共查询到19条相似文献，搜索用时 171 毫秒
1.
CygX—1硬态高能光子的时延 总被引：1，自引：1，他引：0
硬X射线和软射线光子的时延时研究主能辐射的一个重要方面，傅里叶交叉谱常常被用于教育处硬软光子之间的时延，但是交叉说示能在高于30Hz的傅里叶频率上从CygX-1测量到有统计意义的快速光变，由李惕培在时域上发展的交叉相关函方法能有效测量不同时间尺度上的时延，利用此交叉相关分析方法，讨论了不同观测时期CygX-1硬态高能光子时延 的性质，分析结果表明，CygX-1硬态在短的尺度（＜0．1秒）上存存在有意义的时间延迟，并将短时间尺度上的观测结果和各种CygX-1硬态模型进行了比较讨论。 相似文献
2.
李惕碚 《中国天文和天体物理学报》1997,(3)
分析第三个ＢＡＴＳＥγ射线暴表所列γ暴数据，发现γ射线暴参量间的相关性质随时间存在系统的变化．从１９９１年４月至１９９４年９月，γ射线暴能流与暴宽间的相关系数随时间上升．短暴的能谱硬度与暴宽间的相关系数随时间显著上升，而对于长暴未发现类似的变化． 相似文献
3.
分析了１９９３－１９９５年ＢＬＬａｃ、ＯＪ２８７和ＰＫＳ０７３５＋１７８三颗ＢＬＬａｃ天体光变的监测结果,并结合文献上他人发表的资料,发现一些ＢＬＬａｃ天体处于高态时活动性较强,短时标光变频繁发生,而处于低态时活动性较弱,短时标光变很少发生．文中提出活动星系核的相对论性喷流方向会改变,从而导致长期光变;高态是喷流方向与观测者视线夹角较小的表现,而低态则是夹角较大的表现。利用该模型能够解释ＢＬＬａｃ天体短时标光变行为在高态和低态下的差别,并能很好地解释Ｔａｋａｌｏ等人监测ＯＪ２８７时发现的新现象． 相似文献
4.
分析ＲＸＴＥ卫星ＰＣＡ探测器对ＣｙｇＸ－１的观测数据,得到了其处于高态及高低态转换时的Ｘ射线短时标爆发（Ｓｈｏｔ）结构．在所观测到的三种态中是不对称的,并且不同的状态中Ｓｈｏｔ的结构有明显差异．Ｓｈｏｔ前后沿可分别由双指数函数近似拟合．Ｓｈｏｔ中的快时变过程是由慢的上升前沿和快的下降后沿构成．在所观测态中Ｓｈｏｔ平均宽度约为０．１１秒（ＦＷＨＭ）,比低态时的宽度窄．同一状态中高能段的Ｓｈｏｔ宽度较低能段窄,且更加不对称．转换态的硬度在Ｓｈｏｔ峰前有明显下降,之后迅速上升,Ｓｈｏｔ期间的平均硬度低于非Ｓｈｏｔ期平均值;而高态时峰前硬度没有明显下降,Ｓｈｏｔ期间的平均硬度高于非Ｓｈｏｔ期间的平均值．本文还就Ｓｈｏｔ的产生机制进行了讨论． 相似文献
5.
分析ＲＸＴＥ卫星ＰＣＡ探测器对ＣｙｇＸ－１的观测数据,得到了其处于高态及高低高转换时的Ｘ射线短时标爆发（Ｓｈｏｔ）结构。在所观测到的三种态中是不对称的,并且不同的状态中Ｓｈｏｔ的结构有明显差异。Ｓｈｏｔ前后沿可分别由双指数函数近似拟合。Ｓｈｏｔ中的快时变过程是由慢的上升前沿和快的下降后沿构成。在所观测态中Ｓｈｏｔ平均宽度约为０．１１秒（ＦＷＨＭ）,比低态时的宽度窄。同一状态中高能段的Ｓｈｏｔ宽度较 相似文献
6.
针对天文观测数据不等间隔的特点,利用Jurkevich方法对黑洞候选体x射线双星CygX-1近16年的RossiX-rayTimingExplorer（RXTE）All-SkyMonitor（ASM）数据进行了频谱分析,并结合Kidger周期存在可信度的判据,发现CygX-1存在363±11．5d的光变周期,但没有发现420d的光变周期,而且150d的光变周期可能仅仅是51±1．4d光变周期的观测表象。 相似文献
7.
分析第三个ＢＡＴＳＥγ射线暴表所列γ暴数据，发现γ射线暴参量间的相关性质随时间存在系统的变化。从１９９１年４月至１９９４年９月，γ射线暴能流与暴宽间的相关系数随时间上升。短暴的能谱硬度与暴宽间的相关系数随时间显上升，而对于长暴未发现类似的变化。 相似文献
8.
对欧洲γ天文卫星COS-B数据的分析迄今未能发现在天鹅座X-3位置上存在着γ射线点源,从1977年6月到1980年6月,COS-B对Cyg-X天区进行了三次观测,各次观测的主要参数见表1,在第22次观测和第36次观测期间,天鹅区X-3大部分时间处于X辐射低态,各自只有6天左右处于高态;在第51次观测期间,大部分时间为X辐射高态,只有7天左右处于低态。 相似文献
9.
CygX-1 X辐射的功率谱 总被引：1，自引：1，他引：0
运用自回归功率谱研究CygX－1X辐射的频谱特征,结果显示CygX－1转换态和高／软态时变频谱的连续成分,可以统一由有截断的幂律加噪声成分描述,转换态存在小于3Hz的宽峰结构及准周期振荡（QPO）成分（4－12Hz）,而高／软态完全可由截断幂律谱描述,不存在显著的QPO．截断频率在各态都相当稳定,在不同态的演化与平流为主的吸积流模型（ADAF）预期的情形一致．本文结果表明,自回归功率港分析是研究X射线双星光变特征的一个有效的方法． 相似文献
10.
《天文学进展》2015,(3)
在Li-Paczynski新星(LP新星)模型被提出以及短暴的余辉被确认后,人们就积极地在短暴的光学(或光学-近红外)对应体中寻找LP新星存在的证据。第2章总结2013年之前的观测结果。第3、4章分别介绍短暴GRB 130603B、GRB 060614的基本性质与它们的近红外对应体的解释,它们的近红外超可能是LP新星存在的信号。第5章介绍短暴GRB 080503的基本性质以及它的光学对应体与X射线对应体的解释,它的光学与X射线光变曲线的晚期再增亮被解释为中子星并合之后的磁星加热的喷射物辐射(Merger-Nova辐射)。如果对于以上短暴伴随的光学-近红外对应物的解释正确,那么它们就给出了短暴与一些特殊的长暴来自致密星并合的第一批证据。除产生LP新星(与Merger-Novae)外,致密星并合之前的高速轨道运动与并合自身都将产生强烈的引力波暴(Gravitational-Wave Bursts,GWBs)。随着引力波时代的到来,致密星并合对应的各种电磁波现象的理论研究与观测受到更加密集的关注。由于引力波暴定位的不确定性较大,因此伴随引力波暴的LP新星可以作为引力波暴精确定位的最佳候选者之一。正在快速发展的高频度宽场光学-近红外巡天将对LP新星等现象进行富有成效的探索,并与引力波探测研究互相影响。因此,我们在最后介绍未来探测LP新星的方法及其多信使探测的前景。 相似文献
11.
《Chinese Astronomy and Astrophysics》2005,29(2):131-135
Temporal variations in the high-energy radiation of Cyg X-1 can be represented by the properties of its X-ray short bursts (shots). The properties of the X-ray shots of Cyg X-1 have been studied extensively, especially for the Cyg X-1 in its typical low/hard state. In this paper, we study the shot properties when Cyg X-1 is in its high/soft state, using direct superposition of shots and the autocorrelation function. Our result shows that when Cyg X-1 is in the high state, the shot structure is qualitatively similar to that of the low state, and that the full-width at half-maximum (FWHM) of the shot decreases with increasing energy, which is inconsistent with the prediction of the Comptonization model. In addition, the evolution of the shot energy spectrum and the asymmetry of the shot structure can explain the observed time lag in Cyg X-1. 相似文献
12.
Anna Szostek rzej A. Zdziarski Michael L. McCollough 《Monthly notices of the Royal Astronomical Society》2008,388(3):1001-1010
We present a detailed classification of the X-ray states of Cyg X-3 based on the spectral shape and a new classification of the radio states based on the long-term correlated behaviour of the radio and soft X-ray light curves. We find a sequence of correlations, starting with a positive correlation between the radio and soft X-ray fluxes in the hard spectral state, changing to a negative one at the transition to soft spectral states. The temporal evolution can be in either direction on that sequence, unless the source goes into a very weak radio state, from which it can return only following a major radio flare. The flare decline is via relatively bright radio states, which results in a hysteresis loop on the flux–flux diagram. We also study the hard X-ray light curve, and find its overall anticorrelation with the soft X-rays. During major radio flares, the radio flux responds exponentially to the level of a hard X-ray high-energy tail. We also specify the detailed correspondence between the radio states and the X-ray spectral states. We compare our results to those of black hole and neutron star binaries. Except for the effect of strong absorption and the energy of the high-energy break in the hard state, the X-ray spectral states of Cyg X-3 closely correspond to the canonical X-ray states of black hole binaries. Also, the radio/X-ray correlation closely corresponds to that found in black hole binaries, but it significantly differs from that in neutron star binaries. Overall, our results strongly support the presence of a black hole in Cyg X-3. 相似文献
13.
Short timescale bursts or “shots” of Cyg X-1 in one ms time bins were obtained from PCA/RXTE observation. By superposing many shots lined up at the peak, a mean profile was obtained, and this was done seperately for the different states, high, transitional and low. The mean shot profile is different for the different states. The duration of shot is shorter in the high than in the transitional state. In both, the duration is about 0.11 s, which is shorter than in the low state. The profile is more asymmetrical in high than in low energy bands. In the transitional state, the average hardness during shots is lower than that of the steady component. The mechanism of shot generation is discussed. 相似文献
14.
L. Hjalmarsdotter A. A. Zdziarski S. Larsson V. Beckmann M. McCollough D. C. Hannikainen O. Vilhu 《Monthly notices of the Royal Astronomical Society》2008,384(1):278-290
The X-ray binary Cygnus X-3 (Cyg X-3) is a highly variable X-ray source that displays a wide range of observed spectral states. One of the main states is significantly harder than the others, peaking at ∼20 keV, with only a weak low-energy component. Due to the enigmatic nature of this object, hidden inside the strong stellar wind of its Wolf–Rayet companion, it has remained unclear whether this state represents an intrinsic hard state, with truncation of the inner disc, or whether it is just a result of increased local absorption. We study the X-ray light curves from RXTE /ASM and CGRO /BATSE in terms of distributions and correlations of flux and hardness and find several signs of a bimodal behaviour of the accretion flow that are not likely to be the result of increased absorption in a surrounding medium. Using INTEGRAL observations, we model the broad-band spectrum of Cyg X-3 in its apparent hard state. We find that it can be well described by a model of a hard state with a truncated disc, despite the low cut-off energy, provided the accreted power is supplied to the electrons in the inner flow in the form of acceleration rather than thermal heating, resulting in a hybrid electron distribution and a spectrum with a significant contribution from non-thermal Comptonization, usually observed only in soft states. The high luminosity of this non-thermal hard state implies that either the transition takes place at significantly higher L / L E than in the usual advection models, or the mass of the compact object is ≳20 M⊙ , possibly making it the most-massive black hole observed in an X-ray binary in our Galaxy so far. We find that an absorption model as well as a model of almost pure Compton reflection also fit the data well, but both have difficulties explaining other results, in particular the radio/X-ray correlation. 相似文献
15.
R. P. Fender A. M. Stirling R. E. Spencer I. Brown G. G. Pooley T. W. B. Muxlow J. C. A. Miller-Jones 《Monthly notices of the Royal Astronomical Society》2006,369(2):603-607
We report the first observation of a transient relativistic jet from the canonical black hole candidate, Cygnus X-1, obtained with the Multi-Element Radio-Linked Interferometer Network (MERLIN). The jet was observed in only one of six epochs of MERLIN imaging of the source during a phase of repeated X-ray spectral transitions in 2004 Jan–Feb, and this epoch corresponded to the softest 1.5–12 keV X-ray spectrum. With only a single epoch revealing the jet, we cannot formally constrain its velocity. Nevertheless, several lines of reasoning suggest that the jet was probably launched 0.5–4.0 d before this brightening, corresponding to projected velocities of 0.2 c ≲ v app ≲ 1.6 c , and an intrinsic velocity of ≳0.3 c . We also report the occurrence of a major radio flare from Cyg X-1, reaching a flux density of ∼120 mJy at 15 GHz, and yet not associated with any resolvable radio emission, despite a concerted effort with MERLIN. We discuss the resolved jet in terms of the recently proposed 'unified model' for the disc–jet coupling in black hole X-ray binaries, and tentatively identify the 'jet line' for Cyg X-1. The source is consistent with the model in the sense that a steady jet appears to persist initially when the X-ray spectrum starts softening, and that once the spectral softening is complete the core radio emission is suppressed and transient ejecta/shock observed. However, there are some anomalies, and Cyg X-1 clearly does not behave like a normal black hole transient in progressing to the canonical soft/thermal state once the ejection event has happened. 相似文献
16.
Using the All-Sky Monitor (ASM, 1.5–12–kev) data of Rossi X-ray Timing Explorer (RXTE) from January 1996 to May 2005, we have made a detailed analysis of the correlation between photon-count rate and spectral hardness ratio HR2 (5–12 keV/3–5 keV) of the black-hole candidate X-ray binary Cyg X-1 in 3 energy bands, namely the A-band (1.5–3 keV), B-band (3–5 keV) and Cband (5–12 keV). By the study on the ASM data of 1-day time scale, we find: (1) When Cyg X-1 is in the soft state, the A-band photon-count rate and hardness ratio HR2 exhibit an anticorrelation, but in B-band and C-band there appears the positive correlation. When Cyg X-1 is in hard state, the photon-count rates in the A,B,C bands are all inversely correlated with the hardness ratio HR2; (2) No matter whether Cyg X-1 is in the soft state or the hard state, the hardness ratios HR2 and HR1 are always positively correlated. In addition, we have analyzed the “dwell by dwell” data of the ASM, and obtained the following interesting results: (1) In the period of MJD = 52600–52760 (while Cyg X-1 is in the hard state), the photon-count rates in the A-band and B-band are inversely correlated with HR2, but in the C-band there appears a relatively strong positive correlation; (2) During the hard state, a clear anticorrelation exists between the hardness ratios HR2 and HR1. 相似文献
17.
The fluctuating-accretion model of Lyubarskii and its extension by Kotov, Churazov & Gilfanov seek to explain the spectral-timing properties of the X-ray variability of accreting black holes in terms of inward-propagating mass accretion fluctuations produced at a broad range of radii. The fluctuations modulate the X-ray emitting region as they move inwards and can produce temporal-frequency-dependent lags between energy bands, and energy-dependent power spectral densities (PSDs) as a result of the different emissivity profiles, which may be expected at different X-ray energies. Here, we use a simple numerical implementation to investigate in detail the X-ray spectral-timing properties of the model and their relation to several physically interesting parameters, namely the emissivity profile in different energy bands, the geometrical thickness and viscosity parameter of the accretion flow, the strength of damping on the fluctuations and the temporal coherence (measured by the 'quality factor', Q ) of the fluctuations introduced at each radius. We find that a geometrically thick flow with large viscosity parameter is favoured, and we confirm that the predicted lags are quite robust to changes in the emissivity profile and physical parameters of the accretion flow, which may help to explain the similarity of the lag spectra in the low/hard and high/soft states of Cyg X-1. We also demonstrate the model regime where the light curves in different energy bands are highly spectrally coherent. We compare model predictions directly to X-ray data from the narrow line Seyfert 1 galaxy NGC 4051 and the black hole X-ray binary (BHXRB) Cyg X-1 in its high/soft state, and we show that this general scheme can reproduce simultaneously the time lags and energy-dependence of the PSD. 相似文献
18.
S. A. Farrell D. Barret G. K. Skinner 《Monthly notices of the Royal Astronomical Society》2009,393(1):139-156
We present the results of a study with the Swift Burst Alert Telescope in the 14–195 keV range of the long-term variability of five low-mass X-ray binaries with reported or suspected superorbital periods – 4U 1636−536, 4U 1820−303, 4U 1916−053, Cyg X-2 and Sco X-1. No significant persistent periodic modulation was detected around the previously reported periods in the 4U 1916−053, Cyg X-2 or Sco X-1 light curves. The ∼170-d period of 4U 1820−303 was detected up to 24 keV, consistent with variable accretion due to the previously proposed triple system model. The ∼46-d period in 4U 1636−536 was detected up to 100 keV, with the modulation in the low- and high-energy bands found to be phase shifted by ∼180° with respect to each other. This phase shift, when taken together with the near-coincident onset of the ∼46-d modulation and the low/hard X-ray state, leads us to speculate that the modulation could herald transient jet formation. 相似文献
19.
Marek Gierli&#;ski rzej A. Zdziarski Juri Poutanen Paolo S. Coppi Ken Ebisawa W. Neil Johnson 《Monthly notices of the Royal Astronomical Society》1999,309(2):496-512
We present X-ray/ γ -ray spectra of Cyg X-1 observed during the transition from the hard to the soft state and in the soft state by ASCA , RXTE and CGRO /OSSE in 1996 May and June. The spectra consist of a dominant soft component below ∼2 keV and a power-law-like continuum extending to at least ∼800 keV. We interpret them as emission from an optically thick, cold accretion disc and from an optically thin, non-thermal corona above the disc. A fraction f ≳0.5 of total available power is dissipated in the corona.
We model the soft component by multicolour blackbody disc emission taking into account the torque-free inner-boundary condition. If the disc extends down to the minimum stable orbit, the ASCA RXTE data yield the most probable black hole mass of MX ≈10 M⊙ and an accretion rate, , locating Cyg X-1 in the soft state in the upper part of the stable, gas-pressure-dominated, accretion-disc solution branch.
The spectrum of the corona is well modelled by repeated Compton scattering of seed photons from the disc off electrons with a hybrid, thermal/non-thermal distribution. The electron distribution can be characterized by a Maxwellian with an equilibrium temperature of kTe ∼30–50 keV, a Thomson optical depth of τ ∼0.3 and a quasi-power-law tail. The compactness of the corona is 2≲ℓh ≲7, and a presence of a significant population of electron–positron pairs is ruled out.
We find strong signatures of Compton reflection from a cold and ionized medium, presumably an accretion disc, with an apparent reflector solid angle, Ω/2π∼0.5–0.7. The reflected continuum is accompanied by a broad iron K α line. 相似文献
We model the soft component by multicolour blackbody disc emission taking into account the torque-free inner-boundary condition. If the disc extends down to the minimum stable orbit, the ASCA RXTE data yield the most probable black hole mass of M
The spectrum of the corona is well modelled by repeated Compton scattering of seed photons from the disc off electrons with a hybrid, thermal/non-thermal distribution. The electron distribution can be characterized by a Maxwellian with an equilibrium temperature of kT
We find strong signatures of Compton reflection from a cold and ionized medium, presumably an accretion disc, with an apparent reflector solid angle, Ω/2π∼0.5–0.7. The reflected continuum is accompanied by a broad iron K α line. 相似文献