Einstein@Home DISCOVERY OF A PALFA MILLISECOND PULSAR IN AN ECCENTRIC BINARY ORBIT

Journal Article · Wed Jun 10 00:00:00 EDT 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/806/1/140· OSTI ID:22522295

Knispel, B.; Allen, B. ^[1]; Lyne, A. G.; Stappers, B. W. ^[2]; Freire, P. C. C.; Lazarus, P. ^[3]; Aulbert, C.; Bock, O.; Eggenstein, H. -B.; Fehrmann, H. ^[4]; Bogdanov, S.; Camilo, F. ^[5]; Brazier, A.; Chatterjee, S.; Cordes, J. M. ^[6]; Cardoso, F. ^[7]; Crawford, F. ^[8]; Deneva, J. S. ^[9]; Ferdman, R. ^[10]; Hessels, J. W. T., ^[11] ; others, and

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1. Leibniz Universität, Hannover, D-30167 Hannover (Germany)
2. Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester, M13 9PL (United Kingdom)
3. Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany)
4. Max-Planck-Institut für Gravitationsphysik, Callinstr. 38, D-30167 Hannover (Germany)
5. Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States)
6. Department of Astronomy and Center for Radiophysics and Space Research, Cornell University, Ithaca, NY 14853 (United States)
7. Department of Physics and Astronomy, West Virginia University, Morgantown, WV 26506 (United States)
8. Department of Physics and Astronomy, Franklin and Marshall College, Lancaster, PA 17604-3003 (United States)
9. National Research Council, resident at the Naval Research Laboratory, Washington, DC 20375 (United States)
10. Department of Physics, McGill University, Montreal, QC H3A 2T8 (Canada)
11. ASTRON, Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands)

We report the discovery of the millisecond pulsar (MSP) PSR J1950+2414 (P = 4.3 ms) in a binary system with an eccentric (e = 0.08) 22 day orbit in Pulsar Arecibo L-band Feed Array survey observations with the Arecibo telescope. Its companion star has a median mass of 0.3 M{sub ⊙} and is most likely a white dwarf (WD). Fully recycled MSPs like this one are thought to be old neutron stars spun-up by mass transfer from a companion star. This process should circularize the orbit, as is observed for the vast majority of binary MSPs, which predominantly have orbital eccentricities e < 0.001. However, four recently discovered binary MSPs have orbits with 0. 027 < e < 0.44; PSR J1950+2414 is the fifth such system to be discovered. The upper limits for its intrinsic spin period derivative and inferred surface magnetic field strength are comparable to those of the general MSP population. The large eccentricities are incompatible with the predictions of the standard recycling scenario: something unusual happened during their evolution. Proposed scenarios are (a) initial evolution of the pulsar in a triple system which became dynamically unstable, (b) origin in an exchange encounter in an environment with high stellar density, (c) rotationally delayed accretion-induced collapse of a super-Chandrasekhar WD, and (d) dynamical interaction of the binary with a circumbinary disk. We compare the properties of all five known eccentric MSPs with the predictions of these formation channels. Future measurements of the masses and proper motion might allow us to firmly exclude some of the proposed formation scenarios.

• OSTI ID: 22522295
• Journal Information: Astrophysical Journal, Vol. 806, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
BINARY STARS
COMPARATIVE EVALUATIONS
DATA ANALYSIS
DENSITY
MAGNETIC FIELDS
MASS TRANSFER
NEUTRON STARS
ORBITS
PROPER MOTION
PULSARS
SPIN
STAR EVOLUTION
SURFACES
TELESCOPES
WHITE DWARF STARS