Based on current research from the University of Bath in the Uk, new supermassive stars, instead of black holes, might be the reason for gamma ray bursts.
Gamma-ray bursts (GRBs) have been spotted by satellites orbiting the planet as luminous flashes of incredibly intense gamma-ray radiation which last from milliseconds to hundreds of seconds. These devastating blasts happen in distant galaxies billions of light years from Earth.
A kind of GRB, called a short duration GRB, is created when two neutron stars collide. These extremely dense stars, which constrict the mass of our Sun into a size smaller compared to a city, create ripples in space time known as gravitational waves right before initiating a GRB in their last moments.
Up – to – day, space researchers have agreed the motor “driving these kinds of intense as well as short-lived bursts should always originate from a recently formed black hole (an area of space where gravity is so powerful that nothing, not even light, could escape). The latest research by a global group of astrophysicists headed by Dr Nuria Jordana Mitjans at the University of Bath in the Uk is challenging this orthodoxy.
Some short-duration GRBs are brought on by the birth of a supermassive star (referred to as neutron star remnant), not a black hole, say the scientists.
Dr. Jordana-Mitjans said: This kind of data are crucial as they confirm that new neutron stars could power a little short-duration GRBs as well as the vibrant pollutants throughout the electromagnetic spectrum that were detected. “This finding might provide a new method to find neutron star mergers and therefore gravitational waves emitters when we are searching the atmosphere for signals,” it said in a statement.
Competing theories
Concerning short duration GRBs isn’t very well known. They begin their lives when two neutron stars which have been getting closer and closer, continuously speeding up, finally crash. A jetted explosion coming from the crash location emits the gamma ray light which creates a GRB, followed by a longer-lived afterglow. One day later on, the radioactive material dispersed in all directions during the blast created what scientists call a kilonova.
Nevertheless, what remains after two neutron stars collide – the result “of the crash, and so the energy supply that provides a GRB its remarkable energy – is a matter of debate for some time. A Bath-led analysis indicates that scientists might be closer to solving the debate than in the past.
Experts in space possess two competing ideas. The very first idea is the fact that neutron stars merge to create an incredibly massive neutron star briefly, only for this star to collapse in a fraction of a second into a black hole. The next asserts the combination of the two neutron stars would lead to a less heavy neutron star with a longer life expectancy.
The issue then, that’s been pondered for a long time by astrophysicists is this: Are short duration GRBs fueled by a black hole or the appearance of a long- lasting neutron star?
The majority of astrophysicists have endorsed black hole theory to this day, agreeing that for a GRB being created, it’s needed for the enormous neutron star to collapse almost immediately.
Electromagnetic signals
Astronomers find out about neutron star collisions by analyzing the electromagnetic waves of the ensuing GRBs. A signal originating from a black hole could be different from a signal originating from a neutron star remnant.
The electromagnetic signal from the GRB examined for this study (named GRB 180618A) made it obvious to Dr Jordana Mitjans as well as her associates that a neutron star remnant should have brought about this particular burst, instead of a black hole.
Elaborating, Dr. Jordana-Mitjans said “For the very first time, our data highlight a number of signals from a surviving neutron star which lived a minimum of a day after the demise of the initial neutron star binary.”
Professor, PhD student, and Carole Mundell of Extragalactic Astronomy at Bath, wherever she has the Hiroko Sherwin Chair in Extragalactic Astronomy, said: “We were encouraged to get the really first optical light from this quite short gamma ray burst, one thing that’s still mostly not possible without a robotic telescope,” the report stated. Nevertheless, when we examined our extraordinary data, we were shocked to discover we couldn’t clarify it with the regular quick collapse black hole model of GRBs.
“Our finding opens new hope for upcoming sky surveys using telescopes like the Rubin Observatory LSST, with which we might find signals from hundreds of thousands of such long-lived neutron stars before they collapse to be black holes,” he said.
Disappearing afterglow
At first, the scientists were shocked by the actual fact that the optical light from the afterglow that followed GRB 180618A vanished after just thirty five minutes. Further analysis revealed that the material responsible for this sort of a brief emission was expanding from behind because of some resource of constant power pushing it close to the speed of light.
More surprising, this emission had the impression of any newborn, quickly spinning and extremely magnetized neutron star, known as a millisecond magnetar. The team found that the magnetar was reheating the leftover material of the crash while it slowed down, after GRB 180618A.
In GRB 180618A, the magnetar-driven optical emission was one-thousand times greater than the thing that was expected from a classical kilonova.
Reference: “A Short Gamma-Ray Burst from a Protomagnetar Remnant” by N. Jordana-Mitjans, C. G. Mundell, C. Guidorzi, R. J. Smith, E. Ramírez-Ruiz, B. D. Metzger, S. Kobayashi, A. Gomboc, I. A. Steele, M. Shrestha, M. Marongiu, A. Rossi and B. Rothberg, 10 November 2022, The Astronomical Journal.
DOI: 10.3847/1538-4357/ac972b
