paper

Determination of the turbulent parameter in the accretion disks: effects of self-irradiation in 4U 1543-47 during the 2002 outburst

arXiv:1610.01399 · doi:10.1093/mnras/stx768

Abstract

We investigate the viscous evolution of the accretion disk in 4U 1543-47, a black hole binary system, during the first 30 days after the peak of the 2002 burst by comparing the observed and theoretical accretion rate evolution . The observed is obtained from spectral modelling of the archival RXTE/PCA data. Different scenarios of disk decay evolution are possible depending on a degree of self-irradiation of the disk by the emission from its centre. If the self-irradiation, which is parametrized by factor , had been as high as , then the disk would have been completely ionized up to the tidal radius and the short time of the decay would have required the turbulent parameter . We find that the shape of the curve is much better explained in a model with a shrinking high-viscosity zone. If , the resulting lie in the interval for the black hole masses in the range , while the radius of the ionized disk is variable and controlled by irradiation. For very weak irradiation, , the burst decline develops as in normal outbursts of dwarf novae with . The optical data indicate that in 4U 1543-47 (2002) was not greater than approximately . Generally, modelling of an X-ray nova burst allows one to estimate that depends on the black hole parameters. We present the public 1-D code Freddi to model the viscous evolution of an accretion disk. Analytic approximations are derived to estimate in X-ray novae using .

13 pages, 14 figures. Accepted for publication in MNRAS. Code Freddi is publicly available at http://xray.sai.msu.ru/~malanchev/freddi/ V3 fixes a typo in an equation on page 3, we thank Ankit Mishra for pointing it out to us

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