Hubble Reaches the 'Undiscovered Country' of Primeval Galaxies

Jan 05, 2010
This is the deepest image of the universe ever taken in near-infrared light by NASA's Hubble Space Telescope. The faintest and reddest objects (left inset) in the image are galaxies that correspond to "look-back times" of approximately 12.9 billion years to 13.1 billion years ago. No galaxies have been seen before at such early epochs. These galaxies are much smaller than the Milky Way galaxy and have populations of stars that are intrinsically very blue. This may indicate the galaxies are so primordial that they are deficient in heavier elements, and as a result, are quite free of the dust that reddens light through scattering. Credit: NASA, ESA, G. Illingworth (UCO/Lick Observatory and University of California, Santa Cruz), and the HUDF09 Team

(PhysOrg.com) -- NASA's Hubble Space Telescope has broken the distance limit for galaxies and uncovered a primordial population of compact and ultra-blue galaxies that have never been seen before.

The deeper Hubble looks into space, the farther back in time it looks, because light takes billions of years to cross the observable Universe. This makes Hubble a powerful "time machine" that allows astronomers to see galaxies as they were 13 billion years ago, just 600 million to 800 million years after the Big Bang.

"With the rejuvenated Hubble and its new instruments, we are now entering unchartered territory that is ripe for new discoveries," says Garth Illingworth of the University of California, Santa Cruz, leader of the survey team that was awarded the time to take the new WFC3 infrared data on the Hubble Ultra Deep Field (imaged in visible light by the Advanced Camera for Surveys in 2004). "The deepest-ever near-infrared view of the Universe — the HUDF09 image — has now been combined with the deepest-ever optical image — the original HUDF (taken in 2004) — to push back the frontiers of the searches for the first galaxies and to explore their nature," Illingworth says.

Ross McLure of the Institute for Astronomy at Edinburgh University and his team detected 29 galaxy candidates, of which twelve lie beyond redshift 6.3 and four lie beyond redshift 7 (where the redshifts correspond to 890 million years and 780 million years after the Big Bang respectively). He notes that "the unique infrared sensitivity of 3 means that these are the best images yet for providing detailed information about the first galaxies as they formed in the early Universe".

Early Galaxies in HUDF WFC3/IR Closeup. Credit: NASA, ESA, G. Illingworth (UCO/Lick Observatory and University of California, Santa Cruz), and the HUDF09 Team

James Dunlop of the University of Edinburgh agrees. "These galaxies could have roots stretching into an earlier population of stars. There must be a substantial component of galaxies beyond Hubble's detection limit."

Three teams worked hard to find these new galaxies, announced in a burst of papers immediately after the data were released in September, and were soon joined by a fourth team, and later a fifth. A total of 15 papers have been submitted to date by astronomers worldwide. The existence of these newly found galaxies pushes back the time when galaxies began to form to before 500-600 million years after the Big Bang. This is good news for astronomers building the much more powerful James Webb Space Telescope (JWST; planned for launch in 2014), which will allow astronomers to study the detailed nature of primordial galaxies and discover many more even farther away. There should be plenty for JWST to hunt for.

The deep observations also demonstrate the progressive buildup of galaxies and provide further support for the hierarchical model of galaxy assembly where small objects accrete mass, or merge, to form bigger objects over a smooth and steady, but still dramatic, process of collision and agglomeration, as these small building blocks fuse into the larger galaxies known today.

"These ancient galaxies are only one twentieth of the Milky Way's diameter," reports HUDF09 team member Pascal Oesch of the Swiss Federal Institute of Technology in Zurich. "Yet they must be the seeds from which the great galaxies of today were formed," adds HUDF09 team member Marcella Carollo of the Swiss Federal Institute of Technology.

These newly found objects are crucial to understanding the evolutionary link between the birth of the first stars, the formation of the first galaxies and the sequence of evolutionary events that resulted in the assembly of our Milky Way and the other "mature" elliptical and majestic spiral galaxies in today's Universe.

The HUDF09 team also combined the new Hubble data with observations from NASA's Spitzer Space Telescope to estimate the ages and masses of these primordial galaxies. "The masses are just 1 percent of those of the Milky Way," explains team member Ivo Labbe of the Carnegie Institute of Washington, lead author of two papers on the data from the combined NASA Great Observatories. He further noted that "to our surprise, the results show that these galaxies at 700 million years after the Big Bang must have started forming stars hundreds of millions of years earlier, pushing back the time of the earliest star formation in the Universe."

The results are gleaned from the HUDF09 observations, which are deep enough at near-infrared wavelengths to reveal galaxies at redshifts from 7 to beyond redshift 8.[1] The clear detection of galaxies between redshifts 7 and 8.5 corresponds to lookback times of approximately 12.9 billion years to 13.1 billion years.

"This is about as far as we can go to do detailed science with the new HUDF09 image. It shows just how much the James Webb Space Telescope is needed to unearth the secrets of the first galaxies," says Illingworth. The challenge is that spectroscopy is needed to provide definitive redshift values, but the objects are too faint for spectroscopic observations (until JWST is launched), and the redshifts have to be inferred from the apparent colours of the galaxies.

The teams are finding that the number of galaxies per unit of volume of space drops off smoothly with increasing distance, and the HUDF09 team has also found that the galaxies become surprisingly blue intrinsically. The ultra-blue galaxies are extreme examples of objects that appear so blue because they may be deficient in the heavier elements, and as a result, are quite free of the dust that reddens light through scattering.

A longstanding problem with these findings is that it still appears that these early galaxies did not emit enough radiation to "reionise" the by stripping electrons from the neutral hydrogen that cooled after the Big Bang. This "reionisation" event occurred between about 400 million and 900 million years after the Big Bang, but astronomers still don't know which light sources caused it to happen. These newly discovered galaxies date from this important epoch in the evolution of the Universe.

Perhaps the density of very faint galaxies below the current detection limit is so high that there may be enough of them to support reionisation. Or there was an earlier wave of galaxy formation that decayed and then was "rebooted" by a second wave of galaxy formation. Or, possibly the early galaxies were extraordinarily efficient at reionising the Universe.

Due to these uncertainties it is not clear which type of object or evolutionary process did the "heavy lifting" by ionising the young Universe. The calculations are inconclusive, and so galaxies may do more than currently expected, or astronomers may need to invoke other phenomena such as mini-quasars (active supermassive black holes in the cores of galaxies) — current estimates suggest that quasars are even less likely than galaxies to be the cause of reionisation. This is an enigma that still challenges astronomers and the very best telescopes.

"We know the gas between galaxies in the Universe was ionised early in history, but the total light from these new galaxies may not be sufficient to achieve this." said Andrew Bunker of the University of Oxford, a researcher on one of the European teams.

Hubble's WFC3 infrared camera was able to make deep exposures to uncover new at roughly 40 times greater efficiency than its earlier infrared camera that was installed in 1997. The WFC3 brought new infrared technology to Hubble and accomplished in four days of observing what would have previously taken almost half a year for Hubble to complete.

Explore further: Chandra X-ray Observatory finds planet that makes star act deceptively old

More information: [1] The redshift value is a measure of the stretching of the wavelength or "reddening" of starlight due to the expansion of space.

Related Stories

'Big baby' galaxy found in newborn Universe

Sep 28, 2005

The NASA/ESA Hubble Space Telescope and NASA’s Spitzer Space Telescope have teamed up to 'weigh' the stars in distant galaxies. One of these galaxies is not only one of the most distant ever seen, but it appears to be unusually ...

Hubbles most sensitive images show distant galaxies

Sep 23, 2004

The recently released Hubble Space Telescope Ultra Deep Field (HUDF) - the most sensitive image of the distant universe ever obtained - has provided UK astronomers with a window on star formation when the universe was young, revealing some of the earliest sta ...

Astronomers peer back to 'dawn of galaxies'

Oct 01, 2004

Detailed analysis of Hubble Space Telescope images has allowed astronomers to determine a major event in the evolution of the universe. The astronomers used the Hubble Space Telescope’s Ultra Deep Field (UDF) to peer 95 percent of the ...

Colliding galaxies make love, not war

Oct 17, 2006

A new Hubble image of the Antennae galaxies is the sharpest yet of this merging pair of galaxies. As the two galaxies smash together, billions of stars are born, mostly in groups and clusters of stars. The ...

Recommended for you

The entropy of black holes

Sep 12, 2014

Yesterday I talked about black hole thermodynamics, specifically how you can write the laws of thermodynamics as laws about black holes. Central to the idea of thermodynamics is the property of entropy, which c ...

Modified theory of dark matter

Sep 12, 2014

Dark matter is an aspect of the universe we still don't fully understand. We have lots of evidence pointing to its existence (as I outlined in a series of posts a while back), and the best evidence we have point ...

User comments : 24

Adjust slider to filter visible comments by rank

Display comments: newest first

Mr_Frontier
4.3 / 5 (6) Jan 05, 2010
Someone made the right choice to deny Hubble's decommission.
PeterROwen
2 / 5 (1) Jan 05, 2010
What colour are these galaxies if the are blue when heavily red-shifted?
mklnk
5 / 5 (1) Jan 05, 2010
Blue. They are invisible when heavily red shifted. The image above is essentially accounting for the red shift to show us how they would look in the visible spectrum if they were very nearby and not substantially red shifted.
fuzz54
1.6 / 5 (7) Jan 05, 2010
Someone made the right choice to deny Hubble's decommission.
Hubble is a floating rock. Hubble mirror and metering technologies are so heavy that it's ridiculous compared to today's latest and greatest. We probably could have flown a completely new telescope into orbit for the cost of all the Hubble servicing missions.
yyz
4 / 5 (4) Jan 05, 2010
fuzz54,

Keep in mind that the servicing missions were also designed to carry new & improved cameras and electronics to Hubble as well as to repair and service the scope. This seems a cheaper strategy than sending up a completely new scope & new cameras every three or four years. Unfortunately, the retirement of the Shuttle will preclude any further upgrades to Hubble. The camera suite onboard Hubble now is state of the art.
Husky
5 / 5 (2) Jan 05, 2010
How about pair instabillity novae (130 - 250 solar masses, low metallicity stars) as reionisation source, exactly the kind of large stars of pristine gas you'd expect to form in an early universe, burn quickly and blow them selves completely appart in a particular violent display, Not only the emitted rays during the nova could accounts for ionisation of its surroundings, but also the core itselve is scattered into space as radioactive nickel-56, further decay produces other elements, ionised by the radioactive decay, My guess is that if even larger, hyperlarge stars that collapse into a black hole in the process were abandunt in an early universe too much coremass and radiation would be tied up by the black holes to allow such an early reionisation of the universe, or would have occured later / more gradually.
Mr_Frontier
3.7 / 5 (3) Jan 05, 2010
You're right, we should just treat everything as disposable. It's like taking your car to the dump when all it needs is a new windshield. Lets pump more rockets into space for the fun of it; who needed optimization in the first place? Now, go and build Hubble II since it seems like you know what you're doing.
shulsizer
1.5 / 5 (2) Jan 06, 2010
Can someone explain how light traveling 13 billion years from a galaxy dates the universe at 13 billion years? If the big bang was from an infinitesimal point, would it not take at least 13 billion years for the galaxy to reach that point, assuming the galaxy's mass traveled at the speed of light (not really probable)? Doesn't this make the age of the universe at least twice as old as the light seen fro these distant galaxies?
Rajd
not rated yet Jan 06, 2010
Besides all that, ae we being watched as well,does any other living creatures in the universe trying to unreveal the same... we should be thankful to the Hubble to send us such info... can it also predict where is our galaxy moving and placed in the entire universe ... did it find any other spaceship travelling across the universe... we got a lot to still observe and learn... I'm waiting to hear a supernova discovery of an encounter of the unknown. good work Hubble and all the scientist.keep us informed.
frajo
3 / 5 (2) Jan 06, 2010
Can someone explain how light traveling 13 billion years from a galaxy dates the universe at 13 billion years?
[1] Have a look at http://upload.wik...etry.png
[2] Read http://en.wikiped...universe ("Misconceptions").
If the big bang was from an infinitesimal point, would it not take at least 13 billion years for the galaxy to reach that point,
No. As the BigBang predates everything you can't reach it.
assuming the galaxy's mass traveled at the speed of light (not really probable)?
The galaxies don't travel. Space expands and the galaxies float in space.
Doesn't this make the age of the universe at least twice as old as the light seen fro these distant galaxies?
No. Read the Wikipedia page mentioned above.
tkjtkj
not rated yet Jan 06, 2010
I've posed this question before but have yet to have any answer which even attempts to explain a paradox:

If the light from these distant start comes to us from a place close to the Big Bang, how come we are here first, with our fancy lenses, to see this incoming light?
Would not our matter had to have travelled considerably faster than 'c' to do this?
tkjtkj@gmail.com
tkjtkj
not rated yet Jan 06, 2010
assuming the galaxy's mass traveled at the speed of light (not really probable)?
The galaxies don't travel. Space expands and the galaxies float in space.


But does that not violate the 'equivalency' princlple (which would say that if you cant tell the difference between two phenom, then they are the same) ? If space increases between 'stationary' bodies, how do you know that they are not actually moving apart? I'd imagine that the 'particle physics' people would want to weigh in on that one!
frajo
3 / 5 (2) Jan 06, 2010
If the light from these distant start comes to us from a place close to the Big Bang, how come we are here first, with our fancy lenses, to see this incoming light?
Would not our matter had to have travelled considerably faster than 'c' to do this?
No. For simplicity's sake let's say the galaxy was 4 billion LY away from "us" when it produced the light we see today. If there had bee no expansion of space we'd have seen the light 4 billion years after that time, i.e. 9 billion years ago.
But due to expanding space the distance between the galaxy and "us" had become larger after 4 billion years. And so on.
The fact we've seen the galaxy's light now, after 13 billion years means that the light finally reached us. This was only possible because "we" didn't recede faster than light from "them".
BTW, the distance now is 26 billion LY.
Again, have a look at http://upload.wik...etry.png
One picture is worth more than 1000 words.
croghan26
not rated yet Jan 06, 2010
The light reaching Hubble from the distant sources is "approximately 12.9 billion years to 13.1 billion years" old.

How long after the BB did galaxies form? The light indicates that 12.9 to 13.1 years ago there were galaxies - but was this the beginning of our universe? Would not the Big Bang have to predate this by some considerable time?
mklnk
not rated yet Jan 06, 2010
No. For simplicity's sake let's say the galaxy was 4 billion LY away from "us" when it produced the light we see today. If there had bee no expansion of space we'd have seen the light 4 billion years after that time, i.e. 9 billion years ago.
But due to expanding space the distance between the galaxy and "us" had become larger after 4 billion years. And so on.


I thought that, according to relativity, the speed of light is C regardless of how quickly the light source is receding from us.
frajo
1 / 5 (1) Jan 06, 2010
I thought that, according to relativity, the speed of light is C regardless of how quickly the light source is receding from us.
Yes, the speed of light is c. But it is not only the source that is receding from us. All space is expanding, especially the space which defines the distance between the moving light front and the target ("us"). This distance (as all distances) grows all the time. Thus the total length of the light's path amounts to 13 billion LY when it finally reaches us. This is more than the 4 billion LY between source and target when the light was produced and less than the 26 billion LY between source and target now.
bluehigh
1 / 5 (1) Jan 09, 2010
Near one of these so-called early galaxys on a small planet using an orbiting telescope astronomers look across space at our galaxy and conclude the Milky Way is one of the oldest known galaxys occurring just a few hundred million years after creation. In the opposite direction, an advanced civilisation has given up looking because they concluded that nothing could be that far away so as to be older than the calculated age of the universe.

shulsizer
not rated yet Jan 09, 2010
I can sort of buy the receding galaxy concept, but the numbers used don't support a 26 LY. This means that the universe is at least 26 billion yrs old, and the article mentions that Hubble is seeing something only a few hundred million years after BB. Certainly, the universe is not expanding at the speed of light, or we would never see another galaxy. We would be running away from the others as fast as light or oncoming galaxies would be coming at us as fast as light. Talk about blue shift!
frajo
1 / 5 (1) Jan 10, 2010
Near one of these so-called early galaxys on a small planet using an orbiting telescope astronomers look across space at our galaxy and conclude the Milky Way is one of the oldest known galaxys occurring just a few hundred million years after creation.
Creation? Please keep religion and science apart.
Of course the mentioned alien observer sees our galaxy in the light it had emitted 13 billion years ago.
In the opposite direction, an advanced civilisation has given up looking because they concluded that nothing could be that far away so as to be older than the calculated age of the universe.
Are you adding up 13 LY + 13 LY for two opposite directions? That's wrong.
For all observers, no matter how (spatially) far away from us, the BigBang is (on the time axis) 13.5 (or so) billion years away from them.
bluehigh
1 / 5 (1) Jan 10, 2010
13.5 billion LIGHT years. Being a measure of BOTH time and spatial relations. Else if you seperate the dimensions you could see creation (aka the BB) 13.5 billion years ago but it could in fact be just across the road. So; is everything NOW equidistant in time and also NOW equidistant in space (how far the light travels) from creation (with a small C).
frajo
1 / 5 (1) Jan 11, 2010
13.5 billion LIGHT years.
No - LY is a measure of length.
Being a measure of BOTH time and spatial relations.
No - time is measured in years, lenght is measured in lightyears or parsecs.
Else if you seperate the dimensions
We can. And we have to.
you could see creation (aka the BB) 13.5 billion years ago
No - as there is no EM radiation (light) from times earlier than roughly 400000 years after BB.
but it could in fact be just across the road.
No - it was an event of the past.
So; is everything NOW equidistant in time and also NOW equidistant in space (how far the light travels) from creation (with a small C).
Sorry, no.
Rajd
not rated yet Jan 14, 2010
Was there time before the big bang ? how all this calculation is taking place ? are we assuming that's the way it should be.Can anybody explain this ?
frajo
1 / 5 (1) Jan 14, 2010
Was there time before the big bang ?
Depends which cosmological model you choose. The model known as "BigBang model" which happens to be the contemporary "standard cosmology" doesn't know of a time "before" BB. In fact, the word "before" does have no meaning when applied to the BB in this model.
There are alternative models, however, which are not constrained in this way. Look for "ekpyrosis" or "cyclic universe" e.g.
how all this calculation is taking place ?
You could begin with http://en.wikiped...of_space and continue by reading the links mentioned there.
are we assuming that's the way it should be.
No. Most people are assuming that's the way it could be. Some people are assuming that's not the way it could be. They all have their reasons.
Can anybody explain this ?
Certainly. But not here where you don't even have unicode.
Rajd
not rated yet Jan 15, 2010
Then what we should know to be more precise and which model is correct? surely an acceptable equation is in place to master the maths behind all this ... does the calculation on Earth surface correlates to Space reading?