Multifrequency Observations of Crab Pulsar Giant Pulses

N. Lewandowska*, J. Hessels, A. Jessner, M. Kramer, K. Mannheim, R. Karuppusamy, V. Kondratiev, C. Sobey, B. Stappers

YERAC 2013, Bielefeld University

*nlewandowska@astro.uni-wuerzburg.de

Contents

-Motivation

-Anomalous Single Pulse Emission

-The Crab Pulsar

-Giant Pulse Emission

-Multifrequency Study

The Property of a Pulsar

Anomalous Single Pulse Emission

Giant Micropulses Giant Pulses

Drifting Sub-pulses Pulse Nulling Mode Changing

[Lormer & Kramer 2012]

Pulsar Populations

-rotation periods: [~0.001-10] s => Stable observational property of a pulsar! => Most precise clocks in the Universe!

-fastest pulsars known: 716 Hz [PSR J1748-2446ad] 624 Hz [PSR B1937+21]

The Crab Pulsar

The Crab Nebula [Credit: NASA]

[Credit: Chandra]

[Abdo et al. (2010)]

X-Rays + Optical + Infrared

X-Rays

=> Discovered by single, bright pulses!

Crab Pulsar Giant Pulses

[Jessner et al. (2005)]

Phase-bound occurrence-giant pulses occur only at P1 & P2 -imply similar region of origin

Power-law Energetics-distinct characteristic of GPs-regular pulses: Gaussian distribution

Flux Densities & Widths-short giant pulses: 2 ns (103 Jy) => brightness temperatures: 1037 K

=> Sun: 10 kJy => Crab Nebula: 1000 Jy

Crab Pulsar Giant Pulses

[Eilek & Hankins 2007][Eilek & Hankins 2007]

[Moffett & Hankins 1996][Moffett & Hankins 1996]=> P1-GPs & P2-GPs: Different dynamic spectra!

[Knight 2006][Knight 2006]

Millisecond Pulsars

PSR B1937+21PSR J1821-24...

Ordinary Pulsars

Crab PulsarPSR B0540-69...

Slow Rotators

PSR B0031-07PSR J1752+2359...

Giant Pulses – Other Pulsars

=> Common emission mechanism???

Low Frequency Observations

-Motivation-

Steep spectra => More single pulses in the low frequency range!

Low Frequency Observations

Distortion of pulsar signal due to 3 main effects of the ISM:

-Dispersion-Scintillation-Pulse Scattering

[Lormer & Kramer 2012]

[Lormer & Kramer 2012]

LOFAR(Low Frequency Array)

[Credit: ASTRON]

-new generation interferometer

-phased array of dipole antennas

-high sensitvity => coherent combination of stations

-range of operation: 10 – 240 MHz

LBA: 10 – 90 MHz HBA: 110 -240 MHz

-BW= 48 MHz per station

-multiple beams per station possible

=> Wide-band simultaneous observations possible!=> Coverage of low frequency range till 10 MHz possible!

=> MWL Observations: HBA (Superterp)[Credit: MPIfR]

[Credit: A.R. Offringa]

HBA

LBA

[Credit: ASTRON]

Crab Pulsar Multiwavelength Study

Low Frequency Array (LOFAR) Westerbork Synthesis Radio Telescope (WSRT)

Effelsberg Radio Telescope

Covered Frequency Range:

120 MHz - 8.35 GHZ

Crab Pulsar Multiwavelength Study

Extraction of Giant Pulses

-energy statistics of GPs-rates of occurrence-flux densities-GP phase ranges

-differences: P1,P2-GPs-properties of GPs at different frequencies

-stability & definition of GP emission-GP emission mechanism-pulsar radio emission

Summary of Open Questions

Thanks for your attention!

References

Abdo et al. (2010), The Astrophysical Journal, Volume 708, Issue 2, pp. 1254-1267

Eilek & Hankins (2007), arXiv:astro-ph/0701252

Jessner et al. (2005), Advances in Space Research, Volume 35, Issue 6, p. 1166-1171

Knight, H.S. (2006), Chinese Journal of Astronomy and Astrophysics, Supplement, Volume 6, Issue S2

Staelin & Reifenstein (1968), Science 162, 1481-1483