Variability of the Blazar 1156+295 in 2005–2020

Abstract

We present and analyze the monitoring results of the blazar 1156+295 in radio, optical, and gamma ranges in 2005-2020. After a long period of relative quietness at the end of 2017, a sharp increase in activity occurred in all spectral ranges, from radio to gamma. The connection between events that took place in different ranges has been studied. Photometric variability in the optical-infrared region is explained by the presence of a variable component with a constant on average power-law relative energy distribution in the spectrum (F ν ~ ν -1.4 ). Separate sources of polarized radiation with a relatively high degree of polarization are identified. The synchrotron nature of the components responsible for the activity is beyond doubt. During VLBI observations, four components moving at superluminal speeds were found; a connection has been established between the instants of their appearance and events in all spectral ranges. It is noted that the difference in the values of the spectral indices for different time intervals does not allow to explain the variability of the flux by geometric factors only (by the change in the Doppler factor due to the change in the angle between the line of sight and the subluminal motion direction of the emitting ensemble of electrons). For different time intervals, the energy distributions of electrons in ensembles should be different.