Neutral Pion Emission From Accelerated Protons in the Supernova Remnant W44

Giuliani, A.; Cardillo, M.; Tavani, M.; Fukui, Y.; Yoshiike, S.; Torii, Kazufumi; Dubner, G.; Castelletti, G.; Barbiellini, G.; Bulgarelli, A.; Caraveo, P. A.; Costa, E.; Cattaneo, P. W.; Chen, Andrew; Contessi, T.; Monte, E. Del; Donnarumma, I.; Evangelista, Y.; Feroci, M.; Gianotti, F.; Lazzarotto, F.; Lucarelli, F.; Longo, F.; Marisaldi, M.; Mereghetti, S.; Pacciani, L.; Pellizzoni, A.; Piano, G.; Picozza, P.; Pittori, C.; Pucella, G.; Rapisarda, M.; Rappoldi, A.; Sabatini, S.; Soffitta, P.; Striani, E.; Trifoglio, M.; Trois, A.; Vercellone, S.; Verrecchia, F.; Vittorini, V.; Colafrancesco, S.; Giommi, P.; Bignami, G. F.

doi:10.1088/2041-8205/742/2/l30

Cited by 206 publications

(129 citation statements)

References 44 publications

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“…The most plausible source appears to be supernovae remnants (SNRs) and is consistent with X-and gamma-ray data for electron and hadron acceleration respectively [11][12][13]. However the Fermi bubbles could be another powerful accelerator in our galaxy.…”

Section: Introductionsupporting

confidence: 69%

Shocking signals of dark matter annihilation

et al. 2016

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We examine whether charged particles injected by self-annihilating Dark Matter into regions undergoing Diffuse Shock Acceleration (DSA) can be accelerated to high energies. We consider three astrophysical sites where shock acceleration is supposed to occur, namely the Galactic Centre, galaxy clusters and Active Galactic Nuclei (AGN). For the Milky Way, we find that the acceleration of cosmic rays injected by dark matter could lead to a bump in the cosmic ray spectrum provided that the product of the efficiency of the acceleration mechanism and the concentration of DM particles is high enough. Among the various acceleration sources that we consider (namely supernova remnants (SNRs), Fermi bubbles and AGN jets), we find that the Fermi bubbles are a potentially more efficient accelerator than SNRs. However both could in principle accelerate electrons and protons injected by dark matter to very high energies. At the extragalactic level, the acceleration of dark matter annihilation products could be responsible for enhanced radio emission from colliding clusters and prediction of an increase of the anti-deuteron flux generated near AGNs.

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Section: Introductionsupporting

confidence: 69%

Shocking signals of dark matter annihilation

et al. 2016

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“…Modeling of the broadband spectra from such SNRs, in order to ascertain the nature of the γ -ray emission, is complicated and has led to mixed interpretations, making the evidence for ion acceleration controversial in some cases. Gamma-ray emission from some SNRs known to be interacting with molecular clouds seems to require a significant component from pion decay (e.g., Abdo et al 2009Abdo et al , 2010Castro & Slane 2010;Giuliani et al 2011;Ackermann et al 2013), with some remnants requiring nearly all of the SNR kinetic energy to be converted to relativistic electrons for IC emission to dominate the flux (Castro et al 2013;Auchettl et al 2014). For W44 and IC 443, the γ -ray spectra show clear evidence of a kinematic "pion bump," firmly establishing the presence of energetic ions in these remnants (Ackermann et al 2013).…”

Section: Introductionmentioning

confidence: 99%

A Cr-Hydro-Nei Model of the Structure and Broadband Emission From Tycho's Supernova Remnant

Slane

Lee

Ellison

et al. 2014

ApJ

105

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Tycho's supernova remnant (SNR) is well-established as a source of particle acceleration to very high energies. Constraints from numerous studies indicate that the observed γ -ray emission results primarily from hadronic processes, providing direct evidence of highly relativistic ions that have been accelerated by the SNR. Here we present an investigation of the dynamical and spectral evolution of Tycho's SNR by carrying out hydrodynamical simulations that include diffusive shock acceleration of particles in the amplified magnetic field at the forward shock of the SNR. Our simulations provide a consistent view of the shock positions, the nonthermal emission, the thermal X-ray emission from the forward shock, and the brightness profiles of the radio and X-ray emission. We compare these with the observed properties of Tycho to determine the density of the ambient material, the particle acceleration efficiency and maximum energy, the accelerated electron-to-proton ratio, and the properties of the shocked gas downstream of the expanding SNR shell. We find that evolution of a typical Type Ia supernova in a low ambient density (n 0 ∼ 0.3 cm −3 ), with an upstream magnetic field of ∼5 μG, and with ∼16% of the SNR kinetic energy being converted into relativistic electrons and ions through diffusive shock acceleration, reproduces the observed properties of Tycho. Under such a scenario, the bulk of observed γ -ray emission at high energies is produced by π 0 -decay resulting from the collisions of energetic hadrons, while inverse-Compton emission is significant at lower energies, comprising roughly half of the flux between 1 and 10 GeV.

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“…Thanks to their excellent sensitivities, Cherenkov telescopes on the ground and the Large Area Telescope (LAT) on board the Fermi satellite have detected a few tens of SNRs with good spectral measurement in the γ-ray range during the past decade (Ferrand & Safi-Harb 2012;Carrigan et al 2013;Acero et al 2016), revealing a variety of γ-ray spectra . Moreover, analyses of Fermi-LAT and AGILE observations of SNRs W44, IC443 (Tavani et al 2010;Giuliani et al 2011;Ackermann et al 2013), and W51C (Jogler & Funk 2016) have revealed tentative evidence for a low-energy spectral turnover associated with the p 0 decay process.…”

Section: Introductionmentioning

confidence: 99%

Evolution of High-Energy Particle Distribution in Mature Shell-Type Supernova Remnants

Zeng

Xin

Liu

et al. 2017

ApJ

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Multi-wavelength observations of mature supernova remnants (SNRs), especially with recent advances in γ-ray astronomy, make it possible to constrain energy distribution of energetic particles within these remnants. In consideration of the SNR origin of Galactic cosmic rays and physics related to particle acceleration and radiative processes, we use a simple one-zone model to fit the nonthermal emission spectra of three shell-type SNRs located within 2°on the sky: RX J1713.7−3946, CTB 37B, and CTB 37A. Although radio images of these three sources all show a shell (or half-shell) structure, their radio, X-ray, and γ-ray spectra are quite different, offering an ideal case to explore evolution of energetic particle distribution in SNRs. Our spectral fitting shows that (1) the particle distribution becomes harder with aging of these SNRs, implying a continuous acceleration process, and the particle distributions of CTB 37A and CTB 37B in the GeV range are harder than the hardest distribution that can be produced at a shock via the linear diffusive shock particle acceleration process, so spatial transport may play a role; (2) the energy loss timescale of electrons at the high-energy cutoff due to synchrotron radiation appears to be always a bit (within a factor of a few) shorter than the age of the corresponding remnant, which also requires continuous particle acceleration; (3) double power-law distributions are needed to fit the spectra of CTB 37B and CTB 37A, which may be attributed to shock interaction with molecular clouds.

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Neutral Pion Emission From Accelerated Protons in the Supernova Remnant W44

Cited by 206 publications

References 44 publications

Shocking signals of dark matter annihilation

Shocking signals of dark matter annihilation

A Cr-Hydro-Nei Model of the Structure and Broadband Emission From Tycho's Supernova Remnant

Evolution of High-Energy Particle Distribution in Mature Shell-Type Supernova Remnants

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