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

DETERMINATION OF THE POINT-SPREAD FUNCTION FOR THEFERMILARGE AREA TELESCOPE FROM ON-ORBIT DATA AND LIMITS ON PAIR HALOS OF ACTIVE GALACTIC NUCLEI

BALDINI, LUCA;RAZZANO, MASSIMILIANO;TINIVELLA, MARCO;
2013

Abstract

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
M., Ackermann; M., Ajello; A., Allafort; K., Asano; W. B., Atwood; Baldini, Luca; J., Ballet; G., Barbiellini; D., Bastieri; K., Bechtol; R., Bellazzini; E. D., Bloom; E., Bonamente; A. W., Borgland; E., Bottacini; T. J., Brandt; J., Bregeon; M., Brigida; P., Bruel; R., Buehler; T. H., Burnett; G., Busetto; S., Buson; G. A., Caliandro; R. A., Cameron; P. A., Caraveo; J. M., Casandjian; C., Cecchi; E., Charles; S., Chaty; A., Chekhtman; C. C., Cheung; J., Chiang; A. N., Cillis; S., Ciprini; R., Claus; J., Cohen Tanugi; S., Colafrancesco; J., Conrad; S., Cutini; F., D'Ammando; F., de Palma; C. D., Dermer; E. do Couto e., Silva; P. S., Drell; A., Drlica Wagner; R., Dubois; C., Favuzzi; S. J., Fegan; E. C., Ferrara; W. B., Focke; P., Fortin; Y., Fukazawa; S., Funk; P., Fusco; F., Gargano; D., Gasparrini; N., Gehrels; S., Germani; N., Giglietto; F., Giordano; M., Giroletti; T., Glanzman; G., Godfrey; P., Grandi; I. A., Grenier; J. E., Grove; S., Guiriec; D., Hadasch; M., Hayashida; E., Hays; D., Horan; X., Hou; R. E., Hughes; M. S., Jackson; T., Jogler; G., J?hannesson; R. P., Johnson; A. S., Johnson; T., Kamae; J., Kataoka; M., Kerr; J., Kn?dlseder; M., Kuss; J., Lande; S., Larsson; L., Latronico; C., Lavalley; S. H., Lee; F., Longo; F., Loparco; B., Lott; M. N., Lovellette; P., Lubrano; M. N., Mazziotta; W., Mcconville; J. E., Mcenery; J., Mehault; P. F., Michelson; R. P., Mignani; W., Mitthumsiri; T., Mizuno; A. A., Moiseev; C., Monte; M. E., Monzani; A., Morselli; I. V., Moskalenko; S., Murgia; M., Naumann Godo; R., Nemmen; S., Nishino; J. P., Norris; E., Nuss; T., Ohsugi; N., Omodei; M., Orienti; E., Orlando; J. F., Ormes; D., Paneque; J. H., Panetta; V., Pelassa; J. S., Perkins; M., Pesce Rollins; M., Pierbattista; F., Piron; G., Pivato; H., Poon; T. A., Porter; S., Rain?; R., Rando; Razzano, Massimiliano; S., Razzaque; A., Reimer; O., Reimer; L. C., Reyes; S., Ritz; L. S., Rochester; C., Romoli; M., Roth; D. A., Sanchez; P. M., Saz Parkinson; J. D., Scargle; C., Sgr?; E. J., Siskind; A., Snyder; G., Spandre; P., Spinelli; T. E., Stephens; D. J., Suson; H., Tajima; H., Takahashi; T., Tanaka; J. G., Thayer; J. B., Thayer; D. J., Thompson; L., Tibaldo; O., Tibolla; Tinivella, Marco; G., Tosti; E., Troja; T. L., Usher; J., Vandenbroucke; V., Vasileiou; G., Vianello; V., Vitale; A., von Kienlin; A. P., Waite; E., Wallace; P., Weltevrede; B. L., Winer; K. S., Wood; M., Wood; Z., Yang; S., Zimmer
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11568/226347
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 60
  • ???jsp.display-item.citation.isi??? 60
social impact