The Supercritical Accretion Disk of SS 433

The structure of the SS 433 supercritical accretion disk derived from spectral and photometric data is described. In the disk plane, gas outflows at a velocity of about 100-150 km/s, while above the disk plane, the velocity increases sharply and reaches 1500 km/s at polar angle 60°. The outer parts of the accretion disk are involved in the precessional motion, which means that the slaved disk precession model is correct. There is complex periodic variability in the radial velocities of SS 433. Apart from the well-known precessional and orbital variability, the strongest cycle is 1/7 of the precession period, P7 = 23.228 ± 0.005 days. This is interpreted as evidence for a spiral shock in the accretion disk. The He II 4686 line consists of two components: a stream-formed narrow Gaussian profile and a broad double-peaked one. The latter is completely eclipsed at phase 0.0. Its blue and red peaks are probably emitted in gaseous cocoons around the bases of the relativistic jets. A correct value of the mass function has been found, which shows that the optical star is massive. The relativistic star's mass is estimated to be Mx 6M.     

X-ray line formation in the spectrum of SS 433

The mechanisms for the formation of X-ray lines in the spectrum of SS 433 are investigated by taking into account the radiative transfer inside the jets. The results ofMonte Carlo numerical simulations are presented. The effect of a decrease in line intensity due to scattering inside the jet turns out to be pronounced, but it does not exceed 60% in magnitude on the entire grid of parameters. The line broadening due to scattering, nutational motion, and the contribution of satellites can lead to overestimates of the jet opening angle ?? from the line widths in Chandra X-ray observations. The fine structure of the lines turns out to be very sensitive to the scattering effects. This makes its investigation by planned X-ray observatories equipped with high-resolution spectrometers (primarily Astro-H) a powerful tool for diagnosing the parameters of the jets in SS 433.     

Peculiar nature of hard X-ray eclipse in SS433 from INTEGRAL observations

The analysis of hard X-ray INTEGRAL observations (2003–2008) of superaccreting Galactic microquasar SS433 at precessional phases of the source with the maximum disc opening angle is carried out. It is found that the shape and width of the primary X-ray eclipse are strongly variable, suggesting additional absorption in dense stellar wind and gas outflows from the optical A7I component and the wind–wind collision region. The independence of the observed hard X-ray spectrum on the accretion disc precessional phase suggests that hard X-ray emission (20–100 keV) is formed in an extended, hot, quasi-isothermal corona, probably heated by interaction of relativistic jet with inhomogeneous wind outflow from the precessing supercritical accretion disc. A joint modelling of X-ray eclipsing and precessional hard X-ray variability of SS433 revealed by INTEGRAL by a geometrical model suggests the binary mass ratio   q = m_x / m _v ≃  0.25–0.5. The absolute minimum of joint orbital and precessional  χ²  residuals is reached at   q ≃ 0.3  . The found binary mass ratio range allows us to explain the substantial precessional variability of the minimum brightness at the middle of the primary optical eclipse. For the mass function of the optical star   f _v = 0.268 M_⊙  as derived from Hillwig & Gies data, the obtained value of   q ≃ 0.3  yields the masses of the components   m_x ≃ 5.3 M_⊙, m _v ≃ 17.7 M_⊙  , confirming the black hole nature of the compact object in SS433.     

An interpretation of the SS433 phenomenon

We present a model which provides an interpretation of the observations relating to the object SS433. The model represents the logical development of the proposal of Collins and Newsom (1979) and consists of a binary system comprised of a massive early-type stellar primary, containing a substantial magnetic field and stellar wind, which is precessionally driven with a 165 day period by a much less massive secondary. The cool gas Doppler-shifted spectrum occurs behind a shock front propagating around the system in the remote regions of the stellar magnetic field. The constraints placed on any model by observation are set forth, and particular attention is given to how they are met by this model. Specifically, we show that the energetics and emission requirements are easily met while the observed radial velocity curve can be fit within the mostly stochastic variations displayed by the source. Finally we discuss the implications of the model for further observation and for the immediate past and future of the object.Supported in part by the National Science Foundation.     

Monte Carlo simulations of the broad-band X-ray continuum of SS433

We develop a Monte Carlo technique based on L.B. Lucy's indivisible photon packets method to calculate X-ray continuum spectra of Comptonized thermal plasma in arbitrary geometry and apply it to describe the broad-band X-ray continuum of the galactic superaccreting microquasar SS433 observed by INTEGRAL . A physical model of the X-ray emitting region is proposed that includes thermal emission from the accretion disc, jets and hot corona where the photons of different origin are Comptonized. From comparison with INTEGRAL observations, we estimate physical parameters of the complex X-ray emitting region in SS433 and present model spectra for different viewing angles of the object.     

Colliding winds model of X-ray radiation in SS 433: analysis of X-ray eclipses

Interpretation of X-ray eclipses in SS 433 binary system in the framework of wind-wind collision model yields high value of mass ratioq =m _x /m _v > 1 which implies high mass of relativistic objectm _x > 8M .     

Identification of X-ray lines in the spectrum of the arcsec-scale precessing jets of SS 433

The extended X-ray emission observed at arcsec scales along the propagation trajectory of the precessing relativistic jets of the Galactic microquasar SS 433 features a broad emission line, with the position of the centroid being significantly different for the approaching and receding jets (≈7.3 and ≈6.4 keV, respectively). These observed line positions are at odds with the predictions of the kinematic model for any of the plausible bright spectral lines in this band, raising the question of their identification. Here we address this issue by taking into account time delays of the emission coming from the receding regions of the jets relative to that from the approaching ones, which cause a substantial phase shift and distortion of the predicted line positions for the extended (~10¹⁷ cm) emission compared to the X-ray and optical lines observed from the central source (emitted at distances ~10¹¹ and ~10¹⁵ cm, respectively). We demonstrate that the observed line positions are fully consistent with the Fe XXVI Lyα (E ₀ = 6.96 keV) line emerging from a region of size ~6 × 10¹⁶ cm along the jet. This supports the idea that intensive reheating of the jets up to temperatures >10 keV takes place at these distances, probably as a result of partial deceleration of the jets due to interaction with the surrounding medium, which might cause collisions between discrete dense blobs inside the jets.     

Possible origin of the radio emission from SS433 jets

It is shown that radio emission from the jet of the galactic source SS433 as well as the variability of its flux density could be accounted for by the inelastic collision model. Variability in the jet flux is attributed mainly to the variability in the thermal proton number density available in the jet regions.     

Simulations of Gas Flow from a Galactic Disk Towards the Black-Hole Accretion Disk

We report preliminary results of hydrodynamical modeling of gas flow in a galaxy potential towards a central massive black hole. We use a bar-like perturbation on the large scale in order to cause the initial inflow, and we concentrate our attention on the inner parts of the galaxy, where the potential becomes axisymmetric, or where it is dominated by an inner, secondary bar. Our high-resolution grid-based algorithm allows us to get a detailed picture of gas dynamics down to about 10 pc from the galaxy center, where the black hole becomes dominant. We find that inner bars may not increase the gas inflow, but for certain potential and gas parameters, gas flows to the center in a spiral shock. This revised version was published online in September 2006 with corrections to the Cover Date.     

SS433研究的新进展

SS433是银河系内一个著名的高能天体,W50是它周围的超新星遗迹,自20世纪70年代末SS433的运动模型建立以来,已经受到了越来越多的关注,取得了丰富的多波段观测资料。但是,直到现在,关于这一系统的一些基本性质和参数还存在相当大的争论。该文介绍了关于SS433研究的某些新进展,主要包括SS433的运动模型和喷流的膨胀冷却模型,SS433的物质损失,各种时标的光变和喷流的结构,并对关于SS433研究的热点问题作了总结与展望。     

Stochastic Resonance of Accretion Disk and the Persistent Low-Frequency Quasi-Periodic Oscillations in Black Hole X-ray Binaries

In this paper, we use a Langevin type equation with a damping term and stochastic force to describe the stochastic oscillations on the vertical direction of the accretion disk around a black hole, and calculate the luminosity and power spectral density (PSD) for an oscillating disk. Then we discuss the stochastic resonance (SR) phenomenon in PSD curves for different parameter values of viscosity coefficient, accretion rate, mass of black hole and outer radius of the disk. The results show that our simulated PSD curves of luminosity for disk oscillation have the same profile as the observed PSD of black hole X-ray binaries (BHXBs) in the lowhard state, and the SR of accretion disk oscillation may be an alternative interpretation of the persistent low-frequency quasi-periodic oscillations (LFQPOs).     

An estimate of the effects of light travel times in the optical jets of SS433

The effect of the finite extent of the optically radiating region of SS433 is investigated. Light travel time effects are small, but a slightly improved fit to the observational data can be obtained with a dimension ofl _o?10¹⁵ cm for the optical jets.     

Periods ranging from 5 to 1500 days in the anticorrelated moving lines of SS 433

Some tens of harmonic components are found in the moving lines of SS 433, leaving a standard deviation of 0.002 in Z units, that is comparable to the observational error.Ten harmonics appear anticorrelated in the two branches, among which those at 80, 155, and 1500 days are also strong. Their behaviour indicates changing structure in the ejecting mechanism.No secular change is occurring in the precessional 163-day period beyond the estimated error of 5×10^–5 d^–1. No periodicity occurs in beam velocity. One quarter of cases of (Z₁+Z₂) are found outside their mean value by more than 5. This implies either variable beam velocity or absence of strict antiparallelism.Paper presented at the Lembang-Bamberg IAU Colloquium No. 80 on Double Stars: Physical Properties and Generic Relations, held at Bandung, Indonesia, 3–7 June, 1983.     

Exploring the Accretion Disk Structure and X-ray Radiation of GX 17+2 Based on kHz QPOs and Cross-correlations

Applying the timing tools of kilohertz quasi-periodic oscillations(k Hz QPOs) and cross-correlations, we study the influence of the magnetosphere-disk relation on the X-ray radiation process of GX 17+2. First, as the spectral state track of X-ray emission evolves along the horizontal branch(HB), the magnetosphere-disk radii of the source derived by k Hz QPOs shrink from r ～ 24 km to r ～ 18 km, while its average X-ray intensities in ≤10 ke V and in ≥10 ke V show the opposite evolutional trends. M...     

An Upper Limit on Sunspot Activity During the Maunder Minimum

We have estimated the upper and lower limits of sunspot activity, in terms of active day fraction during the Maunder minimum (1645–1710), using raw information on individual daily observations (Hoyt and Schatten, 1998). Establishing the relation between the sunspot activity and active day fraction after 1850, we evaluate the upper limit of annual group sunspot number during the deep Maunder minimum (1645–1700) which does not exceed 4. The earlier finding of a dominant 22-year periodicity during the Maunder minimum is verified and shown to be robust. Also we confirm that the start of the Maunder minimum was very abrupt.     

Indirect Imaging of the Accretion Disk Rim in W Crucis

The eclipsing binary W Crucis belongs to the rare group of strongly interacting binaries, which are believed to be shortly after the first and rapid mass transfer between components, prior to the Algol phase. New 7-colour photometric measurements in the Geneva system are presented for this long period binary. Several consecutive cycles were covered, which revealed rather complex light curves with pronounced bumps and asymmetries in the eclipse shoulders, as well in out-of-eclipse brightness. We modelled light curves with a variant of Rutten’s 3D eclipse-mapping method, which makes it possible to indirectly image the accretion disk rim. A patchy structure has emerged, which explains the rather erratic and complex light curve and its cycle-to-cycle variations.     

Mechanism of jet formation in objects of the type of SS 433

Erevan State University; Institute of Applied Physics Problems, Armenian Academy of Sciences. Translated from Astrofizika, Vol. 31, No. 2, pp. 271–279, September–October, 1989.     

吸积盘与恒星在星云盘中形成时的角动量损失

本文根据吸秘盘理论与天文观测结果,给出一个恒星在星云盘中形成的模型.通过计算角动量方程,获得了质量定常分布ρ(r)～r_(-β)(β=0,1,2)时的一般性解.对1M恒星的数值解表明:恒星在转动磁化的星云盘中形成时,角动量确实发生了巨大转移;并且,β=2的解能较满意地解释太阳系的角动量奇异性.