Extragalactic Pulsar Discovery Is Gamma-Ray Monster
Like a blinding beacon lighting up the night, a powerful gamma-ray generating stellar husk has been seen pulsating in a neighboring galaxy. The discovery, uncovered by NASA's Fermi Gamma-ray Space Telescope, is the first ever gamma-ray pulsar detected outside of the Milky Way. And this extragalactic object is a monster.
ANALYSIS: Wonky, Warped and Weird: Pulsar Vanishes in Spacetime
Pulsars are rapidly-spinning neutron stars and neutron stars are the crazy-dense remains of a once-massive star. After running out of fuel, imploding and then exploding as a supernova, depending on the star's original mass, a neutron star can remain behind - just a lump of degenerate matter, spinning like a perpetual whirling dervish.
As one might expect, the environment surrounding a pulsar is the very definition of extreme. The magnetic field that its younger self used to possess has now been squeezed into a dense mass a fraction of the original star's size, only a couple of dozen miles across. This intense magnetism creates some powerful physics, blasting intense radiation from the spinning neutron star's poles. It's these collimated beams of radiation that give pulsars their name; as the neutron star spins on its axis, the beams of radiation sweep across the sky, sometimes pointing right at Earth. We see these pulses as regular flashes in the sky - a.k.a. pulsars.
Now, astronomers have found a pulsing record breaker in the middle of the Tarantula Nebula inside one of the Milky Way's small galactic neighbors - a satellite galaxy called the Large Magellanic Cloud (or LMC), around 163,000 light-years away.
ANALYSIS: Pulsar Punches Hole Through Star's Disk
As the Tarantula Nebula is an intense star-forming region, it was believed that the immense gamma-ray emissions it is known for are generated by the massive stars that live fast and die young. Put in simple terms, the more massive the star, the faster it will burn through its fuel and the quicker it will explode as a supernova. As the nebula is known to be a hot house of stellar birth and death, it was assumed that the flood of gamma-rays were a byproduct of the stellar drama.
As supernovae popped off in the Tarantula, astrophysicists posited, shockwaves would rumble through the nebula's gases. In doing so, particles were accelerated to high energies, generating cosmic rays (e.g. high-energy protons). The cosmic waves then interact, generating powerful radiation, or gamma-rays.
Case closed? Well, not quite.
Over the years, Fermi has been collecting more and more data from the LMC, gradually forming a more detailed look into the Tarantula Nebula and, by combining these data with new analysis techniques, astronomers have made a pretty astounding discovery. Embedded inside the gamma-ray hum are 2 pulsars and Fermi scientists think one of the pulsars, called PSR J0540-6919, is generating up to 60 percent of the gamma-rays detected in the nebula all by itself.
ANALYSIS: Fermi Spots Antimatter in Thunderstorms