Gamma-Ray Pulsar Glows Outside Milky Way Galaxy


Exciting news for space lovers and exploration seekers: researchers have discovered the first gamma-ray pulsar outside the Milky Way – and it sets the record of being the most luminous known gamma-ray pulsar to date.

Imaged by NASA’s Fermi gamma-ray Space Telescope, the pulsar lies in the Tarantula Nebula’s outskirts in the Large Magellanic Cloud, a small satellite galaxy of the Milky Way found 163,000 light years away. The Tarantula Nebula is the biggest, most active, and most intricate star-formation area in the galactic community, identified as a bright gamma-ray source.

Lead scientist and astrophysicist Pierrick Martin said PSR J0540-6919 is responsible for about half of the gamma-ray brightness originally believed to hail from the nebula.

"That is a genuine surprise," he said.

The new findings were announced Nov. 13 in the journal Science.

The highest-energy light form, gamma-rays are deemed borne out of subatomic particles that collided in the wake of supernova explosions. Extremely condensed having collapsed in on itself, a supernova rotates quickly; during spinning, electromagnetic field shoots out energy pulses in the form of gamma rays, X-rays, radio waves, and visible light.

The Tarantula Nebula is known for another pulsar, PSR J0537−6910 (J0537), discovered with the help of the Rossi X-ray Timing Explorer (RXTE) satellite and spins at nearly 62 times a second, the fastest-known rotation time for a young pulsar. J0540, on the other hand, whirls at just under 20 times per second.

Co-author Lucas Guillemot said J0540’s gamma-ray pulses have 20 times the intensity of the pulsar in the Crab Nebula, the previous record-holder. “[Y]et they have roughly similar levels of radio, optical and X-ray emission,” he explained.

J0540 also has an age of about 1,700 years, twice of the Crab Nebular pulsar’s and in contrast with most of over 2,500 known pulsars ages 10,000 to hundreds of millions of years.

It took over six years for the telescope and for a reanalysis of telescope data to detect the pulsations.

Before Fermi was launched in 2008, there were only seven gamma-ray pulsars detected, unlike today when the mission has found over 160 within the Milky Way. Few gamma rays reach the telescope to detect the pulsations without knowing the period ahead of time.

Discoveries such as this one, according to Guillemot, offer “a better understanding of the extreme physics at work in young pulsars.”

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