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Title: Fermi LAT discovery of GeV gamma-ray emission from the young supernova remnan Cassiopeia A

Abstract

Here, we report on the first detection of GeV high-energy gamma-ray emission from a young supernova remnant (SNR) with the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope. Our observations reveal a source with no discernible spatial extension detected at a significance level of 12.2σ above 500 MeV at a location that is consistent with the position of the remnant of the supernova explosion that occurred around 1680 in the Cassiopeia constellation—Cassiopeia A (Cas A). The gamma-ray flux and spectral shape of the source are consistent with a scenario in which the gamma-ray emission originates from relativistic particles accelerated in the shell of this remnant. The total content of cosmic rays (electrons and protons) accelerated in Cas A can be estimated as W CR sime (1-4) × 1049 erg thanks to the well-known density in the remnant assuming that the observed gamma ray originates in the SNR shell(s). Finally, the magnetic field in the radio-emitting plasma can be robustly constrained as B ≥ 0.1 mG, providing new evidence of the magnetic field amplification at the forward shock and the strong field in the shocked ejecta.

Authors:
 [1]
  1. Naval Research Lab. (NRL), Washington, DC (United States); National Academy of Sciences, Washington, DC (United States); et al.
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
Contributing Org.:
Fermi LAT Collaboration
OSTI Identifier:
1357582
Grant/Contract Number:  
AC02-76SF00515
Resource Type:
Accepted Manuscript
Journal Name:
Astrophysical Journal Letters
Additional Journal Information:
Journal Volume: 710; Journal Issue: 1; Journal ID: ISSN 2041-8205
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; acceleration of particles; ISM: individual objects (cassiopeia A); radiation mechanisms: non-thermal

Citation Formats

Abdo, A. A. Fermi LAT discovery of GeV gamma-ray emission from the young supernova remnan Cassiopeia A. United States: N. p., 2010. Web. doi:10.1088/2041-8205/710/1/L92.
Abdo, A. A. Fermi LAT discovery of GeV gamma-ray emission from the young supernova remnan Cassiopeia A. United States. doi:10.1088/2041-8205/710/1/L92.
Abdo, A. A. Wed . "Fermi LAT discovery of GeV gamma-ray emission from the young supernova remnan Cassiopeia A". United States. doi:10.1088/2041-8205/710/1/L92. https://www.osti.gov/servlets/purl/1357582.
@article{osti_1357582,
title = {Fermi LAT discovery of GeV gamma-ray emission from the young supernova remnan Cassiopeia A},
author = {Abdo, A. A.},
abstractNote = {Here, we report on the first detection of GeV high-energy gamma-ray emission from a young supernova remnant (SNR) with the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope. Our observations reveal a source with no discernible spatial extension detected at a significance level of 12.2σ above 500 MeV at a location that is consistent with the position of the remnant of the supernova explosion that occurred around 1680 in the Cassiopeia constellation—Cassiopeia A (Cas A). The gamma-ray flux and spectral shape of the source are consistent with a scenario in which the gamma-ray emission originates from relativistic particles accelerated in the shell of this remnant. The total content of cosmic rays (electrons and protons) accelerated in Cas A can be estimated as W CR sime (1-4) × 1049 erg thanks to the well-known density in the remnant assuming that the observed gamma ray originates in the SNR shell(s). Finally, the magnetic field in the radio-emitting plasma can be robustly constrained as B ≥ 0.1 mG, providing new evidence of the magnetic field amplification at the forward shock and the strong field in the shocked ejecta.},
doi = {10.1088/2041-8205/710/1/L92},
journal = {Astrophysical Journal Letters},
number = 1,
volume = 710,
place = {United States},
year = {2010},
month = {1}
}

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