ISRO Black Hole Mission Observes Crab Pulsar. Know Interesting Facts About These ‘Cosmic Lighthouses’

The Crab Pulsar, which is ultra-dense core of the star that exploded into a supernova, acts like a lighthouse, ejecting twin beams of radiation. It has a rotational period of 33.33 milliseconds.

XPoSAT (X-ray Polarimeter Satellite), the Indian Space Research Organisation’s (ISRO’s) first mission to study black holes and neutron stars, has yielded interesting results after observing the Crab Pulsar. This is a rapidly spinning neutron star located at the heart of the Crab Nebula. The Crab Nebula, or Messier 1, is a six-light-year-wide remnant of a star’s supernova explosion. XPoSAT’s Polarimeter Instrument in X-rays (POLIX) observed the Crab Pulsar from January 15 to 18, 2024, and using this data, ISRO obtained a pulse profile of the celestial body. A pulsar is a rotating neutron star observed to emit pulses of radiation at very regular intervals that range from milliseconds to seconds, and has very strong magnetic fields which funnel jets of particles out along the two magnetic poles. There is an eerie blue light in the centre of the Crab Nebula. The scientific basis behind this blue light is the movement of electrons at nearly the speed of light around the Crab Pulsar’s magnetic field lines. What has XPoSAT observed? What is the significance of the pulse profile? The Crab Pulsar, which is ultra-dense core of the star that exploded into a supernova, acts like a lighthouse, ejecting twin beams of radiation. As the pulsar rotates, it appears to pulse 30 times per second. This means that the Crab Pulsar rotates 30 times per second around its axis. If the pulsar rotates 30 times in one second, it completes one rotation in 1/30 of a second, or 0.0333 seconds. This is equal to 33.3 milliseconds. The fact that POLIX’s observations helped ISRO scientists generate a pulse profile prove that the payload is functioning well, and can be used to study pulsars, black holes, and other celestial bodies. “The pulse profile is like a fingerprint for a particular pulsar,” Manish Purohit, a former ISRO scientist and solar panel expert, who was involved in the Mangalyaan-1 and Chandrayaan-2 missions, told ABP Live. The pulse profile generated by ISRO is a graph that shows how strong the pulses are over a single rotation cycle, explained Purohit. Comparing the radiation beams emitted by pulsars to lighthouse beams, he said that a pulse profile is similar to a graph that records the brightness of a lighthouse beam as it spins. In any given pulse profile, some parts may be extremely bright, while others may be dim. Since every pulse profile is unique, studying the pattern helps scientists understand the pulsar the graph belongs to, said Purohit. There are different types of pulse profiles: some are simple, some complex. The simple pulse profiles have only one peak, while the complex pulse profiles have multiple peaks and troughs.