Scientists can return to the drafting board. As a result of apparently we nonetheless do not absolutely perceive how lengthy gamma-ray bursts see the sunshine of day.
Gamma-ray bursts are probably the most energetic phenomena within the universe. They’re truly nothing greater than violent bursts of high-energy gamma rays that final from a number of milliseconds to some minutes. Astronomers have lengthy hypothesized that gamma-ray bursts are available two ‘flavors’: the quick GRB and the lengthy GRB, each of which have completely different origins. Or… is that too short-sighted? Lately, researchers have seen gamma-ray bursts that originated otherwise than anticipated. And now there’s a third shocking instance.
Origin
For practically 20 years, astrophysicists have believed that quick GRBs end result from neutron star mergers. Colliding neutron stars can then produce a so-called kilonova; an explosion wherein heavy components reminiscent of gold are thrown away. Lengthy GBRs could be produced solely by the collapse of large stars, making a supernova.
Heart of an historic galaxy
In a brand new research, researchers have studied the aftermath of a gamma-ray burst that was captured on October 19, 2019 by the Neil Gehrels Swift Observatory. They did that with the Gemini Southtelescope in Chile, the Nordic Optical Telescope on the Canary Island of La Palma and Hubble Area Telescope. It results in a startling discovery. The lengthy gamma-ray burst seems to return from the middle of an outdated galaxy. And that’s very unusual. As talked about, lengthy GRBs often type in collapsing large stars. And allow them to simply be lacking within the middle of outdated galaxies. Huge stars are typical for younger galaxies.
3 ways
The brand new commentary turns our understanding of how lengthy gamma-ray bursts are born the other way up. And that isn’t the primary time. Final 12 months, for instance, researchers found an extended GRB brought on by merging neutron stars. In that case, two giant stars, which had orbited one another all their lives, finally become neutron stars and collided right into a kilonova. And that whereas it was assumed that solely quick GRBs may very well be related to kilonovas. That idea might go straight into the trash. And now, in 2023, it appears that evidently lengthy GRBs could type in a 3rd manner.
Supernova
The researchers rule out that the lengthy GRB originated from the collapse of an enormous star (as historically thought). That is as a result of supernovae usually emit brilliant gentle, which the astronomers failed to watch.
Collision
As a substitute, the group suspects that the lengthy GRB noticed within the middle of the outdated galaxy was brought on by a merger of two separate neutron stars. On this case, in contrast to final 12 months’s research, it’s not about neutron stars which were circling one another for a very long time, however about two separate stars that instantly encountered one another. “We expect that the neutron stars are pushed collectively by the gravitational pull of many surrounding stars within the middle of the galaxy,” stated lead researcher Andrew Levan, of Radboud College.
Busy issues
That is not such a loopy idea in any respect. Within the middle of galaxies it is extremely busy. There are lots of of hundreds of regular stars, white dwarfs, neutron stars, black holes, and dirt clouds all circling a supermassive gap. Altogether, there are greater than ten million stars and objects crammed into about 4 light-years. “That is an space akin to the gap between our solar and the following star,” explains Levan. “So the possibility of a collision within the middle of a galaxy is far greater than in our personal cosmic yard.”
Whether or not it truly considerations two colliding neutron stars isn’t totally clear in the intervening time. The researchers are due to this fact nonetheless cautious. For instance, the lengthy GRB within the middle of the outdated galaxy might even have been created by different colliding objects, reminiscent of black holes or white dwarfs. Sooner or later, the group hopes to watch extra lengthy GRBs that act concurrently with gravitational waves. That might allow them to make extra definitive statements concerning the origin of the radiation.
