Constraints on the Intergalactic Magnetic Field from Bow Ties in the Gamma-ray Sky

Paul Tiede, Avery E. Broderick, Mohamad Shalaby, Christoph Pfrommer, Ewald Puchwein, Philip Chang, Astrid Lamberts

Published 2017-02-08Version 1

Pair creation on the cosmic infrared background and subsequent inverse-Compton scattering on the CMB potentially reprocesses the TeV emission of blazars into faint GeV halos with structures sensitive to intergalactic magnetic fields (IGMF). We attempt to detect such halos exploiting their highly anisotropic shape. Their persistent nondetection excludes at greater than $3.9\sigma$ an IGMF with correlation lengths >100 Mpc and current-day strengths in the range $10^{-16}$ to $10^{-15}$ G, and at 2 sigma from $10^{-17}$ to $10^{-14}$ G, covering the range implied by gamma-ray spectra of nearby TeV emitters. Alternatively, plasma processes could pre-empt the inverse-Compton cascade.