A recent discovery by the Einstein Probe X-ray space telescope has left astronomers puzzled. The event, designated EP240408a, is a cosmic explosion that doesn’t fit into any known category of gamma-ray bursts or other transient events.
Initially detected on April 8, 2024, EP240408a appeared to be a run-of-the-mill gamma ray burst, emitting bright X-rays in all. However, when observed by multiple telescopes across various wavelengths, including ultraviolet, optical, near-infrared, radio, and X-ray, they found that it defied explanation.
The current leading theory is that EP240408a resulted from the death throes of a white dwarf being torn apart by a medium-sized black hole. This catastrophic event created a high-speed jet of material that pointed directly at Earth, producing the signature observed.
“This event ticks some boxes for several phenomena but doesn’t tick all,” said Brendan O’Connor, lead author of the study and astronomer at Carnegie Mellon University. “The short duration and high luminosity are hard to explain in other scenarios.”
Astronomers used data from various ground- and space-based telescopes, including NuSTAR, Swift, Gemini, Keck, VLA, ATCA, and NICER, to piece together the event’s properties. Despite this, the mystery only deepened.
EP240408a flared up in soft X-rays for 10 seconds, plateaued at a steady glow for four days, then faded within another day. Its brightness in X-rays was in a “reverse-Goldilocks zone” – too bright for some phenomena and not bright enough for others.
The VLA saw no sign of radio emission from the source when it checked multiple times after the initial flare-up. When scientists ruled out possible explanations, such as quasars or fast blue optical transients, they proposed a new theory: an intermediate-mass black hole devouring a white dwarf star.
However, the team’s hypothesis faces an unexpected challenge – the absence of radio emissions from the jetted material. They speculate that the event was caught too early, and it may take hundreds or thousands of days for the material to slow down enough to begin emitting radio signals.
The research was published in The Astrophysical Journal Letters, leaving scientists with a mystery that could be solved by future observations.
Source: https://www.yahoo.com/news/strange-cosmic-explosion-may-just-231609749.html