Akademik Veri Yönetim Sistemi
Tezin Türü: Yüksek Lisans
Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Fen Edebiyat Fakültesi, Fizik Bölümü, Türkiye
Tezin Onay Tarihi: 2019
Öğrenci: ÇAĞATAY KEREM DÖNMEZ
Danışman: ALTAN BAYKAL
Özet:In this thesis, spectral and timing analysis of the transient high-mass X-ray binary (HMXB) pulsar MAXI J1409-619 are presented. MAXI J1409-619 was discovered in October 2010, and went into an outburst in early December 2010 until February 2011. Observations of Swift and RXTE throughout this period are used in the thesis. The analysis results are in line with the assertion that MAXI J1409-619 is an accretion-powered pulsar. Time-resolved energy spectra of RXTE and Swift data confirm the previously reported findings. At the peak outburst, the spectra are modeled with a power law with a high energy cutoff, plus a Gaussian Fe line fixed at 6.4 keV. On the other hand, a simple power law model is used in observations with unsufficiently low count rates. Absorption-corrected peak flux on MJD 55534 is calculated to be 1.96*10^-9 erg s^-1 cm^-2 in 3-25 keV range. Assuming a distance of ~14.5 kpc, corresponding peak luminosity is L_(3-25 keV) ~ 4.9*10^37 erg s^-1. Furthermore, evolution of spectral parameters of the source and the correlations between these parameters are studied. Throughout the outburst stage, periodic variability in the light curves becomes evident. P_(spin) ~ 503 s is found at the outburst onset. Using phase-resolved spectroscopy, a double-peaked pulse profile is verified, and spectral parameters with changing phases are investigated. Lastly, power spectral analysis confirms the existence of quasi-periodic oscillations (QPO) and their harmonics in MAXI J1409-619. As the outburst progresses, centroid frequency of the QPOs shifts from ~0.2 Hz to ~0.1 Hz, implying the QPO features are linked with flux and mass transfer rates. Two observations on MJD 55541 with 19 ks exposure reveals a QPO at 0.190 Hz with two harmonics, implying a magnetic field of ~1*10^13 G.