2025/09/22 by Crnogorčević, Milena, Linden, Tim, Peter, Annika H. G.
#Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE)
paper · doi:10.48550/arxiv.2509.18239
The γ-ray emission from active galactic nuclei (AGN), including both beamed blazars and misaligned-AGN, dominates the extragalactic γ-ray point-source population count and flux. While multi-wavelength studies have detected an increasing number of AGN within dwarf galaxies in the local Universe, γ-ray emission has so far only been associated with systems hosting supermassive black holes (SMBHs). Dwarf-galaxy AGN are of particular interest because their central black holes fall in the intermediate-mass black hole (IMBH) regime, offering insight into the early evolution of SMBHs. Using 15~years of Fermi-LAT data, we present the first search for γ-ray emission from dwarf-galaxy AGN. In the sample of 74 X-ray-selected dwarf-galaxy AGN, we find no sources that exceed the Fermi-LAT detection threshold. However, a joint-likelihood analysis reveals a modest, trials-corrected population-level excess (∼2σ) above blank-field expectations at very soft photon indices Γ\gtrsim 3.8 above 500~MeV. This hint is most pronounced when source contributions are weighed by Mα_\rm IMBH,i/di2, with α≃1--1.5, suggesting -- but not confirming -- that γ-ray emission could scale with the central black hole mass or a property correlated with it (e.g., accretion rate), but with a markedly softer spectrum than in SMBH-hosted AGN.