Experiment

Japanese groups observe the brightest level gamma-ray burst ever observed

In April, 2013, a gigantic gamma-ray burst, the brightest one in the last 23 years, which can be called a "Monster" was observed near Denebola (β Leo).

An international cooperation observation group including Japanese research teams succeeded in observing the X-ray afterglow of the burst using the Monitor of All-sky X-ray Image (MAXI) on board the ISS. The result was published in Science issued on November 22, 2013.

【Points】

• On April 27, 2013, a gigantic gamma-ray burst, the brightest one in the last 23 years, was observed. This is the largest level ever observed.
• The explosion happened in the Earth's "neighborhood" at about 3.8 billion light-years away. However, its characteristics are the same with the "Monster" bursts blasted in the early universe. and great distances from the Earth.
• This observations challenge the standard model for gamma-ray bursts.

【Summary】
An international cooperation observation group including Japanese research teams (ex. Tokyo Institute of Technology) succeeded in capturing one of the brightest "Monster" gamma-ray burst ever observed before, designated GRB 130427A. As a result of detailed data analysis, the burst occurred when the universe was 10 billion years of age, which is almost the same environment with the current universe. Nevertheless, the burst has same characteristics with the ordinal Monster bursts that occur during the early universe. Since the burst occurred closest to Earth so far had extremely low explosion energy, it was thought to be a different phenomenon.

This time, high quality data of an ordinal monster burst was obtained thanks to its explosion occurred in the Earth's neibourhood. Existing theory for gamma-ray emission mechanism needs to be reconsidered.

Gamma-ray bursts are the extremely energetic explosions emitted from stars with the mass of dozens of times of the Sun. On average they occurred during the early universe, at 3 billion years of the universe age, which means that they occur in far distances, at more than 10 billion light-years away. The gamma-ray burst GRB 130427A occurred on April 27, 2013, was originally a huge one, was seen extremely bright because it happened in the Earth's neighborhood at about 3.8 billion light-years away. The result was published in Science issued on November 22, 2013.

*All times are Japan Standard Time (JST)