Astrophysicists have developed the first 3D simulation of the entire evolution of a jet from its birth to its emission from a falling star by a rotating black hole.
The simulation shows that as Star collapses, its contents fall onto the disc which rotates around black hole, This falling material bends the disc, and in turn, bends the jet, which wobbles as it struggles to return to its original trajectory.
Waver jet explains long-standing mystery why gamma-ray burst In the blink of an eye, these bursts are even rarer than previously thought.
because these jets generate Gamma-ray bursts (GRBs) — The most energetic and brightest events in the universe big Bang – Simulations have shed light on these strange, intense bursts of light. Their new findings include an explanation for the long-standing question of why GRBs are mysteriously punctuated by moments of calm – naps between powerful emissions and a lingering calm. The new simulations also show that GRBs are even rarer than previously thought.
New study Posted on 29 June astrophysical journal letters, This is the first full 3D simulation of the entire evolution of a jet – from its birth near a black hole to its emission after escaping from a collapsing star. The new model is also the highest resolution simulation of a massive jet to date.
“These jets are the most powerful events in the universe,” Told Ore Gottlieb of Northwestern University, who led the study. “Previous studies have tried to understand how they work, but those studies were limited by computational power and involved many assumptions. We were able to model the entire evolution of jets from the beginning – from its birth A black hole – without assuming anything about the jet’s structure. We followed the jet from the black hole to the emission site and found processes that had been overlooked in previous studies.”
Gottlieb is a Rothschild Fellow at the Northwestern Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA). He co-authored the paper with CIERA member Sasha Tchekhovskoye, assistant professor of physics and astronomy at Northwestern’s Weinberg College of Arts and Sciences.
strange stutter
the brightest event in UniverseGRBs are produced when the core of a massive star collapses under its own gravity to form a black hole. As gas falls into the rotating black hole, it activates – launching a jet into the collapsing star. The jet punches the star until it accelerates to a speed close to the speed of light. After being released from the star, the jet generates a bright GRB.
“The jet generates a GRB when it reaches about 30 times the size of a star — or a million times the size of a black hole,” Gottlieb said. “In other words, if the black hole is the size of a beach ball, the jet needs to extend over the entire size of France before it can produce a GRB.”
Due to the enormity of this scale, previous simulations have been unable to model the full evolution of the jet’s birth and subsequent travel. Using assumptions, all previous studies found that the jet propagates along one axis and never deviates from that axis.
But Gottlieb’s simulation showed something very different. As the star collapses into a black hole, material from that star falls onto the disk of magnetic gas that surrounds the black hole. The falling material causes the disc to tilt, which in turn bends the jet. As the jet struggles to re-align with its original trajectory, it wobbles inside the collapse.
This wobble provides a new explanation for why GRBs blink. During quiet moments, the jet doesn’t stop – its emission beams away from EarthTherefore telescopes cannot see it easily.
“Emissions from GRBs are always erratic,” Gottlieb said. “We see spikes in emissions and then a silent time that lasts a few seconds or more. The entire duration of a GRB is about a minute, so these silent times are a non-negligible fraction of the total duration. Previous models did not do this. is able to explain where these quiet times were coming from. This wobble naturally explains the phenomenon. We see the jet when it’s pointing at us. But when the jet wobbles to move away from us , so we can’t see his emission. This is part of Einstein’s theory of relativity,
rare becomes rare
These wobble jets also provide new insights into the rate and nature of GRBs. Although previous studies have estimated that about 1 percent of collapsers produce GRBs, Gottlieb believes that GRBs are actually very rare.
If the jet was constrained to move along one axis, it would only cover a thin piece of sky – limiting the chances of seeing it. But the wobbling nature of the jets means that astrophysicists can observe GRBs at different orientations, increasing their chances of finding them. According to Gottlieb’s calculations, GRBs are 10 times more observable than previously believed, meaning that astrophysicists are missing 10 times fewer GRBs than previously thought.
“The idea is that we observe GRBs on the sky in a certain rate, and we want to know about the actual rate of GRBs in the universe,” Gottlieb explained. “The observed and true rates are different because we can only see the GRBs that are pointing at us. This means that we need to make some approximations about the angle, which is the angle, to estimate the true rate of the GRB. These jets cover over the sky. That is, how much of a GRB we are missing. Wagger increases the number of detectable GRBs, so the improvement in the actual rate from observed is smaller. If we miss fewer GRBs , so the total GRBs in the sky are low.”
If this is true, Gottlieb believes, then most jets either fail to launch or never succeed in escaping the collapser to form a GRB. Instead, they remain buried inside.
mixed energy
The new simulation also showed that some magnetic energy partially converts to jet thermal energy, This suggests that the jet has a hybrid structure of magnetic and thermal energy, which produces the GRB. In a major step forward in understanding the mechanisms that power a GRB, this is the first time researchers have estimated the jet structure of a GRB at the time of emission.
“Studying the jet enables us to see what happens inside a star as it collapses,” Gottlieb said. “Otherwise, it is difficult to learn what happens in a collapsed star because light cannot escape from the stellar interior. But we can learn from jet emissions – the history of jets and the information they carry from the systems that launched them. does.”
The major advancement of the new simulation partly lies in its computational power. Using the code “H-AMR” on super computer At the Oak Ridge Leadership Computing Facility in Oak Ridge, Tennessee, researchers developed the new simulation, which uses graphical processing unit (GPU) instead central processing units (CPU). Highly skilled in manipulating computer graphics and image processing, GPUs accelerate the creation of images on displays.