Modeling the flaring activity of the high z, hard X-ray selected blazar IGR J22517+2217

TL;DR

This study models the spectral energy distribution of the high-redshift blazar IGR J22517+2217 during different activity states, revealing significant variability and a powerful jet driven by external inverse Compton processes.

Contribution

It provides the first detailed modeling of the blazar's SED in multiple states, highlighting the role of external Compton scattering and jet region location in variability.

Findings

High energy hump peaks at 10^20-10^22 Hz, much higher than the synchrotron component.

Variability explained by changes in electron population and dissipation region location.

Flaring state exhibits one of the most powerful jets among similar high-redshift blazars.

Abstract

We present new Suzaku and Fermi data, and re-analyzed archival hard X-ray data from INTEGRAL and Swift-BAT survey, to investigate the physical properties of the luminous, high-redshift, hard X-ray selected blazar IGR J22517+2217, through the modelization of its broad band spectral energy distribution (SED) in two different activity states. Through the analysis of the new Suzaku data and the flux selected data from archival hard X-ray observations, we build the source SED in two different states, one for the newly discovered flare occurred in 2005 and one for the following quiescent period. Both SEDs are strongly dominated by the high energy hump peaked at 10^20 -10^22 Hz, that is at least two orders of magnitude higher than the low energy (synchrotron) one at 10^11 -10^14 Hz, and varies by a factor of 10 between the two states. In both states the high energy hump is modeled as inverse Compton emission between relativistic electrons and seed photons produced externally to the jet, while the synchrotron self-Compton component is found to be negligible. In our model the observed variability can be accounted for by a variation of the total number of emitting electrons, and by a dissipation region radius changing from within to outside the broad line region as the luminosity increases. In its flaring activity, IGR J22517+2217 shows one of the most powerful jet among the population of extreme, hard X-ray selected, high redshift blazar observed so far.