X-ray surges and radio bursts from the Crab Nebula have been detected by a global science collaboration using data from NASA’s Neutron Star Interior Composition Explorer (NICER). Giant radio pulses are the bursts, and they release much more energy than previously thought. A pulsar is a rapidly spinning neutron star that formed from the crushed heart of a star that exploded as a supernova. A young, isolated neutron star will spin thousands of times per second, generating radio waves, visible light, X-rays, and gamma rays with its whirling magnetic field. Astronomers detect clock-like bursts of emission as these beams sweep past Earth, classifying the object as a pulsar.
The Crab pulsar is one of a few of pulsars that sometimes emit massive radio pulses that are hundreds to thousands of times brighter than regular pulses. The Crab pulsar has been studied for decades, and it’s the only pulsar known to boost its massive radio pulses with emissions from other parts of the spectrum.
A neutron star spinning 30 times per second is among the brightest pulsars in the sky at X-ray and radio wavelengths in the Crab Nebula, a six-light-year-wide spreading cloud of debris from a supernova explosion. Different gases emitted in the explosion are seen in this composite of Hubble Space Telescope images: blue indicates neutral oxygen, green indicates singly ionized sulfur, and red indicates doubly ionized oxygen.
“Out of more than 2,800 pulsars cataloged, the Crab pulsar is one of only a few that emit giant radio pulses, which occur sporadically and can be hundreds to thousands of times brighter than the regular pulses,” said lead scientist Teruaki Enoto at the RIKEN Cluster for Pioneering Research in Wako, Saitama prefecture, Japan.
The largest volume of simultaneous X-ray and radio data ever obtained from Pulsar was analyzed in a new study published in Science on April 9th. The observed energy spectrum associated with this augmentation effect is increased by thousands of times as a result of this. The Crab Pulsar is located in the constellation Taurus, around 6500 light-years from Earth. In July 1054, the light from the supernova that produced the Crab Nebula and Pulsar entered Earth for the first time. The brightest pulsar in the sky, neutron stars rotate 30 times a second and have X-ray and radio wave wavelengths in them.
NICER was used by astronomers to detect the Crab pulsar several times between August 2017 and August 2019. In addition to NICER, astronomers used at least one of Japan’s two ground-based radio telescopes, the 34-meter dish at the Kashima Space Technology Center and the 64-meter dish at the Japan Aerospace Exploration Agency’s Usuda Deep Space Center, both of which operate at a frequency of 2 gigahertz. The researchers were able to get nearly a day and a half of simultaneous X-ray and radio coverage thanks to the combined dataset. They recorded activity from 3.7 million pulsar rotations and collected 26,000 giant radio pulses in total.
The precision in which NICER records the arrival time of any X-ray it detects is 100 nanoseconds, but that isn’t the telescope’s only advantage in this analysis. When Enoto’s team combined all of the X-ray data that matched the giant radio pulse, they discovered an X-ray boost of around 4% that happened at the same time. This is somewhat similar to the 2003 discovery of a 3% rise in visible light associated with this phenomenon. These variations are minor when compared to the brightness difference between regular and massive crab pulses, and are difficult to understand with a theoretical model.
Zaven Arzoumanian, the project’s science lead at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said, “The NICER telescope’s ability for detecting bright X-ray sources is almost four times that of the pulsar and its nebula combined. So, these observations were largely unaffected by pileup where a detector counts two or more X-rays as a single event and other issues that have complicated earlier analyses.”
The enhancements mean that giant pulses are the result of underlying processes that generate emission across the electromagnetic spectrum, from radio to X-rays. Since X-rays have millions of times the energy of radio waves, even a small increase adds up to a significant amount of energy. The average released energy associated with a giant pulse, according to the researchers, is thousands to hundreds of times higher than previously calculated based on radio and optical data alone.
Enoto said, “We still don’t know how or where pulsars generate their complex and wide-ranging emission, so it’s satisfying to have added another element to the multiwavelength puzzle of these fascinating artifacts.”
The neutron star rotates 30 times a second and is one of the brightest pulsars in the sky in radio and x-ray waves. X-rays from the pulsar have energies of up to 10,000 electron volts, which is thousands of times that of visible light. NICER is a NASA Explorers program Astrophysics Mission of Opportunity that offers regular flight opportunities for world-class research studies from space using creative, organized, and effective management methods in the heliophysics and astrophysics science fields. The SEXTANT component of the mission, which demonstrates pulsar-based spacecraft navigation, is supported by NASA’s Space Technology Mission Directorate.