On the Measurement of Handedness in Fermi Large Area Telescope Data

Asplund, JuliaStockholms universitet,KTH,Nordic Institute for Theoretical Physics NORDITA,Stockholm Univ, AlbaNova Univ Ctr, Dept Astron, SE-10691 Stockholm, Sweden.,Nordiska institutet för teoretisk fysik (Nordita),Institutionen för astronomi (författare)

QC 20200909
A handedness in the arrival directions of high-energy photons from outside our Galaxy can be related to the helicity of an intergalactic magnetic field. Previous estimates by Tashiro et al. and Chen et al. showed a hint of a signal present in the photons observed by the Fermi Large Area Telescope (LAT). An update on the measurement of handedness in Fermi-LAT data is presented using more than 10 yr of observations. Simulations are performed to study the uncertainty of the measurements, taking into account the structure of the exposure caused by the energy-dependent instrument response and its observing profile, as well as the background from the interstellar medium. The simulations are required to accurately estimate the uncertainty and to show that previously the uncertainty was significantly underestimated. The apparent signal in the earlier analysis of Fermi-LAT data is rendered nonsignificant.

Jóhannesson, GudlaugurKTH,Nordic Institute for Theoretical Physics NORDITA,Univ Iceland, Sci Inst, IS-107 Reykjavik, Iceland.(Swepub:kth)u1dxoc6e (författare)
Brandenburg, AxelStockholms universitet,KTH,Nordic Institute for Theoretical Physics NORDITA,Stockholm Univ, AlbaNova Univ Ctr, Dept Astron, SE-10691 Stockholm, Sweden.;Univ Colorado, JILA, Boulder, CO 80303 USA.;Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80303 USA.;Carnegie Mellon Univ, McWilliams Ctr Cosmol, Pittsburgh, PA 15213 USA.;Carnegie Mellon Univ, Dept Phys, Pittsburgh, PA 15213 USA.,Nordiska institutet för teoretisk fysik (Nordita),Institutionen för astronomi,University of Colorado, USA; Carnegie Mellon University, USA(Swepub:su)brandenb (författare)
KTHNordic Institute for Theoretical Physics NORDITA (creator_code:org_t)

Av författaren/redakt...: Asplund, Julia; Jóhannesson, Gud ...; Brandenburg, Axe ...

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