Fermi-LAT Detection of Gravitational Lens Delayed Gamma-ray Flares from Blazar B0218+357
type: Distribution
access URL: https://in2p3.hal.science/in2p3-00977378
format: HTML
issued: 2026-05-05T15:15:43.096122
modified: 2026-05-05T15:15:43.085787

test_moissonnage_selune
type: Agent

Fermi-LAT Detection of Gravitational Lens Delayed Gamma-ray Flares from Blazar B0218+357
type: Dataset
contact point: Organization
  fn: CCSD
keyword: sduastrhesciences-of-the-universe-physicsastrophysics-astro-phhigh-energy-astrophysical-ph
keyword: quasars-individual-b0218357
keyword: gravitational-lensing-strong
keyword: gamma-rays-galaxies
keyword: infoeu-reposemanticsarticle
keyword: physastrhephysics-physicsastrophysics-astro-phhigh-energy-astrophysical-phenomena-astro-p
keyword: galaxies-active
keyword: journal-articles
landing page: 2041-8205
description: Using data from the Fermi Large Area Telescope (LAT), we report the first clear gamma-ray measurement of a delay between flares from the gravitationally lensed images of a blazar. The delay was detected in B0218+357, a known double-image lensed system, during a period of enhanced gamma-ray activity with peak fluxes consistently observed to reach >20-50 times its previous average flux. An auto-correlation function analysis identified a delay in the gamma-ray data of 11.46 +/- 0.16 days (1 sigma) that is ~1 day greater than previous radio measurements. Considering that it is beyond the capabilities of the LAT to spatially resolve the two images, we nevertheless decomposed individual sequences of superposing gamma-ray flares/delayed emissions. In three such ~8-10 day-long sequences within a ~4-month span, considering confusion due to overlapping flaring emission and flux measurement uncertainties, we found flux ratios consistent with ~1, thus systematically smaller than those from radio observations. During the first, best-defined flare, the delayed emission was detailed with a Fermi pointing, and we observed flux doubling timescales of ~3-6 hrs implying as well extremely compact gamma-ray emitting regions.
issued: 2026-05-05T15:15:43.094937
language: en
modified: 2026-05-05T15:15:43.094941