A strange cosmic explosion detected on April 8, 2024, by the Einstein Probe X-ray telescope has generated a lot of interest among astronomers. The event, designated EP240408a, at first appeared to be a normal gamma-ray burst. However, further observations showed that it did not correspond to any known type of cosmic phenomena.
What exactly did the astronomers observe?
Telescopes studied the event in different wavelength ranges: from ultraviolet to radio waves. However, the properties of the explosion turned out to be extremely atypical. The burst emitted “soft” X-rays for the first 10 seconds, remained stable for about four days, and then quickly faded out within 24 hours. This duration does not belong to any of the known categories of cosmic explosions, because gamma-ray bursts usually last a few hours, while other phenomena last much longer.
Possible explanation
According to a new study, the most likely cause is a tidal disruption event (TDE) during which an intermediate-mass black hole ripped apart and engulfed a white dwarf. Such events are sometimes accompanied by jets of matter that move at tremendous speeds. If one of these jets points toward Earth, it creates a strong visible signal.
However, even this explanation has its mysteries. For example, such events usually leave behind radio emissions. But after EP240408a exploded, radio telescopes, particularly the Very Large Telescope (VLA), did not detect a single signal even 258 days after the burst.
Alternative hypotheses
EP240408a has features of several types of cosmic phenomena, but does not completely correspond to any of them. Quasar scenarios were also excluded. “This event could be a gamma-ray burst, but its duration and brightness don’t fit standard models,” explains Brendan O’Connor, an astronomer at Carnegie Mellon University.
Astronomers suggest that radio emission may still appear, but much later. According to some theories, it takes several hundred or even thousands of days for the jet material to slow down and start emitting radio signals. If this happens, it would support the TDE hypothesis. If not, we will have to admit that we have witnessed a completely new type of cosmic phenomena.
This event demonstrates how mysterious and poorly understood the Universe remains. EP240408a may be the key to understanding the hitherto unknown processes occurring in the cosmos.
Earlier we reported on how the brightest gamma-ray burst in the Universe blinded detectors.
According to livescience.com
