Explosion in space! China's Einstein Telescope detects puzzling anomaly 12.5 billion light-years away

Produced by Tarun Mishra

Soft X-rays

On March 15, 2024, the Einstein Probe’s Wide-field X-ray Telescope (WXT) detected soft X-rays lasting over 17 minutes. These fast X-ray transients (FXRTs) are rare, and the event, named EP240315a, fluctuated in brightness before fading.

Ancient Cosmic Origins

An hour after WXT’s detection, visible light from the same event was recorded by the ATLAS telescope in South Africa. Subsequent redshift measurements confirmed the burst occurred 12.5 billion light-years away when the universe was only 10% of its current age, marking the oldest and longest soft X-ray detection.

Collaborative Follow-Ups

International efforts, including the Gemini-North telescope and the Very Large Telescope, contributed to the analysis. Radio observations by the Australian Telescope Compact Array (ATCA) over three months aligned the burst with a gamma-ray burst (GRB), designated GRB 240315C.

Gamma-Ray Burst

Typically, X-rays precede gamma rays by seconds in GRBs. However, in EP240315a, the X-rays appeared over six minutes before GRB 240315C. This unprecedented delay and the prolonged duration challenge existing GRB models.

Advancing X-ray Detection

Einstein Probe’s ability to detect faint, long-duration soft X-rays highlights its sensitivity and broad sky coverage. It offers a new method to study ancient cosmic explosions even without gamma-ray detection, enabling insights into the early universe.

GRB Models

The delayed gamma-ray emission and the unique characteristics of EP240315a suggest that existing GRB models may need revision. Scientists believe further observations will provide clarity on these unexpected behaviours.

Einstein Probe Mission

Launched on January 9, 2024, the Einstein Probe is a Chinese Academy of Sciences-led mission in collaboration with the European Space Agency, the Max-Planck Institute, and the French Space Agency. It uses the Wide-field X-ray Telescope (WXT) for sky monitoring and the Follow-up X-ray Telescope (FXT) for detailed analysis of detected X-ray sources.