Electrodynamics of Magnetars: Implications for the Persistent X-ray Emission and Spindown of the Soft Gamma Repeaters and Anomalous X-ray Pulsars

(ABBREVIATED) We consider the structure of neutron star magnetospheres threaded by large-scale electrical currents, and the effect of resonant Compton scattering by the charge carriers (both electrons and ions) on the emergent X-ray spectra and pulse profiles. In the magnetar model for the SGRs and AXPs, these currents are maintained by magnetic stresses acting deep inside the star. We construct self-similar, force-free equilibria of the current-carrying magnetosphere with a power-law dependence of magnetic field on radius, B ~ r^(-2-p), and show that a large-scale twist softens the radial dependence to p < 1. The spindown torque acting on the star is thereby increased in comparison with a vacuum dipole. We comment on the strength of the surface magnetic field in the SGR and AXP sources, and the implications of this model for the narrow measured distribution of spin periods. A magnetosphere with a strong twist, B_\phi/B_\theta = O(1) at the equator, has an optical depth ~ 1 to resonant cyclotron scattering, independent of frequency (radius), surface magnetic field strength, or charge/mass ratio of the scattering charge. When electrons and ions supply the current, the stellar surface is also heated by the impacting charges at a rate comparable to the observed X-ray output of the SGR and AXP sources, if B_{dipole} ~ 10^{14} G. Redistribution of the emerging X-ray flux at the ion and electron cyclotron resonances will significantly modify the emerging pulse profile and, through the Doppler effect, generate a non-thermal tail to the X-ray spectrum. The sudden change in the pulse profile of SGR 1900+14 after the 27 August 1998 giant flare is related to an enhanced optical depth to electron cyclotron scattering, resulting from a sudden twist imparted to the external magnetic field.Comment: 31 January 2002, minor revisions, new section 5.4.

The ultraluminous GRB 110918A

GRB 110918A is the brightest long GRB detected by Konus-WIND during its 19 years of continuous observations and the most luminous GRB ever observed since the beginning of the cosmological era in 1997. We report on the final IPN localization of this event and its detailed multiwavelength study with a number of space-based instruments. The prompt emission is characterized by a typical duration, a moderare $E_{peak}$ of the time-integrated spectrum, and strong hard-to-soft evolution. The high observed energy fluence yields, at z=0.984, a huge isotropic-equivalent energy release $E_{iso}=(2.1\pm0.1)\times10^{54}$ erg. The record-breaking energy flux observed at the peak of the short, bright, hard initial pulse results in an unprecedented isotropic-equivalent luminosity $L_{iso}=(4.7\pm0.2)\times10^{54}$erg s$^{-1}$. A tail of the soft gamma-ray emission was detected with temporal and spectral behavior typical of that predicted by the synchrotron forward-shock model. Swift/XRT and Swift/UVOT observed the bright afterglow from 1.2 to 48 days after the burst and revealed no evidence of a jet break. The post-break scenario for the afterglow is preferred from our analysis, with a hard underlying electron spectrum and ISM-like circumburst environment implied. We conclude that, among multiple reasons investigated, the tight collimation of the jet must have been a key ingredient to produce this unusually bright burst. The inferred jet opening angle of 1.7-3.4 deg results in reasonable values of the collimation-corrected radiated energy and the peak luminosity, which, however, are still at the top of their distributions for such tightly collimated events. We estimate a detection horizon for a similar ultraluminous GRB of $z\sim7.5$ for Konus-WIND, and $z\sim12$ for Swift/BAT, which stresses the importance of GRBs as probes of the early Universe.Comment: 22 pages, 20 figures, accepted for publication in Ap

Влияние сорных растений и аммофоса на выход зерна гороха в степной зоне Южного Урала

Increasing the yield of pea grain in agricultural production is an important task for modern agriculture in the Orenburg region. To expand it, long-term studies on the influence of weeds and ammophos on the yield of pea grain were carried out. The article presents the research results for 2002-2019 by weediness of crops, the content of macronutrients and the productivity of pea grain in six-field and two-field crop rotations. Among the main factors affecting the yield of pea grain such as the total number of weeds and the content of accumulated nutrients in the 0-30 cm, soil layer were considered. The total number of weeds on two nutritional backgrounds in the pea germination phase was from 102.0 to 137.0. During the ripening period, respectively, it was from 44.0 to 56.0 pcs / m2. The maximum yield of pea grain is observed in crops after soft wheat with ammophos - 1.03 t / ha, without the use of fertilizer - 0.98 t / ha. The lowest yield of peas was obtained after durum wheat in a two-field crop rotation: according to the fertilized nutrition background - 0.76, unfertilized - 0.70 t / ha. As a result of statistical data processing in the third variant of the experiment (sowing peas after soft wheat in the aftereffect of a busy fallow), it was found that the increase in the productivity of pea grain slightly depended on the weediness of crops and the share of its influence ranged from 13.98 to 18.37%. However, the decrease in the yield of peas in the fifth variant of the experiment (sowing peas in alternation with durum wheat) was largely determined by weeds and the level of their influence was from 40.21 to 54.41%. The content of accumulated nitrate nitrogen and mobile phosphorus from ammophos before all sowing of peas in crop rotations ranged from 1.4 to 2.9 mg / 100 g of soil. The increase in pea grain from mineral fertilizers for 18 years, respectively, for all predecessors was 0.07; 0.05; 0.08 and 0.06 t / ha, except for the second variant of the experiment, where peas were sown after soft wheat in the aftereffect of black steam. The results of mathematical processing of the data on the increase in grain of peas show the effect of ammophos on the increase in grain by options in the range from 55.41 to 81.88%.Повышение урожайности зерна гороха в сельскохозяйственном производстве является важной задачей для современного земледелия Оренбуржья. Для ее решения проведены длительные исследования по влиянию сорных растений и аммофоса на выход зерна гороха. В статье приведены результаты исследований за 2002–2019 гг. по засорённости посевов, содержанию макроэлементов и продуктивности зерна гороха в шестипольных и двупольных севооборотах. Среди основных факторов, влияющих на выход зерна гороха, рассмотрены такие, как общее количество сорных растений и содержание накопленных питательных веществ в слое почвы 0–30 см. В среднем за период исследований наибольшая засорённость посевов наблюдается на делянках гороха после мягкой и твёрдой пшеницы. Общее количество сорных растений на двух фонах питания составило в фазе всходов гороха от 102,0 до 137,0, а в период созревания соответственно от 44,0 до 56,0 шт/м 2. Максимальный выход зерна гороха отмечается в посевах после мягкой пшеницы с аммофосом – 1,03 т/га, без применения удобрения – 0,98 т/га. Наименьшая урожайность гороха получена после твёрдой пшеницы в двупольном севообороте: по удобренному фону питания – 0,76, неудобренному – 0,70 т/га. В результате статистической обработки данных в третьем варианте эксперимента (посев гороха после мягкой пшеницы в последействии занятого пара) установлено, что повышение продуктивности зерна гороха незначительно зависело от засорённости посевов и доля ее влияния находилась в пределах от 13,98 до 18,37%. Однако снижение урожайности гороха в пятом варианте опыта (посев гороха в чередовании с твердой пшеницей) в значительной степени определялось сорными растениями и уровень их влияния составил от 40,21 до 54,41%. Содержание накопленного нитратного азота и подвижного фосфора от аммофоса перед всеми посевами гороха в севооборотах колебалось от 1,4 до 2,9 мг/100 г почвы. Прибавка зерна гороха от минерального удобрения за 18 лет соответственно по всем предшественникам составила 0,07; 0,05; 0,08 и 0,06 т/га, кроме второго варианта опыта, где горох высевали после мягкой пшеницы в последействии черного пара. Результаты математической обработки данных прибавки урожайности зерна гороха показывают влияние аммофоса на прибавку зерна по вариантам в диапазоне от 55,41 до 81,88 %

Resonant Cyclotron Radiation Transfer Model Fits to Spectra from Gamma-Ray Burst GRB870303

We demonstrate that models of resonant cyclotron radiation transfer in a strong field (i.e. cyclotron scattering) can account for spectral lines seen at two epochs, denoted S1 and S2, in the Ginga data for GRB870303. Using a generalized version of the Monte Carlo code of Wang et al. (1988,1989b), we model line formation by injecting continuum photons into a static plane-parallel slab of electrons threaded by a strong neutron star magnetic field (~ 10^12 G) which may be oriented at an arbitrary angle relative to the slab normal. We examine two source geometries, which we denote "1-0" and "1-1," with the numbers representing the relative electron column densities above and below the continuum photon source plane. We compare azimuthally symmetric models, i.e. models in which the magnetic field is parallel to the slab normal, with models having more general magnetic field orientations. If the bursting source has a simple dipole field, these two model classes represent line formation at the magnetic pole, or elsewhere on the stellar surface. We find that the data of S1 and S2, considered individually, are consistent with both geometries, and with all magnetic field orientations, with the exception that the S1 data clearly favor line formation away from a polar cap in the 1-1 geometry, with the best-fit model placing the line-forming region at the magnetic equator. Within both geometries, fits to the combined (S1+S2) data marginally favor models which feature equatorial line formation, and in which the observer's orientation with respect to the slab changes between the two epochs. We interpret this change as being due to neutron star rotation, and we place limits on the rotation period.Comment: LaTeX2e (aastex.cls included); 45 pages text, 17 figures (on 21 pages); accepted by ApJ (to be published 1 Nov 1999, v. 525

Comparison of Image Restoration Methods for Lunar Epithermal Neutron Emission Mapping

Orbital measurements of neutrons by the Lunar Exploring Neutron Detector (LEND) onboard the Lunar Reconnaissance Orbiter are being used to quantify the spatial distribution of near surface hydrogen (H). Inferred H concentration maps have low signal-to-noise (SN) and image restoration (IR) techniques are being studied to enhance results. A single-blind. two-phase study is described in which four teams of researchers independently developed image restoration techniques optimized for LEND data. Synthetic lunar epithermal neutron emission maps were derived from LEND simulations. These data were used as ground truth to determine the relative quantitative performance of the IR methods vs. a default denoising (smoothing) technique. We review and used factors influencing orbital remote sensing of neutrons emitted from the lunar surface to develop a database of synthetic "true" maps for performance evaluation. A prior independent training phase was implemented for each technique to assure methods were optimized before the blind trial. Method performance was determined using several regional root-mean-square error metrics specific to epithermal signals of interest. Results indicate unbiased IR methods realize only small signal gains in most of the tested metrics. This suggests other physically based modeling assumptions are required to produce appreciable signal gains in similar low SN IR applications