Over the next ten years, Vera C.\ Rubin Observatory (VRO) will observe $\sim$10 million active galactic nuclei (AGN) with a regular and high cadence. During this time, intensities of most these AGN fluctuate stochastically. Here, we explore prospects to quantify precisely fluctuations VRO measurements light curves. To do so, suppose that each curve is described by damped random walk given fluct...

Measurement of the invariance of the speed of light observing the active galactic nucleus Mkn421 with the MAGIC Telescope A mi amor, por que su valentía me ha enseñado como recorrer este camino.

A star cluster in a galactic nucleus sinks toward the galactic center due to dynamical friction. As it spirals inward, the cluster loses mass due to stellar evolution, relaxation driven evaporation, and tidal stripping, eventually dissolving in the galactic tidal field. We model the inspiral of dense young star clusters near the center of our Galaxy to study the extent of the region of paramete...

Interactions between galaxies are suggested to be a mechanism responsible for feeding Active Galactic Nuclei (AGN). Theoretical models show that interactions are an efficient way to drive gas from the galaxy to the nucleus, however, the observational evidence on this subject is controversial. Here we review results in this field, discuss possible limitations of previous studies and the importan...

We carried out a one-night optical V and near-infrared JHK monitoring observation of the least luminous Seyfert 1 galaxy, NGC4395, on 2004 May 1, and detected for the first time the intraday flux variations in the J and H bands, while such variation was not clearly seen for the K band. The detected J and H variations are synchronized with the flux variation in the V band, which indicates that t...

About 500d after explosion the light curve of the Type Ia SN 1998bu suddenly flattened and at the same time the spectrum changed from the typical nebular emission to a blue continuum with broad absorption and emission features reminiscent of the SN spectrum at early phases. We show that in analogy to SN 1991T (Schmidt et al. 1994), this can be explained by the emergence of a light echo from a f...