The Propagation of Cosmic Rays from the Galactic Wind Termination Shock: Back to the Galaxy?

Merten, Lukas; Bustard, Chad; Zweibel, Ellen G.; Tjus, J. Becker

doi:10.3847/1538-4357/aabfdd

Cited by 26 publications

(42 citation statements)

References 63 publications

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“…According to the second "stochastic" mechanism of acceleration, instead, particles gain energy gradually through multiple interactions with moving magnetized plasmas. The idea, pioneered by Fermi [45,46], can be realised in a variety of astrophysical environments, including the interplanetary medium [47,48], supernova remnants (SNRs) [49,50,51,52,53,54], the galactic disk and halo [55,56,57,58], AGN's [59,60,61], large-scale jets and lobes of giant radio-galaxies (RG) [62,63,64], blazars [65,66,67,68], gammaray bursts (GRBs) [69,70], starburst superwinds [71,72], galactic microquasar systems [73,74], and clusters of galaxies [75,76,77]. Contrary to the previous case, stochastic acceleration tends to be slow.…”

Section: Acceleration Mechanisms For Uhecrmentioning

confidence: 99%

Accelerating strangelets via Penrose process in non-BPS fuzz-balls

2020

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Ultra High Energy Cosmic Rays may include strangelets, a form of Strange Quark Matter, among their components. We briefly review their properties and discuss how they can be accelerated via Penrose process taking place in singular rotating Kerr black holes or in their smooth, horizonless counterparts in string theory, according to the fuzzball proposal. We focus on non-BPS solutions of the JMaRT kind and compute the efficiency of Penrose process that turns out not to be bounded unlike for Kerr BHs. Introduction and motivationsCosmic rays (CR) and in particular Ultra High Energy CR (UHECR) tend to play an important role in any progress of high-energy physics, from the identification of new elementary particles in the past to the recent confirmation of rare phenomena such as neutrino oscillations. Although the flux is tremendously suppressed at very high energies [1,2,3] and practically ends at the ZeV scale set by the GZK cutoff [4,5], the question remains as for how UHECR can be accelerated up to such high energies.Among the components of UHECR one can include the so-called "strangelets", a form of Strange Quark Matter (SQM) [22,28,30] that can be present in the dense core of a Neutron Star (NS) or in Quark Stars (QS) [23], where the temperature and density may be significantly higher than on the crust. When the mass of a NS exceeds the Chandrasekhar-Oppenheimer-Volkoff bound (around a few solar masses), it becomes unstable wrt gravitational collapse and produces a Black Hole (BH). In turn, BHs may provide both tidal tearing of captured astrophysical objects, including NS and QS, and a powerful acceleration mechanism of UHECR, including strangelets, aka Penrose process [6]. This can take place in rotating (Kerr) BHs surrounded by an 'ergo-region' where a time-like Killing vector becomes space-like. Thanks to Penrose mechanism Kerr/rotating BHs can be used as cosmic slings to accelerate UHECR and reach the GZK cutoff scale. BHs are the epitome of quantum gravity (QG), which is still poorly understood with quantum fieldtheory means. Luckily there is a leading contender: string theory. Based on the idea that point-like particles be replaced by one-dimensional objects, string theory can accommodate gravity (mediated by closed strings) together with gauge interactions (mediated by open strings) in an entirely consistent framework. General Relativity or higher dimensional extensions thereof, coupled to gauge fields and fermions, governs the dynamics at very low energies, compared to the string mass scale. The realization that string theory in addition to fundamental strings admits stable, extended solitons with p spatial dimensions, called p-branes, allows to represent BHs as bound states of strings and branes and to quantitatively address and partly solve some long-standing issues in the physics of BHs [7], including BH production in high-energy collisions [8]. In particular there are classes of charged BPS 1 BHs for which one can precisely count the micro-states responsible for the macroscopic entropy, which accordin...

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Section: Acceleration Mechanisms For Uhecrmentioning

confidence: 99%

Accelerating strangelets via Penrose process in non-BPS fuzz-balls

2020

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“…(12) A CR contribution from the wind-shock of the Galactic plasma wind? This has been explored repeatedly (Jokipii and Morfill 1987 [45]), most recently by Merten et al (2018) [183]. (13) Neutrino production in the Galaxy?…”

Section: The Origin Of High Energy Galactic Cosmic Raysmentioning

confidence: 99%

The Origin of the Most Energetic Galactic Cosmic Rays: Supernova Explosions into Massive Star Plasma Winds

et al. 2019

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We propose that the high energy Cosmic Ray particles up to the upturn commonly called the ankle, from around the spectral turn-down commonly called the knee, mostly come from Blue Supergiant star explosions. At the upturn, i.e., the ankle, Cosmic Rays probably switch to another source class, most likely extragalactic sources. To show this we recently compiled a set of Radio Supernova data where we compute the magnetic field, shock speed and shock radius. This list included both Blue and Red Supergiant star explosions; both data show the same magnetic field strength for these two classes of stars despite very different wind densities and velocities. Using particle acceleration theory at shocks, those numbers can be transformed into characteristic ankle and knee energies. Without adjusting any free parameters both of these observed energies are directly indicated by the supernova data. In the next step in the argument, we use the Supernova Remnant data of the starburst galaxy M82. We apply this analysis to Blue Supergiant star explosions: The shock will race to their outer edge with a magnetic field that is observed to follow over several orders of magnitude B ( r ) × r ∼ c o n s t . , with in fact the same magnetic field strength for such stellar explosions in our Galaxy, and other galaxies including M82. The speed is observed to be ∼0.1 c out to about 10 16 cm radius in the plasma wind. The Supernova shock can run through the entire magnetic plasma wind region at full speed all the way out to the wind-shell, which is of order parsec scale in M82. We compare and identify the Cosmic Ray spectrum in other galaxies, in the starburst galaxy M82 and in our Galaxy with each other; we suggest how Blue Supergiant star explosions can provide the Cosmic Ray particles across the knee and up to the ankle energy range. The data from the ISS-CREAM (Cosmic Ray Energetics and Mass Experiment at the International Space Station) mission will test this cosmic ray concept which is reasonably well grounded in two independent radio supernova data sets. The next step in developing our understanding will be to obtain future more accurate Cosmic Ray data near to the knee, and to use unstable isotopes of Cosmic Ray nuclei at high energy to probe the “piston” driving the explosion. We plan to incorporate these data with the physics of the budding black hole which is probably forming in each of these stars.

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“…The latest version of the publicly available simulation software CRPropa [1] includes an SDE solver to treat the transport equation. In this work, only a short summary of the implementation is given and the interested reader is referred to the original publications in [15,17] for more information. A unique feature of this specific implementation is the solution of the stochastic part of the SDE in the local frame of the magnetic field.…”

Section: Numerical Solutionmentioning

confidence: 99%

“…Assuming that the GWTS is able to accelerate cosmic rays to energies above E ≥ 10 15 eV [3], it is not clear without dedicated simulations if these cosmic rays can propagate back into the Galaxy or are lost to the intergalactic medium. In the following, the main points of such a study of the propagation of GWTS cosmic rays are recapped from [17].…”

Section: Pos(icrc2019)350mentioning

confidence: 99%

Cosmic-Ray Transport between the Knee and the Ankle with CRPropa

Merten¹,

Tjus²,

Bustard³

et al. 2019

Proceedings of 36th International Cosmic Ray Conference — PoS(ICRC2019)

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An appropriate numerical modeling of cosmic-ray transport is a major challenge in modern astroparticle physics. Multi-messenger observations of cosmic rays and their neutral secondary particles like neutrinos and gamma-rays must relate to source models. This requires a detailed description of the propagation and interaction of all particles. Especially in the region between the cosmic-ray knee and ankle, where the transition between Galactic and extra-galactic sources is expected, the modeling of cosmic-ray transport is complicated. Classical simulation frameworks are usually dedicated to lower or to the very highest energies. These software tools use grid-based methods to solve the transport equation (low energies) or propagate single particles solving the equation of motion (highest energies). Both techniques having different problems in the transition region. In this work an innovative technique-based on stochastic differential equations-to solve the transport equation is explained. The ansatz of propagating independent phase-space elements (or pseudo-particles) allows for easy parallelization which makes it attractive for modern large-scale computing architectures. It combines the numerical framework of the single particle propagation with the advantage of ensemble averaged description of the transport equation. Making it an ideal tool to describe the transition between Galactic and extra-galactic cosmic-rays. This approach is implemented in the latest version of the publicly available propagation software CRPropa and already applied to various problems. The influence of different source distributions on the global Galactic cosmic-ray density and the transport of cosmicrays from the Galactic Wind Termination shock are discussed as an example.

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The Propagation of Cosmic Rays from the Galactic Wind Termination Shock: Back to the Galaxy?

Cited by 26 publications

References 63 publications

Accelerating strangelets via Penrose process in non-BPS fuzz-balls

Accelerating strangelets via Penrose process in non-BPS fuzz-balls

The Origin of the Most Energetic Galactic Cosmic Rays: Supernova Explosions into Massive Star Plasma Winds

Cosmic-Ray Transport between the Knee and the Ankle with CRPropa

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