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Synchronous X-ray/Optical QPOs from the Black Hole LMXB MAXI J1820+070 期刊论文 OAI收割
Monthly Notices of the Royal Astronomical Society, 2021
作者: HXMT

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black hole physics Low Mass X-ray Binaries accretion accretion discs stars: individual (MAXI J1820+070) Astrophysics - High Energy Astrophysical Phenomena Abstract: We present high-speed optical photometry from SAAO and SALT on the black hole LMXB MAXI J1820+070 (ASSASN-18ey), some of it simultaneous with NICER, Swift and Insight-HXMT X-ray coverage. We detect optical Quasi-Periodic Oscillations (QPOs) that move to higher frequencies as the outburst progresses, tracking both the frequency and evolution of similar X-ray QPOs previously reported. Correlated X-ray/optical data reveal a complex pattern of lags, including an anti-correlation and a sub-second lag that evolve over the first few weeks of outburst. They also show correlated components separated by a lag equal to the QPO period roughly centered on zero lag, implying that the inter-band variability is strongly and consistently affected by these QPOs at a constant phase lag of roughly ±Ю The synchronisation of X-ray and optical QPOs indicates that they must be produced in regions physically very close to each other we thus propose that they can be explained by a precessing jet model, based on analogies with V404 Cyg and MAXI J1348-630.

Verification of Radiative Transfer Schemes for the EHT 期刊论文 OAI收割
The Astrophysical Journal, 2020, 卷号: 897, 期号: 2, 页码: 21
作者: Gold, Roman; Broderick, Avery E.; Younsi, Ziri; Fromm, Christian M.; Gammie, Charles F.

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black hole physics High energy astrophysics Radiative transfer Relativity General relativity Relativistic disks Very long baseline interferometry Radio astronomy Event horizons

The Nearby Luminous Transient AT2018cow: A Magnetar Formed in a Subrelativistically Expanding Nonjetted Explosion 期刊论文 OAI收割
ASTROPHYSICAL JOURNAL LETTERS, 2020, 卷号: 888, 期号: 2, 页码: 9
作者: Mohan, P.; An, T.; Yang, J.

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收藏 | 浏览/下载：8/0 | 提交时间：2021/12/06

Transient sources High energy astrophysics Very long baseline interferometry Magnetars Burst astrophysics

An underlying clock in the extreme flip-flop state transitions of the black hole transient Swift J1658.2-4242 期刊论文 OAI收割
Astronomy and Astrophysics, 2020, 卷号: 641, 页码: A101
作者: HXMT

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accretion accretion disks black hole physics X-rays: binaries time Astrophysics - High Energy Astrophysical Phenomena Abstract:
Aims: Flip-flops are top-hat-like X-ray flux variations, which have been observed in some transient accreting black hole binary systems, and feature simultaneous changes in the spectral hardness and the power density spectrum (PDS). They occur at a crucial time in the evolution of these systems, when the accretion disc emission starts to dominate over coronal emission. Flip-flops remain a poorly understood phenomenon, so we aim to thoroughly investigate them in a system featuring several such transitions.
Methods: Within the multitude of observations of Swift J1658.2-4242 during its outburst in early 2018, we detected 15 flip-flops, enabling a detailed analysis of their individual properties and the differences between them. We present observations by XMM-Newton, NuSTAR, Astrosat, Swift, Insight-HXMT, INTEGRAL, and ATCA. We analysed their light curves, searched for periodicities, computed their PDSs, and fitted their X-ray spectra, to investigate the source behaviour during flip-flop transitions and how the interval featuring flip-flops differs from the rest of the outburst.
Results: The flip-flops of Swift J1658.2-4242 are of an extreme variety, exhibiting flux differences of up to 77% within 100 s, which is much larger than what has been seen previously. We observed radical changes in the PDS simultaneous with the sharp flux variations, featuring transitions between the quasi-periodic oscillation types C and A, which have never been observed before. Changes in the PDS are delayed, but more rapid than changes in the light curve. Flip-flops occur in two intervals within the outburst, separated by about two weeks in which these phenomena were not seen. Transitions between the two flip-flop states occurred at random integer multiples of a fundamental period of 2.761 ks in the first interval and 2.61 ks in the second. Spectral analysis reveals the high and low flux flip-flop states to be very similar, but distinct from intervals lacking flip-flops. A change of the inner temperature of the accretion disc is responsible for most of the flux difference in the flip-flops. We also highlight the importance of correcting for the influence of the dust scattering halo on the X-ray spectra.

Nanoscale patterns made by using a 13.5-nm Schwarzschild objective and a laser produced plasma source (EI CONFERENCE) 会议论文 OAI收割
Optical Micro- and Nanometrology IV, April 16, 2012 - April 18, 2012, Brussels, Belgium
作者: Wang X.; Wang X.; Wang X.; Wang Z.; Wang Z.

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Lithium fluoride (LiF) crystal is a very promising candidate as nanometer resolution EUV and soft X-ray detector. Compared with other EUV and soft X-ray detectors charge coupled device and photographic films LiF crystal has high resolution large field of view and wide dynamic range. In this paper using LiF crystal as EUV detector and a Schwarzschild objective (SO) working at 13.5nm as projection optics mesh images with 4.2 m 1.2 m and 800 nm line width and pinhole patterns with 1.5m diameter are acquired in projection imaging mode and direct writing mode respectively. Fluorescence intensity profiles of images show that the resolution of mesh image is 900 nm and the one of pinhole image is 800 nm. In the experiments a spherical condense mirror based on normal incidence type is used to eliminate the damage and contamination on the masks (mesh and pinhole) caused by the laser plasma and the energy density is not decreased compared with that the masks are close to the plasma. The development of the SO the alignment of the objective and the imaging experiments are also reported. 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

1D-KBA microscope using double-periodic multilayer (EI CONFERENCE) 会议论文 OAI收割
Advances in X-Ray/EUV Optics and Components IV, August 3, 2009 - August 5, 2009, San Diego, CA, United states
作者: Wang Z.; Wang X.; Wang X.; Wang X.; Wang Z.

收藏 | 浏览/下载：11/0 | 提交时间：2013/03/25

To study the action of shock wave in CH target one-dimensional grazing incidence KBA microscope for 4.75keV energy was set up. Because of strong absorption in air 4.75keV energy microscope can just work in vacuum. Accordingly the alignment and assemblage will be very complicated and difficult. A special multilayer method using double periodic multilayer was proposed to solve this problem. This multilayer has high reflectivity not only for 4.75keV X-rays but also for 8keV X-rays at the same grazing incidence angle. It means 1D-KBA microscope has the same light trace for different working energies. Therefore we can implement the alignment and assembly of 4.75keV system by the help of 8keV X-rays. Because 8keV X-rays is very easy produced by X-ray tube and has strong transmittability in air the alignment and assemblage process became relatively easy. By now we have finished the alignment experiment at 8keV and obtained imaging results. The performance is about 2-3m resolution in 250m field of view. It is coincide with the calculation. 2009 SPIE.

Scaler mode technique for the ARGO-YBJ detector 期刊论文 OAI收割
ASTROPARTICLE PHYSICS, 2008, 卷号: 30, 期号: 2, 页码: 85-95
作者: ARGO-YBJ Collaboration

收藏 | 浏览/下载：22/0 | 提交时间：2015/12/02

GAMMA-RAY BURSTS VERY-HIGH-ENERGY COSMIC-RAYS DURATION SPECTRA

Research on the support structure of the primary mirror of large-aperture telescope (EI CONFERENCE) 会议论文 OAI收割
3rd International Symposium on Advanced Optical Manufacturing and Testing Technologies, AOMATT 2007: Large Mirrors and Telescopes, July 8, 2007 - July 12, 2007, Chengdu, China
Yang W.; Jingxu Z.

收藏 | 浏览/下载：28/0 | 提交时间：2013/03/25

Large-aperture telescope can be used in surveying battlefield researching landform searching object real-time monitoring imaging detecting and identifying spatial targets and so on. A large-aperture telescope for achieving high resolution power is designed to monitor spatial target and image in real time. Real-time monitoring plays an important role in military conflicts. The orbit parameter of object quantity geometrical shape parameter and so on can be obtained by detect spatial target. With the development of optical technology people require larger aperture in optics-electronic (OE) system. By increasing optical aperture the ability of collecting light and resolution power in the system can be enhanced. But the support structure of the primary mirror of large-aperture telescope will be a very difficult problem. With the increase of primary mirror aperture the weight of the primary mirror will become larger than before. The root mean square (rms) of the primary mirror is affected by many factors such as deadweight deformation of heat environment and so on. Due to the primary mirror of telescope is an important component of telescope system. By reducing the weight of primary mirror precision of the system is ensured. During the designing phase one can consider the supporting project of the primary mirror synthetically and analyze it roundly according to technical requirement of optical system and the effect factors. The final structural design can be reasonable. In an astronomical telescope the surface of reflector is an important part for collecting dark radiation of celestial bodies. Its surface shape will have an effect on collecting efficiency of telescope radiant energy directly. So the rms must be very high. Optical system of large aperture small wavelength and small focus can receive maximal light intensity. For ground-based optical astronomical telescope the design proposed in the paper can satisfy the requirement of the possible minimum atmosphere seeing at astronomical observatory site and exert the use efficiency of the telescope adequately. So the accuracy of the traditional surface of reflector can assure that 90% of all the light energy can be focused on within the angle diameter range of the minimum atmosphere seeing then 100% of light energy should be focused on the angle diameter range of minimum atmosphere seeing. Because the rms of mirror is very high precise surface machining and accurate the support of mirror are very important tasks during designing and manufacturing the telescope. In the paper various support techniques of a large-aperture telescope primary mirror are discussed and a 3.5 meter telescope system at the Starfire Optical Range (SOR) overviewed simply which was operated by the Directed Energy Directorate of the Air Force Research Laboratory Kirtland AFB NM USA from the ground-based O-E system for the observations of spatial target. We also analyze Theoretical elastic deformation of the Steward Observatory 2.3 meter mirror is analyzed.

Imaging quality analysis of KBA x-ray microscope working at grazing incidence (EI CONFERENCE) 会议论文 OAI收割
Optical Design and Testing II, November 8, 2004 - November 11, 2004, Beijing, United states
作者: Zhao L.

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In the latest 20 years x-ray imaging technology has developed fast in order to meet the need of x-ray photo-etching spatial exploration technology high-energy physics procedure diagnosis of inertial confinement fusion (ICF) et al. Since refractive index of materials in the x-ray region is lower than 1 and x-ray is strongly absorbed by materials it is very difficult to image objects in the x-ray region. Conventional imaging methods are hardly suitable to x-ray range. In general grazing reflective imaging and coding aperture imaging methods have been adopted more and more. In this paper according to user's requirement we have designed a non-coaxial grazing KBA microscope. The microscope consists of two sets of perpendicular spherical mirrors each set includes two parallel mirrors. Taking it as an example we have compiled an optical computing program for the non-coaxial grazing imaging systems so as to analyze and evaluate aberrations of KBA microscope. Thus it can help us to get an optimal comprehension of KBA x-ray imaging system. In the same time the analytical results provide reliable foundation for evaluating imaging quality of KBA microscope.

Linear bunchers and half-frequency bunching method 期刊论文 OAI收割
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, 2000, 卷号: 455, 期号: 12, 页码: 533-538
作者: Tang, JY; Jiang, JZ; Shi, AM; Yin, ZK; Wang, YF

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收藏 | 浏览/下载：15/0 | 提交时间：2010/10/29

very low energy beam transfer linear buncher half-frequency bunching high-voltage direct forming method