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Issue A&A Volume 404, Number 1, June II 2003 Page(s) L21 - L24 Section Letters DOI 10.1051/0004-6361:20030737

A&A 404, L21-L24 (2003)
DOI: 10.1051/0004-6361:20030737

Letter

Evidence for a 2:3 resonance in Sco X-1 kHz QPOs

M. A. Abramowicz^{1, 2, 3}, T. Bulik⁴, M. Bursa^{3, 5} and W. Kluzniak<sup>1, 4, 6, 7

1</sup>  Visiting Professor, Institut d'Astrophysique de Paris, 98bis Bld. Arago, 75014 Paris, France
²  Université Pierre & Marie Curie (Paris VI), France
³  Department of Astrophysics, Chalmers University, 412-96 Göteborg, Sweden,
    e-mail: marek@fy.chalmers.se
⁴  Copernicus Astronomical Centre, ul. Bartycka 18, 00-716 Warszawa, Poland,
    e-mail: bulik@camk.edu.pl
⁵  Astronomical Institute, Charles University Prague, V Holesovickách 2 CZ-180 00 Praha 8, Czech Republic
    e-mail: bursa@sirrah.troja.mff.cuni.cz
⁶  Institute of Astronomy, Zielona Góra University, Lubuska 2, 65-265 Zielona Góra, Poland,
    e-mail: wlodek@camk.edu.pl
⁷  Centre d'Étude Spatiale des Rayonnements, 9 Av. Colonel-Roche, 31028 Toulouse Cedex 4, France

(Received 28 June 2002 / Accepted 25 April 2003 )

Abstract
We find evidence that the two high frequency QPOs in Sco X-1 are, more often than not, approximately in the 2:3 frequency ratio familiar from studies of black hole candidates (e.g., XTE J1550-564, Remillard et al. 2002). This implies that the double kHz QPO phenomenon in neutron stars has its origin in properties of strong-field gravity and has little to do with the rotation of a stellar surface or any magnetic field structure anchored in the star.

Key words: dense matter -- general relativity -- stars: neutron -- stars: Sco X-1 -- X-rays: stars

Offprint request: W. Kluzniak, wlodek@camk.edu.pl

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