X-ray observations of black widow pulsars
- Department of Physics, West Virginia University, Morgantown, WV 26506 (United States)
- Eureka Scientific Inc., 2452 Delmer Street, Suite 100, Oakland, CA 94602-3017 (United States)
- Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States)
- ASTRON, The Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands)
- Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, CA 94305 (United States)
- National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States)
- Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States)
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada)
We describe the first X-ray observations of five short orbital period (P{sub B} < 1 day), γ-ray emitting, binary millisecond pulsars (MSPs). Four of these—PSRs J0023+0923, J1124–3653, J1810+1744, and J2256–1024—are 'black-widow' pulsars, with degenerate companions of mass <<0.1 M {sub ☉}, three of which exhibit radio eclipses. The fifth source, PSR J2215+5135, is an eclipsing 'redback' with a near Roche-lobe filling ∼0.2 solar mass non-degenerate companion. Data were taken using the Chandra X-Ray Observatory and covered a full binary orbit for each pulsar. Two pulsars, PSRs J2215+5135 and J2256–1024, show significant orbital variability while PSR J1124–3653 shows marginal orbital variability. The lightcurves for these three pulsars have X-ray flux minima coinciding with the phases of the radio eclipses. This phenomenon is consistent with an intrabinary shock emission interpretation for the X-rays. The other two pulsars, PSRs J0023+0923 and J1810+1744, are fainter and do not demonstrate variability at a level we can detect in these data. All five spectra are fit with three separate models: a power-law model, a blackbody model, and a combined model with both power-law and blackbody components. The preferred spectral fits yield power-law indices that range from 1.3 to 3.2 and blackbody temperatures in the hundreds of eV. The spectrum for PSR J2215+5135 shows a significant hard X-ray component, with a large number of counts above 2 keV, which is additional evidence for the presence of intrabinary shock emission. This is similar to what has been detected in the low-mass X-ray binary to MSP transition object PSR J1023+0038.
- OSTI ID:
- 22351336
- Journal Information:
- Astrophysical Journal, Vol. 783, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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