The Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope is a pair-conversion telescope designed to detect photons with energies from approximate to 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 gamma 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 gamma-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.
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; Ajello M; Allafort A; Asano K; Atwood WB; Baldini L; Ballet J; Barbiellini G; Bastieri D; Bechtol K; Bellazzini R; Bloom ED; Bonamente E; Borgland AW; Bottacini E; Brandt TJ; Bregeon J; Brigida M; Bruel P; Buehler R; Burnett TH; Busetto G; Buson S; Caliandro GA; Cameron RA; Caraveo PA; Casandjian JM; Cecchi C; Charles E; Chaty S; Chekhtman A; Cheung CC; Chiang J; Cillis AN; Ciprini S; Claus R; Cohen-Tanugi J; Colafrancesco S; Conrad J; Cutini S; DAmmando F; de Palma F; Dermer CD; Silva EDE; Drell S; Drlica-Wagner A; Dubois R; Favuzzi C; Fegan SJ; Ferrara EC; Focke WB; Fortin P; Fukazawa Y; Funk S; Fusco P; Gargano F; Gasparrini D; Gehrels N; Germani S; Giglietto N; Giordano F; Giroletti M; Glanzman T; Godfrey G; Grandi P; Grenier IA; Grove JE; Guiriec S; Hadasch D; Hayashida M; Hays E; Horan D; Hou X; Hughes RE; Jackson MS; Jogler T; Johannesson G; Johnson RP; Johnson AS; Kamae T; Kataoka J; Kerr M; Knodlseder J; Kuss M; Lande J; Larsson S; Latronico L; Lavalley C; Lee SH; Longo F; Loparco F; Lott B; Lovellette MN; Lubrano P; Mazziotta MN; McConville W; McEnery JE; Mehault J; Michelson PF; Mignani RP; Mitthumsiri W; Mizuno T; Moiseev AA; Monte C; Monzani ME; Morselli A; Moskalenko IV; Murgia S; Naumann-Godo M; Nemmen R; Nishino S; Norris JP; Nuss E; Ohsugi T; Omodei N; Orienti M; Orlando E; Ormes JF; Paneque D; Panetta JH; Pelassa V; Perkins JS; Pesce-Rollins M; Pierbattista M; Piron F; Pivato G; Poon H; Porter TA; Raino S; Rando R; Razzano M; Razzaque S; Reimer A; Reimer O; Reyes LC; Ritz S; Rochester LS; Romoli C; Roth M; Sanchez DA; Parkinson PMS; Scargle JD; Sgro C; Siskind EJ; Snyder A; Spandre G; Spinelli P; Stephens TE; Suson DJ; Tajima H; Takahashi H; Tanaka T; Thayer JG; Thayer JB; Thompson DJ; Tibaldo L; Tibolla O; Tinivella M; Tosti G; Troja E; Usher TL; Vandenbroucke J; Vasileiou V; Vianello G; Vitale V; von Kienlin A; Waite AP; Wallace E; Weltevrede P; Winer BL; Wood KS; Wood M; Yang Z; Zimmer S. - In: THE ASTROPHYSICAL JOURNAL. - ISSN 0004-637X. - STAMPA. - 765:1(2013), pp. 54.54-54.72. [10.1088/0004-637X/765/1/54]
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
D'AMMANDO, FILIPPO;
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 approximate to 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 gamma 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 gamma-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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
