Gamma ray bursts are essentially the most luminous explosions within the universe, briefly outshining total galaxies in a violent flash of excessive power radiation. These – excuse the pun – astronomical detonations launch extra power in a number of seconds than our Solar will produce over its total ten billion 12 months lifetime, sending jets of gamma rays racing via area. Regardless of their unbelievable brightness, gamma ray bursts are fleeting occasions, lasting wherever from milliseconds to a number of minutes earlier than fading away.
On seventh March 2023, satellites detected certainly one of these gamma ray bursts, this one designated GRB 230307A. It was the second brightest burst ever recorded and originated from the collision and merger of two compact stars, doubtless neutron stars, situated in a distant galaxy. What made this occasion significantly curious was its unusually lengthy period of 1 minute, when concept predicted it ought to final lower than two seconds for one of these merger occasion.
Artist’s illustration exhibiting the lifetime of an enormous star: Nuclear fusion converts lighter parts into heavier ones; when fusion now not generates sufficient strain to counteract gravity, the star collapses right into a black gap. Throughout this collapse, power could also be launched as a momentary burst of gamma-rays aligned to the axis of rotation (Credit score : Nationwide Science Basis)
A world crew led by researchers from the College of Hong Kong, Nanjing College, and the Chinese language Academy of Sciences determined to dig deeper into the occasion. They searched via greater than 600,000 datasets collected by China’s GECAM satellites and NASA’s Fermi satellite tv for pc, looking for hidden patterns throughout the burst. What they discovered was a repeating sign that maintained a really constant rhythm over time revealing that the star was spinning at 909 occasions per second. This speedy pulsation represents the primary direct detection of a periodic sign from a millisecond magnetar inside a gamma ray burst.
“This occasion gave us a uncommon alternative, by uncovering its hidden ‘heartbeat’, we are able to lastly say with confidence that some GRBs are powered not by black holes, however by new child magnetars.” – Professor Bing Zhang, Chair Professor of the Division of Physics at HKU and co-corresponding writer of the research.
The shock was understanding why the sign was so temporary. The crew theorise that the magnetar’s speedy spin imprints a periodic sign onto the gamma ray jet via its magnetic area, however as a result of the jet evolves rapidly, this heartbeat turns into seen solely when the emission briefly turns into uneven. For simply 160 milliseconds, the periodic pulse was detectable earlier than the jet’s symmetry hid it once more.
Fermi satellite tv for pc on Earth earlier than launch with its photo voltaic arrays folded (Credit score : Kim Shiflett)
The invention transforms our understanding of essentially the most excessive explosions within the universe and exhibits that newly born magnetars can survive compact star mergers. The analysis opens fascinating new avenues in astronomy, linking gamma rays, gravitational waves, and the physics of compact stars underneath essentially the most excessive circumstances conceivable.
