Possible Episodic Gamma-Ray Sources

Aharonian, F.; Atoyan, A. M.

doi:10.1007/978-94-009-0171-1_26

Cited by 393 publications

(619 citation statements)

References 23 publications

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“…At and outside of the forward shock locations, the TeV morphology of these SNRs might differ from their X-ray morphology, which is dominated by electron synchrotron emission, namely they might extend further outward. Such an effect might be strongly enhanced if the SNR is embedded in areas of dense gas, such as molecular clouds, which serves as target material for π 0 -production preceding the γ-ray emission (Aharonian & Atoyan 1996). Besides such a morphological signature, a spectral signature could also be expected from TeV emission regions outside SNRs, since the energy of the escaping particles depends on the SNR evolutionary stage including the current forward shock speed (e.g., Ptuskin & Zirakashvili 2005;Gabici & Aharonian 2007;Gabici et al 2009); in essence, the spectra may peak at higher energies further away from the SNR.…”

Section: Introductionmentioning

confidence: 99%

A young supernova remnant illuminating nearby molecular clouds with cosmic rays

Cui

Pühlhofer

Santangelo

2016

A&A

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The supernova remnant (SNR) HESS J1731-347 displays strong nonthermal TeV γ-ray and X-ray emission, thus the object is presently accelerating particles to very high energies. A distinctive feature of this young SNR is the nearby (∼30 pc in projection) extended source HESS J1729-345, which is currently unidentified but is in spatial projection coinciding with known molecular clouds (MC). We model the SNR evolution to explore whether the TeV emission from HESS J1729-345 can be explained as emission from runaway hadronic cosmic rays (CRs) that are illuminating these MCs. The observational data of HESS J1729-345 and HESS J1731-347 can be reproduced using core-collapse SN models for HESS J1731-347. Starting with different progenitor stars and their presupernova environment, we model potential SNR evolution histories along with the CR acceleration in the SNR and the diffusion of the CRs. A simplified three-dimensional structure of the MCs is introduced based on 12 CO data of that region, adopting a distance of 3.2 kpc to the source. A Monte Carlo based diffusion model for the escaping CRs is developed to deal with the inhomogeneous environment. The fast SNR forward shock speed, as implied from the X-ray data, can easily be explained when employing scenarios with progenitor star masses between 20 M and 25 M , where the SNR shock is still expanding inside the main-sequence (MS) bubble at present time. The TeV spectrum of HESS J1729-345 is satisfactorily fitted by the emission from the highest energy CRs that have escaped the SNR, using a standard Galactic CR diffusion coefficient in the interclump medium. The TeV image of HESS J1729-345 can be explained with a reasonable three-dimensional structure of MCs. The TeV emission from the SNR itself is dominated by leptonic emission in this model. We also explore scenarios where the shock is starting to encounter the dense MS progenitor wind bubble shell. The escaping hadronic CR hypothesis for the γ-ray emission of HESS J1729-345 can still hold, but even in this case our model cannot easily account for the TeV emission from HESS J1731-347 in a hadronic scenario.

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Section: Introductionmentioning

confidence: 99%

A young supernova remnant illuminating nearby molecular clouds with cosmic rays

Cui

Pühlhofer

Santangelo

2016

A&A

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“…Furthermore, due to their relatively high gas density (n H ∼ 10 2 ÷ 10 6 cm −3 ), GMCs should act as efficient astrophysical beam-dumps converting a relevant fraction of the primary particle energy into secondary γ-ray and neutrino emissions (see e.g. [2,3]). In the following we will generally call SNRs interacting with MCs as embedded SNRs, also in those cases in which the SNR is not completely surrounded by the molecular gas.…”

Section: Introductionmentioning

confidence: 99%

TeV neutrinos from supernova remnants embedded in giant molecular clouds

Cavasinni

Grasso

Maccione

2006

Astroparticle Physics

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The recent detection of γ-rays with energy up to 10 TeV from dense regions surrounding some Supernova Remnants (SNR) provides strong, though still not conclusive, evidence that the nucleonic component of galactic Cosmic Rays is accelerated in the supernova outflows. Neutrino telescopes could further support the validity of such scenario by detecting neutrinos coming from the same regions. We re-evaluate the TeV range neutrino-photon flux ratio to be expected from pion decay, finding small differences respect to previous derivations. We apply our results and the recent HESS measurements of the very high energy γ-ray flux from the molecular cloud complex in the Galactic Centre, to estimate the neutrino flux from that region discussing the detectability perspectives for Mediterranean Neutrino Telescopes. We also discuss under which conditions neutron decay may give rise to a significant TeV antineutrino flux from a SNR embedded in Molecular Cloud complexes.

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“…However, it is not easy to differentiate whether the γ-rays arising from the SNRs are hadronic or leptonic emission. Recent years, a progress has been made by analysing the "illuminating" effect of the nearby MCs by the SNR shock-accelerated protons (e.g., Aharonian & Atoyan 1996;Gabici et al 2009;Li & Chen 2010, 2012Ohira et al 2011).…”

Section: Probe For Hadronic Interactionmentioning

confidence: 99%

Molecular Environments of Supernova Remnants

Chen

Jiang²,

Zhou³

et al. 2013

Proc. IAU

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Abstract. There are about 70 Galactic supernova remnants (SNRs) that are now confirmed or suggested to be in physical contact with molecular clouds (MCs) with six kinds of evidence of multiwavelength observations. Recent detailed CO-line spectroscopic mappings of a series of SNRs reveal them to be in cavities of molecular gas, implying the roles the progenitors may have played. We predict a linear correlation between the wind bubble sizes of main-sequence OB stars in a molecular environment and the stellar masses and discuss its implication for supernova progenitors. The molecular environments of SNRs can serve as a good probe for the γ-rays arising from the hadronic interaction of the accelerated protons, and this paper also discusses the γ-ray emission from MCs illuminated by diffusive protons that escape from SNR shocks.

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Possible Episodic Gamma-Ray Sources

Cited by 393 publications

References 23 publications

A young supernova remnant illuminating nearby molecular clouds with cosmic rays

A young supernova remnant illuminating nearby molecular clouds with cosmic rays

TeV neutrinos from supernova remnants embedded in giant molecular clouds

Molecular Environments of Supernova Remnants

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