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High-speed particle jets from gamma-ray bursts may exceed the speed of light in surrounding gas clouds, but they do not violate Einstein's theory of relativity, according to a team of astrophysicists at Michigan Technological University and the College of Charleston.
Impression of an artist on a jet of particles emanating from a black hole in the center of a blazar. Image credit: DESY / Science Communication Lab.
Gamma-ray bursts are the brightest explosions in the universe.
Most occur when certain types of massive stars run out of fuel and collapse to create new black holes. Others arise when two neutron stars, super remains of stellar explosions, merge.
Both types of cataclysmic events create jets of particles that move at a speed close to that of light.
Professors Robert Nemiroff of Michigan Technological University and Jon Hakkila of Charleston College propose that these jets can reach superluminal velocities and create the reversibility in time observed in light curves of gamma-ray bursts.
However, these proposed jets do not violate Einstein's relativity, because they move only faster than the light passes through the jet, no faster than the light by the vacuum.
"A good way to visualize this superluminal movement is to imagine someone on one side of a pond jumping a stone on the water in your direction," said the professor. Hakkila.
"The frequent jumping rock moves in the air between jumps faster than the waves that it generates do not move in the water."
"You would see the waves created by each stone jump approaching in the reverse order, with the waves of the most recent jump arriving first and those of the initial jump arriving last."
"This superluminal breath explanation retains many of the features of accepted gamma burst jet models."
"However, our scenario involves a Cherenkov radiation, a type of light created by a superluminal motion that was until then not considered important to generate light curves of gamma-ray bursts," added Professor Nemiroff .
"Standard models of gamma-ray burst have neglected the properties of reversible light curves over time," said Professor Hakkila.
"The motion of the superluminal jet accounts for these properties while retaining a large number of standard model features."
The team's paper was published in Astrophysical Journal.
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Jon Hakkila and Robert Nemiroff. 2019. Burst light curve characteristics of gamma rays inverted over time as transitions between subluminal and supraluminal movements. ApJ 883, 70; doi: 10.3847 / 1538-4357 / ab3bdf
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