STUDI X-RAY BURST TIPE-I: BATASAN MASSA DAN RADIUS BINTANG NEUTRON PADA SISTEM SAX J1748.9-2021 BERDASARKAN METODE TOUCHDOWN POINT

• Main Author: Daud, Muhammad
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/57576
• Institution: Institut Teknologi Bandung

Type-I X-ray burst is a thermal instability phenomenon which happens on the surface of an accreting neutron star which belongs to the class of Low-Mass X-Ray Binary (LMXB). Occasionally, the observed flux could reach the Eddington limit during type-I X-ray burst which is best explained by Photospheric Radius Expansion mechanism (PRE). PRE involves quasi-static expansion of neutron star photosphere. Based on type-I X-ray burst studies, the PRE mechanism could gives us a chance to measure the mass and radius of a neutron star in LMXB. The method which can be used to measure the mass and radius of a neutron star based on PRE mechanism is called touchdown point method. In this research, we show how this method is used to measure the mass and radius of a neutron star in Newtonian frame of reference. We analyze data of SAX J1748.9-2021 for this research. SAX J1748.9- 2021 is a well-known LMXB and also an intermittent X-ray pulsar which is located in globular cluster NGC 6440. The X-ray data were gathered from Rossi X-Ray Timing Explorer mission (RXTE) with Proportional Counter Array instrument (PCA). There are more than 20 X-ray burst observed from RXTE, nine of them are PRE burst and used in this research. The X-ray data were analyzed using time-resolved spectroscopy in which burst profile was divided into time segments and spectral analysis was conducted to each segment. Therefore, the blackbody normalization Kbb and temperature kTbb parameters can be plotted against time so that we have some informations about the touchdown point. All of the PRE bursts clearly show the touchdown point feature. Hence, the mass and radii of the neutron star can be determined. We obtain the result for mass in range 0.60 ? 1.88 M? and radius 11.8 ? 18.0 km based on the data and method which are already mentioned.