Supernova remnants in the very–high–energy gamma-ray domain: the role of the Cherenkov telescope array

Abstract

Supernova remnants are often presented as the most probable sources of Galactic cosmic rays. This idea is supported by the accumulation of evidence that particle acceleration is happening at supernova remnant shocks. Observations in the TeV range have especially contributed to increase the understanding of the mechanisms, but many aspects of the particle acceleration at supernova remnant shocks are still debated. The Cherenkov Telescope Array is expected to lead to the detection of many new supernova remnants in the TeV and multi-TeV range. In addition to the individual study of each, the study of these objects as a population can help constrain the parameters describing the acceleration of particles and increase our understanding of the mechanisms involved.

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

“…As a result, it has so far been impossible to unequivocally prove that the population of SNRs in the Galaxy injects the necessary power (about 10 50 erg per SN event) to sustain the CR population. In fact simulations of the SNR population show how the choice of acceleration and ISM parameters lead to remarkably different SNR populations as CR sources (Cristofari et al 2017).…”

“…In fact simulations of the SNR population show how the choice of acceleration and ISM parameters lead to remarkably different SNR populations as CR sources (Cristofari et al. 2017).…”

Time evolution of gamma rays from supernova remnants

“…On the other hand, for a corecollapse (type II) supernova the SNR shock propagates first through the red supergiant wind ̺ ∝ r −2 . After that, in many cases the propagation proceeds through a tenuous bubble inflated by the wind of the progenitor star in main sequence, especially for the most massive progenitors, and finally in the interstellar medium (see, e.g., Ptuskin & Zirakashvili 2005;Cristofari et al 2013Cristofari et al , 2017Dwarkadas 2011). The typical radius of the wind R w is estimated by equating the ram pressure of the wind itself P ram = Mu w /(4πr 2 ) to the thermal pressure of the bubble interior (see, e.g., Parizot et al 2004) and is of the order of few parsecs.…”

“…For the same reason, we do not include TeV data points in the right panel as most of the TeV SNRs are interacting with molecular clouds and/or have larger uncertainties in the spectral indexes. However, future more complete and accurate observational samples both from Fermi -LAT, and hopefully its successors (see, e.g., De Angelis et al 2017), and from CTA (Actis et al 2011;Cristofari et al 2017) will make such comparisons a powerful tool.…”

Galactic Cosmic Rays - Theory and Interpretation

“…We would of course still like to have direct evidence, ideally an irrefutable "smoking gun" proof, that the GCR originate from SNRs [37,29]. While we are not quite there yet substantial progress has been made in the last decade.…”