Using NASA’s Fermi Gamma-ray Space Telescope, researchers have discovered a record-breaking gamma-ray pulsar in a galaxy. It is the most luminous gamma-ray pulsar known and it is also the highest-energy form of light in the Fermi mission.
Stefano Ciprini, who coordinates the Fermi team at the Italian Space Agency’s Science Data Center (ASDC) in Rome, said, “Looking at many years of data from Fermi’s Large Area Telescope (LAT), we picked up indications of a roughly two-year-long variation of gamma rays from a galaxy known as PG 1553+113. This signal is subtle and has been seen over less than four cycles, so while this is tantalizing we need more observations.”
Professor Sergio Colafrancesco, DST/NRF SKA Research Chair in the Wits School of Physics had earlier stated that very high-energy gamma rays are the best tracers of cosmic accelerators such as supernova remnants and pulsar wind nebulae end-products of massive stars.
NASA’s Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership, developed in collaboration with the U.S. Department of Energy and with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the United States.
“This campaign began as a search for a pulsar created by SN 1987A, the closest supernova seen since the invention of the telescope,” said co-author Francis Marshall, an astrophysicist at NASA‘s Goddard Space Flight Center in Greenbelt, Maryland. “That search failed, but it discovered J0537.”
The pulsar can be found in the outskirts of the Tarantula Nebula in the Large Magellanic Cloud (LMC). The Tarantula Nebula is located 163,000 light-years away, in a small galaxy, the LMC, that orbits our Milky Way.
These findings were published in the November 13 edition of the journal Science.
The Tarantula Nebula was identified as a bright source of gamma rays. Astronomers had credited this glow to the impact of subatomic particles accelerated by the shock waves that were likely caused by supernova explosions.
Lead scientist Pierrick Martin, an astrophysicist at the National Center for Scientific Research (CNRS) and the Research Institute in Astrophysics and Planetology in Toulouse, France, said, “Roughly half of the gamma-ray brightness we originally thought came from the nebula is due to a single pulsar, PSR J0540-6919 and this is definitely a surprise.”
J0540 is an uncommon find; it has an age of roughly 1,700 years, which is about twice that of the Crab Nebula pulsar.
A star’s core may live on as a neutron star when a huge star explodes as a supernova. Every second, a young isolated neutron star spins tens of times. Every time this happens, the spinning magnetic field powers beams of radio waves, visible light, X-rays and gamma rays. An object is classified as pulsar when the beams sweep past Earth because then astronomers observe a regular pulse of emission terming objects as pulsars.
The Tarantula Nebula was known to host two pulsars and NASA’s Einstein and Rossi X-ray Timing Explorer (RXTE) satellites discovered PSR J0540-6919 and PSR J0537. Both pulsars spin at a very high speed with J0540 spinning just under 20 times a second, while J0537 whirls at nearly 62 times a second.
Co-author Lucas Guillemot, at the Laboratory for Physics and Chemistry of Environment and Space, operated by CNRS and the University of Orléans in France, stated that, “As compared to the previous record holder, the gamma-ray pulses from J0540 have 20 times the intensity. These differences when taken into consideration will guide us to a better understanding of the extreme physics at work in young pulsars.”
There are over 2,500 known pulsars and most of them are 10,000 to hundreds of millions years old. Fermi was launched in 2008 and before it was launched, only seven gamma-ray pulsars were known. That was just the beginning as the mission has found over 160 since then.