MACSJ0417’s giant radio halo shows spectral steepening and radio–X-ray correlation consistent with turbulence from a 6:1 off-axis merger that preserved the cool core; pure hadronic models are energetically excluded.
On the amplification of magnetic fields in cosmic filaments and galaxy clusters
5 Pith papers cite this work. Polarity classification is still indexing.
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abstract
The amplification of primordial magnetic fields via a small-scale turbulent dynamo during structure formation might be able to explain the observed magnetic fields in galaxy clusters. The magnetisation of more tenuous large-scale structures such as cosmic filaments is more uncertain, as it is challenging for numerical simulations to achieve the required dynamical range. In this work, we present magneto-hydrodynamical cosmological simulations on large uniform grids to study the amplification of primordial seed fields in the intracluster medium (ICM) and in the warm-hot-intergalactic medium (WHIM). In the ICM, we confirm that turbulence caused by structure formation can produce a significant dynamo amplification, even if the amplification is smaller than what is reported in other papers. In the WHIM inside filaments, we do not observe significant dynamo amplification, even though we achieve Reynolds numbers of $R_{\rm e} \sim 200-300$. The maximal amplification for large filaments is of the order of $\sim 100$ for the magnetic energy, corresponding to a typical field of a few $\sim \rm nG$ starting from a primordial weak field of $10^{-10}$ G (comoving). In order to start a small-scale dynamo, we found that a minimum of $\sim 10^2$ resolution elements across the virial radius of galaxy clusters was necessary. In filaments we could not find a minimum resolution to set off a dynamo. This stems from the inefficiency of supersonic motions in the WHIM in triggering solenoidal modes and small-scale twisting of magnetic field structures. Magnetic fields this small will make it hard to detect filaments in radio observations.
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Radio observations of Faraday rotation in CARLA J1510+5958 at z=1.72 yield a lower limit of 0.4 μG on the average magnetic field strength in the proto-intra-cluster medium.
JWST UV luminosity function calibration of reionization history bounds primordial magnetic fields to √<B²> < 0.27 nG (n_B=-2) and < 0.18 nG (n_B=2) at 95% CL by ruling out double reionization at z≈24.
Alternative ISRF models produce only modest changes to the LHAASO diffuse gamma-ray fit; the associated pp neutrinos remain consistent with IceCube all-sky data and compatible with ANTARES/KM3NeT limits.
This review chapter summarizes the cosmic web's theoretical framework, recent radio observations of diffuse gas, and the expected impact of the SKA on detecting baryons in filaments and cluster outskirts.
citing papers explorer
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Multi-Wavelength Signatures of a Giant Cometary Radio Halo in MACSJ0417-1154
MACSJ0417’s giant radio halo shows spectral steepening and radio–X-ray correlation consistent with turbulence from a 6:1 off-axis merger that preserved the cool core; pure hadronic models are energetically excluded.
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Magnetic fields at the dawn of structure formation I. The CARLA J1510+5958 proto-cluster
Radio observations of Faraday rotation in CARLA J1510+5958 at z=1.72 yield a lower limit of 0.4 μG on the average magnetic field strength in the proto-intra-cluster medium.
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JWST Constraints on Primordial Magnetic Fields
JWST UV luminosity function calibration of reionization history bounds primordial magnetic fields to √<B²> < 0.27 nG (n_B=-2) and < 0.18 nG (n_B=2) at 95% CL by ruling out double reionization at z≈24.
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TeV-PeV Gamma-ray and Neutrino Emission in the Galactic Plane
Alternative ISRF models produce only modest changes to the LHAASO diffuse gamma-ray fit; the associated pp neutrinos remain consistent with IceCube all-sky data and compatible with ANTARES/KM3NeT limits.
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The Large-Scale Structure of the Universe through the SKA lenses
This review chapter summarizes the cosmic web's theoretical framework, recent radio observations of diffuse gas, and the expected impact of the SKA on detecting baryons in filaments and cluster outskirts.