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Title: Theoretical Interpretation of Pass 8 Fermi -LAT e {sup +} + e {sup −} Data

Abstract

The flux of positrons and electrons ( e {sup +} + e {sup −}) has been measured by the Fermi Large Area Telescope (LAT) in the energy range between 7 GeV and 2 TeV. We discuss a number of interpretations of Pass 8 Fermi -LAT e {sup +} + e {sup −} spectrum, combining electron and positron emission from supernova remnants (SNRs) and pulsar wind nebulae (PWNe), or produced by the collision of cosmic rays (CRs) with the interstellar medium. We find that the Fermi -LAT spectrum is compatible with the sum of electrons from a smooth SNR population, positrons from cataloged PWNe, and a secondary component. If we include in our analysis constraints from the AMS-02 positron spectrum, we obtain a slightly worse fit to the e {sup +} + e {sup −} Fermi -LAT spectrum, depending on the propagation model. As an additional scenario, we replace the smooth SNR component within 0.7 kpc with the individual sources found in Green’s catalog of Galactic SNRs. We find that separate consideration of far and near sources helps to reproduce the e {sup +} + e {sup −} Fermi -LAT spectrum. However, we show that the fit degrades when the radiomore » constraints on the positron emission from Vela SNR (which is the main contributor at high energies) are taken into account. We find that a break in the power-law injection spectrum at about 100 GeV can also reproduce the measured e {sup +} + e {sup −} spectrum and, among the CR propagation models that we consider, no reasonable break of the power-law dependence of the diffusion coefficient can modify the electron flux enough to reproduce the observed shape.« less

Authors:
 [1]; ; ; ; ;  [2];  [3]; ; ;  [4]; ;  [5]; ; ;  [6]
  1. W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States)
  2. Department of Physics, University of Torino, via P. Giuria 1, I-10125 Torino (Italy)
  3. Physik-Department T30D, Technische Universität München, James-Franck Straße 1, D-85748 Garching (Germany)
  4. Università di Pisa and Istituto Nazionale di Fisica Nucleare, Sezione di Pisa I-56127 Pisa (Italy)
  5. Istituto Nazionale di Fisica Nucleare, via P. Giuria 1, I-10125 Torino (Italy)
  6. Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy)
Publication Date:
OSTI Identifier:
22663237
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 845; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; CATALOGS; COSMIC RADIATION; DIFFUSION; ELECTRON-POSITRON INTERACTIONS; ELECTRONS; EMISSION; GEV RANGE; INJECTION; NEBULAE; POSITRONS; PULSARS; SPECTRA; STELLAR WINDS; SUPERNOVA REMNANTS; TELESCOPES; TEV RANGE

Citation Formats

Di Mauro, M., Manconi, S., Donato, F., Fornengo, N., Bonino, R., Negro, M., Vittino, A., Baldini, L., Di Lalla, N., Manfreda, A., Latronico, L., Maldera, S., Pesce-Rollins, M., Sgrò, C., and Spada, F. Theoretical Interpretation of Pass 8 Fermi -LAT e {sup +} + e {sup −} Data. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA8225.
Di Mauro, M., Manconi, S., Donato, F., Fornengo, N., Bonino, R., Negro, M., Vittino, A., Baldini, L., Di Lalla, N., Manfreda, A., Latronico, L., Maldera, S., Pesce-Rollins, M., Sgrò, C., & Spada, F. Theoretical Interpretation of Pass 8 Fermi -LAT e {sup +} + e {sup −} Data. United States. doi:10.3847/1538-4357/AA8225.
Di Mauro, M., Manconi, S., Donato, F., Fornengo, N., Bonino, R., Negro, M., Vittino, A., Baldini, L., Di Lalla, N., Manfreda, A., Latronico, L., Maldera, S., Pesce-Rollins, M., Sgrò, C., and Spada, F. Sun . "Theoretical Interpretation of Pass 8 Fermi -LAT e {sup +} + e {sup −} Data". United States. doi:10.3847/1538-4357/AA8225.
@article{osti_22663237,
title = {Theoretical Interpretation of Pass 8 Fermi -LAT e {sup +} + e {sup −} Data},
author = {Di Mauro, M. and Manconi, S. and Donato, F. and Fornengo, N. and Bonino, R. and Negro, M. and Vittino, A. and Baldini, L. and Di Lalla, N. and Manfreda, A. and Latronico, L. and Maldera, S. and Pesce-Rollins, M. and Sgrò, C. and Spada, F.},
abstractNote = {The flux of positrons and electrons ( e {sup +} + e {sup −}) has been measured by the Fermi Large Area Telescope (LAT) in the energy range between 7 GeV and 2 TeV. We discuss a number of interpretations of Pass 8 Fermi -LAT e {sup +} + e {sup −} spectrum, combining electron and positron emission from supernova remnants (SNRs) and pulsar wind nebulae (PWNe), or produced by the collision of cosmic rays (CRs) with the interstellar medium. We find that the Fermi -LAT spectrum is compatible with the sum of electrons from a smooth SNR population, positrons from cataloged PWNe, and a secondary component. If we include in our analysis constraints from the AMS-02 positron spectrum, we obtain a slightly worse fit to the e {sup +} + e {sup −} Fermi -LAT spectrum, depending on the propagation model. As an additional scenario, we replace the smooth SNR component within 0.7 kpc with the individual sources found in Green’s catalog of Galactic SNRs. We find that separate consideration of far and near sources helps to reproduce the e {sup +} + e {sup −} Fermi -LAT spectrum. However, we show that the fit degrades when the radio constraints on the positron emission from Vela SNR (which is the main contributor at high energies) are taken into account. We find that a break in the power-law injection spectrum at about 100 GeV can also reproduce the measured e {sup +} + e {sup −} spectrum and, among the CR propagation models that we consider, no reasonable break of the power-law dependence of the diffusion coefficient can modify the electron flux enough to reproduce the observed shape.},
doi = {10.3847/1538-4357/AA8225},
journal = {Astrophysical Journal},
number = 2,
volume = 845,
place = {United States},
year = {Sun Aug 20 00:00:00 EDT 2017},
month = {Sun Aug 20 00:00:00 EDT 2017}
}