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

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-...

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Autor principal:	Ackermann, M.
Formato:	JOUR
Materias:	galaxies: active galaxies: halos gamma rays: galaxies instrumentation: detectors intergalactic medium
Acceso en línea:	http://hdl.handle.net/20.500.12110/paper_0004637X_v765_n1_p_Ackermann
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	todo:paper_0004637X_v765_n1_p_Ackermann
record_format	dspace
spelling	todo:paper_0004637X_v765_n1_p_Ackermann2023-10-03T14:02:32Z 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 Ackermann, M. galaxies: active galaxies: halos gamma rays: galaxies instrumentation: detectors intergalactic medium 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 the detector is determined here from two years of on-orbit data by examining the distributions of γ 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 γ-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. © 2013. The American Astronomical Society. All rights reserved. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_0004637X_v765_n1_p_Ackermann
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	galaxies: active galaxies: halos gamma rays: galaxies instrumentation: detectors intergalactic medium
spellingShingle	galaxies: active galaxies: halos gamma rays: galaxies instrumentation: detectors intergalactic medium Ackermann, M. 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
topic_facet	galaxies: active galaxies: halos gamma rays: galaxies instrumentation: detectors intergalactic medium
description	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 the detector is determined here from two years of on-orbit data by examining the distributions of γ 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 γ-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. © 2013. The American Astronomical Society. All rights reserved.
format	JOUR
author	Ackermann, M.
author_facet	Ackermann, M.
author_sort	Ackermann, M.
title	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
title_short	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
title_full	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
title_fullStr	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
title_full_unstemmed	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
title_sort	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
url	http://hdl.handle.net/20.500.12110/paper_0004637X_v765_n1_p_Ackermann
work_keys_str_mv	AT ackermannm determinationofthepointspreadfunctionforthefermilargeareatelescopefromonorbitdataandlimitsonpairhalosofactivegalacticnuclei
_version_	1807322033430724608

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

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