EDP Sciences
Free access
Volume 373, Number 1, July I 2001
Page(s) 236 - 240
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20010618

A&A 373, 236-240 (2001)
DOI: 10.1051/0004-6361:20010618

RXTE observations of single pulses of PSR B0531+21

I. Flux variations
M. Vivekanand

National Center for Radio Astrophysics, TIFR, Pune University Campus, PO Box 3, Ganeshkhind, Pune 411007, India

(Received 8 November 2000 / Accepted 2 May 2001)

This article is the first in the series that analyze about 1.87 million periods of PSR B0531+21 (Crab pulsar), observed by the PCA detector aboard the RXTE X-ray observatory. The Crab pulsar's X-ray light curve shows little variation over time scales ranging from days to a period (33.46 milliseconds). The standard deviation of its X-ray flux variation is $\approx$0.7% of its mean value, which is negligible compared to its radio flux variations. The phase resolved power spectrum of pulse to pulse X-ray flux variation shows no spectral feature; an upper limit to the peak of any possible broad spectral feature is 0.06% of the mean power. The X-ray fluxes in the two components of its integrated profile are unrelated to each other; their linear correlation coefficient is $0.0004 \pm 0.0010$. "Giant pulses" that are routinely seen at radio wavelengths are absent here. This work sets very strong constraints on the connection (if any) between the flux variations at radio and X-ray energies, for example due to variation in the degree of coherence of the basic emitters. Its phase resolved X-ray flux variation shows a weak correlation with the integrated profile. If confirmed, this might be an important clue to understanding the X-ray emission mechanism of Crab pulsar.

Key words: pulsars -- individual: PSR B0531+21 -- X-ray: stars

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© ESO 2001