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Chandra Deep Field South : NASA's Chandra Finds Massive Black Holes Common in Early Universe

Correction: After this paper (Treister et al. 2011) was published and publicized a problem was discovered with the background subtraction used. Analysis by several groups, including the Treister et al. team, plus Willott (2011) and Cowie et al. (2012), shows that a significant detection of AGN (growing black holes) in the early universe can no longer be claimed.

Editor's Note: Honest errors such as this are part of the scientific process, especially on the frontiers of discovery. To quote Nobel laureate Frank Wilczek, "If you don't make mistakes, you're not working on hard enough problems. And that's a big mistake."


Cowie, L. et al. 2012, ApJ, in press

Treister, E. et al. 2011, Nature, 474, 356

Willott, C. 2011, ApJ, 742, L8

  • The deepest X-ray image of the sky shows that black holes are aggressively growing by 800 million years after the Big Bang.

  • These black holes are growing in tandem with the galaxies in which they reside.

  • The new results show there were at least 30 million black holes before the Universe was a billion years old.

  • The Chandra Deep Field South was made by pointing the telescope at the same patch of sky for over six weeks of time.

This composite image from NASA's Chandra X-ray Observatory and Hubble Space Telescope (HST) combines the deepest X-ray, optical and infrared views of the sky. Using these images, astronomers have obtained the first direct evidence that black holes are common in the early Universe and shown that very young black holes grew more aggressively than previously thought.

Astronomers obtained what is known as the Chandra Deep Field South (CDFS) by pointing the telescope at the same patch of sky for over six weeks of time. The composite image shows a small section of the CDFS, where the Chandra sources are blue, the optical HST data are shown in green and blue, and the infrared data from Hubble are in red and green.

The new Chandra data allowed astronomers to search for black holes in 200 distant galaxies, from when the Universe was between about 800 million and 950 million years old. These distant galaxies were detected using the HST data and the positions of a subset of them are marked with the yellow circles (roll your mouse over the image above).

The rest of the 200 galaxies were found in other deep HST observations located either elsewhere in the CDFS or the Chandra Deep Field North, a second ultra- deep Chandra field in a different part of the sky.

None of the galaxies was individually detected with Chandra, so the team used a technique that relied on Chandra's ability to very accurately determine the direction from which the X-rays came to add up all the X-ray counts near the positions of these distant galaxies. The two "stacked" images resulting from this analysis are on the right side of the graphic, where the bottom image shows the low-energy X- rays and the top image has the high-energy X-rays. Statistically significant signals are found in both images.

These results imply that between 30% and 100% of the distant galaxies contain growing supermassive black holes. Extrapolating these results from the relatively small field of view that was observed to the full sky, there are at least 30 million supermassive black holes in the early Universe. This is a factor of 10,000 larger than the estimated number of quasars in the early Universe.

Illustration of Baby Black Hole

The stronger signal in high-energy X-rays implies that the black holes are nearly all enshrouded in thick clouds of gas and dust. Although copious amounts of optical light are generated by material falling onto the black holes, this light is blocked within the core of the black hole's host galaxy and is undetectable by optical telescopes. However, the high energies of X-ray light can penetrate these veils, allowing the black holes inside to be studied.

Fast Facts for Chandra Deep Field South :
Credit  X-ray: NASA/CXC/U.Hawaii/E.Treister et al; Infrared: NASA/STScI/UC Santa Cruz/G.Illingworth et al; Optical: NASA/STScI/S.Beckwith et al
Release Date  June 15, 2011
Scale  Main image is 27 arcsec across (about 490 thousand light years) | CDFS image is 19.6 arcmin across. (about 21 million light years across)
Category  Cosmology/Deep Fields/X-ray Background, Black Holes
Coordinates (J2000)  RA 03h 32m 28s | Dec -27° 48' 30.00"
Constellation  Fornax
Observation Date  54 pointings between Oct 15, 1999 to Jul 22, 2010
Observation Time  1111 hours 6 min (46 days 7 hours 6 min)
Obs. ID  441, 581-582, 1431, 1672, 2239, 2312-2313, 2405-2406, 2409, 8591-8597, 9575, 9578, 9593, 9596, 9718, 12043-12055, 12123, 12128-12129, 12135, 12137-12138, 12213, 12218-12220, 12222-12223, 12227, 12230-12234
References Treister et al., (2011), Nature, in press; arXiv:1106.3079


Color Code  X-ray (Blue); IR (Red, Green); Optical (Green, Dark Blue)
Distance Estimate  12.7 to 12.9 billion light years (z = 6-7)
distance arrow
Visitor Comments (21)

Thanks for your question. Light can exist inside a black hole, it just cannot escape from beyond the event horizon.
-P. Edmonds, CXC

Posted by P. Edmonds on Friday, 11.9.12 @ 11:29am

Is there really light in a black hole?

Posted by Shock on Friday, 10.12.12 @ 12:02pm

The discovery of these BHs is a huge support for New Physics.!
According to the alternative standard model SM based Quantum FFF theory the Big bang is a splitting black hole process or splitting bunch of concentrated higgs particles leaving massive galaxy creating tandems of accelerated black holes behind, forming the Lyman alpha forest structure of the symmetrical entangled multi-universe


Posted by leo vuyk on Saturday, 06.2.12 @ 07:54am

Well, its not the universe expanding its the space between it.

Posted by austin virag on Sunday, 12.4.11 @ 17:44pm

On the picture I see 5 black holes just wondering if some day couple holes will be next to earth?

Posted by Joseph on Saturday, 08.27.11 @ 03:56am

Well if the early universe had so much black holes then expansion might have not happened at all due to force of gravity. The information which I believe will be more useful might to be find the number of black holes per square light year or something like that.

Posted by Shreyas Becker on Thursday, 06.23.11 @ 10:47am

Dear Ralph,
The assumption used here is that on large scales the Universe is uniform, if you look in one direction things are going to look similar to the way they look in any other direction. This assumption has been reinforced by decades of observations, so it is a perfectly reasonable one to make in this case (it's impossible to make these very deep observations across large sections of the sky). Also, it should be pointed out that the estimate of 30 million black holes in the early Universe is a conservative value, because it uses the lower limit on the number of growing black holes in the field. More importantly, there are likely to be many faint galaxies and black holes that are below the detection limits of our best telescopes.

Posted by P, Edmonds on Wednesday, 06.22.11 @ 10:33am

Thanks Marco for the compliments!
P. Edmonds, CXC

Posted by P. Edmonds on Wednesday, 06.22.11 @ 10:32am

Dear Ed,
These are all good questions. The stacked images take all the X-ray counts near the positions of the distant galaxies and add them up (this analysis was done separately for the low and high energy X-rays). So, just to make up some numbers you might have 4 counts from the source and 4 from the nearby background. This doesn't give a significant detection by itself, but if you add up hundreds of similar objects the counts from the sources will accumulate quickly, while the counts from the background will not accumulate so quickly because they're scattered around the sources in different positions (since they're noise).
For the scale of the image a redshift of 6.5 was assumed. The redshift was determined by HST observers using special photometric techniques used for very distant galaxies where spectroscopic redshifts are very difficult or impossible to obtain. A description is given here (q3):

It is the brightness of the X-ray emission and the large number of galaxies containing X-ray sources that implies the black holes are growing aggressively.

Posted by P. Edmonds on Wednesday, 06.22.11 @ 10:27am

Dear Andy,
The percentage of all material trapped in black holes continues to rise, although not as quickly as it did a few billion years ago and periods earlier than that. For example, there are several relatively nearby supermassive black holes that continue to grow at reasonably high rates, such as the object in Centaurus A. But, the number of growing black holes has decreased with time:
P. Edmonds, CXC

Posted by P. Edmonds on Wednesday, 06.22.11 @ 10:25am

Dear Marvin,
That's an interesting thought. There are certainly theories about why black holes come into existence, but I wouldn't say that black holes have a purpose any more than stars or galaxies have a purpose.
P. Edmonds, CXC

Posted by P. Edmonds on Wednesday, 06.22.11 @ 10:22am

Dear WebDev,
Thanks for your interesting ideas.
These observations detect objects in the early Universe, but not the *very* early Universe. It is generally believed that, not long after the Big Bang, the Universe entered a period called the Dark Ages before any star or black hole formed. This period is believed to have lasted about 100 million years.
P. Edmonds, CXC

Posted by P. Edmonds on Wednesday, 06.22.11 @ 10:20am

Dear Bill,
I like your analogy about black holes being like roach motels (and having lived in Sydney I'm very familiar with *big* roaches). Echoing another answer, it is generally believed that, not long after the Big Bang, the Universe entered a period called the "dark ages" before any star or black hole formed. So, these big black holes weren't around from the *very* beginning. Also, it must be remembered that although black holes have powerful gravity, they are not all-powerful. So, as a thought experiment, imagine the Sun turning into a black hole (which won't happen). The Earth would continue rotating around this black hole just like before and wouldn't be pulled in. Of course without radiation life on Earth wouldn't last very long!
P. Edmonds, CXC

Posted by P. Edmonds on Wednesday, 06.22.11 @ 10:17am

Seems like a bit of fanciful writing. First, the article claims astronomers have found "direct evidence that black holes are common in the early Universe", but later in the article we are told that, results imply "distant galaxies contain" black holes and that by, "extrapolating these results" to the full sky, there are calculated to be 30 million black holes in the early Universe.
That's what passes for direct evidence now. Sad.

Posted by Ralph on Monday, 06.20.11 @ 06:13am

As usual, something new to earn and most interesting. Are there any theories of what the purposes of Black Holes are?

Marvin L. S.

Posted by Marvin L. S . on Monday, 06.20.11 @ 01:20am

The first thing that came to my mind when I heard this news was:
- maybe what we call the edge of the universe is actually an infinite collection of black holes and
- maybe the big bang is actually a big fountain, forever streaming the raw materials that form galaxies and then black holes as they move away from the center.
Is anyone thinking along these lines?

Posted by WebDevDude on Sunday, 06.19.11 @ 20:44pm

Congratulations to the team for the discovery of Chandra, we are slowly uncovering the veil that separates us from the remotest times more towards the beginning of everything. Who knows if what they find will fulfill our expectations and our hopes of scientific men.
The definitive answer to the ultimate questions of infinity is getting closer and understandable. Thank you for your exciting research that arouse in us wonder and a sense of vertigo, and the truth will soon be a household name.
A greeting from Marco Avanzi Genoa, Italy

Posted by Marco Avanzi on Saturday, 06.18.11 @ 16:39pm

Please don't ask me to explain the laws of gravity, but it appears that a set percentage of all matter and energy generated in our early universe was trapped inside black holes and that no matter what size the universe grows to, the same set percentage of all matter and energy is still trapped inside black holes now. Maybe this is the constant that keeps the number and size of black holes in check.

Posted by Andy McDowall on Friday, 06.17.11 @ 06:02am

Oh my gosh, that's amazing and huge.

Posted by amani on Thursday, 06.16.11 @ 16:30pm

It is unclear what the "stacked" images show and how they were obtained. In stating that the image is 6.6 Myr across does one refer to the redshift 6-7 distance? and is it the size of the area at the time or today? How is the redshift determined Lyman 1216A H line? And how does one know that the holes are growing aggressively? For people with little expertise like myself, I feel the explanations are not quite adequate.

Posted by Ed Bond on Thursday, 06.16.11 @ 14:59pm

It makes me wonder what portion of all the normal matter that was created in the Big Bang has been trapped inside the holes? At least some stars recycle some stuff when they blow up. The Holes are like roach motels, the atoms go in, and never come out. Why didn't a big black hole eat up the entire early universe? Or did one almost succeed? And how did they interact with dark matter and energy, if they did at all. You have a few more thousand years of work to do.

Posted by Bill Simpson on Thursday, 06.16.11 @ 01:49am

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