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CDF-S Transient: Mysterious Cosmic Explosion Puzzles Astronomers

  • A mysterious X-ray source became 1,000 times brighter over a few hours before fading dramatically in about a day.

  • This source was discovered in Chandra Deep Field-South data, giving the deepest X-ray image ever made.

  • Hubble and Spitzer data indicate this source is likely located in a small galaxy about 10.7 billion light years from Earth.

  • Evidence points to this being some sort of destructive event but perhaps unlike any ever seen before.

Scientists have discovered a mysterious flash of X-rays using NASA's Chandra X-ray Observatory, in the deepest X-ray image ever obtained, as reported in our latest press release. The X-ray source is located in a region of the sky known as the Chandra Deep Field-South (CDF-S), which is shown in the main panel of this graphic. Over the 17 years Chandra has been operating, the telescope has observed this field many times, resulting in a total exposure time of 7 million seconds, equal to two and a half months. In this CDF-S image, the colors represent different bands of X-ray energy, where red, green, and blue show the low, medium, and high-energy X-rays that Chandra can detect.

The mysterious source that scientists discovered, shown in the inset box, has remarkable properties. Prior to October 2014, this source was not detected in X-rays, but then it erupted and became at least a factor of 1,000 brighter in a few hours. After about a day, the source had faded completely below the sensitivity of Chandra.

Thousands of hours of legacy data from the Hubble and Spitzer Space Telescopes helped determine that the event came from a faint, small galaxy about 10.7 billion light years from Earth. For a few minutes, the X-ray source produced a thousand times more energy than all the stars in this galaxy.

While scientists think this source likely comes from some sort of destructive event, its properties do not match any known phenomenon. This means this source may be of a variety that scientists have never seen before.

The researchers do, however, have some ideas of what this source could be. Two of the three main possibilities to explain the X-ray source invoke gamma-ray burst (GRB) events, which are jetted explosions triggered either by the collapse of a massive star or by the merger of a neutron star with another neutron star or a black hole. If the jet is pointing towards the Earth, a burst of gamma-rays is detected. As the jet expands, it loses energy and produces weaker, more isotropic radiation at X-ray and other wavelengths.

Possible explanations for the CDF-S X-ray source, according to the researchers, are a GRB that is not pointed toward Earth, or a GRB that lies beyond the small galaxy. A third possibility is that a medium-sized black hole shredded a white dwarf star.

Thousands of hours of legacy data from the Hubble and Spitzer Space Telescopes helped determine that the event came from a faint, small galaxy about 10.7 billion light years from Earth. For a few minutes, the X-ray source produced a thousand times more energy than all the stars in this galaxy.

The mysterious X-ray source was not seen at any other time during the two and a half months of exposure time Chandra has observed the CDF-S region. Moreover, no similar events have yet been found in Chandra observations of other parts of the sky.

This X-ray source in the CDF-S has different properties from the as yet unexplained variable X-ray sources discovered in the elliptical galaxies NGC 5128 and NGC 4636 by Jimmy Irwin and collaborators. In particular, the CDF-S source is likely associated with the complete destruction of a neutron star or white dwarf, and is roughly 100,000 times more luminous in X-rays. It is also located in a much smaller and younger host galaxy, and is only detected during a single, several-hour burst.

Additional highly targeted searches through the Chandra archive and those of ESA's XMM-Newton and NASA's Swift satellite may uncover more examples of this type of variable object that have until now gone unnoticed. Future X-ray observations by Chandra and other X-ray telescopes may also reveal the same phenomenon from other objects.

A paper describing this result appears in the June 2017 issue of the Monthly Notices of the Royal Astronomical Society and is available online. NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations.


Fast Facts for CDF-S Transient:
Credit  X-ray: NASA/CXC/Universidad Católica de Chile/F.Bauer et al.
Release Date  March 30, 2017
Scale  Main Image is 16 arcmin across; Inset Image is 3.7 arcsec across
Category  Cosmology/Deep Fields/X-ray Background, Black Holes
Coordinates (J2000)  RA 03h 32m 39s | Dec -27° 51' 34"
Constellation  Fornax
Observation Date  Inset Image: October 2, 2014
Observation Time  Inset Image: 26 hours 7 minutes.
Obs. ID  Inset Image: 16454
Instrument  ACIS
References Bauer, F. et al., 2017, MNRAS (in press); arXiv:1702.04422
Color Code  Inset Image: X-ray (Blue)
Distance Estimate  About 10.7 billion light years
distance arrow
Visitor Comments (12)

What if two dying stars suddenly merged in a death spiral the length of the burst creating a rapid violent usage of of their remaining fuel and formed a black hole causing the fade. There seems to be some transit rotation during the burst in the video of the blue flash I saw at least.

Posted by Buki on Sunday, 08.19.18 @ 14:01pm

This is so thrilling and I must thank all the scientists who have made it possible for all of us to see the magic in our universe.

Posted by Shirley Stapleton on Monday, 05.1.17 @ 10:15am

Thank you for this. You're making America smart again.

Posted by Thomas Kester on Monday, 05.1.17 @ 10:14am


Posted by Dr.Mauricio Pérez-Badell on Monday, 05.1.17 @ 09:49am

Obviously the destruction of the Death Star by Rebel forces in a galaxy far, far away ......

Posted by Brian on Monday, 05.1.17 @ 09:19am

WOW... cool. I wish we knew what was in the Early Universe part.

Posted by Anonymous on Monday, 04.24.17 @ 10:17am

Why a white hole phenomenon isn't in the list of possible explanations?

Posted by Giovanni della Rossa on Sunday, 04.16.17 @ 11:47am

Could this be an actual visual representation of Hawkins release of information energy as death of a blackhole? This massive amount of energy could back that up correct.

Posted by Justin t Copeland on Saturday, 04.15.17 @ 19:09pm

Is there any chance of this being a microlensing event? It just seems very similar it effect and time frame.

Posted by Ben Hart on Sunday, 04.2.17 @ 19:33pm

It is mind boggling that the X-ray source is approx. six and a half billion yrs. older than our earth...

Posted by Sam Shipley on Friday, 03.31.17 @ 17:06pm

We have enough problems on our own planet. We can't even stop incoming asteroids. ENJOY LIFE NOW

Posted by paul skillman on Friday, 03.31.17 @ 12:05pm

Incredible observation from Chandra. Thank you for all the work.

Posted by William Askew on Thursday, 03.30.17 @ 17:02pm

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