Sensitivity of the Cherenkov Telescope Array to spectral signatures of hadronic PeVatrons with application to Galactic Supernova Remnants

Angüner, E. O.; Spengler, G.; Costantini, H.; Cristofari, Pierre; Armstrong, T. P.; Giunti, Luca

doi:10.1016/j.astropartphys.2023.102850

Cited by 11 publications

(8 citation statements)

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“…The presence of leptonic sources as PeVatron candidates is not surprising since leptonic accelerators can have spectra extending to very high energies, as suggested also by recent LHAASO measurements [14,96]. Therefore, it is clear that the PeVatron identification methodology discussed in [94] and used in our work needs to be expanded in order to properly distinguish between leptonic and hadronic PeVatrons. However, this is beyond the scope of this paper and left for future work.…”

Section: Pevatronsmentioning

confidence: 77%

“…We assess the potential of the GPS to find PeVatrons (or candidates) following the approach presented in [94]. For this analysis we have considered catalogue B from which we extracted a list of sources with TS > 25 in the 1-200 TeV energy range and with a number of predicted events from the fitted spectral model at energies higher than 50 TeV greater than 1.…”

Section: Pevatronsmentioning

confidence: 99%

“…To identify a source as a PeVatron we used the PeVatron Test Statistic [P T S, 94] which is a likelihood ratio test with the null hypothesis corresponding to a spectral model with proton energy cutoff equal to 1 PeV. Following the methodology in [94], a source is identified as a PeVatron if one can exclude the null hypothesis with a statistical significance of 5σ which corresponds to a threshold value of the PeVatron Test Statistic (PTS) of 35.6, taking into account the trials factor in the analysis of 231 sources [94,95]. If a source is not identified as a PeVatron (PTS < 35.6), it is considered as a PeVatron candidate when it presents a 95% CL lower limit on the proton energy cutoff (LL p ) higher than 1 PeV.…”

Section: Pevatronsmentioning

confidence: 99%

See 2 more Smart Citations

Survey of the Galactic Plane with the Cherenkov Telescope Array

Remy¹,

Tibaldo²,

Acero³

et al. 2021

Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021)

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Observations with the current generation of very-high-energy gamma-ray telescopes have revealed an astonishing variety of particle accelerators in the Milky Way, such as supernova remnants, pulsar wind nebulae, and binary systems. The upcoming Cherenkov Telescope Array (CTA) will be the first instrument to enable a survey of the entire Galactic plane in the energy range from a few tens of GeV to 300 TeV with unprecedented sensitivity and improved angular resolution. In this contribution we will revisit the scientific motivations for the survey, proposed as a Key Science Project for CTA. We will highlight recent progress, including improved physically-motivated models for Galactic source populations and interstellar emission, advance on the optimization of the survey strategy, and the development of pipelines to derive source catalogues tested on simulated data. Based on this, we will provide a new forecast on the properties of the sources that CTA will detect and discuss the expected scientific return from the study of gamma-ray source populations.

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Section: Pevatronsmentioning

confidence: 77%

Section: Pevatronsmentioning

confidence: 99%

Section: Pevatronsmentioning

confidence: 99%

See 1 more Smart Citation

Survey of the Galactic Plane with the Cherenkov Telescope Array

Remy¹,

Tibaldo²,

Acero³

et al. 2021

Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021)

View full text Add to dashboard Cite

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“…Note that the γ-ray cutoff of a leptonic-dominated SNR is not representative of the maximum energy of the accelerated hadrons, which raises the question of whether γ-ray emission at energies 10 TeV can be used to identify SNR PeVatrons, (i.e., as in, e.g., Cao et al 2021;Acero et al 2023;MAGIC Collaboration et al 2023). Yet, since PeVatrons must have very large magnetic fields, our model suggests that their TeV emission should generally be hadronic, and thus a good probe of their ability to accelerate Galactic CRs up to the knee.…”

Section: Discussionmentioning

confidence: 99%

Hadronic versus Leptonic Origin of Gamma-Ray Emission from Supernova Remnants

Corso,

Diesing,

Caprioli

2023

ApJ

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GeV and TeV emission from the forward shocks of supernova remnants (SNRs) indicates that they are capable particle accelerators, making them promising sources of Galactic cosmic rays (CRs). However, it remains uncertain whether this γ-ray emission arises primarily from the decay of neutral pions produced by very-high-energy hadrons, or from inverse-Compton and/or bremsstrahlung emission from relativistic leptons. By applying a semi-analytic approach to non-linear diffusive shock acceleration, and calculating the particle and photon spectra produced in different environments, we parameterize the relative strength of hadronic and leptonic emission. We show that even if CR acceleration is likely to occur in all SNRs, the observed photon spectra may primarily reflect the environment surrounding the SNR: the emission is expected to look hadronic unless the ambient density is particularly low (with proton number density ≲0.1 cm−3) or the photon background is enhanced with respect to average Galactic values (with radiation energy density u rad ≳ 10 eV cm−3). We introduce a hadronicity parameter to characterize how hadronic or leptonic we expect a source to look based on its environment, which can be used to guide the interpretation of current γ-ray observations and the detection of high-energy neutrinos from SNRs.

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“…Finally, it is worth noting that the postcursor effect, introduced in Section 2.2, has implications for PeVatron searches with γ-ray observatories or neutrino detectors, particularly those that select sources based on their γ-ray luminosities at lower energies (e.g., Acero et al 2023). Namely, in this paradigm, faster shocks, which exhibit stronger amplified magnetic fields via the nonresonant instability, are expected to have faster-drifting magnetic fluctuations and thus steeper spectra.…”

Section: Considerations For Pevatron Searchesmentioning

confidence: 99%

The Maximum Energy of Shock-accelerated Cosmic Rays

Diesing

2023

ApJ

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Identifying the accelerators of Galactic cosmic ray (CR) protons with energies up to a few PeV (1015 eV) remains a theoretical and observational challenge. Supernova remnants (SNRs) represent strong candidates because they provide sufficient energetics to reproduce the CR flux observed at Earth. However, it remains unclear whether they can accelerate particles to PeV energies, particularly after the very early stages of their evolution. This uncertainty has prompted searches for other source classes and necessitates comprehensive theoretical modeling of the maximum proton energy, E max , accelerated by an arbitrary shock. While analytic estimates of E max have been put forward in the literature, they do not fully account for the complex interplay between particle acceleration, magnetic field amplification, and shock evolution. This paper uses a multizone, semianalytic model of particle acceleration based on kinetic simulations to place constraints on E max for a wide range of astrophysical shocks. In particular, we develop relationships between E max , shock velocity, size, and ambient medium. We find that SNRs can only accelerate PeV particles under a select set of circumstances, namely, if the shock velocity exceeds ∼104 km s−1 and escaping particles drive magnetic field amplification. However, older and slower SNRs may still produce observational signatures of PeV particles due to populations accelerated when the shock was younger. Our results serve as a reference for modelers seeking to quickly produce a self-consistent estimate of the maximum energy accelerated by an arbitrary astrophysical shock. 1 1 Presented as a thesis to the Department of Astronomy and Astrophysics, The University of Chicago, in partial fulfillment of the requirements for a Ph.D. degree.

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Sensitivity of the Cherenkov Telescope Array to spectral signatures of hadronic PeVatrons with application to Galactic Supernova Remnants

Cited by 11 publications

References 100 publications

Survey of the Galactic Plane with the Cherenkov Telescope Array

Survey of the Galactic Plane with the Cherenkov Telescope Array

Hadronic versus Leptonic Origin of Gamma-Ray Emission from Supernova Remnants

The Maximum Energy of Shock-accelerated Cosmic Rays

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