{"arxiv_id":"2607.16880","title":"Electromagnetic Emission from a Black Hole Evaporating in External Magnetic Field","abstract":"We describe a classical (non-quantum) radiation process: additional (to Hawking) emission by a black hole evaporating in an external magnetic field in vacuum. The electromagnetic radiation process is completely electric charge-free and bears some resemblance to the Gertsenshtein-Zel'dovich effect. The time evolution of the spacetime metric perturbs a static background magnetic field, inducing a radiative field that acts as an effective electromagnetic source even in the absence of physical charges or currents. To isolate the dynamic effects of the time-dependent spacetime on the external magnetic field, we approximate Hawking radiation as a spherically symmetric outflow of null fluid governed by the prescribed time-dependence of the central mass $M(t)$.\n  We employ Laplace transform, which selects the retarded outgoing branch of the electromagnetic response, producing fields proportional to $\\Theta(t-r)$ and thereby fixing a causal radiative arrow of emission. The emitted spectral energy is red-dominated, scaling as $d\\mathcal{E}_B/d\\omega \\propto B_0^2 m_0^2 \\tau_H^{-2/3} \\omega^{-8/3}$, where $\\tau_H$ is the Hawking evaporation timescale, and corresponds to a pure Transverse Electric (TE) mode. There is no final bright burst at the end of the evaporation. We offer classical analogues for this mechanism as transmission-line emission and, separately, as the displacement current emission from a medium with time-varying dielectric permittivity.","primary_cat":"astro-ph.HE","cross_cats":["gr-qc"],"submitted_at":"2026-07-18T16:39:06+00:00","latest_version":1,"source":"arxiv","source_label":"arXiv","source_url":null,"has_pdf":true,"has_source":false,"verdict":"REJECT","confidence":"HIGH","one_line_summary":"Spacetime evolution during Hawking evaporation is claimed to convert a static external magnetic field into low-frequency TE-mode radiation with spectral energy ∝ ω^{-8/3}; the spectral law stems from a spurious transform of the mass-loss law.","novelty_score":5.0,"correctness_risk":"high","formal_verification":"none","upvotes":0,"downvotes":0,"pith_score":0.0,"inbound_count":0,"_links":{"html":"https://pith.science/paper/2607.16880","verdict":"/api/v1/verdicts/2607.16880"}}