Details

Autor(en) / Beteiligte

• Barnacka, A.
• Glicenstein, J.-F.
• Moudden, Y.

Titel

First evidence of a gravitational lensing-induced echo in gamma rays with Fermi LAT

Ist Teil von

• Astronomy and astrophysics (Berlin), 2011-04, Vol.528, p.L3

Ort / Verlag

Les Ulis: EDP Sciences

Erscheinungsjahr

2011

Link zum Volltext

Quelle

Elektronische Zeitschriftenbibliothek - Frei zugängliche E-Journals

Beschreibungen/Notizen

• Aims. This article shows the first evidence ever of gravitational lensing phenomena in high energy gamma-rays. This evidence comes from the observation of an echo in the light curve of the distant blazar PKS 1830-211 induced by a gravitational lens system. Methods. Traditional methods for estimating time delays in gravitational lensing systems rely on the cross-correlation of the light curves from individual images. We used the 300 MeV–30 GeV photons detected by the Fermi-LAT instrument. It cannot separate the images of known lenses, so the observed light curve is the superposition of individual image light curves. The Fermi-LAT instrument has the advantage of providing long, evenly spaced, time series with very low photon noise. This allows us to use Fourier transform methods directly. Results. A time delay between the two compact images of PKS 1830-211 has been searched for by both the autocorrelation method and the “double power spectrum” method. The double power spectrum shows a 4.2σ proof of a time delay of 27.1 ± 0.6 days, consistent with others’ results.