The Broadband Spectral Behaviour of Crab Giant Pulses
Abstract
Pulsars provide unparalleled Galactic laboratories to study astrophysical coherent emission processes. The Crab pulsar (PSR J0534+2200) is a young (~1260 yr), energetic pulsar that sporadically emits intense (brightness temperatures >1042 K), intrinsically short-duration (~1 ns) giant pulses, that can be detected with a high signal-to-noise ratio across a range of observing frequencies. The frequency dependence of giant pulse emission provides vital information about the emission processes involved, but has not been examined in detail, especially at low frequencies. To study the spectral behaviour of Crab giant pulses, we conducted simultaneous wideband observations of the Crab pulsar with the Parkes radio telescope and the Murchison Widefield Array (MWA), spanning a frequency range of 120-3100 MHz. We found that the mean spectral index of Crab giant pulses flattens at low frequencies, from -2.6±0.5 between the Parkes bands (~700-3100 MHz), to -0.7±1.4 between the lowest MWA subbands (~120-210 MHz). This intriguing result motivated a recent coordinated simultaneous observing campaign that involved multiple radio telescopes, from Australia, India, China and the USA, spanning 20-8000 MHz, and was complimented by simultaneous high-energy observations from NASA’s Neutron star Interior Composition Explorer (NICER). Data from this campaign will allow an in-depth investigation of giant pulse emission characteristics including the spectral behaviour and will prompt further development of theoretical models pertaining to the emission of giant pulses.
- Publication:
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American Astronomical Society Meeting Abstracts #233
- Pub Date:
- January 2019
- Bibcode:
- 2019AAS...23315310M