Microarcsecond VLBI pulsar astrometry with PSRπ. I. Two binary millisecond pulsars with white dwarf companions
- ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands)
- University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, WI 53201 (United States)
- National Radio Astronomy Observatory, Socorro, NM 87801 (United States)
- Department of Astronomy, Cornell University, Ithaca, NY 14853 (United States)
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)
- Astrogeo Center, Falls Church, VA 22043 (United States)
- University of Manchester, Jodrell Bank Centre for Astrophysics, Manchester M13 9PL (United Kingdom)
Model-independent distance constraints to binary millisecond pulsars (MSPs) are of great value to both the timing observations of the radio pulsars and multiwavelength observations of their companion stars. Astrometry using very long baseline interferometry (VLBI) can be employed to provide these model-independent distances with very high precision via the detection of annual geometric parallax. Using the Very Long Baseline Array, we have observed two binary MSPs, PSR J1022+1001 and J2145–0750, over a two-year period and measured their distances to be 700{sub −10}{sup +14} pc and 613{sub −14}{sup +16} pc respectively. We use the well-calibrated distance in conjunction with revised analysis of optical photometry to tightly constrain the nature of their massive (M∼0.85 M{sub ⊙}) white dwarf companions. Finally, we show that several measurements of the parallax and proper motion of PSR J1022+1001 and PSR J2145–0750 obtained by pulsar timing array projects are incorrect, differing from the more precise VLBI values by up to 5σ. We investigate possible causes for the discrepancy, and find that imperfect modeling of the solar wind is a likely candidate for the errors in the timing model given the low ecliptic latitude of these two pulsars.
- OSTI ID:
- 22868756
- Journal Information:
- Astrophysical Journal, Vol. 828, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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