High-Energy Particles and Radiation in Star-Forming Regions

Bykov, A. M.; Marcowith, A.; Amato, Elena; Kalyashova, M. E.; Kruijssen, J. M. Diederik; Waxman, Eli

doi:10.1007/s11214-020-00663-0

Cited by 87 publications

(54 citation statements)

References 215 publications

(227 reference statements)

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“…This GC PeVatrons together with the other massive star-forming regions, such as Westerlund 1 and Cygnus OB2, would represent the major factories of Galactic CRs (Aharonian et al 2019). A broader review of this subject, including a discussion of the subtleties associated with acceleration and propagation of CRs in these environments, may be found in Bykov et al (2020).…”

Section: Star Clustersmentioning

confidence: 99%

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On particle acceleration and transport in plasmas in the Galaxy: theory and observations

Amato

Casanova

2021

J. Plasma Phys.

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Accelerated particles are ubiquitous in the Cosmos and play a fundamental role in many processes governing the evolution of the Universe at all scales, from the sub-AU scale relevant for the formation and evolution of stars and planets to the Mpc scale involved in Galaxy assembly. We reveal the presence of energetic particles in many classes of astrophysical sources thanks to their production of non-thermal radiation, and we detect them directly at the Earth as cosmic rays. In the last two decades both direct and indirect observations have provided us a wealth of new, high-quality data about cosmic rays and their interactions both in sources and during propagation, in the Galaxy and in the Solar System. Some of the new data have confirmed existing theories about particle acceleration and propagation and their interplay with the environment in which they occur. Some others have brought about interesting surprises, whose interpretation is not straightforward within the standard framework and may require a change of paradigm in terms of our ideas about the origin of cosmic rays of different species or in different energy ranges. In this article, we focus on cosmic rays of galactic origin, namely with energies below a few petaelectronvolts, where a steepening is observed in the spectrum of energetic particles detected at the Earth. We review the recent observational findings and the current status of the theory about the origin and propagation of galactic cosmic rays.

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Section: Star Clustersmentioning

confidence: 99%

“…A broader review of this subject, including a discussion of the subtleties associated with acceleration and propagation of CRs in these environments, may be found in Bykov et al. (2020).…”

Section: Alternative Cr Sourcesmentioning

confidence: 99%

On particle acceleration and transport in plasmas in the Galaxy: theory and observations

Amato

Casanova

2021

J. Plasma Phys.

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“…The upper end of this range had been disputed for some time, particularly by researchers inferring ζ H from the chemical balances of species influenced by CR ionization; however, later studies showed CR ionization rates to be consistent with the lower end of this range (e.g., Glassgold & Langer 1974), with a consensus now having largely been reached, that the rate is around 10 −16 s −1 for diffuse interstellar cloud environments (see, e.g., Black et al 1978;Hartquist et al 1978;van Dishoeck & Black 1986;Federman et al 1996;Geballe et al 1999Geballe et al , 2007Indriolo et al 2007;Indriolo 2012;Indriolo & McCall 2012;Padovani et al 2009Padovani et al , hereafter P09, 2020Draine 2011;Indriolo 2013 for overviews). CRs with energies above a GeV can also play a role (Bykov et al 2020). These are associated with star-forming activities, which yield massive stellar end products, e.g., SN remnants (see Blasi 2011 for a discussion).…”

Section: Introductionmentioning

confidence: 99%

Observational Signatures of Cosmic-Ray Interactions in Molecular Clouds

Owen

Lai

et al. 2021

ApJ

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We investigate ionization and heating of gas in the dense, shielded clumps/cores of molecular clouds bathed by an influx of energetic, charged cosmic rays (CRs). These molecular clouds have complex structures, with substantial variation in their physical properties over a wide range of length scales. The propagation and distribution of CRs is thus regulated accordingly, in particular, by the magnetic fields threaded through the clouds and into the dense regions within. We have found that a specific heating rate reaching 10 −26 erg cm −3 s −1 can be sustained in the dense clumps/cores for Galactic environments, and this rate increases with CR energy density. The propagation of CRs and heating rates in some star-forming filaments identified in IC 5146 are calculated, with the CR diffusion coefficients in these structures determined from magnetic field fluctuations inferred from optical and near-infrared polarizations of starlight, which is presumably a magnetic field tracer. Our calculations indicate that CR heating can vary by nearly three orders of magnitude between different filaments within a cloud due to different levels of CR penetration. The CR ionization rate among these filaments is similar. The equilibrium temperature that could be maintained by CR heating alone is of order 1 K in a Galactic environment, but this value would be higher in strongly star-forming environments, thus causing an increase in the Jeans mass of their molecular clouds.

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“…Moreover, as massive stars tend to form in clusters, it has been proposed that the shock created by the collective effects of the winds of individual stars could accelerate protons above the PeV range, and contribute to the production of Galactic CRs [143,144]. For a review on particle acceleration from star forming regions we refer the reader to Bykov et al [145].…”

Section: Massive Stars Ob Associations and Stellar Clustersmentioning

confidence: 99%

The Hunt for Pevatrons: The Case of Supernova Remnants

Cristofari

2021

Universe

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The search for Galactic pevatrons is now a well-identified key science project of all instruments operating in the very-high-energy domain. Indeed, in this energy range, the detection of gamma rays clearly indicates that efficient particle acceleration is taking place, and observations can thus help identify which astrophysical sources can energize particles up to the ~PeV range, thus being pevatrons. In the search for the origin of Galactic cosmic rays (CRs), the PeV range is an important milestone, since the sources of Galactic CRs are expected to accelerate PeV particles. This is how the central scientific goal that is ’solving the mystery of the origin of CRs’ has often been distorted into ’finding (a) pevatron(s)’. Since supernova remnants (SNRs) are often cited as the most likely candidates for the origin of CRs, ’finding (a) pevatron(s)’ has often become ’confirming that SNRs are pevatrons’. Pleasingly, the first detection(s) of pevatron(s) were not associated to SNRs. Moreover, all clearly detected SNRs have yet revealed to not be pevatrons, and the detection from VHE gamma rays from regions unassociated with SNRs, are reminding us that other astrophysical sites might well be pevatrons. This short review aims at highlighting a few important results on the search for Galactic pevatrons.

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High-Energy Particles and Radiation in Star-Forming Regions

Cited by 87 publications

References 215 publications

On particle acceleration and transport in plasmas in the Galaxy: theory and observations

On particle acceleration and transport in plasmas in the Galaxy: theory and observations

Observational Signatures of Cosmic-Ray Interactions in Molecular Clouds

The Hunt for Pevatrons: The Case of Supernova Remnants

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