Transcript High energy counter parts of giant radio pulses

Giant Radio Pulses
Radio Properties
Mechanism
High Energy Properties
With Astrosat & LOFT
Giant Radio Pulses
Crab
•Flux density
> M Jy
Tb > 1037 K!
• Highly variable
polarisation
•Scales ~ 1 m
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
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
Giant Radio Pulses
Crab
Popov et al. 2007
Karuppusamy et al. 2010
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
Giant Radio Pulses
PSR B1937+21
Kinkhabwala et al. 2000
Giant Radio Pulses
PSR B1937+21
Kinkhabwala et al. 2000
Giant Radio Pulses
PSR B1937+21
Soglasnov et al. 2004
Width: < 15 ns
T_B : 5 x 10^39 K
Discharges in the polar cap region
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)
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 J0218+4232
PSR B1937+21
RXTE
GBT 850 MHz
BeppoSAX
Chandra 0.1-10kev
Radio
(Knight et al. 2006)
(Cusumano et al. 2003)
Giant Pulses and High Energy emission: Crab
•Optical
•Flux enhancement: 3%
•Enhancement of electron positron plasma
(Shearer et al. 2003)
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)
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
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)
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)
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
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
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
Stability of X-ray Pulse Profiles: Crab
Jain and Paul 2011
ISRO HQ - 22 Apr 2014