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Post Info TOPIC: CTB 109

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Posts: 131433
Date:
 Magnetar 1E 2259+586 Permalink Title: Anti-glitch of magnetar 1E 2259+586 in the wind braking scenario Authors: H. Tong The anti-glitch of magnetar 1E 2259+586 is analysed theoretically. It is shown that the internal origin is not favoured, while there are enough parameter space for this anti-glitch in the wind braking model of magnetars. An enhanced particle wind during the observational interval will taken away additional rotation energy of the neutron star. This will result in a net spin-down of the magnetar, i.e. an anti-glitch. In the wind braking scenario of magnetar anti-glitch, there are several predictions: (1) A radiative event will always accompany the anti-glitch, (2) Decrease/variation of braking index after anti-glitch, (3) Anti-glitch is just a period of enhanced spin-down etc. These predictions can be tested by future observations. Applications to previous timing events of SGR 1900+14, and PSR J1846-0258 are also included. It is shown that current timing events of 1E 2259+586, SGR 1900+14, and PSR J1846-0258 can be understood safely in the wind braking model. Read more (34kb, PDF) __________________

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Posts: 131433
Date:
 1E 2259+586 Permalink Title: An Anti-Glitch in a Magnetar Authors: R. F. Archibald, V. M. Kaspi, C. -Y. Ng, K. N. Gourgouliatos, D. Tsang, P. Scholz, A. P. Beardmore, N. Gehrels, J. A. Kennea Magnetars are neutron stars showing dramatic X-ray and soft $\gamma$-ray outbursting behaviour that is thought to be powered by intense internal magnetic fields. Like conventional young neutron stars in the form of radio pulsars, magnetars exhibit "glitches" during which angular momentum is believed to be transferred between the solid outer crust and the superfluid component of the inner crust. Hitherto, the several hundred observed glitches in radio pulsars and magnetars have involved a sudden spin-up of the star, due presumably to the interior superfluid rotating faster than the crust. Here we report on X-ray timing observations of the magnetar 1E 2259+586 which we show exhibited a clear "anti-glitch" -- a sudden spin down. We show that this event, like some previous magnetar spin-up glitches, was accompanied by multiple X-ray radiative changes and a significant spin-down rate change. This event, if of origin internal to the star, is unpredicted in models of neutron star spin-down and is suggestive of differential rotation in the neutron star, further supporting the need for a rethinking of glitch theory for all neutron stars. Read more (63kb, PDF) __________________

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Posts: 131433
Date:
 Permalink Super-dense star is first ever found suddenly slowing its spin One of the densest objects in the universe, a neutron star about 10,000 light years from Earth, has been discovered suddenly putting the brakes on its spinning speed. The event is a mystery that holds important clues for understanding how matter reacts when it is squeezed more tightly than the density of an atomic nucleus -- a state that no laboratory on Earth has achieved. The discovery, by an international team of scientists that includes a Penn State University astronomer, will be published in the journal Nature on May 30. The scientists detected the neutron star's abrupt slow-down with NASA's Swift observatory, a satellite with three telescopes whose science and flight operations are controlled by Penn State from the Mission Operations Centre on the University Park campus. Read more __________________

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Posts: 131433
Date:
 CTB 109 Permalink Title: Fermi-LAT Observations and A Broadband Study of Supernova Remnant CTB 109 Authors: Daniel Castro, Patrick Slane, Donald C. Ellison, Daniel J. Patnaude CTB 109 (G109.1-1.0) is a Galactic supernova remnant (SNR) with a hemispherical shell morphology in X-rays and in the radio band. In this work we report the detection of gamma-ray emission coincident with CTB 109, using 37 months of data from the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. We study the broadband characteristics of the remnant using a model that includes hydrodynamics, efficient cosmic ray acceleration, nonthermal emission and a self-consistent calculation of the X-ray thermal emission. We find that the observations can be successfully fit with two distinct parameter sets, one where the gamma-ray emission is produced primarily by leptons accelerated at the SNR forward shock and the other where gamma-rays produced by forward shock accelerated cosmic-ray ions dominate the high-energy emission. Consideration of thermal X-ray emission introduces a novel element to the broadband fitting process, and while it does not rule out either the leptonic or the hadronic scenarios, it constrains the parameter sets required by the model to fit the observations. Moreover, the model which best fits the thermal and nonthermal emission observations is an intermediate case, where both radiation from accelerated electrons and hadrons contribute almost equally to the gamma-ray flux observed. Read more (7492kb, PDF)Ed ~ CTB 109 associated with AXP 1E 2259+586Position (J2000): R.A. 23 01 08.295  |  Dec. +58° 52' 44.45'' __________________
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