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Giant Radio Pulses: Properties, Mechanism & High Energy Emission

Explore the phenomena of Giant Radio Pulses in Crab Pulsar, their mechanisms, properties & high-energy emissions observed with Astrosat & LOFT. Discover the pulsar's intense pulses, polarizations, and the significance of their occurrences at specific phases. Learn about the mechanisms behind Giant Radio Pulses, including electrostatic turbulence conversion and magnetic reconnection events. See how these phenomena lead to high-energy emissions, enhancing flux and radiation across various wavelengths.

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Giant Radio Pulses: Properties, Mechanism & High Energy Emission

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  1. Giant Radio Pulses Radio Properties Mechanism High Energy Properties With Astrosat & LOFT

  2. Giant Radio Pulses Crab • Flux density > M Jy Tb > 1037 K! • Highly variable polarisation • Scales ~ 1 m

  3. Giant Radio Pulses Crab Giant pulses in different Radio frequencies are simultaneous GPs occur only at the normal pulse Phases MP and IP Mickaliger et al. 2012

  4. Giant Radio Pulses First observed in the Crab pulsar - discovered through its giant pulses! • Intense narrow pulses (~10 ns) • Brightness Temp: upto 5 x 10^39 • Random in occurrence, at certain pulse phases • Pulse energy many times that of an average pulse • One or more power-law distribution of pulse energies • Highly polarizeded/variable

  5. Giant Radio Pulses Crab Popov et al. 2007 Karuppusamy et al. 2010

  6. Giant Radio Pulses Crab Pulse width up to 100 s 50-90% of total pulse Flux energy is in the Giant pulses Majid et al. 2011

  7. Giant Radio Pulses PSR B1937+21 Kinkhabwala et al. 2000

  8. Giant Radio Pulses PSR B1937+21 Kinkhabwala et al. 2000

  9. Giant Radio Pulses PSR B1937+21 Width: < 15 ns T_B : 5 x 10^39 K Discharges in the polar cap region Soglasnov et al. 2004

  10. Giant Radio Pulse: Mechanism • Conversion of electrostatic turbulence in the pulsar magnetosphere by the mechanism of spatial collapse of nonlinear wave packets (Hankins et al.,2003) • Electric discharge due to the magnetic reconnection of field lines connecting the opposite magnetic poles (Istmin Ya. N., 2004) • Coherent curvature radiation of charged relativistic solitons associated with sparking discharge of the inner gap potential drop above the polar cap (Gil, J & Melikadze G., 2004) • Induced Compton scattering of pulsar radiation off the particles of the plasma flow (Petrova S. A. 2004) • Cyclotron line at the light cylinder during reconnection events (Lyutikov 2013)

  11. Giant Pulses from MSPs • Large magnetic field at the light cylinder • Pulsed non-thermal X-ray emission • X-ray emission at the same phase of GP PSR B1937+21 PSR J0218+4232 RXTE GBT 850 MHz BeppoSAX Chandra 0.1-10kev Radio (Knight et al. 2006) (Cusumano et al. 2003)

  12. Giant Pulses and High Energy emission: Crab • Optical • Flux enhancement: 3% • Enhancement of electron positron plasma (Shearer et al. 2003)

  13. Giant Pulses and High Energy emission: Crab • Optical • Peak flux enhancement: 11% for Giant Pulses near the peak of the optical pulse, 3% otherwise • Flux enhancement: 3% for Giant Pulses at the Main Pulse (Strader et al. 2013)

  14. Giant Pulses and High Energy emission: Crab • Chandra HRC: 1.5 - 4.5 keV (Bilous et al. 2012) • Chandra HCR: 1.5 - 4.5 keV • Upper limit of flux enhancement in pulses with GPs: 10% for MP GPs and 30% for IP GPs • Upper limit of flux enhancement during the GPs: 2 for MP GPs and 5 for IP GPs • Due to changes in coherent radio emissiom

  15. Giant Pulses and High Energy emission: Crab • Suzaku HXD, 15-75 keV and 35-315 keV • 1 σ upper limit of flux enhancement: 70% (Mikami et al. 2014)

  16. Giant Pulses and High Energy emission: Crab • Fermi: 100 MeV - 5 GeV • 95% confidence upper limit of flux enhancement: 4 times for all GPs and 12 for IP GPs • Due to changes in coherent radio emissiom and not due to enhanced particle density (Bilous et al. 2011)

  17. Giant Pulses and High Energy emission: Crab • Veritas: > 150 GeV • Upper limit of flux enhancement: 5 times for pulses with GP • Upper limit of flux enhancement: 2 times for 8s window around GP Aliu et al. 2012

  18. Giant Pulses and High Energy emission: 1937+21 • X-ray emission is at the same phase as the Giant Pulses Cusumano et al. 2003, Nicastro et al. 2004

  19. Giant Pulses and High Energy emission • S/N = sA*T/sqrt((sA+bA)T)= sqrt(AT)*s/sqrt(s+b) RXTE-PCA/ASTROSAT-LAXPC s Chandra T • Crab: 10 hrs  10000 bursts  0.2 sec, 400 photons, • 100 photons (5 sigma)  sensitivity of 0.01 photon per GP • 10^33 erg per GP in X-rays

  20. Stability of X-ray Pulse Profiles: Crab Jain and Paul 2011 ISRO HQ - 22 Apr 2014

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