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This theoretical study investigates the electromagnetic signatures that could be detected if black holes undergo a quantum transition to white holes, as some theories of quantum gravity predict. The researchers modeled how high-energy material ejected during such a transition would interact with surrounding interstellar gas, producing a distinctive pattern of gamma-ray and X-ray emission lasting seconds to tens of seconds. The predicted signal would be faster, fainter, and more uniformly distributed across the sky than typical gamma-ray bursts, providing potential observational criteria to identify these exotic events.
Why it matters
If confirmed observationally, these signatures could provide the first direct evidence for quantum gravity effects in black holes and validate theories about their ultimate fate. The work gives astronomers specific detection targets to search for in existing and future high-energy observatories.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
Abstract: We study the non-thermal electromagnetic counterpart expected when the relativistic, near-isotropic ejecta of a black-to-white hole transition sweep up the interstellar medium (ISM). Building on a photospheric model for the prompt $gamma$-ray emission~cite{Villani2026}, we parametrize the kinetic energy available for an external shock, $eiso=R_kegprompt$, and model the resulting collisionless forward shock with a Weibel-mediated field~cite{Weibel1959,MedvedevLoeb1999,SironiSpitkovsky2011}. We estimate the synchrotron and synchrotron self-Compton (SSC) emission from shock-accelerated electrons in a one-zone, Thomson-regime approximation, including inverse-Compton cooling, Klein-Nishina suppression, self-absorption, and $gamma$-$gamma$ opacity, all at order-of-magnitude or first-order accuracy. For illustrative parameters ($egpromptsim10^{44}$ erg, $R_k=0.1$, $Gamma_0=100$), the electrons are slow-cooling, so for $p=2.5<3$ the synchrotron spectrum peaks at the cooling frequency $nu_c$, in the MeV-to-GeV range and softening with time; the afterglow evolves in a fraction of a second to tens of seconds — orders of magnitude faster than a classical long-duration GRB afterglow at comparable energy, density, and Lorentz factor — with duration, peak energy, and flux depending sensitively on $R_k$, $nism$, and $epse,epsB,xie$. We identify parameter regions where a 1 keV photon-count estimate, below the intrinsic peak, exceeds a nominal detection threshold, and discuss features — a fast, faint, roughly isotropic transient after a hard-spectrum prompt flash, without an achromatic jet break — that may distinguish this scenario from short GRBs, magnetar giant flares, and other fast transients, while flagging the assumptions (forward-shock-only dynamics, one-zone Thomson-regime radiation, an illustrative detectability criterion) limiting its quantitative reach.