Neutron Star Low-mass X-ray Binary: a natural laboratory to probe extreme environments

 A neutron star is an extremely dense star with a core density of five to ten times the density of an atomic nucleus. Such a 
 star provides a unique opportunity to probe some aspects of extreme environments, ranging from supranuclear matter to 
 very strong gravity. A neutron star low-mass X-ray binary (LMXB) is a binary stellar system with a neutron star and a low-mass 
 companion star rotating around each other. In this system the neutron star accretes matter from the companion, and as this 
 matter falls into the deep potential well of the neutron star, the gravitational potential energy is released primarily in the 
 X-ray wavelengths. Timing and spectral analysis of this X-ray emission can be used to probe the extreme environments 
 mentioned above. Here we will discuss three X-ray phenomena of neutron star LMXBs: kilohertz quasi-periodic oscillations, 
 broad relativistic spectral iron emission lines and thermonuclear X-ray bursts.