A Deeply Embedded Companion to LkHα198

Lagage, Pierre-Olivier; Oloffson, G.; Cabrit, S.; Césarsky, C. J.; Nordh, L.; Espinosa, J. M. Rodríguez

doi:10.1007/978-94-011-1070-9_104

Cited by 225 publications

(319 citation statements)

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“…This association has gained important observational support in recent years thanks to the data collected by X-ray telescopes such as Chandra and XMM-Newton and gamma-ray telescopes such as Fermi and AGILE, with the former instruments showing accelerated electrons with energies of up to tens of TeV (Reynolds et al 2012;Vink 2012) and the latter highlighting for the first time the presence of relativistic protons in SNRs (Abdo et al 2010a,b;Giuliani et al 2011;Tavani et al 2010). However, a number of questions on the details of the acceleration processes remain open (e.g., Balogh et al 2013;Lagage & Cesarsky 1983;Reynolds et al 2012;Helder et al 2012;Amato 2014).…”

Section: Introductionmentioning

confidence: 99%

Transport of relativistic electrons at shocks in shell-type supernova remnants: diffusive and superdiffusive regimes

Perri

Amato

Zimbardo

2016

A&A

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Context. Understanding the transport properties of energetic particles in the presence of magnetic turbulence is crucial for interpreting observations of supernova remnants (SNR) and for assessing the cosmic-ray acceleration mechanism. Aims. We aim at obtaining information on the transport regimes of energetic electrons upstream and downstream of SNR blast waves by studying the X-ray rims. Methods. We considered emission profiles expected when synchrotron energy losses dominate, normal diffusion (typically causing an exponential decay), and superdiffusion (causing a power-law decay) for a spherically symmetric model. Then we compared the model profiles, projected on the plane of the sky, with Chandra observations of supernova (SN)1006 and Tycho's SN. Results. Our study shows that downstream of the blast wave the observed profile is exponentially cutoff due to synchrotron energy losses in the amplified and shock compressed magnetic field present. Upstream of the blast wave and close to the shock, the observed profile of SN1006 is well reproduced by electron diffusion in the Bohm regime. However, the long X-ray tail far upstream of the shock is better explained by considering a change in the energetic electrons' transport regime, that appears to become superdiffusive and gives rise to a power law intensity profile on scales over which the magnetic field strength can be assumed to be constant. Similar results are obtained for Tycho, although in this case the nonlinear effects associated with particle acceleration appear to be stronger close to the shock. Conclusions. The analysis of Chandra observations of the X-ray thin rims of SN1006 and of Tycho's SN, SN 1572, can be well explained assuming normal diffusion in the vicinity of the blast wave and superdiffusion far upstream, similarly to what has been found for particles accelerated at interplanetary shocks. This suggests that anomalous transport is common in both interplanetary space and interstellar medium.

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Section: Introductionmentioning

confidence: 99%

Transport of relativistic electrons at shocks in shell-type supernova remnants: diffusive and superdiffusive regimes

Perri

Amato

Zimbardo

2016

A&A

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“…where D Bohm is the Bohm diffusion coefficient [18]. By equating t synchr = t acc , and inserting Eq.…”

Section: On the Maximum Energy Of Electronsmentioning

confidence: 99%

On the maximum energy of protons in the hotspots of AGN jets

et al. 2019

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We study particle acceleration and magnetic field amplification in the termination shocks (hotspots) of radiogalaxy jets. The cut-off of the synchrotron spectrum in the hotspots of powerful radiogalaxies is typically observed between infrared and optical frequencies, indicating that the maximum energy of non-thermal electrons accelerated at the jet termination shock is about 1 TeV for a canonical magnetic field of 100 μG. Based on theoretical considerations and observational data we show that the maximum energy of electrons cannot be constrained by synchrotron losses as usually assumed, unless the jet density is unreasonable large and most of the jet kinetic energy goes to non-thermal electrons. The maximum energy is ultimately determined by the ability to scatter particles back and forth the shock, and this limit applies to both electrons and protons. Therefore, the maximum energy of protons is also about 1 TeV when radiative cooling is not efficient. We show that non-resonant hybrid (Bell) instabilities generated by the streaming of cosmic rays can grow fast enough to amplify the jet magnetic field up to 100 μG and accelerate particles up to the maximum energies observed in the hotspots of radiogalaxies.

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“…Magnetohydrodynamical simulations demonstrated that this instability could produce a turbulent magnetic field whose RMS amplitude exceeded B 0 by more than an order of magnitude (Bell, 2004;. If correctly understood, this mechanism could explain the strong fields inferred for some SNR from X-ray observations (Vink and Laming, 2003;Völk et al, 2005); moreover, a sufficiently amplified magnetic field might increase the maximum energy for particle acceleration in supernova shocks from the limit calculated by Lagage and Cesarsky (1983), perhaps extending the source spectrum to the observed "knee" at a few PeV.…”

Section: Bell's Non-resonant Streaming Instabilitymentioning

confidence: 89%

“…Prospects looked bleak early on: Lagage and Cesarsky (1983) investigated various detailed models of the upstream diffusive transport, and found that even in the best-case scenario, for the typical Galactic magnetic-field amplitude of ∼ 1−3µG, cosmic rays produced in a supernova remnant could not exceed E max ∼ 10 14 eV; for a more realistic scenario they estimated E max an order of magnitude lower. For SNR shocks to remain a contender in the quest for the cosmic-ray sources, some improvement or perhaps some loophole would be necessary.…”

Section: The Limits Of Dsamentioning

confidence: 99%

“…However, it seems that without some sort of magnetic-field amplification, the maximum energy of cosmic rays produced via DSA falls at least an order of magnitude short of the knee (Lagage and Cesarsky, 1983). Much of the work described within this document , / Chapter 5) was motivated by recent predictions of significant amplification of the magnetic field in the upstream cosmic-ray precursor (Bell, 2004).…”

Section: Chapter 7 Conclusionmentioning

confidence: 99%

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Particle-in-cell simulation of astrophysical plasmas: probing the origin of cosmic rays

Stroman¹

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A Deeply Embedded Companion to LkHα198

Cited by 225 publications

References 1 publication

Transport of relativistic electrons at shocks in shell-type supernova remnants: diffusive and superdiffusive regimes

Transport of relativistic electrons at shocks in shell-type supernova remnants: diffusive and superdiffusive regimes

On the maximum energy of protons in the hotspots of AGN jets

Particle-in-cell simulation of astrophysical plasmas: probing the origin of cosmic rays

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