Hadronic gamma-rays from RX J1713.7−3946?

Gabici, S.; Aharonian, F.

doi:10.1093/mnrasl/slu132

Cited by 115 publications

(123 citation statements)

References 33 publications

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“…Slow and energy-dependent diffusion of cosmic rays into these clouds would then lead to a hard particle spectrum at the high-density core of the cloud. Gabici & Aharonian (2014) demonstrate that a fit to the GeV-to-TeV spectrum can be achieved, albeit apparently requiring a mass of ∼500 M inside the SNR, carried only by massive clouds that GeV-TeV-scale cosmic rays cannot fully penetrate. This is much more than can condense out of the wind of the massive progenitor star of RX J1713.7-3946, and so the scenario would require that pre-existing clouds have been unaffected by the wind.…”

Section: Hadronic Emission From the Snr Interiormentioning

confidence: 95%

Analysis of GeV-bandγ-ray emission from supernova remnant RX J1713.7-3946

Federici¹,

Pohl

Telezhinsky

et al. 2015

A&A

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Context. RX J1713.7-3946 is the brightest shell-type supernova remnant (SNR) of the TeV γ-ray sky. Earlier Fermi-LAT results on low energy γ-ray emission suggested that, despite large uncertainties in the background determination, the spectrum is inconsistent with a hadronic origin. Aims. We update the GeV-band spectra using improved estimates for the diffuse Galactic γ-ray emission and more than double the volume of data. We further investigate the viability of hadronic emission models for RX J1713.7-3946. Methods. We produced a high-resolution map of the diffuse Galactic γ-ray background corrected for the HI self-absorption and used it in the analysis of more than five years worth of Fermi-LAT data. We used hydrodynamic scaling relations and a kinetic transport equation to calculate the acceleration and propagation of cosmic rays in SNR. We then determined spectra of hadronic γ-ray emission from RX J1713.7-3946, separately for the SNR interior and the cosmic-ray precursor region of the forward shock, and computed flux variations that would allow us to test the model with observations. Results. We find that RX J1713.7-3946 is now detected by Fermi-LAT with very high statistical significance, and the source morphology is best described by that seen in the TeV band. The measured spectrum of RX J1713.7-3946 is hard with index γ = 1.53 ± 0.07, and the integral flux above 500 MeV is F = (5.5 ± 1.1) × 10 −9 photons cm −2 s −1 . We demonstrate that scenarios based on hadronic emission from the cosmic-ray precursor region are acceptable for RX J1713.7-3946, and we predict a secular flux increase at a few hundred GeV at the level of around 15% over ten years, which may be detectable with the upcoming Cherenkov Telescope Array (CTA) observatory.

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Section: Hadronic Emission From the Snr Interiormentioning

confidence: 95%

Analysis of GeV-bandγ-ray emission from supernova remnant RX J1713.7-3946

Federici¹,

Pohl

Telezhinsky

et al. 2015

A&A

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“…Theoretical possibilities for explaining a hard spectral index (Γ HE < 2.0) within a hadronic scenario include back reaction effects (Berezhko & Völk 2006;Zirakashvili & Aharonian 2010) or shock-cloud interaction (Inoue et al 2012;Gabici & Aharonian 2014). However, in young SNRs where the hadronic hypothesis is preferred, the measured spectral indices are softer than or equal to 2.0 as in Cassiopeia A (2.0 ± 0.1 stat ± 0.1 syst , Abdo et al 2010) and Tycho (2.3 ± 0.2 stat ± 0.1 syst , Giordano et al 2012).…”

Section: Source Class Comparison At He and Vhementioning

confidence: 99%

Study of TeV shell supernova remnants at gamma-ray energies

Acero

Lemoine‐Goumard

Renaud

et al. 2015

A&A

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Context. The breakthrough developments of Cherenkov telescopes in the past decade have led to angular resolution of 0.1 • and an unprecedented sensitivity. This has allowed the current generation of Cherenkov telescopes (H.E.S.S., MAGIC, and VERITAS) to discover a population of supernova remnants (SNRs) radiating in very-high-energy (VHE; E > 100 GeV) γ-rays. A number of those VHE SNRs exhibit a shell-type morphology that is spatially coincident with the shock front of the SNR. Aims. The members of this VHE shell SNR club are RX J1713.7−3946, RX J0852.0−4622, RCW 86, SN 1006, and HESS J1731−347. The last two objects have been poorly studied in high-energy (HE; 0.1 < E < 100 GeV) γ-rays and need to be investigated in order to draw the overall picture of this class of SNRs and to constrain the characteristics of the underlying population of accelerated particles. Methods. Using 6 years of Fermi-LAT P7 reprocessed data, we studied the GeV counterpart of the SNRs HESS J1731−347 and SN 1006. The two SNRs are not detected in the data set, and given that there is no hint of detection, we do not expect any detection in coming years from the SNRs. However in both cases, we derived upper limits that significantly constrain the γ-ray emission mechanism and can rule out a standard hadronic scenario with a confidence level >5σ. Results. With this Fermi analysis, we now have a complete view of the HE to VHE γ-ray emission of TeV shell SNRs. All five sources have a hard HE photon index (Γ < 1.8), which suggests a common scenario where the bulk of the emission is produced by accelerated electrons radiating from radio to VHE γ-rays through synchrotron and inverse Compton processes. In addition when correcting for the distance, all SNRs show a surprisingly similar γ-ray luminosity supporting the idea of a common emission mechanism. While the γ-ray emission is likely to be leptonic-dominated at the scale of the whole SNR, this does not rule out efficient hadron acceleration in those objects.

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“…Synchrotron X-ray emission has been detected from RX J1713.7-3946 at a flux level of E 2 X F X ≈ 10 −10 erg/cm 2 /s, while the VHE gamma-ray emission E 2 F lays roughly one order of magnitude below that. If both X-rays and gamma rays are produced by the same electrons through synchrotron and inverse Compton scattering in the cosmic microwave background, respectively, then their flux ratio should reflect the ratio between the energy density in magnetic field B = B 2 /8 ≈ 2.5 (B/10 G) 2 eV/cm 3 and in the cosmic microwave Hadronic model for RX J1713.7-3946, under the assumption that the remnant originated from a type II supernova explosion in a molecular cloud [10]. The SNR is assumed to expand in a rarefied (∼ 2 × 10 −2 cm −3 ) cavity inflated by the wind of the progenitor star.…”

Section: Spectral Shape Of the Gamma-ray Emissionmentioning

confidence: 99%

Gamma-ray emission from young supernova remnants: Hadronic or leptonic?

Gabici

Aharonian

2016

EPJ Web of Conferences

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Abstract. The debate on the nature of the gamma-ray emission from young supernova remnants is still open. Ascribing such emission to hadronic rather than leptonic processes would provide an evidence for the acceleration of protons and nuclei, and this fact would fit with the very popular (but not proven) paradigm that supernova remnants are the sources of Galactic cosmic rays. Here, we discuss this issue with a particular focus on the best studied gamma-ray-bright supernova remnant: RX J1713.7-3946.

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Hadronic gamma-rays from RX J1713.7−3946?

Cited by 115 publications

References 33 publications

Analysis of GeV-bandγ-ray emission from supernova remnant RX J1713.7-3946

Analysis of GeV-bandγ-ray emission from supernova remnant RX J1713.7-3946

Study of TeV shell supernova remnants at gamma-ray energies

Gamma-ray emission from young supernova remnants: Hadronic or leptonic?

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