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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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收藏 | 浏览/下载：58/0 | 提交时间：2022/02/08

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.

Unified calculations of optical and EPR data for Cu3+ ion in Al2O3 crystal 期刊论文 OAI收割
Journal of Magnetism and Magnetic Materials, 2015, 卷号: 377, 页码: 190-192
W. L. Feng; W. C. Zheng; J. Y. Xue; F. Zhao

收藏 | 浏览/下载：25/0 | 提交时间：2015/01/14

Electron paramagnetic resonance Optical spectra Crystal and ligand-field theory Defect structure Cu3+ Al2O3 spin-hamiltonian parameters atomic screening constants temperature-dependence scf functions ruby ti-al2o3 centers spectra fields laser

Spin-Hamiltonian parameters for the tetragonal Gd-M(3+)-F-i(-) centers in CaF2 and SrF2 crystals 期刊论文 OAI收割
Journal of Magnetic Resonance, 2013, 卷号: 227, 页码: 62-65
W. Q. Yang; Y. Zhang; Y. Lin; W. C. Zheng

收藏 | 浏览/下载：39/0 | 提交时间：2013/12/24

Electron paramagnetic resonance Crystal and ligand-field theory Defect structure Gd3+ Calcium fluoride Strontium fluoride electron-paramagnetic-resonance superposition-model analysis temperature-dependence optical spectroscopy magnetic-resonance laser applications local-structure epr-spectra gd3+ fluorites

Diagnostics of electron temperature and density in a capillary predischarge Ar plasma (EI CONFERENCE) 会议论文 OAI收割
2011 Academic International Symposium on Optoelectronics and Microelectronics Technology, AISOMT 2011, October 12, 2011 - October 16, 2011, Harbin, China
作者: Zhao Y.; Xie Y.; Zhao Y.; Zhao Y.

收藏 | 浏览/下载：24/0 | 提交时间：2013/03/25

The spectra of the argon plasma generated by capillary predischarge are observed in the experiments. The electron temperature and density are obtained with the method of spectrum analysis. The electron temperatures are approximately 0.7eV and the electron densities are about 11022 m-3. When increasing the pressure the electron temperature decreases and the electron density increases on the contrary. 2011 IEEE.

Theoretical studies on the SH parameters and local distortion structure of KCl:Ag(2+) crystal 期刊论文 OAI收割
Physica B-Condensed Matter, 2011, 卷号: 406, 期号: 1, 页码: 56-58
W. L. Li; X. M. Li; W. L. Feng; W. J. Yang; C. Y. Tao

收藏 | 浏览/下载：23/0 | 提交时间：2012/04/13

Crystal- and ligand-field theory Spin-Hamiltonian (SH) parameters Distortion structure Ag(2+) KCl spin-hamiltonian parameters atomic screening constants single-crystals paramagnetic-resonance epr parameters scf functions ions spectra field temperature

Synthesis, morphology and optical properties of SrTiO3:Pr 3+ phosphors (EI CONFERENCE) 会议论文 OAI收割
3rd International Symposium on Functional Materials 2009, ISFM 2009, June 15, 2009 - June 18, 2009, Jinju, Korea, Republic of
作者: Li W.; Li W.

收藏 | 浏览/下载：23/0 | 提交时间：2013/03/25

SrTiO3:Pr3+ phosphors with different morphologies were prepared by using high-temperature solid-state reaction the solvothermal method and sol-gel synthesis. All the products were systematically characterized by powder x-ray diffraction (XRD) infrared spectroscopy (IR) scanning electron microscopy (SEM) photoluminescence (PL) and photoluminescent excitation spectra (PLE). The influence of different synthesis methods on the morphology and optical properties of SrTiO3:Pr3+ was discussed. 2010 The Royal Swedish Academy of Sciences.

Investigations of the spin-Hamiltonian parameters and tetragonal distortion due to the Jahn-Teller effect for Cu(H(2)O)(6)(2+) clusters in C(NH(2))(3)Al(SO(4))(2)center dot 6H(2)O: Cu(2+) crystal 期刊论文 OAI收割
Physica B-Condensed Matter, 2010, 卷号: 405, 期号: 8, 页码: 2018-2020
W. L. Feng; W. Q. Yang; W. C. Zheng; H. G. Liu

收藏 | 浏览/下载：14/0 | 提交时间：2012/04/13

Spin-Hamiltonian parameters Crystal- and ligand-field theory Jahn-Teller effect C(NH(2))(3)Al(SO(4))(2)center dot 6H(2)O: Cu(2+) electron-paramagnetic-resonance aluminum sulfate hexahydrate atomic screening constants single-crystal epr-spectra scf functions field ions temperature systems

Statistics of gravity wave spectra in the troposphere and lower stratosphere over beijing 期刊论文 iSwitch采集
Science china-earth sciences, 2010, 卷号: 53, 期号: 1, 页码: 141-149
作者: Yuan Wei; Xu JiYao; Wu YongFu; Chen HongBin; Bian JianChun

收藏 | 浏览/下载：28/0 | 提交时间：2019/05/10

Balloon measurements Temperature and temperature spectra Gravity waves and saturation mode Dominant vertical wavelengths

Vertical wavenumber spectra of atmospheric ozone measured from ozonesonde observations 期刊论文 OAI收割
Advances in Space Research, 2009, 卷号: 43, 期号: 9, 页码: 1364-1371
Yuan, W.; Xu, J. Y.; Wu, Y. F.; Bian, J. C.; Chen, H. B.

收藏 | 浏览/下载：38/0 | 提交时间：2014/04/30

Ozonesonde measurement Ozone and ozone spectra Gravity waves and saturation models Dominant vertical wavelength gravity-waves commercial aircraft universal spectrum middle atmosphere temperature saturation winds stratosphere climatology variability

Vertical-external-cavity surface-emitting lasers: Numerical simulation, and characterization (EI CONFERENCE) 会议论文 OAI收割
Optoelectronic Materials and Devices III, October 27, 2008 - October 30, 2008, Hangzhou, China
作者: Qin L.

收藏 | 浏览/下载：26/0 | 提交时间：2013/03/25

Firstly the vertical external-cavity surface-emiting lasers (VECSELs) device structure and model was given and the output characteristic was simple calculated. Then in experiment the VECSELs were grown bonded on to the heat sink and optically pumped by high-power 808nm diode laser array with fiber output module the light emission spectra were measured. Finally The thermal characteristic of the VECSELs was investigated by changing the temperature of the substrate. 2008 SPIE.