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On the Origin of Clustering of Frequency Ratios in the Atoll Source 4U 1636-53

Författare och institution:
G. Török (-); Marek A Abramowicz (Institutionen för fysik (GU)); P Bakala (-); M. Bursa (-); J Horak (-); Paola Rebusco (-); Z. Stuchlik (-)
Publicerad i:
Acta Astronomica, 58 s. 113-119
Artikel, refereegranskad vetenskaplig
Sammanfattning (abstract):
A long discussion has been devoted to the issue of clustering of the kHz quasi periodic oscillation (QPO) frequency ratios in neutron star sources. While the distribution of ratios inferred from an occurrence of a single QPO seems to be consistent with a random walk, the distribution based on simultaneous detections of both peaks indicates a preference of ratios of small integers. Based on the public RXTE data we further investigate this issue for the source 4U 1636-53. Quality factors and rms amplitudes of both the QPOs nearly equal at the points where the frequencies are commensurable, and where the twin QPO detections cluster. We discuss a connection of the clustering with the varying properties of the two QPO modes. Assuming approximate relations for the observed correlations of the QPO properties, we attempt to reproduce the frequency and ratio distributions using a simple model of a random-walk evolution along the observed frequency-frequency correlation. We obtain results which are in qualitative agreement with the observed distributions.
Ämne (baseras på Högskoleverkets indelning av forskningsämnen):
Fysik ->
Astronomi, astrofysik och kosmologi
X-rays: binaries, Stars: neutron, Accretion, accretion disks
Postens nummer:
Posten skapad:
2008-10-27 11:18

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