The First Fermi Lat Supernova Remnant Catalog

Abstract

To uniformly determine the properties of supernova remnants (SNRs) at high energies, we have developed the first systematic survey at energies from 1 to 100 GeV using data from the Fermi Large Area Telescope (LAT). Based on the spatial overlap of sources detected at GeV energies with SNRs known from radio surveys, we classify 30sources as likely GeV SNRs. We also report 14marginal associations and 245flux upper limits. A mock catalog in which the positions of known remnants are scrambled in Galactic longitude allows us to determine an upper limit of 22% on the number of GeV candidates falsely identified as SNRs. We have also developed a method to estimate spectral and spatial systematic errors arising from the diffuse interstellar emission model, a key component of all Galactic Fermi LAT analyses. By studying remnants uniformly in aggregate, we measure the GeV properties common to these objects and provide a crucial context for the detailed modeling of individual SNRs. Combining our GeV results with multiwavelength (MW) data, including radio, X-ray, and TeV, we demonstrate the need for improvements to previously sufficient, simple models describing the GeV and radio emission from these objects. We model the GeV and MW emission from SNRs in aggregate to constrain their maximal contribution to observed Galactic cosmic rays.

Observations of M31 and M33 with the Fermi Large Area Telescope: A Galactic Center Excess in Andromeda?

“…This model is developed from radio and infrared tracers of interstellar gas (Acero et al 2016). In particular, it is based on the Leiden-Argentine-Bonn 1.4 GHz observations of atomic gas (Kalberla et al 2005) and on a dust reddening map (Schlegel et al 1998), both of which are all-sky data in which M31 appears.…”

“…Yet, this confusion happens over a very restricted region compared to the full extent of M31, and at a distance of 1°.25 from the center of the galaxy, such that any gamma-ray emission correlated with the disk of M31 should safely be recovered. Another possible source of bias in the study of extended sources is that they may be part of the largescale residuals reinjected into the final model (see Acero et al 2016, for details), and we checked that it is not the case for the region around M31.…”

Fermi/Lat Study of Gamma-Ray Emission in the Direction of the Monoceros Loop Supernova Remnant

“…For P7REP_SOURCE_V15, these studies suggest a 10% systematic uncertainty below 100MeV, decreasing linearly with the logarithm of energy to 5% in the range between 316MeV and 10 GeV and increasing linearly with the logarithm of energy up to 15% at 1TeV. We adopted the strategy described in Ackermann et al (2013) and Acero et al (2016b) to evaluate the systematic uncertainties due to the modeling of interstellar emission. Results obtained using the standard model in Section 3.2 were compared with the results of eight alternative interstellar emission models.…”

“…Gamma-ray observations in the GeV domain are a powerful probe of these mechanisms. The Large Area Telescope(LAT) on board the Fermi Gamma-ray Space Telescope has detected GeV gamma-rays from several supernova remnants (SNRs; e.g., Thompson et al 2012;Acero et al 2016b, and references therein).…”

“…However, the two sources (2FGL J0634.3+0356c and 2FGL J0637.0+0416c) associated with the Rosette Nebula were classified as "c" sources that require caution in interpreting or analyzing. In addition, the extended emission around the SNR was reported in the first Fermi/LAT SNR catalog (Acero et al 2016b), which was modeled as a uniform disk with the radius of 2°. 3.…”