ABSOLUTE TIMING OF THE CRAB PULSAR WITH THE INTEGRAL/SPI TELESCOPE

Journal Article · Fri Jan 01 00:00:00 EST 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/708/1/403· OSTI ID:21392469

Molkov, S; Jourdain, E

We have investigated the pulse shape evolution of the Crab pulsar emission in the hard X-ray domain of the electromagnetic spectrum. In particular, we have studied the alignment of the Crab pulsar phase profiles measured in the hard X-rays and in other wavebands. To obtain the hard X-ray pulse profiles, we have used six years (2003-2009, with a total exposure of about 4 Ms) of publicly available data of the SPI telescope on-board the International Gamma-Ray Astrophysics Laboratory observatory, folded with the pulsar time solution derived from the Jodrell Bank Crab Pulsar Monthly Ephemeris. We found that the main pulse in the hard X-ray 20-100 keV energy band leads the radio one by 8.18 +- 0.46 milliperiods in phase, or 275 +- 15 mus in time. Quoted errors represent only statistical uncertainties. Our systematic error is estimated to be approx40 mus and is mainly caused by the radio measurement uncertainties. In hard X-rays, the average distance between the main pulse and interpulse on the phase plane is 0.3989 +- 0.0009. To compare our findings in hard X-rays with the soft 2-20 keV X-ray band, we have used data of quasi-simultaneous Crab observations with the proportional counter array monitor on-board the Rossi X-Ray Timing Explorer mission. The time lag and the pulses separation values measured in the 3-20 keV band are 0.00933 +- 0.00016 (corresponding to 310 +- 6 mus) and 0.40016 +- 0.00028 parts of the cycle, respectively. While the pulse separation values measured in soft X-rays and hard X-rays agree, the time lags are statistically different. Additional analysis show that the delay between the radio and X-ray signals varies with energy in the 2-300 keV energy range. We explain such a behavior as due to the superposition of two independent components responsible for the Crab pulsed emission in this energy band.

• OSTI ID: 21392469
• Journal Information: Astrophysical Journal, Vol. 708, Issue 1; Other Information: DOI: 10.1088/0004-637X/708/1/403; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ASTROPHYSICS
EMISSION
GAMMA RADIATION
HARD X RADIATION
KEV RANGE 10-100
NEUTRON STARS
PROPORTIONAL COUNTERS
PULSARS
PULSE SHAPERS
SIGNALS
SOFT X RADIATION
TELESCOPES
COSMIC RADIO SOURCES
ELECTROMAGNETIC RADIATION
ELECTRONIC CIRCUITS
ENERGY RANGE
IONIZING RADIATIONS
KEV RANGE
MEASURING INSTRUMENTS
PHYSICS
PULSE CIRCUITS
RADIATION DETECTORS
RADIATIONS
SIGNAL CONDITIONERS
STARS
X RADIATION