No abstract

Black hole is a kind of special celestial subject whose density is so great that even the light cannot escape, which has always been a popular topic. This study will present the recent progress of observation related to three quantities of black holes. As a leading-in, we first introduced some of the most commonly discussed black holes by demonstrating their field equations, metric, and some other representative quantities. On this basis, the formation process of a black hole will be described. In addition, a picture of the detectors used in cosmology observation is discussed before getting any further into the methods applied in observation. Subsequently, we summarized observations regarding the three elements of a black hole (mass, charge and spin). For these three different characters of black hole, different methods and theories were put into use, including gravitational retro-lensing, twin-peak QPOs, accretion disks, continuum fitting method, and black body radiation. Eventually, possible limitations are evaluated and possible improving approaches on current observations are proposed. Overall, these results shed light on guiding further researches focusing on exploring the black holes.