Microsecond Timing of PSR B1821−24 withChandraHigh Resolution Camera–S
| Autor: | Stephen S. Murray, Ismaël Cognard, S. R. Kulkarni, Robert E. Rutledge, Derek Fox, Bryan A. Jacoby, D. C. Backer |
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| Rok vydání: | 2004 |
| Předmět: | |
| Zdroj: | The Astrophysical Journal. 613:522-531 |
| ISSN: | 1538-4357 0004-637X |
| DOI: | 10.1086/380299 |
| Popis: | We perform absolute timing of PSR B1821-24 in M28, using a 50 ksec observation with Chandra/HRC-S. We have obtained the highest signal-to-noise X-ray pulsed lightcurve of this source to date, detecting two X-ray pulses, as well as significant non-pulsed emission -- a persistent X-ray flux which comprises 15+/-3% of the total X-ray flux of the pulsar. The Gaussian width of the sharp X-ray peak is 34+/-3 micro-sec in time, implying a size of the X-ray beam as it crosses the line of sight of 4.0+/-0.4 deg. We find evidence for a significant trailing component in both X-ray peaks of the pulse profile. Including three RXTE/PCA observations in our analysis, and tying the phases together using a radio ephemeris obtained at Nancay, we find the absolute phases in the X-ray wander with respect to this radio ephemeris by up to 60 micro-sec, likely due to the variable dispersion measure, which changes the pulse arrival time in the radio band but not the X-ray band. The present analysis makes clear that study of pulsar timing noise properties in millisecond pulsars such as PSR B1821-24 -- hitherto only studied at radio wavelengths, where variable dispersion measure requires a significant correction -- can be studied at X-ray wavelengths, where the effect of variable dispersion measure is negligible. We also examine the known uncertainties in the absolute Chandra/HRC-S timing accuracy, which amount to +/-12 microsec. We limit the amount of linear drift in the relative timing accuracy of HRC-S to |
| Databáze: | OpenAIRE |
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