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Title: Quasi-periodic oscillations in short recurring bursts of the soft gamma repeater J1550–5418

The discovery of quasi-periodic oscillations (QPOs) in magnetar giant flares has opened up prospects for neutron star asteroseismology. The scarcity of giant flares makes a search for QPOs in the shorter, far more numerous bursts from soft gamma repeaters (SGRs) desirable. In Huppenkothen et al., we developed a Bayesian method for searching for QPOs in short magnetar bursts, taking into account the effects of the complicated burst structure, and have shown its feasibility on a small sample of bursts. Here we apply the same method to a much larger sample from a burst storm of 286 bursts from SGR J1550–5418. We report a candidate signal at 260 Hz in a search of the individual bursts, which is fairly broad. We also find two QPOs at ∼93 Hz, and one at 127 Hz, when averaging periodograms from a number of bursts in individual triggers, at frequencies close to QPOs previously observed in magnetar giant flares. Finally, for the first time, we explore the overall burst variability in the sample and report a weak anti-correlation between the power-law index of the broadband model characterizing aperiodic burst variability and the burst duration: shorter bursts have steeper power-law indices than longer bursts. This indicatesmore » that longer bursts vary over a broader range of timescales and are not simply longer versions of the short bursts.« less
Authors:
; ; ; ; ;  [1] ;  [2] ;  [3] ; ;  [4] ;  [5] ;  [6] ;  [7] ;  [8]
  1. Astronomical Institute "Anton Pannekoek," University of Amsterdam, Postbus 94249, 1090 GE Amsterdam (Netherlands)
  2. Astrophysics Office, ZP 12, NASA-Marshall Space Flight Center, Huntsville, AL 35812 (United States)
  3. Department of Physics and Astronomy, Rice University, MS-108, P.O. Box 1892, Houston, TX 77251 (United States)
  4. SabancıUniversity, Orhanlı-Tuzla, İstanbul 34956 (Turkey)
  5. Department of Natural Sciences, The Open University of Israel, 1 University Road, P.O. Box 808, Ra'anana 43537 (Israel)
  6. François Arago Centre, APC, 10 rue Alice Domon et Léonie Duquet, F-75205 Paris (France)
  7. Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching (Germany)
  8. NSSTC, 320 Sparkman Drive, Huntsville, AL 35805 (United States)
Publication Date:
OSTI Identifier:
22356772
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 787; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CORRELATIONS; COSMIC GAMMA BURSTS; DATA ANALYSIS; MAGNETIC FIELDS; NEUTRON STARS; NEUTRONS; OSCILLATIONS; PERIODICITY; X RADIATION