Blast from the past (photo)

The presented image was obtained by the X-Shooter receiver mounted on the ESO’s Very Large Telescope (VLT). In its center you can see, at first glance, an unremarkable little red spot. This is the afterglow of a gamma-ray burst — one of the brightest and most mysterious phenomena in the universe.

Afterglow of a gamma-ray burst. Source: ESO/A. Rossi et al.

In September 2021, the Swift Space Observatory registered a powerful gamma-ray burst that occurred in the direction of the constellation Microscopium. The peculiarity of such events is their extremely short duration. Usually, the initial flash lasts from a few seconds to several minutes. Then there is an afterglow at longer wavelengths in the visible and infrared ranges. But it also fades very quickly — therefore, the reaction of astronomers should be immediate.

In the case of the gamma-ray burst captured in the image, scientists reacted in time. Using the X-Shooter receiver, a group of Italian researchers managed not only to get a photo, but also spectra of the event. They concluded that the surge occurred in an exceptionally distant galaxy, when the age of the Universe was only 6% of the current one. Thus, this gamma-ray burst turned out to be one of the most distant ever recorded.

The exact origin of gamma-ray bursts is still a mystery. Astronomers associate them with events such as collapses of massive luminaries, as well as mergers of super compact objects. As for the VLT burst photographed, according to the researchers, so much energy was released during it that it was most likely caused by a fall of matter on a black hole or (less likely) on a magnetar — neutron star with a very strong magnetic field.

Gamma-ray bursts in the artist’s image. Source:

In the study of gamma-ray bursts, astronomers have high hopes for an Extremely Large Telescope (ELT), which will be put into operation in the second half of this decade. It will let us study the properties of such events in more detail and clarify their nature.

According to

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