A Tour of CDF-S Transient XT1

Narrator (April Hobart, CXC): Scientists have discovered a mysterious flash of X-rays using NASA's Chandra X-ray Observatory, in the deepest X-ray image ever obtained. The X-ray source is located in a region of the sky known as the Chandra Deep Field-South. Over the 17 years Chandra has been operating, the telescope has observed this field many times, resulting in an exposure time equivalent to 7 million seconds.

The mysterious source that scientists discovered 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 over a few hours. After about a day, the source had faded completely below the sensitivity of Chandra.

While scientists think this source likely comes from some sort of destructive event, its properties do 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 involve gamma-ray bursts, some of the most powerful explosions in the Universe. However, unusual properties are needed for such a burst to explain the source's behavior. A third possibility is that a medium-sized black hole shredded a white dwarf star.

While they still don't have the final answers, researchers are still working hard to make progress. By combing the archives of Chandra and XMM-Newton data, they hope to find another object that has similar properties to the one they discovered. They also plan to continue to use Chandra to obtain new observations to help solve this high-energy puzzle.