Submitted on March 10, 2008
Accepted on April 29, 2008
An Eccentric Binary Millisecond Pulsar in the Galactic Plane
David J. Champion 1*, Scott M. Ransom 2, Patrick Lazarus 3, Fernando Camilo 4, Cees Bassa 3, Victoria M. Kaspi 3, David J. Nice 5, Paulo C. C. Freire 6, Ingrid H. Stairs 7, Joeri van Leeuwen 8, Ben W. Stappers 9, James M. Cordes 10, Jason W. T. Hessels 11, Duncan R. Lorimer 12, Zaven Arzoumanian 13, Don C. Backer 8, N. D. Ramesh Bhat 14, Shami Chatterjee 15, Ismaël Cognard 16, Julia S. Deneva 10, Claude-André Faucher-Giguère 17, Bryan M. Gaensler 15, JinLin Han 18, Fredrick A. Jenet 19, Laura Kasian 7, Vlad I. Kondratiev 12, Michael Kramer 9, Joseph Lazio 20, Maura A. McLaughlin 12, Arun Venkataraman 6, Wouter Vlemmings 21
1 Department of Physics, McGill University, Montreal, QC H3A 2T8, Canada.; ATNF-CSIRO, PO Box 76, Epping NSW 1710, Australia.
2 NRAO, 520 Edgemont Rd., Charlottesville, VA 22903, USA.
3 Department of Physics, McGill University, Montreal, QC H3A 2T8, Canada.
4 Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, NY 10027, USA.
5 Physics Department, Bryn Mawr College, Bryn Mawr, PA 19010, USA.
6 NAIC, Arecibo Observatory, HC03 Box 53995, PR 00612, USA.
7 Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1, Canada.
8 Astronomy Department, 441 Campbell Hall, University of California at Berkeley, Berkeley, CA 94720, USA.
9 Jodrell Bank Observatory, Manchester University, Macclesfield, Cheshire SK11 9DL, UK.
10 Astronomy Department, Cornell University, Ithaca, NY 14853, USA.
11 Astronomical Institute "Anton Pannekoek," University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands.
12 Department of Physics, West Virginia University, Morgantown, WV 26506, USA.
13 CRESST and X-ray Astrophysics Laboratory, NASA-GSFC, Code 662, Greenbelt, MD 20771, USA.
14 Swinburne University of Technology, P.O. Box 218, Hawthorn, Victoria 3122, Australia.
15 School of Physics, The University of Sydney, NSW 2006 Australia.
16 LPCE/CNRS, UMR 6115 3A, Av. de la Recherche Scientifique, F-45071 Orleans Cedex 2, France.
17 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-10, Cambridge, MA 02138, USA.
18 National Astronomical Observatories, CAS, Jia-20 DaTun Rd., Chaoyang Dist., Beijing 100012, China.
19 Center for Gravitational Wave Astronomy, University of Texas at Brownsville, TX 78520, USA.
20 Naval Research Laboratory, 4555 Overlook Avenue, SW, Washington, DC 20375, USA.
21 Argelander-Institut für Astronomie, University of Bonn, Auf dem Hügel 71, 53121 Bonn, Germany.
* To whom correspondence should be addressed.
David J. Champion , E-mail: David.Champion{at}atnf.csiro.au
Binary pulsar systems are superb probes of stellar and binary evolution and the physics of extreme environments. In a survey with the Arecibo telescope, we have found PSR J1903+0327, a radio pulsar with a rotational period of 2.15 milliseconds in a highly eccentric (e = 0.44) 95-day orbit around a solar mass companion. Infrared observations identify a possible main-sequence companion star. Conventional binary stellar evolution models predict neither large orbital eccentricities nor main-sequence companions around millisecond pulsars. Alternative formation scenarios involve recycling a neutron star in a globular cluster, then ejecting it into the Galactic disk or membership in a hierarchical triple system. A relativistic analysis of timing observations of the pulsar finds its mass to be 1.74 ± 0.04 M
, an unusually high value.
