How a black hole accretes matter and how this process is regulated are fundamental but unsolved questions in astrophysics. In transient black-hole binaries, a lot of mass stored in an accretion disk is suddenly drained to the central black hole because of thermal-viscous instability. This phenomenon is called an outburst and is observable at various wavelengths.
Our scientific article opens a new window to measure black-hole masses accurately by systematic optical time-series observations which can be performed even by amateur observers.
Link to the scientific paper: OAR@UM: Optical variability correlated with X-ray spectral transition the black-hole transient ASASSN-18ey = MAXI J1820+070