天⽂瞬變源的 X 光波段研究

Abstract

Astronomical transients are all kinds of celestial objects that show rapid brightening in any forms of electromagnetic wave. Although there are no standard criterion on flux variation or outburst duration to define a transient, the baseline amplitude is often set to at least an order of magnitude brighter than the quiescent flux level on timescales of seconds, weeks, or even longer, making these phenomena extremely important to discover and investigate faint objects, like slowly-accreting white dwarfs, quiescent X-ray binaries and distant inactive galactic nuclei, of which most are hard to be detected outside the active phase. In particular, transients with luminosities higher than the super-Eddington limits of 10-100 M_sun are good candidates of intermediate mass black holes (IMBHs), of which the mysterious mechanism of formation is still under debate. In addition to the ancient compact objects, core collapse supernovae, the deadly transients of massive stars, are another valuable transient class, which is important for the studies of the stellar evolution and how the compact objects form from the ordinary stars. In this thesis, we present X-ray studies of four transient sources MAXI J1058-744, SN 2013df, SN 1986L, and PSR J1023+0038, mainly using the public archive of the X-ray Telescope (XRT) on board the Swift satellite. This work provides better understandings to various classes of transient, which is useful for the X-ray transient identifications in the future.