We propose that superluminous transients that appear at central regions of active galactic nuclei ( AGNs ) such as CSS100217:102913+404220 ( CSS100217 ) and PS16dtm , which reach near or super-Eddington luminosities of the central black holes , are powered by the interaction between accretion disk winds and clouds in broad-line regions ( BLRs ) surrounding them .
If the disk luminosity temporary increases by , e.g. , limit-cycle oscillations , leading to a powerful radiatively driven wind , strong shock waves propagate in the BLR .
Because the dense clouds in the AGN BLRs typically have similar densities to those found in Type IIn supernovae , strong radiative shocks emerge and efficiently convert the ejecta kinetic energy to radiation .
As a result , transients similar to Type IIn supernovae can be observed at AGN central regions .
Since a typical black-hole disk wind velocity is \simeq 0.1 c where c is the speed of light , the ejecta kinetic energy is expected to be \simeq 10 ^ { 52 } ~ { } \mathrm { erg } when \simeq 1 ~ { } M _ { \odot } is ejected .
This kinetic energy is transformed to radiation energy in a timescale for the wind to sweep up a similar mass to itself in the BLR , which is a few hundred days .
Therefore , both luminosities ( \sim 10 ^ { 44 } ~ { } \mathrm { erg~ { } s ^ { -1 } } ) and timescales ( \sim 100 days ) of the superluminous transients from AGN central regions match to those expected in our interaction model .
If CSS100217 and PS16dtm are related to the AGN activities triggered by limit-cycle oscillations , they become bright again in coming years or decades .