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— Fermi LAT count map in the vicinity of SNR W49B in units of counts per pixel. The pixel size is 0. @BULLET 01. The LAT localization is represented by a black circle with a radius of 0. @BULLET 024 (95 % confidence level) centered at (α, δ)=(287. @BULLET 756, 9. @BULLET 096). Cyan circles represent radii of the effective LAT PSF at 75%, 50% and 25% of the peak. Magenta and green contours indicate W49B and W49A in the Spitzer IRAC 5.8 µm, respectively. (Top) The count map in 2–6 GeV is smoothed by a Gaussian kernel of σ = 0. @BULLET 2. (Bottom) The count map in 6–30 GeV is smoothed by a Gaussian kernel of σ = 0. @BULLET 1.
Source publication
We present an analysis of the gamma-ray data obtained with the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope in the direction of SNR W49B (G43.3−0.2). A bright unresolved gamma-ray source detected at a significance of 38σ is found to coincide with SNR W49B. The energy spectrum in the 0.2–200 GeV range gradually steepens tow...
Contexts in source publication
Context 1
... LAT observation revealed significant (38σ) gamma-ray emission from the direction of SNR W49B with 17 months of data. Figure 1 shows LAT count maps in the vicinity of SNR W49B in the 2-6 GeV and 6-30 GeV bands. Only front events are used in the count map to achieve better angular resolution. ...
Context 2
... evaluate the consistency with a point source quantita- tively, we compared the likelihood of the spectral fit for a point source and an elliptical shape (3 ′ × 4 ′ in size; compat- ible with the extent of the IR image as shown in Figure 1) with a uniform surface brightness. Here, we assumed a bro- ken power law function to model the source spectrum in the fit (see §3.3 for details). ...
Context 3
... 096) with an error radius of 0. • 024 at 95% confidence level using gtfindsrc, as indicated by the black circle in Figure 1. ...
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marginalize over point source and diffuse background parameters in the region
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spectral shape of Fermi-LAT measured MSPs was able to fit the GC excess
emission. For DM, we found that a pure $\tau^+\tau^-$ annihilation channel is
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a $\left<\sigma v\right>$ of order the thermal relic value and a DM mass of
around 20 to 60 GeV provides an adequate fit.
With the observation of high-energy astrophysical neutrinos by the IceCube Neutrino Observatory, interest has risen in models of PeV-mass decaying dark matter particles to explain the observed flux. We present two dedicated experimental analyses to test this hypothesis. One analysis uses 6 years of IceCube data focusing on muon neutrino 'track' events from the Northern Hemisphere, while the second analysis uses 2 years of 'cascade' events from the full sky. Known background components and the hypothetical flux from unstable dark matter are fitted to the experimental data. Since no significant excess is observed in either analysis, lower limits on the lifetime of dark matter particles are derived: we obtain the strongest constraint to date, excluding lifetimes shorter than
10
28
s
at 90% CL for dark matter masses above
10
TeV
.
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Energetic gamma rays (GeV to TeV photon energy) have been detected toward
several supernova remnants (SNR) that are associated with molecular clouds. If
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processes like bremsstrahlung, then the flux of energetic cosmic ray nuclei (>1
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ionizing interstellar gas, which leaves an observable imprint on the
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origin of the gamma rays and to constrain the acceleration of ionizing cosmic
rays in SNR. Using observational gamma ray data, the primary cosmic ray proton
spectrum can be modeled for E >1 GeV, and careful extrapolation of the spectrum
to lower energies offers a method to calculate the ionization rate of the
molecular cloud.
