STUDY OF HARD X-RAY SPECTRUM OF BLACK HOLE X-RAY BINARY TRANSIENTS USING NUSTAR MISSION DATA

• Main Author: Rahmawati, Novia
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/81626
• Institution: Institut Teknologi Bandung

Black Hole X-ray Binaries or BHXBs are black holes that are found in a binary system that emits X-rays. BHXBs that show significant changes in their intensity at certain times are known as transient sources. The increase in intensity is called as outburst phase, which is characterized by an intensity rise on the order of hundreds to thousands of times in a short period, followed by a decrease to the previous state over a relatively longer period. Transient sources also have a quiescent phase, a phase when the object does not exhibit significant X-ray activity and tends to be observed as a faint X-ray source. In transient sources, various spectral states during outburst and quiescent phase can be studied. Generally, spectral states are dominated by two states: the soft state, dominated by low-energy range photons (soft X-ray), and the hard state, dominated by high-energy range photons (hard X-ray). Most researchs are focused on soft X-ray, given that most X-ray telescope missions operate in this range. Since the launch of the NuSTAR mission in 2012, the X-ray observations have been able to cover energies in the hard X-ray range. In this Final Project, the modeling of NuSTAR X-ray spectra in the range 3 – 50 keV is conducted to identify differences in the hard X-ray spectral characteristics of MAXI J1820+070 during outburst and quiescent phase. The differences in spectral characteristics during outburst and quiescent phase are indicated by decreasing photon index values when the spectrum is dominated by non-thermal components. From the analysis of 8 observational data, results were obtained in the form of hardness ratio, hardness intensity diagram, and spectral models. Based on the comparison of spectral models, it was concluded that power-law, accretions disk, and Fe emission line components are required.