Spectrum formation in X-ray pulsars at very low mass accretion rate: Monte Carlo approach

Large scale structure and cosmolog

Constraints on the magnetic field structure in accreting compact objects from aperiodic variability

Galaxie

Investigation of system for external injection of H⁻ ion beam on cyclotrons

The article presents results of experimental studies carried out at an installation (“SVITS”) simulating a system for external injection of H⁻ions with the beam current of up to 2 mA and energy up to 30 keV for cyclotrons. The beam characteristics (current, current density distribution over cross-section, phase diagrams) as well as gas pressure were measured in three points along the beam axis. The influence of the compensation and de-compensation of the beam space charge on the beam dynamics in the plasma produced under beam transportation was studied.Приводяться результати експериментальних досліджень, виконаних на установці, що моделює систему зовнішньої інжекції Н⁻ зі струмом пучка до 2 мА й енергією до 30 кеВ для циклотрону. Вимір характеристик пучка (струму, розподілу густини струму по перетині, фазових діаграм), а також тиску газу провадиться в трьох точках уздовж осі пучка. Відзначено вплив на динаміку пучка в інжекторі ефекту компенсації власного просторового заряду пучка іонами плазми, що напрацьовується при русі пучка в залишковому газі.Приводятся результаты экспериментальных исследований, выполненных на установке, моделирующей систему внешней инжекции Н⁻ с током пучка до 2 мА и энергией до 30 кэВ для циклотрона. Измерение характеристик пучка (тока, распределения плотности тока по сечению, фазовых диаграмм), а также давления газа производится в трех точках вдоль оси пучка. Отмечено влияние на динамику пучка в инжекторе эффекта компенсации собственного пространственного заряда пучка ионами плазмы, нарабатываемой при движении пучка в остаточном газе

Losing a minute every two years: SRG X-ray view of the rapidly accelerating X-ray pulsar SXP 1323

High Energy Astrophysic

First characterization of a new high-mass X-ray binary in LMC eRASSU J050810.4-660653 with SRG/ART-XC, NuSTAR, and Swift

Galaxie

High-energy characteristics of the accretion-powered millisecond pulsar IGR J17591-2342 during its 2018 outburst: XMM-Newton, NICER, NuSTAR, and INTEGRAL view of the 0.3-300 keV X-ray band

IGR J17591−2342 is an accreting millisecond X-ray pulsar, discovered with INTEGRAL, which went into outburst around July 21, 2018. To better understand the physics acting in these systems during the outburst episode, we performed detailed temporal-, timing-, and spectral analyses across the 0.3–300 keV band using data from NICER, XMM-Newton, NuSTAR, and INTEGRAL. The hard X-ray 20–60 keV outburst profile covering ∼85 days is composed of four flares. Over the course of the maximum of the last flare, we discovered a type-I thermonuclear burst in INTEGRAL JEM-X data, posing constraints on the source distance. We derived a distance of 7.6±0.7 kpc, adopting Eddington-limited photospheric radius expansion and assuming anisotropic emission. In the timing analysis, using all NICER 1–10 keV monitoring data, we observed a rather complex set of behaviours starting with a spin-up period (MJD 58345–58364), followed by a frequency drop (MJD 58364–58370), an episode of constant frequency (MJD 58370–58383), concluded by irregular behaviour till the end of the outburst. The 1–50 keV phase distributions of the pulsed emission, detected up to ∼120 keV using INTEGRAL ISGRI data, was decomposed in three Fourier harmonics showing that the pulsed fraction of the fundamental increases from ∼10% to ∼17% going from ∼1.5 to ∼4 keV, while the harder photons arrive earlier than the soft photons for energies .10 keV. The total emission spectrum of IGR J17591−2342 across the 0.3–150 keV band could adequately be fitted in terms of an absorbed compPS model yielding as best fit parameters a column density of NH = (2.09 ± 0.05) × 1022 cm−2 , a blackbody seed photon temperature kTbb,seed of 0.64±0.02 keV, electron temperature kTe = 38.8±1.2 keV and Thomson optical depth τT = 1.59 ± 0.04. The fit normalisation results in an emission area radius of 11.3 ± 0.5 km adopting a distance of 7.6 kpc. Finally, the results are discussed within the framework of accretion physics- and X-ray thermonuclear burst theor

SRG/ART-XC, Swift, NICER, and NuSTAR study of different states of the transient X-ray pulsar MAXI J0903-531

High Energy Astrophysic

The C-80 cyclotron system. Current status

The C-80 cyclotron system is intended to produce proton beams with an energy ranging from 40 up to 80 MeV and current up to 200 μA. The beams with the aforementioned parameters will be used for commercial production of a wide assortment of isotopes for medicine including radiation generators. In addition, creation of a special beamline to form homogeneous proton beams of ultra-low intensity (10⁷…10⁹) will allow the proton therapy of eye diseases and superficial oncological diseases as well as tests of radioelectronic components for radiation resistance to be performed. The equipment of the cyclotron and the first section of the beam transport system has been manufactured, tested at test facilities in the Efremov Institute, installed in the PNPI and made ready for acceptance tests.Циклотронный комплекс Ц-80 предназначен для получения протонных пучков с энергией 40…80 МэВ и током до 200 мкА. Пучки с такими параметрами будут использоваться для производства широкого спектра изотопов медицинского назначения, в том числе генераторов излучения, в коммерческих масштабах. Кроме того, создание специального тракта формирования гомогенных пучков протонов ультрамалой интенсивности (10⁷…10⁹) позволит осуществлять протонную лучевую терапию глаза и поверхностных форм онкологических заболеваний, а также проводить испытания радиоэлектронных изделий на радиационную стойкость. Оборудование циклотрона и первого участка системы транспортировки изготовлено и испытано на стендах НИИЭФА им. Д.В. Ефремова, смонтировано в ПИЯФ им. Б.П. Константинова и подготовлено для проведения приемосдаточных испытаний.Циклотронний комплекс Ц-80 призначений для отримання протонних пучків з енергією 40...80 МеВ і струмом до 200 мкА. Пучки з такими параметрами використовуватимуться для виробництва широкого спек-тра ізотопів медичного призначення, у тому числі генераторів випромінювання, в комерційних масштабах. Крім того, створення спеціального тракту формування гомогенних пучків протонів ультрамалої інтенсивності (10⁷…10⁹) дозволить здійснювати протонну променеву терапію ока і поверхневих форм онкологічних захворювань, а також проводити випробування радіоелектронних виробів на радіаційну стійкість. Устаткування циклотрона і першої ділянки системи транспортування виготовлене та випробуване на стендах НДІЕФА ім. Д.В. Єфремова, змонтовано в ПІЯФ ім. Б.П. Константинова і підготовлено для проведення приймальноздавальних випробувань

Multiwavelength monitoring and reverberation mapping of a changing look event in the Seyfert galaxy NGC 3516

We present the results of photometric and spectroscopic monitoring campaigns of the changing look AGN NGC 3516 carried out in 2018 to 2020 covering the wavelength range from the X-ray to the optical. The facilities included the telescopes of the CMO SAI MSU, the 2.3-m WIRO telescope, and the XRT and UVOT of Swift. We found that NGC 3516 brightened to a high state and could be classified as Sy1.5 during the late spring of 2020. We have measured time delays in the responses of the Balmer and He ii λ4686 lines to continuum variations. In the case of the best-characterized broad H β line, the delay to continuum variability is about 17 d in the blue wing and is clearly shorter, 9 d, in the red, which is suggestive of inflow. As the broad lines strengthened, the blue side came to dominate the Balmer lines, resulting in very asymmetric profiles with blueshifted peaks during this high state. During the outburst the X-ray flux reached its maximum on 2020 April 1 and it was the highest value ever observed for NGC 3516 by the Swift observatory. The X-ray hard photon index became softer, ∼1.8 in the maximum on 2020 April 21 compared to the mean ∼0.7 during earlier epochs before 2020. We have found that the UV and optical variations correlated well (with a small time delay of 1–2 d) with the X-ray until the beginning of 2020 April, but later, until the end of 2020 June, these variations were not correlated. We suggest that this fact may be a consequence of partial obscuration by Compton-thick clouds crossing the line of sight.</p