SPECTRAL VARIABILITY STUDY AND MASS ESTIMATION OF INTERMEDIATE-MASS BLACK HOLE CANDIDATE M82 X-1 USING SWIFT/XRT DATA

• Main Author: Hafizah, Izatul
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/39242
• Institution: Institut Teknologi Bandung

Ultraluminous X-ray source (ULX) is a class of X-ray emitters with luminosities >3×2039 erg/s. Due to the similarity of observational properties between ULX and Galactic Black Hole Binary (BHB), the central engine of a ULX is expected to be an accreting black hole. However, the black hole mass in ULX currently remains debated. M82 X-1 is one of the brightest ULX and was first discovered using ASCA satellites in the 2000s. This object has been observed to undergo spectral transition as the source brightened. The mass of black hole in M82 X-1 is also still uncertain. This Final Project aims to study the variability of the X-ray spectra and determine the mass of the black hole in M82 X-1. M82 X-1 data in this Final Project was taken from Swift/XRT observation archives. There are a total of 360 observation IDs until August 2018. Only 30 observation IDs are selected for currently study, consisting of 12 observation IDs fron 2014 and 18 observation IDs from 2015. Spectral fitting shows that M82 X-1 can be modeled with combination of power-law and disk blackbody components. The flux of M82 X-1 is found to increase from 2014 to 2015. Most of the 2015 data shows a greater dominance of hard components than those of 2014. Mass estimation is obtained by using 2 observation IDs only of 2015 data, which are the only observation IDs that show thermal spectra and satisfy the assumptions used in mass calculation. The obtained black hole masses imply a stellar-mass black hole of 4,10±2,78 ????? and 34,28±23,20 ????? for non-rotating and maximally rotating black hole, respectively, in M82 X-1. The mass estimation obtained in this Final Project does not support the existence of intermediate-mass black hole in M82 X-1.