Microlensing constraint on the size of the gamma-ray emission region in blazar B0218+357

Abstract

Context. Observations of the effect of microlensing in gravitationally lensed quasars could potentially be used to study the structure of the source on distance scales down to the size of the supermassive black hole powering the quasar activity. Aims. We search for the microlensing effect in the gamma-ray band using the signal from a gravitationally lensed blazar B0218+357. Methonds. We develop a method of deconvolution of contributions of two images of the source into the gamma-ray band flaring lightcurve. We use this method to study the evolution of the magnification factor ratio between the two images throughout the flaring episodes. We interpret the time variability of the ratio as a signature of the microlensing effect and derive constraints on the physical parameters of the gamma-ray source by comparing the observed variability properties of the magnification factor ratio with those derived from numerical simulations of the microlensing caustics networks. Results. We find that the magnification factor ratio has experienced a change characteristic for a microlensing caustic crossing event during a 100 d flaring period in 2012. It has further changed between 2012 and a recent flaring episode in 2014. We use the measurement of the maximal magnification and duration of the caustic crossing event to derive an estimate of the projected size of the gamma-ray emission region in B0218+357, $R_{\gamma }\sim 10^{14}$ cm. This estimate is compatible with a complementary estimate found from the minimal variability time scale. The microlensing / minimal variability time scale measurements of the source size suggest that the gamma-ray emission is produced at the base of the blazar jet, in the direct vicinity of the central supermassive black hole.

7 pages, 5 figures

References in corpus (13)

• Fast TeV variability in blazars: jets in a jet
• Jet Launching Structure Resolved Near the Supermassive Black Hole in M87
• Sizes and Temperature Profiles of Quasar Accretion Disks from Chromatic Microlensing
• Production of TeV gamma-radiation in the vicinity of the supermassive black hole in the giant radiogalaxy M87
• Rapid variability in TeV blazars: the case of PKS 2155-304
• Microlensing variability in the gravitationally lensed quasar QSO 2237+0305 = the Einstein Cross. II. Energy profile of the accretion disk
• Gamma-ray flaring activity from the gravitationally lensed blazar PKS 1830-211 observed by Fermi LAT
• TeV variability in blazars: how fast can it be?
• Free-free absorption in the gravitational lens JVAS B0218+357
• Statistics of Microlensing Caustic Crossings in Q~2237+0305: Peculiar Velocity of the Lens Galaxy and Accretion Disk Size
• Resolving the High Energy Universe with Strong Gravitational Lensing: The Case of PKS 1830-211
• Measuring parameters of AGN central engines with very high energy gamma-ray flares
• Fermi-LAT Detection of a Hard Spectrum Flare from the Gravitationally Lensed Blazar B0218+357

Cited by in corpus (12)

• Detection of very high energy gamma-ray emission from the gravitationally-lensed blazar QSO B0218+357 with the MAGIC telescopes
• The Extragalactic Gamma-ray Sky in the Fermi era
• Particle acceleration in the vacuum gaps in black hole magnetospheres
• Temporal correlation between the optical and γ-ray flux variations in the blazar 3C 454.3
• A revised lens time delay for JVAS B0218+357 from a reanalysis of VLA monitoring data
• Gravitational Lenses as High-Resolution Telescopes
• Spectroscopy and polarimetry of the gravitationally lensed quasar SDSS J1004+4112 with the 6m SAO RAS telescope
• Constraints on the location of $\gamma$-ray emitting region for a sample of blazars with radio core-shift measurements
• Variability of GeV gamma-ray emission in QSO B0218+357 due to microlensing on intermediate size structures
• Multiwavelength study of the gravitationally lensed blazar QSO B0218+357 between 2016 and 2020
• High-resolution polarization imaging of the Fermi blazar 3C 279
• Hard X-ray view of microlensing events in RX J1131-1231