Measurement of Separate Cosmic-Ray Electron and Positron Spectra with the Fermi Large Area Telescope

Ackermann M, Ajello M, Allafort A, Atwood WB, Baldini L, Barbiellini G, Bastieri D, Bechtol K, Bellazzini R, Berenji B, Blandford RD, Bloom ED, Bonamente E, Borgland AW, Bouvier A, Bregeon J, Brigida M, Bruel P, Buehler R, Buson S, Caliandro GA, Cameron RA, Caraveo PA, Casandjian JM, Cecchi C, Charles E, Chekhtman A, Cheung CC, Chiang J, Ciprini S, Claus R, Cohen-Tanugi J, Conrad J, Cutini S, De Angelis A, De Palma F, Dermer CD, Digel SW, Do Couto E Silva E, Drell PS, Drlica-Wagner A, Favuzzi C, Fegan SJ, Ferrara EC, Focke WB, Fortin P, Fukazawa Y, Funk S, Fusco P, Gargano F, Gasparrini D, Germani S, Giglietto N, Giommi P, Giordano F, Giroletti M, Glanzman T, Godfrey G, Grenier IA, Grove JE, Guiriec S, Gustafsson M, Hadasch D, Harding AK, Hayashida M, Hughes RE, Johannesson G, Johnson AS, Kamae T, Katagiri H, Kataoka J, Knoedlseder J, Kuss MW, Lande J, Latronico L, Lemoine-Goumard M, Garde ML, Longo F, Loparco F, Lovellette MN, Lubrano P, Madejski GM, Mazziotta MN, Mcenery JE, Michelson PF, Mitthumsiri W, Mizuno T, Moiseev AA, Monte C, Monzani ME, Morselli A, Moskalenko IV, Murgia S, Nakamori T, Nolan PL, Norris JP, Nuss E, Ohno M, Ohsugi T, Okumura A, Omodei N, Orlando E, Ormes JF, Ozaki M, Paneque D, Parent D, Pesce-Rollins M, Pierbattista M, Piron F, Pivato G, Porter TA, Raino S, Rando R, Razzano M, Razzaque S, Reimer A, Reimer O, Reposeur T, Ritz S, Romani RW, Roth M, Sadrozinski HFW, Sbarra C, Schalk TL, Sgro C, Siskind EJ, Spandre G, Spinelli P, Strong AW, Takahashi HH, Takahashi T, Tanaka T, Thayer JG, Thayer JB, Tibaldo L, Tinivella M, Torres DF, Tosti G, Troja E, Uchiyama Y, Usher TL, Vandenbroucke J, Vasileiou V, Vianello G, Vitale V, Waite AP, Winer BL, Wood KS, Wood M, Yang Z, Zimmer S (2012)

Publication Type: Journal article

Publication year: 2012

Journal

Book Volume: 108

Journal Issue: 1

DOI: 10.1103/PhysRevLett.108.011103

Abstract

We measured separate cosmic-ray electron and positron spectra with the Fermi Large Area Telescope. Because the instrument does not have an onboard magnet, we distinguish the two species by exploiting Earth's shadow, which is offset in opposite directions for opposite charges due to Earth's magnetic field. We estimate and subtract the cosmic-ray proton background using two different methods that produce consistent results. We report the electron-only spectrum, the positron-only spectrum, and the positron fraction between 20 and 200 GeV. We confirm that the fraction rises with energy in the 20-100 GeV range. The three new spectral points between 100 and 200 GeVare consistent with a fraction that is continuing to rise with energy.

Authors with CRIS profile

Involved external institutions

Deutsches Elektronen-Synchrotron DESY Germany (DE) Stanford University United States (USA) (US) University of California Santa Cruz United States (USA) (US) National Institute for Nuclear Physics / Istituto Nazionale di Fisica Nucleare (INFN) Italy (IT) Politecnico di Bari Italy (IT) École Polytechnique - Université Paris-Saclay France (FR) Institut de Ciències de l'Espai (ICE) Spain (ES) National Institute for Astrophysics / Istituto Nazionale Astrofisica (INAF) Italy (IT) University of Paris 7 - Denis Diderot / Université Paris VII Denis Diderot France (FR) National Academy of Sciences United States (USA) (US) Università degli Studi di Perugia Italy (IT) University of Montpellier / Université Montpellier France (FR) Stockholm University / Stockholms universitet Sweden (SE) Italian Space Agency / Agenzia Spaziale Italiana (ASI) Italy (IT) University of Udine / Università degli Studi di Udine Italy (IT) U.S. Naval Research Laboratory United States (USA) (US) National Aeronautics and Space Administration (NASA) United States (USA) (US) Hiroshima University / 広島大学 Japan (JP) University of Alabama in Huntsville (UAH) United States (USA) (US) Artep United States (USA) (US) Ibaraki University / 茨城大学 Japan (JP) Waseda University / 早稲田大学 Japan (JP) University of Padua / Universita degli Studi di Padova Italy (IT) NYCB Real-Time Computing, Inc. United States (USA) (US) Ohio State University United States (USA) (US) University of Iceland (UI) / Háskóli Íslands Iceland (IS) Institut de Recherche en Astrophysique et Planétologie (IRAP) France (FR) Boise State University United States (USA) (US) Japan Aerospace eXploration Agency (JAXA) Japan (JP) University of Denver United States (USA) (US) George Mason University United States (USA) (US) Université Bordeaux 1, Sciences et Technologies France (FR) University of Washington United States (USA) (US) Max-Planck-Institut für extraterrestrische Physik (MPE) / Max Planck Institute for Extraterrestrial Physics Germany (DE)

How to cite

APA:

Ackermann, M., Ajello, M., Allafort, A., Atwood, W.B., Baldini, L., Barbiellini, G.,... Zimmer, S. (2012). Measurement of Separate Cosmic-Ray Electron and Positron Spectra with the Fermi Large Area Telescope. Physical Review Letters, 108(1). https://doi.org/10.1103/PhysRevLett.108.011103

MLA:

Ackermann, Markus, et al. "Measurement of Separate Cosmic-Ray Electron and Positron Spectra with the Fermi Large Area Telescope." Physical Review Letters 108.1 (2012).

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