Jets, Blazars and the EBL in the GLAST-EXIST Era

TL;DR

This paper discusses how the combined capabilities of the GLAST and EXIST missions can advance understanding of blazar spectra, jet physics, and the extragalactic background light through simultaneous multi-wavelength observations.

Contribution

It proposes utilizing the synergy between GLAST and EXIST to measure blazar spectra and variability, enabling new insights into jet physics and the cosmic diffuse background.

Findings

Simultaneous X-ray and gamma-ray observations constrain blazar spectra.

High-energy spectral breaks help measure the extragalactic background light.

The combined data improve understanding of jet physics and gamma-ray backgrounds.

Abstract

The synergy of GLAST and the proposed EXIST mission as the Black Hole Finder Probe in the Beyond Einstein Program is remarkable. With its full-sky per orbit hard X-ray imaging (3-600 keV) and "nuFnu" sensitivity comparable to GLAST, EXIST could measure variability and spectra of Blazars in the hard X-ray synchrotron component simultaneous with GLAST (~10-100GeV) measures of the inverse Compton component, thereby uniquely constraining intrinsic source spectra and allowing measured high energy spectral breaks to measure the cosmic diffuse extra-galactic background light (EBL) by determining the intervening diffuse IR photon field required to yield the observed break from photon-photon absorption. Such studies also constrain the physics of jets (and parameters and indeed the validity of SSC models) and the origin of the >100 MeV gamma-ray diffuse background likely arising from Blazars and jet-dominated sources. An overview of the EXIST mission, which could fly in the GLAST era, is given together with a synopsis of other key synergies of GLAST-EXIST science.