On the outburst light curves of soft X-ray transients as response of the accretion disk to mass deposition

Ertan, U
Alpar, MA
We note that the solution of accretion disk dynamics for an initial delta-function mass distribution gives a light curve that fits both the rise and the decay pattern of the outburst light curves of black-hole Soft X-ray transients (BSXTs) until the onset of the first mini outburst quite well. The Green's function solution of Lynden-Bell & Pringle (1974) is employed for two different time-independent viscosity laws to calculate the expected count rates of X-ray photons in the Ginga energy bands as a function of time. For both models basic characteristics of the outburst light curves of two typical sources GS 2000+25 and GS/GRS 1124-68 are reproduced together with plausible values of the thin disk parameter alpha and the recurrence times. This agreement with the outburst light curves and the source properties during quiescence support the idea of mass accumulation and the sporadic release of accumulated mass at the outer disk.


On the outbursts of black hole soft X-ray transients
Ertan, U; Alpar, MA (EDP Sciences, 2002-10-01)
We suggest a new scenario to explain the outburst light curves of black hole soft X-ray transients together with the secondary maximum and the bump seen on their decay phases. Our explanations are based on the disk instability models considering the effect of X-ray irradiation. The scenario is consistent with the observed X-ray delays by a few days with respect to the optical rise for both the main outburst and the later maxima. We test our scenario by numerically solving the disk diffusion equation. The ob...
On the wake pattern of symmetric airfoils for different incidence angles at Re=1000
Kurtuluş, Dilek Funda (SAGE Publications, 2016-06-01)
In the current study, numerical simulations are performed in order to investigate effects of incidence angle and airfoil thickness on alternating vortex pattern of symmetric airfoils at Re = 1000. This alternating vortex pattern is found to be significantly varying in shape as the incidence angle increases. The results are obtained with 1 degrees increment from 0 degrees to 41 degrees and then with 10 degrees increment from 40 degrees until 180 degrees. The instantaneous and mean vortex patterns are investi...
On the Unsteady Behavior of the Flow Around NACA 0012 Airfoil with Steady External Conditions at Re=1000
Kurtuluş, Dilek Funda (2015-09-01)
Even for the stationary airfoils, due to the boundary and shear layer interactions of upper and lower surface of the airfoils, alternating vortex patterns form and the flow becomes time dependent. In the current study, the unsteady behavior of the flow around a symmetric airfoil is considered as incidence angle increases. The flow patterns are presented for wide range of angles of attack values. The vortex pattern generated is analyzed numerically for different angles of attack at Re=1000 around NACA 0012 a...
The gravitational effect on induced charge density for an obliquely rotating neutron start
De Paolis, F; Qadir, A; Tarman, Işık Hakan (1999-11-01)
The effect on the induced charge density of the gravitational field of a rotating neutron star with its magnetic axis inclined with respect to the rotational axis is investigated. While gravitation increases the charge density the obliquity reduces it.
Studies of Beauty Suppression via Nonprompt D-0 Mesons in Pb-Pb Collisions at root s(NN)=5.02 TeV
Sirunyan, A. M.; et. al. (American Physical Society (APS), 2019-07-01)
The transverse momentum spectra of D-0 mesons from b hadron decays are measured at midrapidity (vertical bar y vertical bar < 1) in pp and Pb-Pb collisions at a nucleon-nucleon center of mass energy of 5.02 TeV with the CMS detector at the LHC. The D-0 mesons from b hadron decays are distinguished from prompt D-0 mesons by their decay topologies. In Pb-Pb collisions, the B -> D-0 yield is found to be suppressed in the measured p(T) range from 2 to 100 GeV/c as compared to pp collisions. The suppression is w...
Citation Formats
U. Ertan and M. Alpar, “On the outburst light curves of soft X-ray transients as response of the accretion disk to mass deposition,” ASTRONOMY & ASTROPHYSICS, pp. 220–230, 1998, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/65952.