Mysterious signal from the distant past

The Einstein Probe wide-angle X-ray telescope has detected an X-ray signal from the transient EP240315a.

Observations have shown that the signal is an echo of a powerful cosmic flare that occurred in the early Universe.

The study was published in the journal Nature Astronomy. The Einstein Probe caught the first signal on March 15, 2025.

It was initially identified as a burst of low-energy X-rays.

The mysterious burst lasted for more than 17 minutes, with its brightness varying. Then it faded.

The event was classified as a fast X-ray transient (FXRT) and given the designation EP240315a.

About an hour later, visible light from the same source was detected by a ground-based telescope located in South Africa.

It is part of the ATLAS rapid warning system for asteroid impacts on Earth.

Some time later, the flash was recorded by ground-based telescopes located in Hawaii and Chile.

Scientists have determined that the flash occurred approximately 12.5 billion years ago.

At that time, the age of the Universe was only 10 percent of its current age.