An eccentric binary millisecond pulsar with a helium white dwarf companion in the galactic field
- Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St. George Street Toronto, Ontario M5S 3H4 (Canada)
- Department of Physics, University of Wisconsin-Milwaukee, 1900 East Kenwood Boulevard, Milwaukee, WI 53211 (United States)
- Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87131 (United States)
- Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany)
- National Research Council, resident at the Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375 (United States)
- Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Univeristät Kiel, D-24098 Kiel (Germany)
- Center for Advanced Radio Astronomy, Department of Physics and Astronomy, University of Texas at Brownsville, Brownsville, TX 78520 (United States)
Low-mass white dwarfs (LMWDs) are believed to be exclusive products of binary evolution, as the universe is not old enough to produce them from single stars. Because of the strong tidal forces operating during the binary interaction phase, the remnant systems observed today are expected to have negligible eccentricities. Here, we report on the first unambiguous identification of an LMWD in an eccentric (e = 0.13) orbit around the millisecond pulsar PSR J2234+0511, which directly contradicts this picture. We use our spectra and radio-timing solution (derived elsewhere) to infer the WD temperature (T{sub eff}=8600±190 K), and peculiar systemic velocity relative to the local standard of rest (≃31 km s{sup −1}). We also place model-independent constraints on the WD radius (R{sub WD}=0.024{sub −0.002}{sup +0.004} R{sub ⊙}) and surface gravity (log g=7.11{sub −0.16}{sup +0.08} dex). The WD and kinematic properties are consistent with the expectations for low-mass X-ray binary evolution and disfavor a dynamic three-body formation channel. In the case of the high eccentricity being the result of a spontaneous phase transition, we infer a mass of ∼1.60 M {sub ⊙} for the pulsar progenitor, which is too low for the quark-nova mechanism proposed by Jiang et al., and too high for the scenario of Freire and Tauris, in which a WD collapses into a neutron star via a rotationally delayed accretion-induced collapse. We find that eccentricity pumping via interaction with a circumbinary disk is consistent with our inferred parameters. Finally, we report tentative evidence for pulsations that, if confirmed, would transform the star into an unprecedented laboratory for WD physics.
- OSTI ID:
- 22868612
- Journal Information:
- Astrophysical Journal, Vol. 830, 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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