Hunting for Evidence of the Black Hole Event Horizon in X-Ray Binaries Using RXTE and Swift Data

• Main Author: Iman Alfarizki, Fahmi
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/39243
• Institution: Institut Teknologi Bandung

Black holes and neutron stars are compact objects that have many similar observational properties which are not easily distinguishable. The most fundamen- tal physical dierence is neutron stars have a solid surface, whereas black holes do not, as an event horizon is merely an imaginary surface. The results of X-ray bi- naries spectral studies for black holes and neutron stars at high luminosity state indicate that there are observational properties which are only in black holes that are expected to be used to prove the existence of the event horizon black holes. In this Final Project, the evidence for black hole event horizon is attempted to be searched using RXTE and Swift data from 2004 until 2012. The objects studied are Cyg X-1 and XTE J1752-223 for black holes and Cir X-1 and 4U 1608-522 for neutron stars, for comparison. Spectral tting are carried out on the data of each mission and simultaneously using an accretion disk model and its supporting components. Fluxes in certain energy ranges are obtained from spectral tting are used to construct color-color diagram, whereas uxes in 3-20 keV is used to measured luminosity assuming a certain distance. Luminosity and Tin can be used to obtain the innermost radius of an accretion disk, rin, which at certain cases can be assumed as rISCO. The results of data processing indicate that neutron stars data are located outside the forbidden area for neutron stars in the color-color diagram. Black hole spectra which are found in the forbidden area for neutron stars in the color-color diagram is in thermal state but the thermal component is not greatly dominated the overall spectra. These spectra could not be modeled with the standard model of accretion disk but slim disk model instead. The values of Rin of Cyg X-1 show a constant trend as the luminosity varies by a factor of 3, so that it can be used to determine rISCO and also as evidence of the existence of the event horizon, while similar trend cannot be seen in XTE J1752-223. Average value of rin from observational data for Cyg X-1 is 15,661,22 km and XTE J1752-223 is 8,610,56 km.