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Nuclear Theory·nucl-th

Thursday·August 11, 2016

6 papers—4 primary·2 cross-listed

All6Primary4Cross-lists2
  1. 05

    [Submitted on 9 Aug 2016] (cross-list from astro-ph.HE)

    Millihertz Quasi-periodic Oscillations in 4U 1636-536: Putting Possible Constraints on the Neutron Star Size

    H. Stiele · W. Yu · A. K. H. Kong

    Based on previous studies of quasi-periodic oscillations in neutron star LMXBs, mHz quasi-periodic oscillations (QPO) are believed to be related to `marginally stable' burning on the neutron star (NS) surface. Our study of phase resolved energy spectra of these oscillations in 4U 1636-53 shows that the oscillations are not caused by variations in the blackbody temperature of the neutron star, but reveals a correlation between the change of the count rate during the mHz QPO pulse and the spatial extend of a region emitting blackbody emission. The maximum size of the emission area km, provides the direct evidence that the oscillations originate from a variable surface area constrained on the NS and are therefore not related to instabilities in the accretion disk. The obtained lower limit on the size of the neutron star (11.0 km) rules out equations of state that prefer small NS radii. Observations of mHz QPOs in NS LMXBs with NICER and eXTP will reduce the statistical uncertainty in the lower limit on the NS radius, which together with better estimates of the hardening factor and distance, will allow improving discrimination between different equations of state and compact star models. Furthermore, future missions will allow us to measure the peak blackbody emission area for a single mHz QPO pulse, which will push the lower limit to larger radii.

    Comments:
    10 pages, 4 figures, accepted for publication in ApJ
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    1608.02947 [pdf]
    ApJ(2016)·17 citations
  2. 06

    [Submitted on 10 Aug 2016] (cross-list from nucl-ex)

    Recent Experimental Results on Nuclear Cluster Physics

    C. Beck (IPHC Strasbourg)🇫🇷

    Knowledge on nuclear cluster physics has increased considerably since the pioneering discovery of 12C+12C resonances half a century ago and nuclear clustering remains one of the most fruitful domains of nuclear physics, facing some of the greatest challenges and opportunities in the years ahead. The occurrence of "exotic" shapes and/or Bose-Einstein alpha condensates in light N-Z alpha-conjugate nuclei is investigated. Evolution of clustering from stability to the drip-lines examined with clustering aspects persisting in light neutron-rich nuclei is consistent with the extension of the "Ikeda-diagram" to non alpha-conjugate nuclei.

    Comments:
    14 pages, 2 figures, extended version of the written contribution (6 pages) of the introductory talk given at the CLUSTER '16 Conference held in May 2016 in Napoli, Italy which Proceedings will be published in J. Phys. Conferences Series. arXiv admin note: substantial text overlap with arXiv:1408.0684, arXiv:1603.02574, arXiv:1402.6590, arXiv:1303.0960
    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1608.03190 [pdf]
    J.Phys.Conf.Ser.(2017)·5 citations

Affiliations

first authorsco-authorsvia INSPIRE