Research on the uncertainties of black hole spin measurement

Abstract

Black hole is an important object and research object in astronomy and spin is one of the three physical quantities used to describe them. Its vital to get the spin parameter of a black hole as accurate as possible. Recently, researchers have used many methods to measure the spin parameter and two of them are most commonly used, the continuum-fitting method and the reflection-fitting method. Its difficult to avoid errors in the measurement of the two methods, but we can use various methods to minimize the error in the measurement. In this paper, we try to figure out using the two methods in measuring what kind of black holes spin can we reduce errors. We consider both the systematic error caused by model assumptions and the accidental error caused by dynamical parameter. Finally, we conclude that both the two methods can only measure black holes with certain accretion rate between 0.01 - 0.3. The continuum-fitting method can reduce errors in measuring high-spin black hole with small viscosity of the accretion disk. The reflection-fitting method can reduce errors in measuring high-spin/ low corona-height black hole.