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Magnetar
About: Magnetar is a research topic. Over the lifetime, 2905 publications have been published within this topic receiving 106806 citations.
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TL;DR: In the hot environments of anomalous X-ray pulsars (AXPs) and the soft gamma-ray repeaters (SGRs), gamma rays generated from the inner gaps may have shorter attenuation lengths via two-photon pair production rather than via magnetic photon splitting as discussed by the authors.
Abstract: In the hot environments of the anomalous X-ray pulsars (AXPs) and the soft gamma-ray repeaters (SGRs), as indicated by their luminous, pulsed, quiescent X-ray emission, gamma rays generated from the inner gaps may have shorter attenuation lengths via two-photon pair production rather than via magnetic photon splitting. The AXP/SGR environments may not be pairless, even if photon splitting could completely suppress one-photon pair production in superstrong magnetic fields, as conjectured by Baring and Harding. Two-photon pair production more likely occurs near the threshold, which tends to generate low-energy pairs that are not energetic enough to power radio emission in the observed bands. However, emission in longer wavelengths may not be prohibited, in principle, if these objects are indeed magnetars. The so-called photon-splitting deathlines are still valid for high magnetic field pulsars that are much dimmer in X-rays, if gamma rays with both polarization modes split.
33 citations
TL;DR: In this paper, the authors reported the unambiguous identification of a distinct population of four local (999% confidence) magnetar giant flares (MGFs) from the Milky Way and its satellite galaxies, and they have long been suspected to constitute a third class of extragalactic GRBs.
Abstract: Cosmological gamma-ray bursts (GRBs) are known to arise from distinct progenitor channels: short GRBs mostly from neutron star mergers and long GRBs from a rare type of core-collapse supernova (CCSN) called collapsars Highly magnetized neutron stars called magnetars also generate energetic, short-duration gamma-ray transients called magnetar giant flares (MGFs) Three have been observed from the Milky Way and its satellite galaxies, and they have long been suspected to constitute a third class of extragalactic GRBs We report the unambiguous identification of a distinct population of four local ( 999% confidence These properties, the host galaxies, and nondetection in gravitational waves all point to an extragalactic MGF origin Despite the small sample, the inferred volumetric rates for events above 4 × 1044 erg of Gpc−3 yr−1 make MGFs the dominant gamma-ray transient detected from extragalactic sources As previously suggested, these rates imply that some magnetars produce multiple MGFs, providing a source of repeating GRBs The rates and host galaxies favor common CCSN as key progenitors of magnetars
33 citations
TL;DR: In this paper, the role of a strong magnetic field on the neutron-drip transition in the crust of a magnetar is studied, and the composition of the crust is determined numerically for different magnetic field strengths using the experimental atomic mass measurements from the 2012 Atomic Mass Evaluation complemented with theoretical masses calculated from the Brussels-Montreal Hartree-Fock-Bogoliubov nuclear mass model HFB-24.
Abstract: The role of a strong magnetic field on the neutron-drip transition in the crust of a magnetar is studied. The composition of the crust and the neutron-drip threshold are determined numerically for different magnetic field strengths using the experimental atomic mass measurements from the 2012 Atomic Mass Evaluation complemented with theoretical masses calculated from the Brussels-Montreal Hartree-Fock-Bogoliubov nuclear mass model HFB-24. The equilibrium nucleus at the neutron-drip point is found to be independent of the magnetic field strength. As demonstrated analytically, the neutron-drip density and pressure increase almost linearly with the magnetic field strength in the strongly quantizing regime for which electrons lie in the lowest Landau level. For weaker magnetic fields, the neutron-drip density exhibits typical quantum oscillations. In this case, the neutron-drip density can be either increased by about $14%$ or decreased by $25%$ depending on the magnetic field strength. These variations are shown to be almost universal, independently of the nuclear mass model employed. These results may have important implications for the physical interpretation of timing irregularities and quasiperiodic oscillations detected in soft gamma-ray repeaters and anomalous x-ray pulsars, as well as for the cooling of strongly magnetized neutron stars.
33 citations
TL;DR: In this article, a physically motivated model was proposed to explain the apparent energy injection in the X-ray light curves of short gamma-ray bursts (SGRBs) and its implications across the full broadband spectrum are explored.
Abstract: The magnetar model has been proposed to explain the apparent energy injection in the X-ray light curves of short gamma-ray bursts (SGRBs), but its implications across the full broadband spectrum are not well explored. We investigate the broadband modelling of four SGRBs with evidence for energy injection in their X-ray light curves, applying a physically motivated model in which a newly-formed magnetar injects energy into a forward shock as it loses angular momentum along open field lines. By performing an order of magnitude search for the underlying physical parameters in the blast wave, we constrain the characteristic break frequencies of the synchrotron spectrum against their manifestations in the available multi-wavelength observations for each burst. The application of the magnetar energy injection profile restricts the succesful matches to a limited family of models that are self-consistent within the magnetic dipole spin-down framework. Because of this, we are able to produce synthetic light curves that describe how the radio signatures of these SGRBs ought to have looked at a variety of frequencies, given the restrictions imposed by the available data. We discuss the detectability of these signatures in the context of present day and near future radio telescopes. Our results show that previous observations were not deep enough to place meaningful constraints on the model, but that both ALMA and the upgraded VLA are now sensitive enough to detect the radio signature within two weeks of trigger in most SGRBs, assuming our sample is representative of the population as a whole. We also find that the upcoming Square Kilometer Array will be sensitive to depths greater than those of our lower limit predictions.
33 citations
TL;DR: In this article, the observed pulsed optical emission of anomalous X-ray pulsar 4U 0142+61 can be accounted for by both the magnetar outer gap models and the disk-star dynamo gap models, therefore is not an evidence in favor of one of these models as its responsible mechanism.
Abstract: We show that the observed pulsed optical emission of the anomalous X-ray pulsar 4U 0142+61 can be accounted for by both the magnetar outer gap models and the disk-star dynamo gap models, therefore is not an evidence in favor of one of these models as its responsible mechanism. Nevertheless, the estimated high energy gamma-ray spectra from these models have different power-low indices, and can be tested by future observations of the Gamma-ray Large-Area Space Telescope (GLAST). Furthermore, we show by analytical estimations that the expectations of a standard disk model is in agreement with the observed unpulsed optical and infrared luminosities of the AXP 4U 0142+61.
33 citations