 across the entire sky. So then at 4.6 arcmin^2 this XDF represents 1/32,286,522nds of the whole sky. If this 5500 galaxies per 4.6 acrmin^2 is a fair sampling of the universe at this distance then we can extrapolate the existence of around 1.776x10^11 galaxies, NOT COUNTING all galaxies closer than the distances sampled by the XDF! Therefore the often quoted estimate of 100 billion (1x10^11) would appear to be too low. 300 billion would seem more accurate, but my pure guess is that 1 trillion galaxies may also be on the low side. I wonder how many more the JWST might be able to reel in.

Is my mathmatical thinking on this accurate?

Bruce

[kimmeyh]

What would a version of this picture look like if everything < 12.5 billion years old was removed?

[BDanielMayfield]

What would a version of this picture look like if everything < 12.5 billion years old was removed?

Good question kimmeyh. I would imagine that the larger and brighter galaxies would be filtered out, but the great majority of the faint fuzzies would still be there, and those make up the large majority of the 5500 count.

Bruce

[Chris Peterson]

What would a version of this picture look like if everything < 12.5 billion years old was removed?

I assume you are asking what the image would look like if all the galaxies that formed in the first billion years of the Universe were removed? There would be a lot fewer galaxies in the image. Probably only a few percent are that old.

[ErnieM]

Bystander write:

ErnieM wrote:
Is this the only sweet spot Hubble is able to see galaxies as young as 13 billions years ago? Are we looking towards the direction of a long (13 billion years) elongated tapering tube of a Picard horn shaped universe? The farther we are able to see, space are more compact and dense hence the red-shifted young galaxies are much closer to each other.

This is just one relatively "blank" spot in the sky where they chose to aim the Hubble. We could choose any other "blank" spot and get much the same results, just different galaxies. The HDF-S and HDF-N are two early results of the same type of images.

The HEDF 2012Oct12 is a "blank" spot towards the Forrmax constellation. Where HDF-S and HDG-N? How do this three "blank" spots triangulate? What would it mean if the farthest red-shifting galaxies in these "blank" spots were relatively of the same age of 13 billion years, equidistant to and moving away from earth in opposite directions? Is this even possible? Could it be that the 14+ billion years to the BB is simply a limitation of current technological capabilities?

[rstevenson]

... What would it mean if the farthest red-shifting galaxies in these "blank" spots were relatively of the same age of 13 billion years, equidistant to and moving away from earth in opposite directions? ... .

That's exactly what we see. The universe looks the same to us in all directions. But that does not mean we just happen to be in the center of the universe. It means we are in the center of our observable universe. The universe itself is larger than the part of it that we can see. (There is some disagreement about how much larger.)

Rob

[bystander]

What would a version of this picture look like if everything < 12.5 billion years old was removed?

I assume you are asking what the image would look like if all the galaxies that formed in the first billion years of the Universe were removed? There would be a lot fewer galaxies in the image. Probably only a few percent are that old.

I think they may be asking "What if everything closer than 12.5 bly was removed?"

[Chris Peterson]

The HEDF 2012Oct12 is a "blank" spot towards the Forrmax constellation. Where HDF-S and HDG-N? How do this three "blank" spots triangulate? What would it mean if the farthest red-shifting galaxies in these "blank" spots were relatively of the same age of 13 billion years, equidistant to and moving away from earth in opposite directions? Is this even possible? Could it be that the 14+ billion years to the BB is simply a limitation of current technological capabilities?

A "blank" spot is just a part of the sky chosen that doesn't have any local objects blocking it (stars, dust, or nebulas within the Milky Way, or nearby galaxies outside it). For small fields of view, most of the sky is "blank" in this way.

The most redshifted galaxies we can detect will be about 13 billion years old (i.e. we are seeing them as they were when the Universe was less than 1 billion years old) no matter where we look. It is nothing technical that limits how far we can potentially see- that is a limitation of physics. We can't see any photons emitted by objects moving away from us at greater than c, which is what all objects beyond our observable universe are doing.

We see bodies moving away from us at very high speeds and in opposite parts of the sky. We see them because they are inside our observable universe. These same bodies would not be in each others observable universes, however. Observers at either of those distant spots would be seeing the Milky Way as it was early in the Universe, and not much beyond that.

[BMAONE23]

Perhaps what is needed is another copy of the image with a rollover giving the various distances to some of the galaxies like different colored circles for varying distances, this would stop confusion with the misinterpretation of the text implying that all the galaxies in the image are 13GLY away. Anyone up for the task?

Determining the redshift means placing a spectroscopic instrument on different galaxies- something that I doubt has been done for many of those showing in this image. And tracking down the handful that have been measured and finding them in this image sounds like quite a lot of effort.

Here is a good visual displaying the relative distances of various objects in the Hubble Extreme Deep Field image

[Chris Peterson]

Here is a good visual displaying the relative distances of various objects in the Hubble Extreme Deep Field image

That makes sense. However, I suspect that this doesn't reflect the known position of any of the objects, but is simply a statistical distribution based on size, color, and the fact that the volume of space in this image is greater for objects seen earlier in the Universe.

[ErnieM]

That makes sense. However, I suspect that this doesn't reflect the known position of any of the objects, but is simply a statistical distribution based on size, color, and the fact that the volume of space in this image is greater for objects seen earlier in the Universe.

I vision the galaxies when the universe was only 1BLY old to be closer to each other and now have "moved away?" from each other and in our real time have "moved out" of the Hubble's line of site due to the expansion of space.

[Chris Peterson]

I vision the galaxies when the universe was only 1BLY old to be closer to each other and now have "moved away?" from each other and in our real time have "moved out" of the Hubble's line of site due to the expansion of space.

I'm not sure what you mean by that. Where the galaxies are "now" doesn't matter. All that we can see is where they were when the photons we are now capturing were emitted.