EVIDENCE FOR GAMMA-RAY HALOS AROUND ACTIVE GALACTIC NUCLEI AND THE FIRST MEASUREMENT OF INTERGALACTIC MAGNETIC FIELDS

Journal Article · Sun Oct 10 00:00:00 EDT 2010 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/722/1/L39· OSTI ID:21452761

Ando, Shin'ichiro ^[1]; Kusenko, Alexander ^[2]

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1. California Institute of Technology, Mail Code 350-17, Pasadena, CA 91125 (United States)
2. Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States)

Intergalactic magnetic fields (IGMFs) can cause the appearance of halos around the gamma-ray images of distant objects because an electromagnetic cascade initiated by a high-energy gamma-ray interaction with the photon background is broadened by magnetic deflections. We report evidence of such gamma-ray halos in the stacked images of the 170 brightest active galactic nuclei (AGNs) in the 11 month source catalog of the Fermi Gamma-Ray Space Telescope. Excess over the point-spread function in the surface brightness profile is statistically significant at 3.5{sigma} (99.95% confidence level), for the nearby, hard population of AGNs. The halo size and brightness are consistent with IGMF, B {sub IGMF} {approx} 10{sup -15} G. The knowledge of IGMF will facilitate the future gamma-ray and charged-particle astronomy. Furthermore, since IGMFs are likely to originate from the primordial seed fields created shortly after the big bang, this potentially opens a new window on the origin of cosmological magnetic fields, inflation, and the phase transitions in the early universe.

• OSTI ID: 21452761
• Journal Information: Astrophysical Journal Letters, Vol. 722, Issue 1; Other Information: DOI: 10.1088/2041-8205/722/1/L39; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ASTRONOMY
BRIGHTNESS
CHARGED PARTICLES
GALAXIES
GALAXY NUCLEI
GAMMA RADIATION
INFLATIONARY UNIVERSE
MAGNETIC FIELDS
PHOTONS
TELESCOPES
UNIVERSE
BOSONS
COSMOLOGICAL MODELS
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
IONIZING RADIATIONS
MASSLESS PARTICLES
MATHEMATICAL MODELS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
RADIATIONS