Determination of the point-spread function for the fermi large area telescope from on-orbit data and limits on pair halos of active galactic nuclei
MetadataShow full item record
The Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope is a pair-conversion telescope designed to detect photons with energies from ˜20 MeV to >300 GeV. The pre-launch response functions of the LAT were determined through extensive Monte Carlo simulations and beam tests. The point-spread function (PSF) characterizing the angular distribution of reconstructed photons as a function of energy and geometry in thedetector is determined here from two years of on-orbit data by examining the distributions of ? rays from pulsars and active galactic nuclei (AGNs). Above 3 GeV, the PSF is found to be broader than the pre-launch PSF. We checked for dependence of the PSF on the class of ? -ray source and observation epoch and found none. We also investigated several possible spatial models for pair-halo emission around BL Lac AGNs. We found no evidence for a component with spatial extension larger than the PSF and set upper limits on the amplitude of halo emission in stacked images of low- and high-redshift BL Lac AGNs and the TeV blazars 1ES0229 + 200 and 1ES0347-121.
Showing items related by title, author, creator and subject.
Bonafede, A.; Intema, Hubertus; Brüggen, M.; Vazza, F.; Basu, K.; Sommer, M.; Ebeling, H.; De Gasperin, F.; Röttgering, H.; Van Weeren, R.; Cassano, R. (2015)© 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Radio haloes are synchrotron radio sources detected in some massive galaxy clusters. Their size of Mpc indicates that ...
Van Weeren, R.; Intema, Hubertus; Lal, D.; Andrade-Santos, F.; Brüggen, M.; De Gasperin, F.; Forman, W.; Hoeft, M.; Jones, C.; Nuza, S.; Röttgering, H.; Stroe, A. (2014)We report the discovery of extended radio emission in the Phoenix cluster (SPT-CL J2344-4243, z = 0.596) with the Giant Metrewave Radio Telescope (GMRT) at 610 MHz. The diffuse emission extends over a region of at least ...
Sommer, M.; Basu, K.; Intema, Hubertus; Pacaud, F.; Bonafede, A.; Babul, A.; Bertoldi, F. (2017)© 2016 The Authors. Radio haloes are diffuse synchrotron sources on scales of ~1 Mpc that are found in merging clusters of galaxies, and are believed to be powered by electrons re-accelerated by mergerdriven turbulence. ...