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“X-ray Spectroscopy of the High-Mass X-ray Binary Pulsar Centaurus X-3 Over its Binary Orbit”. - Sachindra Naik, Biswajit Paul, and Zulfikar Ali. Introduction:. Interest: Extended dips in the light curve Cen-X: Eclipsing HMXRB pulsar Orbital period ~2.1 days, pulse period ~4.8 s
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“X-ray Spectroscopy of the High-Mass X-ray Binary Pulsar Centaurus X-3 Over its Binary Orbit” -Sachindra Naik, Biswajit Paul, and Zulfikar Ali
Introduction: • Interest: Extended dips in the light curve • Cen-X: Eclipsing HMXRB pulsar • Orbital period ~2.1 days, pulse period ~4.8 s • Composed of two stars: • Neutron star: mass of 1.21 ± 0.21 • O 6-8 III Supergiant (V779 Cen): mass of 20.5 ± 0.7 & radius of 12 • Distance = 5.7 ± 1.5 kpc • Luminosity ~5.0 x 1037 erg s-1 • B-field strength = (2.4-3.0) x 1012G • Spectra: 6.4 keV, 6.7 keV, & 6.97 keV iron emission lines
Light curves & other info The XIS detectors cover the 0.2-12 keV range and the HXD/PIN detectors cover 10-70 keV. The end of one eclipse is seen at about 0-50 ks; the beginning of another comes at about 150 ks. These eclipses and other features are present in the data up to about 40 keV; at higher energies, on the other hand, the graph becomes essentially featureless. The graph obviously has many features other than the eclipses at the ends; besides these two, it contains three dips, four egresses, five ingresses, six high-count regions, and two bumps that have different exposure times and count rates.
Discussion: • The X-ray light curve of the system shows a lot of variation presence of dips. • The dips are due to the presence of dense matter that absorbs the X-ray photons. • Partial covering absorption model • Problem: Iron emission lines
Bibliography: • Naik, S., Paul, B., & Ali, Z. (2011). X-RAY SPECTROSCOPY OF THE HIGH-MASS X-RAY BINARY PULSAR CENTAURUS X-3 OVER ITS BINARY ORBIT. The Astrophysical Journal,737(79), 1-8.