DISCOVERY OF AN ACCRETING MILLISECOND PULSAR IN THE ECLIPSING BINARY SYSTEM SWIFT J1749.4-2807

Journal Article · Thu Jan 20 00:00:00 EST 2011 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/727/1/L18· OSTI ID:21560557

Altamirano, D; Cavecchi, Y; Patruno, A; Watts, A; Degenaar, N; Kalamkar, M; Van der Klis, M; Armas Padilla, M; Kaur, R; Yang, Y J; Wijnands, R ^[1]; Linares, M ^[2]; Rea, N ^[3]; Casella, P ^[4]; Soleri, P ^[5]

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1. Astronomical Institute, 'Anton Pannekoek', University of Amsterdam, Science Park 904, 1098XH, Amsterdam (Netherlands)
2. Massachusetts Institute of Technology-Kavli Institute for Astrophysics and Space Research, Cambridge, MA 02139 (United States)
3. Institut de Ciencies de l'Espai (ICE, CSIC-IEEC), Campus UAB, Facultat de Ciencies, Torre C5-parell, 2a planta, 08193, Bellaterra (Barcelona) (Spain)
4. School of Physics and Astronomy, University of Southampton, Southampton, Hampshire SO17 1BJ (United Kingdom)
5. Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700 AV Groningen (Netherlands)

We report on the discovery and the timing analysis of the first eclipsing accretion-powered millisecond X-ray pulsar (AMXP): SWIFT J1749.4-2807. The neutron star rotates at a frequency of {approx}517.9 Hz and is in a binary system with an orbital period of 8.8 hr and a projected semimajor axis of {approx}1.90 lt-s. Assuming a neutron star between 0.8 and 2.2 M{sub sun} and using the mass function of the system and the eclipse half-angle, we constrain the mass of the companion and the inclination of the system to be in the {approx}0.46-0.81 M{sub sun} and {approx} 74.{sup 0}4-77.{sup 0}3 range, respectively. To date, this is the tightest constraint on the orbital inclination of any AMXP. As in other AMXPs, the pulse profile shows harmonic content up to the third overtone. However, this is the first AMXP to show a first overtone with rms amplitudes between {approx}6% and {approx}23%, which is the strongest ever seen and which can be more than two times stronger than the fundamental. The fact that SWIFT J1749.4-2807 is an eclipsing system that shows uncommonly strong harmonic content suggests that it might be the best source to date to set constraints on neutron star properties including compactness and geometry.

• OSTI ID: 21560557
• Journal Information: Astrophysical Journal Letters, Vol. 727, Issue 1; Other Information: DOI: 10.1088/2041-8205/727/1/L18; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ECLIPSE
MASS
NEUTRON STARS
PULSARS
X RADIATION
COSMIC RADIO SOURCES
ELECTROMAGNETIC RADIATION
IONIZING RADIATIONS
RADIATIONS
STARS