Gamma-ray observations of blazars and the intergalactic magnetic field spectrum

Abstract

Very-high energy observations of blazars can be used to constrain the strength of the intergalactic magnetic field. A simplifying assumption which is often made is that of a magnetic field of constant strength composed by randomly oriented and identical cells. In this paper, we demonstrate that a more realistic description of the structure of the intergalactic magnetic field is indeed needed. If such a description is adopted, the observational bounds on the field strength are significantly affected in the limit of short field correlation lengths: in particular, they acquire a dependence on the magnetic field power spectrum. In the case of intergalactic magnetic fields which are generated causally, for which the magnetic field large scale spectral index is $n_B\ge 2$ and even, the observational lower bound becomes more constraining by about a factor 3. If instead $-3<n_B<-2$, the lower bound is significantly relaxed. Such magnetic fields with very red spectra can in principle be produced during inflation, but remain up to now speculative.

9 pages, 5 figures

References in corpus (9)

• Lower limit on the strength and filling factor of extragalactic magnetic fields
• Magnetic fields from inflation?
• Gravitational waves from stochastic relativistic sources: primordial turbulence and magnetic fields
• Adding helicity to inflationary magnetogenesis
• Universal upper limit on inflation energy scale from cosmic magnetic field
• A method of measurement of extragalactic magnetic fields by TeV gamma ray telescopes
• Cascading on extragalactic background light
• Parity-odd correlators of diffuse gamma rays and intergalactic magnetic fields
• Gamma ray signatures of ultra high energy cosmic ray accelerators: electromagnetic cascade versus synchrotron radiation of secondary electrons

Cited by in corpus (23)

• Potential of radio telescopes as high-frequency gravitational wave detectors
• Gauge-field production during axion inflation in the gradient expansion formalism
• The Gamma-Ray Window to Intergalactic Magnetism
• Constraints on the intergalactic magnetic field using Fermi-LAT and H.E.S.S. blazar observations
• A survey of the thermal and non-thermal properties of cosmic filaments
• Backreaction from gauge fields produced during inflation
• Hypermagnetogenesis from axion inflation: Model-independent estimates
• Simulations and observational tests of primordial magnetic fields from Cosmic Microwave Background constraints
• Magnetogenesis in Higgs-Starobinsky inflation
• Physics of cosmological cascades and observable properties
• Scalar perturbations from inflation in the presence of gauge fields
• Revisiting Magnetogenesis during Inflation
• Schwinger production of scalar particles during and after inflation from the first principles
• Gradient expansion formalism for magnetogenesis in the kinetic coupling model
• Primordial Helical Magnetic Fields from Inflation?
• Simulating the LOcal Web (SLOW) -- III: Synchrotron emission from the local cosmic web
• Chirality production during axion inflation
• Generation of an electromagnetic field nonminimally coupled to gravity during Higgs inflation
• Probing axion-like particles with multimessenger observations of neutron star mergers
• Constraints on the intergalactic magnetic field from Fermi-LAT observations of GRB 221009A
• Magnetogenesis in non-local models during inflation
• Primordial magnetic fields in theories of gravity with non-minimal coupling between curvature and matter
• Displacement of ultra-high-energy cosmic ray source images by the intergalactic magnetic field: the cases of Cen A and M83