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SUMMARY:Spectral lags as a new window on GeV–TeV emission and particle a
 cceleration in ultra‑relativistic jets
DTSTART:20261202T120000Z
DTEND:20261203T150000Z
DTSTAMP:20260724T043500Z
UID:indico-event-40366@indico.in2p3.fr
DESCRIPTION:Spectral lags are time delays between emission peaks observed 
 at different photon energies in the same high‑energy transient or variab
 le source. In simple terms\, they quantify the fact that “hard” (high
 ‑energy) and “soft” (low‑energy) photons do not always arrive at e
 xactly the same time\, and thus provide a direct handle on how emission re
 gions evolve and how particles are accelerated and cooled in these regions
 .In gamma‑ray bursts\, spectral lags have been measured for decades and 
 are known to correlate with luminosity\, but they have rarely been used to
  constrain detailed prompt‑emission models\, largely because these model
 s remain highly degenerate and difficult to formulate self‑consistently.
  In active galactic nuclei\, by contrast\, even the simplest time‑depend
 ent one‑zone leptonic scenarios for GeV–TeV flares predict energy‑de
 pendent spectral delays\, making lags a promising — yet still under‑ex
 ploited — diagnostic of jet structure and particle acceleration. In puls
 ars\, phase lags between radio and gamma‑ray peaks\, and between multipl
 e gamma‑ray peaks\, have long been recognized as key probes of magnetosp
 heric geometry and emission zones\, but the corresponding energy‑depende
 nt (GeV–TeV) lag phenomenology remains largely unexplored.This workshop 
 will bring together observers and theorists to assess the potential of spe
 ctral‑lag measurements as a new observational window on GeV–TeV emissi
 on and particle acceleration in ultra‑relativistic jets and pulsar envir
 onments.\n\nhttps://indico.in2p3.fr/event/40366/
LOCATION:1222-RC-08 (LPNHE)
URL:https://indico.in2p3.fr/event/40366/
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