活动星系核的尘埃环反响映射
AGN Dust reverberation mapping
Dust reverberation mapping (DRM) is a powerful technique that we can use the time lags between the optical light curves and the infrared light curves to determine the geometry and kinematics of the dust torus. The larger size scale of the dusty torus compared to the disk and BLR leads to longer lags and slower and weaker variability, affording lower cadence monitoring but requiring longer campaigns. In the last 20 years, a number of dedicated dust reverberation campaigns have substantially increased the sample of lags and established the relation between the torus size and luminosity. On average the dust lags are ∼4 times longer than Hβ lags. But recent observation shows that the torus sizes measured from interferometric observations are always larger than that found from DRM. Some papers tried to use the anisotropic bowl-shaped dust torus to explain it. From the high-cadence DRM observations, the NIR echo was found, which means that the varying hot dust is essentially located at the edge rather than along the entire bowl rim. I will introduce the theory and observation results of the DRM, and use some well-studied AGNs to introduce the details.
