Radio timing and optical photometry of the black widow system PSR J1953+1846A in the globular cluster M71

Journal Article · Wed Jul 01 04:00:00 EDT 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/807/1/91· OSTI ID:22882951

Cadelano, M.; Pallanca, C.; Ferraro, F. R.; Dalessandro, E.; Lanzoni, B. ^[1]; Stairs, I. ^[2]; Ransom, S. M. ^[3]; Hessels, J. W. T. ^[4]; Freire, P. C. C. ^[5]

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1. Dipartimento di Fisica e Astronomia, Università di Bologna, Viale Berti Pichat 6/2, I-40127 Bologna (Italy)
2. Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T1Z1 (Canada)
3. National Radio Astronomy Observatory (NRAO), 520 Edgemont Road, Charlottesville, VA 22901 (United States)
4. ASTRON, The Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands)
5. Max-Planck-Institute für Radioastronomie, D-53121 Bonn (Germany)

We report on the determination of the astrometric, spin, and orbital parameters for PSR J1953+1846 A, a “black widow” binary millisecond pulsar in the globular cluster M71. By using the accurate position and orbital parameters obtained from radio timing, we identified the optical companion in Advanced Camera for Surveys/Hubble Space Telescope images. It turns out to be a faint (m{sub F606W}≳24, m{sub F814W}≳23) and variable star located at only ∼0.″06 from the pulsar timing position. The light curve shows a maximum at the pulsar inferior conjunction and a minimum at the pulsar superior conjunction, thus confirming the association with the system. The shape of the optical modulation suggests that the companion star is heated, likely by the pulsar wind. The comparison with the X-ray light curve possibly suggests the presence of an intra-binary shock due to the interaction between the pulsar wind and the material released by the companion. This is the second identification (after COM-M5C) of an optical companion to a black widow pulsar in a globular cluster. Interestingly, the two companions show a similar light curve and share the same position in the color–magnitude diagram.

• OSTI ID: 22882951
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 807; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United Kingdom
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COMPARATIVE EVALUATIONS
PHOTOMETRY
PULSARS
SPACE
STELLAR WINDS
TELESCOPES
VARIABLE STARS
X RADIATION