Göttingen 2025 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 78: Gamma Astronomy II

T 78.1: Vortrag

Donnerstag, 3. April 2025, 16:15–16:30, VG 2.103

Constraining the intergalactic Magnetic field with Fermi-LAT observations — •Yosef Abed, Dieter Horns, and Matías Sotomayor — Institut für Experimentalphysik, Universität Hamburg

The intergalactic magnetic field (IGMF) represents a weak and omnipresent magnetic field permeating the intergalactic medium. Its origins are unclear and a detection of the IGMF has yet to be achieved. The most sensitive method to search indirectly for evidence of the existence of the IGMF are based upon γ-ray observations.This talk presents a conservative lower limit for the IGMF, calculated from Fermi-LAT data and ELMAG simulations. Extended source templates for several blazars were generated using ELMAG simulations with varying magnetic field strengths of the IGMF, where its coherence length was taken into account. In the Fermi binned likelihood analysis of these blazars, the extended templates were added as diffuse sources and from the loglikelihood profile, the normalization with 95% confidence level was calculated for each template. Then the spectral energy distributions of the normalized fitted template and the non-fitted simulation template were compared, from which the conservative lower limit for the IGMF was estimated.

Keywords: Intergalactic Magnetic Field; Fermi-LAT observations; Blazars; ELMAG