X-ray emissions from the Crab Pulsar are more intense during giant radio pulses (GRPs), researchers report. The new findings provide constraints on the mechanisms underlying GRPs and may provide insights into other transient radio phenomena observed throughout the Universe.
Pulsars, or rapidly spinning neutron stars, emit pulses of electromagnetic radiation from their magnetospheres and are observed from Earth as regular sequences of radio pulses. Most radio pulses from these distant objects are of a consistent intensity. Occasionally, however, sporadic and short-lived bursts from these sources are observed hundreds to thousands of times brighter than normal.
Scientists using data from NASA’s Neutron star Interior Composition Explorer (NICER) telescope on the International Space Station have discovered X-ray surges accompanying radio bursts from the pulsar in the Crab Nebula. The finding shows that these bursts, called giant radio pulses, release far more energy than previously suspected. Credit: NASA’s Goddard Space Flight Center
What causes these unpredictable bursts, also known as GRPs, is unknown. Teruaki Enoto and colleagues observed the Crab Pulsar using both X-ray and radio telescopes and found that X-ray emission during GRPs is slightly brighter than during normal pulses.
By comparing the radio and X-ray enhancements, Enoto et al. found that the total emitted energy from GRPs is tens to hundreds of times higher than previously known. According to the authors, the findings also help constrain extragalactic fast radio bursts (FRBs), whose mysterious origins remain unknown.
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Reference: “Enhanced x-ray emission coinciding with giant radio pulses from the Crab Pulsar” by Teruaki Enoto, Toshio Terasawa, Shota Kisaka, Chin-Ping Hu, Sebastien Guillot, Natalia Lewandowska, Christian Malacaria, Paul S. Ray, Wynn C.G. Ho, Alice K. Harding, Takashi Okajima, Zaven Arzoumanian, Keith C. Gendreau, Zorawar Wadiasingh, Craig B. Markwardt, Yang Soong, Steve Kenyon, Slavko Bogdanov, Walid A. Majid, Tolga Güver, Gaurava K. Jaisawal, Rick Foster, Yasuhiro Murata, Hiroshi Takeuchi, Kazuhiro Takefuji, Mamoru Sekido, Yoshinori Yonekura, Hiroaki Misawa, Fuminori Tsuchiya, Takahiko Aoki, Munetoshi Tokumaru, Mareki Honma, Osamu Kameya, Tomoaki Oyama, Katsuaki Asano, Shinpei Shibata and Shuta J. Tanaka, 9 April 2021, Science.