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alright folks, buckle up. tonight I’m going to take you on a journey across the Cosmos, where we meet the brightest events in the Universe: relativistic space fireballs. (more formally known as gamma ray bursts (GRBs), but that’s a lil less fun.)
gamma ray bursts are thought to be produced by some of the most exotic phenomena in the Universe: core collapse supernovae, neutron-neutron star mergers, and neutron star-black hole mergers.
core collapse supernovae can produce two possibilities: (1) a magnetar, which is a rapidly rotating, highly magnetic neutron star; or (2) a hypernova, which is a superluminous supernova— an exploding star 10x as luminous as it’s standard counterpart.
all of these things could potentially produce relativistic fireballs shooting across the Universe. I wanna remind you: GRBs are insanely energetic. a typical GRB can release as much energy in seconds as our Sun releases over its entire 10 billion year life. let’s talk about how!
right after the explosion, a soup of photons and particles are streaming away from the compact object and become collimated in a jet. this jet becomes so highly focused and beamed, that it’s rapidly accelerated to relativistic velocities.
remember that things are relativistic when they’re moving really close to the speed of light, the cosmic speed limit. these lil dudes are faaaast. that’s how we get SUCH high energies from gamma ray bursts! relativity! (go Einstein yay)
astronomers think that shells of matter and energy expanding at slightly different velocities away from the compact source *collide* with each other, flash heating and converting their energy into radiation streaming away that can be observed from Earth.
this emission mechanism (the process of converting kinetic energy into the radiation we observe) is still being studied. magnetic fields certainly play a role, accelerating charged particles along their field lines and complicating the physics. anyway...
on Earth, we see a HUGE burst of energy— of order 10^53 ergs, 100x more energetic than a standard supernovae— in a matter of seconds to hours. afterwards, we see an ”afterglow” that spans the entire electromagnetic spectrum.
okay, so they’re bright and hot and insane. are they a danger to us? in short...yeah. however, gamma ray bursts are so rare (1 per million years per galaxy) and occur so far outside of the Milky Way in distant galaxies, that I’m not too concerned.
that being said, a gamma ray burst within our galaxy with a jet pointed directly at as would royally screw all life on Earth ☠️
pretty illustration of a gamma ray burst produced by a supernova collapsing into a black hole. note the beamed jets spewing out into the interstellar medium. (NASA/GSFC) 
