Sensitivity reach of gamma-ray measurements for strong cosmological magnetic fields

Abstract

A primordial magnetic field with the strength in the 1-10 pG range can resolve the tension between different measurements of the Hubble constant and provide an explanation for the excess opacity in the 21 cm line at redshift $15<z<20$, if it is present during the recombination and reionization epochs. This field can also survive in the voids of the large-scale Structure in the present day universe. We study the sensitivity reach of the gamma-ray technique for measurement of such relatively strong cosmological magnetic field using deep exposure(s) of the nearest hard spectrum blazar(s) with CTA telescopes. We show that the gamma-ray measurement method can sense the primordial magnetic field with a strength of up to $10^{-11}$~G. Combination of the cosmic microwave background and gamma-ray constraints can thus sense the full range of possible cosmological magnetic fields to confirm or rule out their relevance to the problem of the origin of cosmic magnetic fields, as well as their influence on recombination and reionization epochs.

9 pages, 7 figures, accepted to ApJ

References in corpus (3)

• Large Magellanic Cloud Cepheid Standards Provide a 1% Foundation for the Determination of the Hubble Constant and Stronger Evidence for Physics Beyond LambdaCDM
• Relieving the Hubble tension with primordial magnetic fields
• The jet of Markarian 501 from millions of Schwarzschild radii down to a few hundreds

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• Modelling the propagation of very-high-energy gamma rays with the CRbeam code: Comparison with CRPropa and ELMAG codes
• Detectability of large correlation length inflationary magnetic field with Cherenkov telescopes
• Gravitational wave signal from primordial magnetic fields in the Pulsar Timing Array frequency band
• LISA and $\gamma$-ray telescopes as multi-messenger probes of a first-order cosmological phase transition
• Kinematic dynamos and resolution limits for Smoothed Particle Magnetohydrodynamics