1,021 research outputs found

    Uniting the Quiescent Emission and Burst Spectra of Magnetar Candidates

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    Spectral studies of quiescent emission and bursts of magnetar candidates using XMM-Newton, Chandra and Swift data are presented. Spectra of both the quiescent emission and the bursts for most magnetar candidates are reproduced by a photoelectrically absorbed two blackbody function (2BB). There is a strong correlation between lower and higher temperatures of 2BB (kT_LT and kT_HT) for the magnetar candidates of which the spectra are well reproduced by 2BB. In addition, a square of radius for kT_T (R_LT^2) is well correlated with a square of radius for kT_HT (R_HT^2). A ratio kT_LT/kT_HT ~ 0.4 is nearly constant irrespective of objects and/or emission types (i.e., the quiescent emission and the bursts). This would imply a common emission mechanism among the magnetar candidates. The relation between the quiescent emission and the bursts might be analogous to a relation between microflares and solar flares of the sun. Three AXPs (4U 0142+614, 1RXS J170849.0-400910 and 1E 2259+586) seem to have an excess above ~7 keV which well agrees with a non-thermal hard component discovered by INTEGRAL.Comment: 17 pages, 5 figures, 12 tables, Accepted for publication in PAS

    Does mass accretion lead to field decay in neutron stars

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    The recent discovery of cyclotron lines from gamma-ray bursts indicates that the strong magnetic fields of isolated neutron stars might not decay. The possible inverse correlation between the strength of the magnetic field and the mass accreted by the neutron star suggests that mass accretion itself may lead to the decay of the magnetic field. The spin and magnetic field evolution of the neutron star was calculated under the hypothesis of the accretion-induced field decay. It is shown that the calculated results are consistent with the observations of binary and millisecond radio pulsars

    Exploring teachers views of creativity: A comparative study

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    Previous research on creativity has focussed on what Balkin (1990) called ʻthe three ‘P’s of the creative equation’. Interviews were carried out with 12 music teachers. The two countries were selected as being appropriate representations of an ‘individualist’ and a ‘collectivist’ culture (Triandis, 1995). The study aimed to explore the extent to which the cultural ideology existing on a macro level, can impact on the beliefs and practices of teachers on a ‘micro’ level, in this instance the music classroom. The data suggested that teachers’ basic beliefs about creativity often seemed to reflect their cultural contexts, namely individualism and collectivism. The study also explored the extent to which teachers in both countries worked towards adaptive or innovative forms of creativity and what impact this appeared to have on the resulting creative musical products

    Pulse Profile Change Possibly Associated with a Glitch in an Anomalous X-Ray Pulsar 4U 0142+61

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    We report a glitch-like pulse frequency deviation from the simple spin-down law in an anomalous X-ray pulsar (AXP) 4U 0142+61 detected by ASCA observations. We also found a significant pulse profile change after the putative glitch. The glitch parameters resemble those found in another AXP 1RXS J170849.0-400910, in the Vela pulsar, and in other radio pulsars. This suggests that the radio pulsars and AXPs have the same internal structure and glitch mechanism. It must be noted, however, that the pulse frequency anomaly can also be explained by a gradual change of the spin-down rate (P˙\dot{P}) without invoking a glitch.Comment: 14 pages, 4 figures, accepted by Ap

    Using music in dementia care

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    This paper presents a summary of the initial findings from a research project carried out between January 2014 and November 2015. In the UK, the work was carried out in association with the Charity ‘Music in Hospitals’, whilst in Japan, the research was arranged through independent musicians with significant experience in providing music concerts in care facilities. In total, 30 concerts were included in the project which took place in a total of 6 care facilities; 3 in Japan and 3 in the UK. The research method involved a series of interviews with service users, service providers and their family members as well as both open and systematic observations of clients’ responses to musical elements. Initial results suggest that musical events can be a worthwhile and important non-pharmacological intervention in promoting wellbeing. In this paper, we argue that music can play a significant role in improving the care of the elderly and in particular those with early to mid stage dementia as well as providing significant benefits for their family members and their service providers

    Quasiperiodic oscillations in bright galactic-bulge X-ray sources

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    Quasiperiodic oscillations with frequencies in the range 5-50 Hz have recently been discovered in X-rays from two bright galactic-bulge sources and Sco X-1. These sources are weakly magnetic neutron stars accreting from disks which the plasma is clumped. The interaction of the magnetosphere with clumps in the inner disk causes oscillations in the X-ray flux with many of the properties observed

    Correlation between X-ray flux and rotational acceleration in Vela X-1

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    The results of a search for correlations between X-ray flux and angular acceleration for the accreting binary pulsar Vela X-1 are presented. Results are based on data obtained with the Hakucho satellite during the interval 1982 to 1984. In undertaking this correlation analysis, it was necessary to modify the usual statistical method to deal with conditions imposed by generally unavoidable satellite observing constraints, most notably a mismatch in sampling between the two variables. The results are suggestive of a correlation between flux and the absolute value of the angular acceleration, at a significance level of 96 percent. The implications of the methods and results for future observations and analysis are discussed

    Soft and Hard X-Ray Emissions from the Anomalous X-ray Pulsar 4U 0142+61 Observed with Suzaku

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    The anomalous X-ray pulsar 4U 0142+61 was observed with Suzaku on 2007 August 15 for a net exposure of -100 ks, and was detected in a 0.4 to ~70 keV energy band. The intrinsic pulse period was determined as 8.68878 \pm 0.00005 s, in agreement with an extrapolation from previous measurements. The broadband Suzaku spectra enabled a first simultaneous and accurate measurement of the soft and hard components of this object by a single satellite. The former can be reproduced by two blackbodies, or slightly better by a resonant cyclotron scattering model. The hard component can be approximated by a power-law of photon index \Gamma h ~0.9 when the soft component is represented by the resonant cyclotron scattering model, and its high-energy cutoff is constrained as >180 keV. Assuming an isotropic emission at a distance of 3.6 kpc, the unabsorbed 1-10 keV and 10-70 keV luminosities of the soft and hard components are calculated as 2.8e+35 erg s^{-1} and 6.8e+34 erg s^{-1}, respectively. Their sum becomes ~10^3 times as large as the estimated spin-down luminosity. On a time scale of 30 ks, the hard component exhibited evidence of variations either in its normalization or pulse shape.Comment: 24 pages, 8 figures, accepted for publication in Publications of the Astronomical Society of Japa

    Search for Near-Infrared Pulsation of the Anomalous X-ray Pulsar 4U 0142+61

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    We have searched for pulsation of the anomalous X-ray pulsar (AXP) 4U 0142+61 in the K' band (λeff=2.11\lambda_{\rm eff} = 2.11 μ\mum) using the fast-readout mode of IRCS at the Subaru 8.2-m telescope. We found no significant signal at the pulse frequency expected by the precise ephemeris obtained by the X-ray monitoring observation with RXTE. Nonetheless, we obtained a best upper limit of 17% (90% C.L.) for the root-mean-square pulse fraction in the K' band. Combined with i' band pulsation (Dhillon et al. 2005), the slope of the pulsed component (FνναF_\nu \propto \nu^\alpha) was constrained to α>0.87\alpha > -0.87 (90% C.L.) for an interstellar extinction of AV=3.5A_{V} = 3.5.Comment: 11 pages, 3 figures, Accepted for publication in PAS
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