Variações em curta e longa escalas de tempo do perfil em duplo-pico de Ha da Galáxia Pictor A

Abstract

In the current paradigm nuclear activity in a galaxy happens when the central Supermassive Black Hole (SMBH) is being fed by an accretion disk of gas. The spectral signature of the accretion disk is the presence of broad double-peaked Balmer emission lines, as seen in the optical spectra from the AGN of the galaxy Pictor A. In this work it is presented a dataset of 18 spectroscopic observations corresponding to a 12 year monitoring of the Ha double-peak profile of the Pictor A galaxy, with the goal of studying the variability of the profile in short and long time scales. For this purpose, measurements were performed in the double-peak profile using the IFSCUBE software, which indicated that variations of the integrated flux of the broad line occur in short time scales, on the order of 40 days, and also that significant variations in the relative intensity of the red and blue sides of the profile occurs on time scales of years. The physical scenario proposed to explain the observed variations is a scenario in which the doublepeaked profile originates in an accretion disk with Keplerian and relativistic orbits, is inclined with respect to the plane of sky, and has an axially asymmetric surface emissivity with a radius of maximum emissivity. In order to make the theoretical time scales of the accretion disk to agree with the observed time scales of variability of the double-peaked profile, it is required that the gas in the disk orbits a SMBH with a mass of M 2 108M . In this scenario the physical extent of the line emitting region is in the range from 6–48 light-days.