Broad-band non-thermal emission from molecular clouds illuminated by cosmic rays from nearby supernova remnants

By S. Gabici, F. Aharonian, S. Casanova. 2009

242 citations recorded by the source corpus.

Molecular clouds are expected to emit non-thermal radiation due to cosmic ray interactions in the dense magnetized gas. Such emission is amplified if a cloud is located close to an accelerator of cosmic rays and if energetic particles can leave the accelerator site and diffusively reach the cloud. We consider here a situation in which a molecular cloud is located in the proximity of a supernova remnant which is efficiently accelerating cosmic rays and gradually releasing them in the interstellar medium. We calculate the multiwavelength spectrum from radio to gamma rays which is emerging from the cloud as the result of cosmic ray interactions. The total energy output is dominated by the gamma-ray emission, which can exceed the emission in other bands by an order of magnitude or more. This suggests that some of the unidentified TeV sources detected so far, with no obvious or very weak counterparts in other wavelengths, might be in fact associated with clouds illuminated by cosmic rays coming from a nearby source. Moreover, under certain conditions, the gamma-ray spectrum exhibits a concave shape, being steep at low energies and hard at high energies. This fact might have important implications for the studies of the spectral compatibility of GeV and TeV gamma-ray sources.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/6f29b5ef34b096281dc28d3894e6c6e4b80ffb1e

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In Nuclear and High Energy Physics

Citations in the corpus

Gamma-rays from molecular clouds illuminated by cosmic rays escaping from interacting supernova remnants (2010, background): “Aharonian & Atoyan (1996) and Gabici et al. (2009) have investigated the gamma-ray spectrum from molecular clouds illuminated by CRs which have escaped from a nearby SNR.”
PHYSICAL PROPERTIES AND GALACTIC DISTRIBUTION OF MOLECULAR CLOUDS IDENTIFIED IN THE GALACTIC RING SURVEY (2010, methodology): “The masses and radii of molecular clouds might also be used to predict gamma ray fluxes emanating from the interaction between molecular clouds and cosmic rays (Aharonian et al. 2008; Gabici et al. 2009).”
THE FIRST FERMI LAT SUPERNOVA REMNANT CATALOG (2015, background): “Nearby regions of high-density gas may be illuminated by CRs escaping the SNR (e.g. Gabici et al. 2009), which interact to produce detectable GeV emission regardless of whether the SNR itself is sufficiently bright to be detected.”
NEUTRAL PION EMISSION FROM ACCELERATED PROTONS IN THE SUPERNOVA REMNANT W44 (2011, background): “…a high energy cut-off, F1e(E) = KeE −pe− E Ec , (as in Hendrick et al. 2001), 2) a power-law with a low energy cut-off, F2e(E) = KeE −pe− Ec E , (as in Gabici et al. 2009), 3) a broken power-law, F3e(E) = Ke ( E Ec )p1 ( 1 2 ( 1 + EEc ))p1−p2 , (as in Zirakashvili et al. 2007), where Ec is the…”
Observational Signatures of Particle Acceleration in Supernova Remnants (2012, background): “The interaction between thes escaping CRs and molecular clouds can produce γ-rays outside supernova remnants and can explain the unidentified very-high-energy γ-ray sources (Aharonian and Atoyan, 1996; Gabici et al., 2009).”
The origin of galactic cosmic rays (2013, unknown): “The second scenario has received more attention (see for instance Gabici et al. 2007, 2009, Rodriguez Marrero et al. 2008).”