Magnetar

About: Magnetar is a research topic. Over the lifetime, 2905 publications have been published within this topic receiving 106806 citations.

Ultrahigh energy cosmic ray acceleration in newly born magnetars and their associated gravitational wave signatures

Abstract: Newly born magnetars are good candidate sources of ultrahigh energy cosmic rays. These objects can in principle easily accelerate particles to the highest energies required to satisfy the ultrahigh energy cosmic ray scenario ($E\ensuremath{\sim}{10}^{20\ensuremath{-}21}\text{ }\text{ }\mathrm{eV}$), thanks to their important rotational and magnetic energy reservoirs. Their acceleration mechanism, based on unipolar induction, predicts however a hard particle injection that does not fit the observed ultrahigh energy cosmic ray spectrum. Here we show that an adequate distribution of initial voltages among magnetar winds can be found to soften the spectrum. We discuss the effect of these distributions for the stochastic gravitational wave background signature produced by magnetars. The magnetar population characteristics needed to fit the ultrahigh energy cosmic ray spectrum could lead in most optimistic cases to gravitational wave background signals enhanced of up to four orders of magnitudes in the range of frequency 1--100 Hz, compared to the standard predictions. These signals could reach the sensitivities of future detectors such as DECIGO or BBO.

A long optical plateau in the afterglow of the Extended Emission short GRB 150424A. Evidence for energy injection by a magnetar

Abstract: Short-duration GRBs with extended emission form a subclass of short GRBs, comprising about 15% of the short-duration sample. Afterglow detections of short GRBs are also rare (about 30%) due to their smaller luminosity. We present a multi-band data set of the short burst with extended emission GRB 150424A, comprising of GROND observations, complemented with data from Swift/UVOT, Swift/XRT, HST, Keck/LRIS and data points from the literature. The GRB 150424A afterglow shows an extended plateau phase, lasting about 8hrs. The analysis of this unique GRB afterglow might shed light on the understanding of afterglow plateau emission, the nature of which is still under debate. We present a phenomenological analysis by applying fireball closure relations, and interpret the findings in the context of the fireball model. We discuss the plausibility of a magnetar as a central engine, being responsible for additional and prolonged energy injection into the fireball. We find convincing evidence for energy injection into the afterglow of GRB 150424A. We find that a magnetar spin down as source for a prolonged energy injection requires that at least 4% of the spin-down energy is converted to radiation.

Isolated magnetar spin-down, soft X-ray emission and RXJ1856.5-3754

Abstract: When an isolated magnetar with magnetic dipole field B ~ 10^15 G moves at high velocity (v > 10^7 cm/s) through the ISM, its transition into propeller effect driven spin-down may occur in less than 10^6 years. We propose that the nearby neutron star RXJ1856.5-3754 is such a magnetar, and has spun down by the propeller effect to a period greater than 10^4 sec within ~5*10^5 years. This magnetar scenario is consistent with observed thermal X-ray emission properties and the absence of detectable spin-modulations of them. Detection of other rapidly moving long period (> 100 sec) magnetars with known ages would strongly constrain the very great variety of predicted propeller-effect torque magnitudes.

A Phase-connected Timing Solution for the Magnetar Candidate 1E 1841–045

Abstract: We report on a long-term monitoring campaign of 1E 1841-045, the 12 s anomalous X-ray pulsar and magnetar candidate at the center of the supernova remnant Kes 73. We have obtained approximately monthly observations of the pulsar with the Rossi X-Ray Timing Explorer (RXTE) spanning over 2 years, during which time 1E 1841-045 is found to be rotating with sufficient stability to derive a phase-connected timing solution. A linear ephemeris is consistent with measurements of the pulse period made over the last 15 years with the Ginga, ASCA, RXTE, and BeppoSAX observatories. Phase residuals suggest the presence of "timing noise," as is typically observed from young radio pulsars. These results confirm a rapid, constant spin-down for the pulsar, which continues to maintain a steady flux; this is inconsistent with most accretion scenarios.

Spectral and timing properties of the magnetar CXOU~J164710.2-455216

Abstract: We report on spectral and timing properties of the magnetar CXOU J164710.2-455216 in the massive star cluster Westerlund 1. Using 11 archival observations obtained with Chandra and XMM-Newton over approximately 1000 days after the source's 2006 outburst, we study the flux and spectral evolution of the source. We show that the hardness of the source, as quantified by hardness ratio, blackbody temperature or power-law photon index, shows a clear correlation with the 2--10 keV absorption-corrected flux and that the power-law component flux decayed faster than the blackbody component for the first ~100 days. We also measure the timing properties of the source by analyzing data spanning approximately 2500 days. The measured period and period derivative are 10.610644(17) s (MJD 53999.06) and <4 X 10^{-13} s s^-1 (90% confidence) which imply that the spin-inferred dipolar magnetic field of the source is less than 7 X 10^{13} G. This is significantly smaller than was suggested previously. We find evidence for a second flux increase, suggesting a second outburst between MJDs 55068 and 55832. Finally, based on a crustal cooling model, we find that the source's cooling curve can be reproduced if we assume that the energy was deposited in the outer crust and that the temperature profile of the star right after the 2006 outburst was relatively independent of density.