DISCOVERY OF ECLIPSES FROM THE ACCRETING MILLISECOND X-RAY PULSAR SWIFT J1749.4-2807

Journal Article · Sat Jul 10 04:00:00 EDT 2010 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/717/2/L149· OSTI ID:21451037

Markwardt, C B ^[1]

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1. Department of Astronomy, University of Maryland, College Park, MD 20742 (United States)

We report the discovery of X-ray eclipses in the recently discovered accreting millisecond X-ray pulsar SWIFT J1749.4-2807. This is the first detection of X-ray eclipses in a system of this type and should enable a precise neutron star mass measurement once the companion star is identified and studied. We present a combined pulse and eclipse timing solution that enables tight constraints on the orbital parameters and inclination and shows that the companion mass is in the range 0.6-0.8 M{sub sun} for a likely range of neutron star masses, and that it is larger than a main-sequence star of the same mass. We observed two individual eclipse egresses and a single ingress. Our timing model shows that the eclipse features are symmetric about the time of 90{sup 0} longitude from the ascending node, as expected. Our eclipse timing solution gives an eclipse duration (from the mid-points of ingress to egress) of 2172 {+-} 13 s. This represents 6.85% of the 8.82 hr orbital period. This system also presents a potential measurement of 'Shapiro' delay due to general relativity; through this technique alone, we set an upper limit to the companion mass of 2.2 M{sub sun}.

• OSTI ID: 21451037
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 2 Vol. 717; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BARYONS
COSMIC RADIO SOURCES
ECLIPSE
ELEMENTARY PARTICLES
FERMIONS
FIELD THEORIES
GENERAL RELATIVITY THEORY
HADRONS
INCLINATION
MAIN SEQUENCE STARS
MASS
NEUTRON STARS
NEUTRONS
NUCLEONS
PULSARS
PULSES
RELATIVITY THEORY
STARS
SYMMETRY