THE STUDY OF X-RAY NOVA OUTBURST WITHIN THE FRAMEWORK OF DISK INSTABILITY MODEL (DIM)

• Main Author: Andamari Saraswati, Tiara
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/50000
• Institution: Institut Teknologi Bandung

X-ray Nova (XRN) especially those harboring a black hole, which belongs to Low Mass X-ray Binary (LMXB) class, exhibit transient phenomena when its luminosity increase by 2 order of magnitude or more (so-called, outburst) after being almost undetected for decades (so-called, quiescent). This phenomenon cannot be explained by steady state accretion into a compact object as in the case of the standard disk model. To ll in the gaps between observation and the existing theory, Disk Instability Model (DIM) was proposed. In this Final Project, investigation on whether the DIM could possibly explain all of the behaviour observed from XRN during outburst and quiescent was conducted. Because this study required a large sample of repeated observation data and good time resolution, All Sky Monitor (ASM) and Proportional Counter Array (PCA) from RXTE mission were used. The objects of interest in this study were XTE J1118 + 480, XTE J1550 - 564, GRO J1655 - 40, and GX 339 - 4. Morphology and basic parameter analysis such as timescale, peak luminosity, and total radiated energy during outburst have been done to the light curve datasets (2 - 12 keV). Spectral tting was done using standard accretion disk and additional models to the spectral data (3 - 20 keV). The most common morphology found within the sample of the light curve data is tri- angular with average rise and decay timescale were 27; 35 0; 48 and 13; 32 4; 33 days for outburst and 66; 53 4; 71 and 34; 09 9; 62 days for minioutburst. Positive correla- tion was evident between total radiated energy and peak luminosity which implies that disk mass governs the maximum rate of energy release during the outburst. Spectral data shows that all of the outburst in the sample was started and ended by hard state while being in the thermal, steep-power-law, or intermediate state in between; this phenomenon was not observed in minioutburst. The following results of this work are in good agreement with DIM prediction: spectral evolution as a manifestation for the existence of limit-cycle and positive correlation between total radiated energy and peak luminosity. On the other hand, some ndings in this work cannot be explain within the framework of DIM, such as: obtained timescale diers from the typical value that results in a morphology other than FRED and the frequency and amplitude of the re ares feature. All things considered, it can be concluded that DIM alone cannot explain all of the observed phenomenon from XRN.