کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5487757 1523720 2018 6 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Modeling the response of a standard accretion disc to stochastic viscous fluctuations
ترجمه فارسی عنوان
مدل سازی واکنش یک دیسک تحرک استاندارد به نوسانات غلطی غلیظ
موضوعات مرتبط
مهندسی و علوم پایه فیزیک و نجوم نجوم و فیزیک نجومی
چکیده انگلیسی
The observed variability of X-ray binaries over a wide range of time-scales can be understood in the framework of a stochastic propagation model, where viscous fluctuations at different radii induce accretion rate variability that propagate inwards to the X-ray producing region. The scenario successfully explains the power spectra, the linear rms-flux relation as well as the time-lag between different energy photons. The predictions of this model have been obtained using approximate analytical solutions or empirically motivated models which take into account the effect of these propagating variability on the radiative process of complex accretion flows. Here, we study the variation of the accretion rate due to such viscous fluctuations using a hydro-dynamical code for the standard geometrically thin, gas pressure dominated α-disc with a zero torque boundary condition. Our results confirm earlier findings that the time-lag between a perturbation and the resultant inner accretion rate variation depends on the frequency (or time-period) of the perturbation. Here we have quantified that the time-lag tlag∝f−0.54, for time-periods less than the viscous time-scale of the perturbation radius and is nearly constant otherwise. This, coupled with radiative process would produce the observed frequency dependent time-lag between different energy bands. We also confirm that if there are random Gaussian fluctuations of the α-parameter at different radii, the resultant inner accretion rate has a power spectrum which is a power-law.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: New Astronomy - Volume 58, January 2018, Pages 84-89
نویسندگان
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