Fermi Gamma-ray Imaging of a Radio Galaxy

Abstract

The Fermi Gamma-ray Space Telescope has detected the gamma-ray glow emanating from the giant radio lobes of the radio galaxy Centaurus A. The resolved gamma-ray image shows the lobes clearly separated from the central active source. In contrast to all other active galaxies detected so far in high-energy gamma-rays, the lobe flux constitutes a considerable portion (>1/2) of the total source emission. The gamma-ray emission from the lobes is interpreted as inverse Compton scattered relic radiation from the cosmic microwave background (CMB), with additional contribution at higher energies from the infrared-to-optical extragalactic background light (EBL). These measurements provide gamma-ray constraints on the magnetic field and particle energy content in radio galaxy lobes, and a promising method to probe the cosmic relic photon fields.

27 pages, includes Supplementary Online Material; corresponding authors: C.C. Cheung, Y. Fukazawa, J. Knodlseder, L. Stawarz

References in corpus (8)

• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Data Processing, Sky Maps, and Basic Results
• High-energy particle acceleration at the radio-lobe shock of Centaurus A
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• The Discovery of Cepheids and a Distance to NGC 5128
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• Compton X-ray and Gamma-ray Emission from Extended Radio Galaxies

Cited by in corpus (2)

• VHE Gamma-Ray Induced Pair Cascades in the Radiation Fields of Dust Tori of AGN: Application to Cen A
• The Production of Ultra High Energy Cosmic Rays during the Early Epochs of Radio-loud AGN