scholarly journals Observational Constraints on the Maximum Energies of Accelerated Particles in Supernova Remnants: Low Maximum Energies and a Large Variety

2022 ◽  
Vol 924 (2) ◽  
pp. 45
Author(s):  
Hiromasa Suzuki ◽  
Aya Bamba ◽  
Ryo Yamazaki ◽  
Yutaka Ohira
Keyword(s):  
Particle Acceleration ◽  
Cosmic Rays ◽  
Supernova Remnants ◽  
Gamma Ray ◽  
Galactic Cosmic Rays ◽  
Maximum Energy ◽  
Average Maximum ◽  
Maximum Particle ◽  
Accelerated Particles ◽  
Age Estimates

Abstract Supernova remnants (SNRs) are thought to be the most promising sources of Galactic cosmic rays. One of the principal questions is whether they are accelerating particles up to the maximum energy of Galactic cosmic rays (∼PeV). In this work, a systematic study of gamma-ray-emitting SNRs is conducted as an advanced study of Suzuki et al. Our purpose is to newly measure the evolution of maximum particle energies with increased statistics and better age estimates. We model their gamma-ray spectra to constrain the particle-acceleration parameters. Two candidates of the maximum energy of freshly accelerated particles, the gamma-ray cutoff and break energies, are found to be well below PeV. We also test a spectral model that includes both the freshly accelerated and escaping particles to estimate the maximum energies more reliably, but no tighter constraints are obtained with current statistics. The average time dependences of the cutoff energy (∝t −0.81±0.24) and break energy (∝t −0.77±0.23) cannot be explained with the simplest acceleration condition (Bohm limit) and require shock–ISM (interstellar medium) interaction. The average maximum energy during lifetime is found to be ≲20 TeV ( t M / 1 kyr ) − 0.8 with t M being the age at the maximum, which reaches PeV if t M ≲ 10 yr. The maximum energies during lifetime are suggested to have a variety of 1.1–1.8 dex from object to object. Although we cannot isolate the cause of this variety, this work provides an important clue to understanding the microphysics of particle acceleration in SNRs.

scholarly journals SNR G39.2−0.3, an hadronic cosmic rays accelerator

2020 ◽  
Vol 497 (3) ◽  
pp. 3581-3590
Author(s):  
Emma de Oña Wilhelmi ◽  
Iurii Sushch ◽  
Robert Brose ◽  
Enrique Mestre ◽  
Yang Su ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
Supernova Remnants ◽  
Gamma Ray ◽  
Spectral Energy Distribution ◽  
Galactic Cosmic Rays ◽  
Spectral Energy ◽  
Core Collapse ◽  
Heavy Nuclei ◽  
The Rich

ABSTRACT Recent results obtained with gamma-ray satellites have established supernova remnants as accelerators of GeV hadronic cosmic rays. In such processes, CRs accelerated in SNR shocks interact with particles from gas clouds in their surrounding. In particular, the rich medium in which core-collapse SNRs explode provides a large target density to boost hadronic gamma-rays. SNR G39.2–0.3 is one of the brightest SNR in infrared wavelengths, and its broad multiwavelength coverage allows a detailed modelling of its radiation from radio to high energies. We reanalysed the Fermi-LAT data on this region and compare it with new radio observations from the MWISP survey. The modelling of the spectral energy distribution from radio to GeV energies favours a hadronic origin of the gamma-ray emission and constrains the SNR magnetic field to be at least ∼100 µG. Despite the large magnetic field, the present acceleration of protons seems to be limited to ∼10 GeV, which points to a drastic slow down of the shock velocity due to the dense wall traced by the CO observations, surrounding the remnant. Further investigation of the gamma-ray spectral shape points to a dynamically old remnant subjected to severe escape of CRs and a decrease of acceleration efficiency. The low-energy peak of the gamma-ray spectrum also suggests that that the composition of accelerated particles might be enriched by heavy nuclei which is certainly expected for a core-collapse SNR. Alternatively, the contribution of the compressed pre-existing Galactic cosmic rays is discussed, which is, however, found to not likely be the dominant process for gamma-ray production.

scholarly journals High-energy emission from transients

2013 ◽  
Vol 371 (1992) ◽  
pp. 20120279 ◽  
Author(s):  
J. A. Hinton ◽  
R. L. C. Starling
Keyword(s):  
Particle Acceleration ◽  
Time Scales ◽  
Supernova Remnants ◽  
Gamma Ray ◽  
Experimental Situation ◽  
High Energy ◽  
Galactic Cosmic Rays ◽  
Time Variable ◽  
Wide Range ◽  
Cosmic Explosions

Cosmic explosions dissipate energy into their surroundings on a very wide range of time scales: producing shock waves and associated particle acceleration. The historical culprits for the acceleration of the bulk of Galactic cosmic rays are supernova remnants: explosions on approximately 10 4 year time scales. Increasingly, however, time-variable emission points to rapid and efficient particle acceleration in a range of different astrophysical systems. Gamma-ray bursts have the shortest time scales, with inferred bulk Lorentz factors of approximately 1000 and photons emitted beyond 100 GeV, but active galaxies, pulsar wind nebulae and colliding stellar winds are all now associated with time-variable emission at approximately teraelectron volt energies. Cosmic photons and neutrinos at these energies offer a powerful probe of the underlying physical mechanisms of cosmic explosions, and a tool for exploring fundamental physics with these systems. Here, we discuss the motivations for high-energy observations of transients, the current experimental situation, and the prospects for the next decade, with particular reference to the major next-generation high-energy observatory, the Cherenkov Telescope Array.

scholarly journals Particle acceleration in winds of star clusters

2021 ◽  
Author(s):  
G Morlino ◽  
P Blasi ◽  
E Peretti ◽  
P Cristofari
Keyword(s):  
Particle Acceleration ◽  
Cosmic Rays ◽  
Supernova Remnants ◽  
Star Clusters ◽  
Cosmic Ray ◽  
Maximum Energy ◽  
Termination Shock ◽  
Shock Acceleration ◽  
Acceleration Process ◽  
Diffusive Shock Acceleration

Abstract The origin of cosmic rays in our Galaxy remains a subject of active debate. While supernova remnant shocks are often invoked as the sites of acceleration, it is now widely accepted that the difficulties of such sources in reaching PeV energies are daunting and it seems likely that only a subclass of rare remnants can satisfy the necessary conditions. Moreover the spectra of cosmic rays escaping the remnants have a complex shape that is not obviously the same as the spectra observed at the Earth. Here we investigate the process of particle acceleration at the termination shock that develops in the bubble excavated by star clusters’ winds in the interstellar medium. While the main limitation to the maximum energy in supernova remnants comes from the need for effective wave excitation upstream so as to confine particles in the near-shock region and speed up the acceleration process, at the termination shock of star clusters the confinement of particles upstream in guaranteed by the geometry of the problem. We develop a theory of diffusive shock acceleration at such shock and we find that the maximum energy may reach the PeV region for powerful clusters in the high end of the luminosity tail for these sources. A crucial role in this problem is played by the dissipation of energy in the wind to magnetic perturbations. Under reasonable conditions the spectrum of the accelerated particles has a power law shape with a slope 4÷4.3, in agreement with what is required based upon standard models of cosmic ray transport in the Galaxy.

scholarly journals Gamma-ray emitting supernova remnants as the origin of Galactic cosmic rays

2015 ◽  
Vol 2 ◽  
pp. 57-62 ◽  
Author(s):  
M. Kroll ◽  
J. Becker Tjus ◽  
B. Eichmann ◽  
N. Nierstenhöfer
Keyword(s):  
Cosmic Rays ◽  
Energy Budget ◽  
Thermal Energy ◽  
Supernova Remnants ◽  
Gamma Ray ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Below The Knee ◽  
Individual Contributions ◽  
First Time

Abstract. It is generally believed that the cosmic ray spectrum below the knee is of Galactic origin, although the exact sources making up the entire cosmic ray energy budget are still unknown. Including effects of magnetic amplification, Supernova Remnants (SNR) could be capable of accelerating cosmic rays up to a few PeV and they represent the only source class with a sufficient non-thermal energy budget to explain the cosmic ray spectrum up to the knee. Now, gamma-ray measurements of SNRs for the first time allow to derive the cosmic ray spectrum at the source, giving us a first idea of the concrete, possible individual contributions to the total cosmic ray spectrum. In this contribution, we use these features as input parameters for propagating cosmic rays from its origin to Earth using GALPROP in order to investigate if these supernova remnants reproduce the cosmic ray spectrum and if supernova remnants in general can be responsible for the observed energy budget.

scholarly journals Direct Numerical Simulations of Cosmic-ray Acceleration at Dense Circumstellar Medium: Magnetic-field Amplification and Maximum Energy

2021 ◽  
Vol 922 (1) ◽  
pp. 7
Author(s):  
Tsuyoshi Inoue ◽  
Alexandre Marcowith ◽  
Gwenael Giacinti ◽  
Allard Jan van Marle ◽  
Shogo Nishino
Keyword(s):  
Cosmic Rays ◽  
Mass Loss ◽  
Supernova Remnants ◽  
Mass Loss Rate ◽  
Spherical Geometry ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Maximum Energy ◽  
Blast Waves ◽  
Loss Rates

Abstract Galactic cosmic rays are believed to be accelerated at supernova remnants. However, whether supernova remnants can be PeV is still very unclear. In this work we argue that PeV cosmic rays can be accelerated during the early phase of a supernova blast-wave expansion in dense red supergiant winds. We solve in spherical geometry a system combining a diffusive–convection equation that treats cosmic-ray dynamics coupled to magnetohydrodynamics to follow gas dynamics. A fast shock expanding in a dense ionized wind is able to trigger fast, non-resonant streaming instability over day timescales and energizes cosmic rays even under the effect of p–p losses. We find that such environments produce PeV blast waves, although the maximum energy depends on various parameters such as the injection rate and mass-loss rate of the winds. Multi-PeV energies can be reached if the progenitor mass-loss rates are of the order of 10−3 M ⊙ yr−1. It has been recently proposed that, prior to the explosion, hydrogen-rich massive stars can produce enhanced mass-loss rates. These enhanced rates would then favor the production of a PeV phase in early times after shock breakout.

scholarly journals Shock Waves, Particle Acceleration and Non-Thermal Emission

1988 ◽  
Vol 101 ◽  
pp. 309-324
Author(s):  
R.D. Blandford
Keyword(s):  
Numerical Simulation ◽  
Particle Acceleration ◽  
Cosmic Rays ◽  
Shock Waves ◽  
Supernova Remnants ◽  
Thermal Emission ◽  
Interplanetary Shock ◽  
Galactic Cosmic Rays ◽  
Recent Developments ◽  
Shock Fronts

AbstractSome recent developments in the theory of particle acceleration at supernova shock fronts are reviewed and the confrontation of this theory with measurements of galactic cosmic rays and observations of supernova remnants is discussed. Supernova shock waves are able to account for the energetics, spectrum and composition of galactic cosmic rays, though it remains difficult to understand acceleration of ∼ 105 GeV particles. Recent developments in the analysis of interplanetary shock waves and in the numerical simulation of quasi-parallel shocks are encouraging. Interpretations of different categories of remnants are reviewed and a speculative interpretation of the optical companion to SN1987a is discussed.

scholarly journals Supernova remnants and the origin of cosmic rays

2013 ◽  
Vol 9 (S296) ◽  
pp. 305-314
Author(s):  
Jacco Vink
Keyword(s):  
Synchrotron Radiation ◽  
Cosmic Rays ◽  
Magnetic Fields ◽  
Supernova Remnants ◽  
Supernova Remnant ◽  
Gamma Ray ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Long Time ◽  
Gamma Ray Emission

AbstractSupernova remnants have long been considered to be the dominant sources of Galactic cosmic rays. For a long time the prime evidence consisted of radio synchrotron radiation from supernova remnants, indicating the presence of electrons with energies of several GeV. However, in order to explain the cosmic ray energy density and spectrum in the Galaxy supernova remnant should use 10% of the explosion energy to accelerate particles, and about 99% of the accelerated particles should be protons and other atomic nuclei.Over the last decade a lot of progress has been made in providing evidence that supernova remnant can accelerate protons to very high energies. The evidence consists of, among others, X-ray synchrotron radiation from narrow regions close to supernova remnant shock fronts, indicating the presence of 10-100 TeV electrons, and providing evidence for amplified magnetic fields, gamma-ray emission from both young and mature supernova remnants. The high magnetic fields indicate that the condition for accelerating protons to >1015 eV are there, whereas the gamma-ray emission from some mature remnants indicate that protons have been accelerated.

scholarly journals Gamma-ray observations of supernova remnants

2013 ◽  
Vol 9 (S296) ◽  
pp. 287-294
Author(s):  
Marianne Lemoine-Goumard
Keyword(s):  
Cosmic Rays ◽  
Supernova Remnants ◽  
Gamma Ray ◽  
Galactic Cosmic Rays ◽  
Cherenkov Telescopes ◽  
Gamma Ray Astronomy ◽  
Morphological Studies ◽  
Shell Type ◽  
Order Of Magnitude ◽  
Gamma Ray Emission

AbstractIn the past few years, gamma-ray astronomy has entered a golden age. At TeV energies, only a handful of sources were known a decade ago, but the current generation of ground-based imaging atmospheric Cherenkov telescopes has increased this number to more than one hundred. At GeV energies, the Fermi Gamma-ray Space Telescope has increased the number of known sources by nearly an order of magnitude in its first 2 years of operation. The recent detection and unprecedented morphological studies of gamma-ray emission from shell-type supernova remnants is of great interest, as these analyses are directly linked to the long standing issue of the origin of the cosmic-rays. However, these detections still do not constitute a conclusive proof that supernova remnants accelerate the bulk of Galactic cosmic-rays, mainly due to the difficulty of disentangling the hadronic and leptonic contributions to the observed gamma-ray emission. In the following, I will review the most relevant results of gamma ray astronomy concerning supernova remnants (shell-type and middle-age interacting with molecular clouds).

scholarly journals Radiation from accelerated particles in shocks

2011 ◽  
Vol 7 (S279) ◽  
pp. 371-372
Author(s):  
K.-I. Nishikawa ◽  
B. Zhang ◽  
E. J. Choi ◽  
K. W. Min ◽  
J. Niemiec ◽  
...  
Keyword(s):  
Particle Acceleration ◽  
Magnetic Fields ◽  
Supernova Remnants ◽  
Gamma Ray ◽  
Small Scale ◽  
Spectral Structure ◽  
Electron Positron ◽  
Jitter Radiation ◽  
Transverse Deflection ◽  
Accelerated Particles

AbstractRecent PIC simulations of relativistic electron-positron (electron-ion) jets injected into a stationary medium show that particle acceleration occurs in the shocked regions. Simulations show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields and for particle acceleration. These magnetic fields contribute to the electron's transverse deflection behind the shock. The “jitter” radiation from deflected electrons in turbulent magnetic fields has properties different from synchrotron radiation calculated in a uniform magnetic field. This jitter radiation may be important for understanding the complex time evolution and/or spectral structure of gamma-ray bursts, relativistic jets in general, and supernova remnants. In order to calculate radiation from first principles and go beyond the standard synchrotron model, we have used PIC simulations. We present synthetic spectra to compare with the spectra obtained from Fermi observations.

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