Magnetar

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

PSR J1847–0130: A Radio Pulsar with Magnetar Spin Characteristics

Abstract: We report the discovery of PSR J18470130, a radio pulsar with a 6.7 s spin period, in the Parkes Multibeam Pulsar Survey of the Galactic plane. The slowdown rate for the pulsar, s s 1 , is high and implies a 12 1.3 # 10 surface dipole magnetic field strength of G. This inferred dipolar magnetic field strength is the highest 13 9.4 # 10 by far among all known radio pulsars and over twice the “quantum critical field” above which some models predict radio emission should not occur. The inferred dipolar magnetic field strength and period of this pulsar are in the same range as those of the anomalous X-ray pulsars, which have been identified as being “magnetars” whose luminous X-ray emission is powered by their large magnetic fields. We have examined archival ASCA data and place an upper limit on the X-ray luminosity of J18470130 that is lower than the luminosities of all but one anomalous X-ray pulsar. The properties of this pulsar prove that inferred dipolar magnetic field strength and period cannot alone be responsible for the unusual high-energy properties of the magnetars and create new challenges for understanding the possible relationship between these two manifestations of young neutron stars. Subject headings: pulsars: individual (PSR J18470130) — stars: magnetic fields — stars: neutron — X-rays: stars

Formation of high-field magnetic white dwarfs from common envelopes

Abstract: The origin of highly magnetized white dwarfs has remained a mystery since their initial discovery. Recent observations indicate that the formation of high-field magnetic white dwarfs is intimately related to strong binary interactions during post-main-sequence phases of stellar evolution. If a low-mass companion, such as a planet, brown dwarf, or low-mass star, is engulfed by a post-main-sequence giant, gravitational torques in the envelope of the giant lead to a reduction of the companion’s orbit. Sufficiently low-mass companions in-spiral until they are shredded by the strong gravitational tides near the white dwarf core. Subsequent formation of a super-Eddington accretion disk from the disrupted companion inside a common envelope can dramatically amplify magnetic fields via a dynamo. Here, we show that these disk-generated fields are sufficiently strong to explain the observed range of magnetic field strengths for isolated, high-field magnetic white dwarfs. A higher-mass binary analogue may also contribute to the origin of magnetar fields.

Superluminous supernova progenitors have a half-solar metallicity threshold

Abstract: Host galaxy properties provide strong constraints on the stellar progenitors of superluminous supernovae By comparing a sample of 19 low-redshift (z < 03) superluminous supernova hosts to galaxy populations in the local Universe, we show that sub-solar metallicities seem to be a requirement All superluminous supernovae in hosts with high measured gas-phase metallicities are found to explode at large galactocentric radii, indicating that the metallicity at the explosion site is likely lower than the integrated host value We found that superluminous supernova hosts do not always have star formation rates higher than typical star-forming galaxies of the same mass However, we confirm that high absolute specific star formation rates are a feature of superluminous supernova host galaxies, but interpret this as simply a consequence of the anticorrelation between gas-phase metallicity and specific star formation rate and the requirement of on-going star formation to produce young, massive stars greater than ∼10–20 M⊙ Based on our sample, we propose an upper limit of ∼05Z ⊙ ∼05Z⊙ for forming superluminous supernova progenitors (assuming an N2 metallicity diagnostic and a solar oxygen abundance of 869) Finally, we show that if magnetar powering is the source of the extreme luminosity, then the required initial spins appear to be correlated with metallicity of the host galaxy This correlation needs further work, but if it applies, it is a powerful link between the supernova parameters and nature of the progenitor population

2D Cooling of Magnetized Neutron Stars

Abstract: Context: Many thermally emitting isolated neutron stars have magnetic fields larger than 10^13 G. A realistic cooling model that includes the presence of high magnetic fields should be reconsidered. Aims: We investigate the effects of anisotropic temperature distribution and Joule heating on the cooling of magnetized neutron stars. Methods: The 2D heat transfer equation with anisotropic thermal conductivity tensor and including all relevant neutrino emission processes is solved for realistic models of the neutron star interior and crust. Results: The presence of the magnetic field affects significantly the thermal surface distribution and the cooling history during both, the early neutrino cooling era and the late photon cooling era. Conclusions: There is a large effect of the Joule heating on the thermal evolution of strongly magnetized neutron stars. Both magnetic fields and Joule heating play a key role in keeping magnetars warm for a long time. Moreover, this effect is important for intermediate field neutron stars and should be considered in radio-quiet isolated neutron stars or high magnetic field radio-pulsars.

The Anomalous X-ray Pulsar 4U 0142+61: Variability in the infrared and a spectral break in the optical

Abstract: We present new optical and infrared observations of the counterpart to the Anomalous X-ray Pulsar (AXP) 4U 0142+61 taken with the Keck I telescope. The counterpart is found to be variable in the infrared. This contrasts with our optical observations, which do not show any evidence for variability. Apart from the variability the AXP shows a remark- able spectral energy distribution. In particular, we find a sudden drop in flux going from V to B, presumably due to a spectral feature. We compare our results to those obtained for the two other securely identified AXP counterparts, to 1E 2259+586 and 1E 1048.1−5937. 4U 0142+61 is very similar to the former source in its X-ray timing and spectral properties, and we find that this similarity extends to the quiescent infrared to X-ray flux ratio. For 1E 1048.1−5937, which has different X-ray properties, the situation is less clear: in one observation, the infrared to X-ray flux ratio was much larger, but another observation gave an upper limit which is consistent with that observed for 4U 0142+61. Assuming the quiescent ratios are all similar, we estimate the optical and infrared brightnesses for the three AXPs that remain to be identified as well as for the four Soft Gamma-ray Repeaters. We also discuss briefly how the observed optical and infrared emission might arise, in particular in the context of the magnetar model.