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Gaussian kernel ( σ = 0 . 2 ◦ ) smoothed model counts maps (left panels) and residual maps (right panels) of the region of
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Context: The Large Magellanic Cloud (LMC) is to date the only normal external galaxy that has been detected in high-energy gamma rays. High-energy gamma rays trace particle acceleration processes and gamma-ray observations allow the nature and sites of acceleration to be studied. Aims: We characterise the distribution and sources of cosmic rays in...
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Context 1
... 10 21 H cm −2 of the LMC to indicate the extent and shape of the galaxy. The boxes show the locations of the 6 point sources that have been included in the background model. The right panel has a true dynamic range from −46 to +248 counts deg −2 that has been expanded for display to cover the full dynamic range of the residuals that are shown in Fig. 4. 54777.8 -54808.2) near 30 Doradus, and thus we excluded the data within this time interval from our analysis. This results in a dataset that corresponds to 248.7 days of continuous sky survey observations during which a total exposure of ∼ 2.3 × 10 10 cm 2 s (at 1 GeV) was obtained for the ...
Context 2
... illustrate how well the models fit the data we show in Fig. 4 the model counts map and the residual counts that are left in the ROI after subtracting the PS or 2DG model from the data. The colour scale and dynamic range of the residual maps has been chosen identical to that of the right panel of Fig. 1 to allow the comparison of the residuals before and after subtraction of the LMC model. ...
Context 3
... and we tested whether gamma-ray emission is possibly only correlated to one of these H I components. We did this by separating the H I data of Kim et al. (2005) into two maps covering the heliocentric ra- dial velocity intervals 190 < V rad < 270 km s −1 (L) and 270 < V rad < 386 km s −1 (D) that roughly separate the two components (see Fig. 4 of Luks & Rohlfs 1992). Fitting both maps simulta- neously with independent scaling factors and power law indices to our data only marginally improved the fit upon the N(H I) gas map (∆TS = 21.1). We therefore conclude that the gamma-ray emission does also not follow the distribution of either the D or the L component identified by ...
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... The interstellar ultraviolet radiation field in the LMC and SMC is 10-100 higher than typical Galactic values (e.g., 13 ). Gamma-ray observations indicate that the cosmic-ray density in the LMC and SMC is, respectively, ∼25% and ∼15% of that measured in the solar neighborhood ( 14,15 ). All these low metallicity effects may have direct consequences on the formation efficiency and survival of COMs, although their relative importance remains unclear. ...
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represent guaranteed contributors to the DGRB. More exotic scenarios, such as
dark matter annihilation or decay, may contribute as well. In this review, we
describe how these components have been modeled in the literature and how the
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cross-correlation with tracers of the large-scale structure of the Universe.
New data sets already (or soon) available are expected to provide further
insight on the nature of this emission. By summarizing where we stand on the
current knowledge of the DGRB, this review is intended both as a useful
reference for those interested in the topic and as a means to trigger new ideas
for further research.
Cosmic rays fill up the entire volume of galaxies, providing an
important source of heating and ionization of the interstellar medium,
and may play a significant role in the regulation of star formation and
evolution of galaxies. Diffuse emissions from radio to highenergy gamma
rays (< 100 MeV) arising from various interactions between cosmic
rays and the interstellar medium, interstellar radiation field, and
magnetic field, are currently the best way to trace the intensities and
spectra of cosmic rays in the Milky Way and other galaxies. In this
talk, I will give an overview of the observations of the cosmic-ray
induced emissions from our own and other galaxies, in particular,
results from the Fermi-LAT and Imaging Air Cerenkov telescopes. I will
also talk about what can be deduced about the cosmic-ray origin and
propagation from these observations.
