Affiliation: INAF-Osservatorio Astrofisico di Torino

Contribution: Oral

Title: Outflows in blazars

Abstract: Among the multitude of AGN types, blazars stand up for their bright and strongly variable emission at all wavelengths and on all timescales. This is due to Doppler beaming of the non-thermal radiation emitted from a relativistic plasma jet closely aligned with the line of sight, which usually overwhelms the contributions from the other AGN emission components. 4C 71.07 is a bright blazar at redshift of about 2, showing a prominent big blue bump and a strong Compton dominance in the spectral energy distribution. This makes it the ideal target to study both the beamed jet and unbeamed nuclear contributions to the observed emission. The source was the subject of an intensive 2-yr long monitoring campaign by the Whole Earth Blazar Telescope (WEBT) Collaboration. The optical and radio data from the WEBT were complemented with high-energy observations by the Swift and Fermi satellites to have a complete broad-band knowledge of the multiwavelength behaviour (Raiteri et al. 2019, MNRAS 489, 1837). During the campaign, the source experienced a gamma-ray outburst , which allowed us to analyse the variability properties of the jet (Vercellone et al. 2019, A&A, 621, A82). Moreover, we performed optical spectroscopic monitoring at the NOT and WHT, and obtained near-infrared spectra at TNG. These observations were meant to reveal the unbeamed properties of the blazar quasar-like core. We could not identify any narrow emission lines, and estimated the systemic redshift from the Hbeta and Halpha broad emission lines. In spite of the blazar orientation, which implies a nearly face-on accretion disc, the high-ionization lines are very broad. They are also blueshifted, the shift increasing with ionization potential. This indicates the presence of a strong ionized outflow (Raiteri et al. 2020, MNRAS, 493, 2793). We are now investigating the presence of outflows in a sample of blazars at about the same redshift as 4C 71.07 observed by the Gemini and SOAR telescopes to assess what are the physical conditions that lead to this phenomenon and what information we can extract from it.

This contribution can be found here (pdf).