Fast radio bursts are among the most mysterious phenomena in modern astrophysics. Since their discovery in 2007, dozens of models have been proposed, ranging from magnetars to neutron star mergers, but no unified explanation exists. This work joins attempts to link bursts to accretion disks around compact objects, but proposes a new mechanism: an electrical discharge, rather than magnetic reconnection or shock waves.
The authors construct an analytical model, treating the accretion disk as a natural capacitor. X-ray photons from the inner regions of the disk Compton-scatter off free electrons, pushing them outward and creating a negatively charged layer, while positive ions remain inside. Equilibrium between radiation pressure and electrostatic attraction holds the charge. When radiation fluctuates, equilibrium is disrupted, and a discharge occurs, described as an RC circuit with exponential decay. Model parameters are fitted to the observed light curve of FRB20180725A.
For FRB20180725A, the characteristic decay time is T = 5.88×10⁻³ s and the dipole moment is Ql ≈ 1.3×10³⁰ C·m. The theoretical estimate of accumulated charge for a stellar-mass black hole (10 M☉) at Eddington luminosity gives Q ≈ 10²⁰ C. Combining observational and theoretical constraints allows determining allowed values for electron density in the disk (on the order of 10¹⁸ m⁻³) and X-ray photon energy (about 10 keV).
The model offers a unified mechanism for a wide class of fast radio bursts, linking them to ordinary accreting compact objects rather than only exotic magnetars. Unlike neighboring works that explain bursts via magnetic processes, here electrostatic charge separation plays the key role. This is the first quantitative test of the 'cosmic capacitor' idea against real data.
Further model refinements could include disk rotation, magnetic fields, and turbulence. This would help explain repeating bursts and finer spectral features. Predictions could be tested by correlating bursts with X-ray emission from accretion disks.
The results may influence the interpretation of observations of accreting black holes and neutron stars, as well as the statistics of fast radio bursts.
The model needs to be tested on a larger sample of bursts and compared with data from X-ray observatories to identify sources.
This work directly addresses the unresolved problem of the origin of fast radio bursts and their connection to accretion processes in compact objects. It remains an open question whether repeating and non-repeating bursts are manifestations of the same mechanism.
This section is addressed to the author of the paper and their colleagues. Neighbouring works were found by meaning-based search across our archive, not by word overlap. We do not review: we show the field around the work.
What the work does
The paper proposes a model of fast radio bursts as electrical discharges in the accretion disk of a compact object. The authors treat the disk as a capacitor, where Compton scattering of X-ray photons off electrons creates charge separation. The model is compared with the light curve of FRB 20180725A, yielding estimates of electron density and photon energy.
Where its strength is
The strength of the work lies in its concrete mechanism, quantitatively tested against a real event. The 'cosmic capacitor' model provides a unified explanation for a wide class of bursts, not tied to exotic magnetars.
Where it could go next
Worth trying
Why this may matter
If the model is correct, it links fast radio bursts to ordinary accreting objects, radically expanding the possible sources and turning bursts into a tool for probing the physics of accretion disks.
Nearby works in our archive
The archive is sparse around this work: the closest review is only 0.60, against a usual 0.64. It looks like few have drilled nearby.
The accumulated charge in the model is comparable to the charge carried by a lightning bolt on Earth, but concentrated in a region the size of a city.