Fermi Gamma-ray Space Telescope

Search for High-Redshift Blazars with Fermi/LAT

Michael Kreter
(M. Kadler, R. Ojha, S. Buson, J. Wilms, M. Boettcher, on behalf of the Fermi/LAT Collaboration)


High-redshift blazars are difficult to study with Fermi/LAT, as their emission peaks are often downshifted to energies below the GeV band and at their large distances, only the very brightest objects are detectable. On the other hand, high-redshift blazars are highly important targets, because they serve as cosmological probes and represent the most powerful class of gamma-ray sources in the Universe. Unfortunately, only a small number of high-redshift blazars could be detected with Fermi/LAT so far. In this work, we present a strategy to significantly increase the detection statistics at redshift z ≥ 2.5 via a search for flaring events in high-redshift gamma-ray blazars whose long-term flux is just below the sensitivity limit of Fermi/LAT.