Publication:
A Search for Cosmic-Ray Proton Anisotropy with the Fermi Large Area Telescope

Issued Date

2019-09-20

Resource Type

Article

ISSN

15384357
0004637X

DOI

10.3847/1538-4357/ab3a2e

Other identifier(s)

2-s2.0-85073070536

Rights

Mahidol University

Rights Holder(s)

SCOPUS

Bibliographic Citation

Astrophysical Journal. Vol.883, No.1 (2019)

Suggested Citation

The Fermi-Lat Collaboration, M. Ajello, L. Baldini, G. Barbiellini, D. Bastieri, K. Bechtol, R. Bellazzini, E. Bissaldi, R. D. Blandford, R. Bonino, E. Bottacini, T. J. Brandt, P. Bruel, S. Buson, R. A. Cameron, R. Caputo, E. Cavazzuti, S. Chen, G. Chiaro, S. Ciprini, J. Cohen-Tanugi, D. Costantin, A. Cuoco, S. Cutini, F. D'Ammando, P. De La Torre Luque, F. De Palma, A. Desai, S. W. Digel, N. Di Lalla, L. Di Venere, A. Domínguez, S. J. Fegan, Y. Fukazawa, S. Funk, P. Fusco, F. Gargano, D. Gasparrini, N. Giglietto, F. Giordano, M. Giroletti, D. Green, I. A. Grenier, S. Guiriec, K. Hayashi, E. Hays, J. W. Hewitt, D. Horan, G. Jóhannesson, M. Kuss, L. Latronico, J. Li, I. Liodakis, F. Longo, F. Loparco, P. Lubrano, S. Maldera, A. Manfreda, G. Martí-Devesa, M. N. Mazziotta, M. Meehan, I. Mereu, M. Meyer, P. F. Michelson, N. Mirabal, W. Mitthumsiri, T. Mizuno, A. Morselli, M. Negro, E. Nuss, N. Omodei, M. Orienti, E. Orlando, V. S. Paliya, D. Paneque, M. Persic, M. Pesce-Rollins, F. Piron, T. A. Porter, G. Principe, S. Rainò, R. Rando, M. Razzano, S. Razzaque, A. Reimer, O. Reimer, D. Serini, C. Sgrò, E. J. Siskind, G. Spandre, P. Spinelli, D. J. Suson, H. Tajima, J. B. Thayer, D. F. Torres, E. Troja, J. Vandenbroucke, M. Yassine, S. Zimmer A Search for Cosmic-Ray Proton Anisotropy with the Fermi Large Area Telescope. Astrophysical Journal. Vol.883, No.1 (2019). doi:10.3847/1538-4357/ab3a2e Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/50753

Research Projects

Organizational Units

Authors

Journal Issue

Thesis

Title

A Search for Cosmic-Ray Proton Anisotropy with the Fermi Large Area Telescope

Author(s)

The Fermi-Lat Collaboration
 M. Ajello
 L. Baldini
 G. Barbiellini
 D. Bastieri
 K. Bechtol
 R. Bellazzini
 E. Bissaldi
 R. D. Blandford
 R. Bonino
 E. Bottacini
 T. J. Brandt
 P. Bruel
 S. Buson
 R. A. Cameron
 R. Caputo
 E. Cavazzuti
 S. Chen
 G. Chiaro
 S. Ciprini
 J. Cohen-Tanugi
 D. Costantin
 A. Cuoco
 S. Cutini
 F. D'Ammando
 P. De La Torre Luque
 F. De Palma
 A. Desai
 S. W. Digel
 N. Di Lalla
 L. Di Venere
 A. Domínguez
 S. J. Fegan
 Y. Fukazawa
 S. Funk
 P. Fusco
 F. Gargano
 D. Gasparrini
 N. Giglietto
 F. Giordano
 M. Giroletti
 D. Green
 I. A. Grenier
 S. Guiriec
 K. Hayashi
 E. Hays
 J. W. Hewitt
 D. Horan
 G. Jóhannesson
 M. Kuss
 L. Latronico
 J. Li
 I. Liodakis
 F. Longo
 F. Loparco
 P. Lubrano
 S. Maldera
 A. Manfreda
 G. Martí-Devesa
 M. N. Mazziotta
 M. Meehan
 I. Mereu
 M. Meyer
 P. F. Michelson
 N. Mirabal
 W. Mitthumsiri
 T. Mizuno
 A. Morselli
 M. Negro
 E. Nuss
 N. Omodei
 M. Orienti
 E. Orlando
 V. S. Paliya
 D. Paneque
 M. Persic
 M. Pesce-Rollins
 F. Piron
 T. A. Porter
 G. Principe
 S. Rainò
 R. Rando
 M. Razzano
 S. Razzaque
 A. Reimer
 O. Reimer
 D. Serini
 C. Sgrò
 E. J. Siskind
 G. Spandre
 P. Spinelli
 D. J. Suson
 H. Tajima
 J. B. Thayer
 D. F. Torres
 E. Troja
 J. Vandenbroucke
 M. Yassine
 S. Zimmer

Other Contributor(s)

Istituto Nazionale di Fisica Nucleare, Sezione di Trieste
 Istituto Nazionale di Fisica Nucleare, Sezione di Perugia
 Istituto Nazionale di Fisica Nucleare, Sezione di Bari
 Istituto Nazionale di Fisica Nucleare, Sezione di Torino
 Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
 Istituto Nazionale Di Fisica Nucleare, Sezione di Padova
 Laboratoire Univers et Particules de Montpellier
 Universite Paris-Saclay
 Laboratoire Leprince-Ringuet
 Kavli Institute for Particle Astrophysics and Cosmology
 INAF Istituto di Astrofisica Spaziale e Fisica Cosmica, Milan
 NYCB Realtime Computing Inc.
 University Science Institute Reykjavik
 Institució Catalana de Recerca i Estudis Avançats
 University of Wisconsin-Madison
 Agenzia Spaziale Italiana
 Hiroshima University
 Deutsches Elektronen-Synchrotron (DESY)
 Osservatorio Astronomico di Trieste
 Stockholms universitet
 Alma Mater Studiorum Università di Bologna
 Universidad Complutense de Madrid
 Clemson University
 University of Maryland, Baltimore County
 Universitat Autònoma de Barcelona
 Università degli Studi di Bari
 Istituto Nazionale di Fisica Nucleare - INFN
 University of Maryland
 Purdue University Calumet
 Università degli Studi di Trieste
 Rheinisch-Westfälische Technische Hochschule Aachen
 Mahidol University
 Julius-Maximilians-Universität Würzburg
 Istituto Di Radioastronomia, Bologna
 Università degli Studi di Torino
 Max-Planck-Institut für Physik (Werner-Heisenberg-Institut)
 Medizinische Universitat Innsbruck
 NASA Goddard Space Flight Center
 Université de Genève
 The George Washington University
 Università degli Studi di Perugia
 Friedrich-Alexander-Universität Erlangen-Nürnberg
 University of Johannesburg
 Università degli Studi di Padova
 Nagoya University
 University of North Florida

Abstract

© 2019. The American Astronomical Society. All rights reserved. The Fermi Large Area Telescope (LAT) has amassed a large data set of primary cosmic-ray protons throughout its mission. In fact, it is the largest set of identified cosmic-ray protons ever collected at this energy. The LAT's wide field of view and full-sky survey capabilities make it an excellent instrument for studying cosmic-ray anisotropy. As a space-based survey instrument, the LAT is sensitive to anisotropy in both R.A. and decl., while ground-based observations only measure the anisotropy in R.A. We present the results of the first-ever proton anisotropy search using Fermi LAT. The data set was collected over eight years and consists of approximately 179 million protons above 78 GeV, enabling it to probe dipole anisotropy below an amplitude of 10-3, resulting in the most stringent limits on the decl. dependence of the dipole to date. We measure a dipole amplitude δ = 3.9 ±1.5 ×10-4 with a p-value of 0.01 (pretrials) for protons with energy greater than 78 GeV. We discuss various systematic effects that could give rise to a dipole excess and calculate upper limits on the dipole amplitude as a function of minimum energy. The 95% confidence level upper limit on the dipole amplitude is δ UL = 1.3 ×10-3 for protons with energy greater than 78 GeV and δ UL = 1.2 ×10-3 for protons with energy greater than 251 GeV.

Keyword(s)

Earth and Planetary Sciences

Availability

URI

https://repository.li.mahidol.ac.th/handle/20.500.14594/50753

Collections

Scopus 2019