AGN Forecasts for the Cherenkov Telescope Array

TL;DR

This paper predicts the detection capabilities of the Cherenkov Telescope Array for active galactic nuclei by extrapolating Fermi-LAT data and modeling EBL absorption, indicating a significant increase in detectable sources and potential insights into the EBL.

Contribution

It provides the first detailed prediction of CTA's AGN detection rate and its ability to observe high-redshift blazars, expanding current gamma-ray astronomy capabilities.

Findings

CTA will triple current AGN detection rates.

CTA can observe blazars up to redshift z ~ 2.

Potential to study the EBL shape with gamma-ray data.

Abstract

The First Fermi-LAT catalog (1FGL) represents the most complete list of sources in the GeV sky to date. We use the reported 1FGL spectral parameters to extrapolate Fermi AGN spectra to the very-high energy (VHE) range (15 GeV - 300 TeV). The extrapolated VHE spectra are then attenuated using current estimations of the extragalactic background light (EBL) absorption as a function of redshift. Using the expected effective areas and background rates of the Cherenkov Telescope Array (CTA) from Monte Carlo simulations, we make a first order prediction of the AGN population accessible to CTA in the VHE sky. We find that CTA should easily triple the AGN detection rate of current ground-based Cherenkov telescopes. In addition, CTA will allow unprecedented access to high-redshift blazars out to z ~ 2, and hence will start to reveal the EBL shape with gamma-ray observations.