Tidal disruption events and their echoes

Supermassive black holes are widely believed to be present in the center of massive galaxies. When a star passes too close to the black hole, it will be tidally disrupted and partially accreted, producing a flash of radiation over an energy range from soft X-ray to UV,which is called a tidal disruption event (TDE). As a special form of accretion, a TDE is one of the key topics of the explosively growing field of time-domain astronomy. Although TDEs are rare, they have aroused great interest because they can serve as a unique laboratory to study various physics problems associated with black holes. Moreover, the gas and dust echoes of TDEs not only provide us with a novel method to probe the interstellar medium in the vicinity of black holes, but also signify a new approach to detect new TDEs, particularly those obscured by dust. We report our series of advances in this field.