Article
Astronomy & Astrophysics
Ottavio Fornieri, Heshou Zhang
Summary: The study discusses the mechanism of cosmic-ray diffusion, noting that the diffusion of particles is closely related to the description of injected turbulent models and that uneven energy distribution may lead to different diffusion characteristics in different regions. By tracking the three-dimensional transport of CR injected by two prominent sources, the authors explain the γ-ray diffuse radiation in the Cygnus-X region, observed by Fermi-LAT and HAWC Collaborations.
Article
Physics, Multidisciplinary
Peng-Xiong Ma, Zhi-Hui Xu, Qiang Yuan, Xiao-Jun Bi, Yi-Zhong Fan, Igor V. V. Moskalenko, Chuan Yue
Summary: The measurements by DAMPE reveal hardenings in the boron-to-carbon and boron-to-oxygen ratios around 100 GeV/n, indicating the influence of turbulence on cosmic ray propagation and acceleration. These findings have significant implications for our understanding of Galactic cosmic rays. Various models proposed in literature are examined in light of these results, but some fail to reproduce the observed hardenings in the ratios.
FRONTIERS OF PHYSICS
(2023)
Article
Astronomy & Astrophysics
Yuichi Oyama
Summary: Possible evidence of high-energy neutrinos from SN1987A was found through the observation of upward-going muons recorded by the Kamiokande-II experiment and the IMB experiment.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
G. Li, A. Bruno, M. A. Lee, N. Lugaz, G. A. de Nolfo, J. M. Ryan
Summary: This study presents an analytical model for diffusive shock acceleration (DSA) at stationary planar shocks in the lower corona. The model introduces an upstream escape boundary to allow a constant flux of protons streaming out of the system. The nonvanishing flux limits the maximum attainable energy of DSA and produces a rollover in the high-energy spectra of the shock-accelerated protons. The model-derived condition for the rollover energy explains the approximately linear relation observed between the natural logarithm of event-integrated fluences and the natural logarithm of rollover energies.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
J. Giacalone, D. Burgess, S. D. Bale, M. Desai, J. G. Mitchell, D. Lario, C. H. K. Chen, E. R. Christian, G. A. de Nolfo, M. E. Hill, W. H. Matthaeus, D. J. McComas, R. L. McNutt, D. G. Mitchell, E. C. Roelof, N. A. Schwadron, Tibebu Getachew, C. J. Joyce
Summary: The Parker Solar Probe crossed a coronal mass ejection-driven shock and an isolated magnetic structure, experiencing changes in ion fluxes as the shock front and back edge passed. This suggests that the movement of the magnetic structure may contribute to variations in energetic particles during solar wind interactions.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
D. Kantzas, S. Markoff, A. J. Cooper, D. Gaggero, M. Petropoulou, P. De La Torre Luque
Summary: The source of high-energy cosmic rays (CRs) has been a longstanding question. Supernova remnants (SNRs) have traditionally been thought of as the main source for Galactic CRs with energy up to 10^15 eV, but recent observations have challenged this paradigm. In this study, we investigate the gamma-ray and neutrino emission from CRs accelerated in Galactic jets of stellar-mass black holes in X-ray binaries (BHXBs) and discuss their potential contribution to the observed spectrum of Galactic CRs.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Engineering, Aerospace
A. M. Bykov, M. E. Kalyashova
Summary: OB-associations and superbubbles are important sites for the acceleration of galactic cosmic rays. The emission profile of γ-ray sources related to superbubbles and stellar clusters indicates continuous particle acceleration. This study focuses on the Cygnus Cocoon superbubble and proposes a model of particle acceleration and transport to explain its γ-ray spectrum. The results suggest that the γ rays are produced by hadronic interactions of high-energy protons accelerated by shocks from winds of massive stars and supernovae in the Cygnus Cocoon.
ADVANCES IN SPACE RESEARCH
(2022)
Article
Physics, Nuclear
Yu Wang, Juan Wu, Wei-Cheng Long
Summary: One of the fundamental challenges in cosmic ray physics is to explain the nature of cosmic ray acceleration and propagation mechanisms. Recent space experiments have provided precise cosmic ray data that allow for more comprehensive and reliable investigation of cosmic ray acceleration and propagation models. This study combines data from different experiments to constrain the cosmic ray source and transport parameters. The results show that heavy and light particles can provide compatible results at medium to high energies, but significant differences exist at low energies. A better understanding of the consistency/inconsistency between heavy and light cosmic rays requires more precise data, better constraints on systematic errors, more accurate estimations of galaxy halo size, and a more robust description of solar modulation.
Article
Astronomy & Astrophysics
Federico Fraschetti
Summary: The energetic particle spectra at interplanetary shocks often exhibit a power law with softening at higher energy levels. A transport equation has been introduced to account for particle acceleration and escape, with diffusion generated by turbulence close to the shock and preexisting turbulence far upstream. The momentum spectrum is controlled by macroscopic parameters and can be simplified to a log-parabola or a broken power law, depending on the conditions.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
T. Vieu, S. Gabici, V Tatischeff
Summary: The linear theory of diffusive shock acceleration breaks down when the pressure of particles accelerated at shock waves becomes significant compared to the kinetic pressure of the gas. Non-linear backreaction of particles on the magnetohydrodynamic flow needs to be taken into account in order to describe these systems. The presence of pre-existing energetic particles strongly affects the shock profile and reduces the efficiency of reaccelerating non-thermal particles. The study of the evolution of particle distribution after multiple shocks indicates that the spectrum converges towards a concave solution and the post-shock cosmic ray pressure only accounts for a small fraction of the shock pressure.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
T. Vieu, S. Gabici, V Tatischeff, S. Ravikularaman
Summary: We study the production of cosmic rays in dynamical superbubbles formed by a cluster of massive stars. Stellar winds, supernova remnants, and turbulence efficiently accelerate particles, and their nonlinear feedback is important for maintaining energy balance. High-energy particles escape quickly after each supernova explosion, while low-energy particles are stochastically accelerated and harden the spectra. The presence of a magnetized shell enhances the confinement of cosmic rays in the bubble. We estimate the overall contribution of superbubbles to Galactic cosmic ray content and present the expected gamma-ray spectra from hadronic interactions in superbubble shells.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
A. R. Bell, J. H. Matthews
Summary: This study explores the possibility that the detected hotspot of ultra-high-energy cosmic rays (UHECRs) from the direction of M82 and the M81 group of galaxies could be the result of echoes from previous emissions by Centaurus A. The research also considers the impact of echoes from other starburst galaxies or groups of galaxies on the UHECR flux at Earth. Synthetic sky maps are created using a Monte Carlo model of monoenergetic UHECR transport by small-angle scattering, providing insights into energetics, time scales, and distance scales. The findings suggest that the observed UHECR hotspots can be explained by a viable echo model if Centaurus A had 200 times its present luminosity 20 million years ago and if ordered magnetic fields exceeding 10-20 nG were present in the circumgalactic medium of M82 and other starburst galaxies extending up to a distance of 400-800 kpc.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Physics, Particles & Fields
Prabir Banik, Arunava Bhadra
Summary: The IceCube Neutrino Observatory recently detected the neutrino event IceCube-170922A from the radio-emitting tidal disruption event (TDE) named AT2019dsg, suggesting it as a potential source of high-energy cosmic rays. This study examines the possibility of describing IceCube-170922A and the broadband electromagnetic emission from the same source using a pure hadronic emission model, and finds that it can successfully explain the observations without exceeding the flux upper limits imposed by other telescopes.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Astronomy & Astrophysics
A. M. Taylor, J. H. Matthews, A. R. Bell
Summary: Recent anisotropy studies have found a correlation between the angular distribution of UHECRs and the extragalactic local structure. Monte Carlo simulations suggest that these UHECRs were accelerated by Centaurus A and scattered by magnetic fields associated with the local extragalactic structure. The presence of local structures creates 'echoes' of UHECRs and the composition of the light component across the sky offers prospects for testing the echo model using future facilities.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Zhi-Qiu Huang, Brian Reville, John G. Kirk, Gwenael Giacinti
Summary: We conducted test-particle Monte Carlo simulations to study the acceleration of charged particles by ultra-relativistic shocks. Two field configurations were considered: shocks with uniform upstream magnetic field and shocks with cylindrical upstream magnetic field. The particles were assumed to diffuse in angle due to frequent non-resonant scattering. The distribution of particles' Lorentz factors was found to approximately follow dN/d gamma proportional to gamma(-2.2) when the particle motion was scattering dominated on at least one side of the shock. The acceleration rate scaled as t(acc) proportional to t(1/2) for scattering dominated transport, but recovered Bohm scaling t(acc) proportional to t if particles became magnetized on one side of the shock. A limiting energy was reached for uniform field configurations when particles were magnetized on both sides of the shock, but this limit did not apply to cylindrical field configurations. In the cylindrical field configuration, particles of one sign of charge experienced a curvature drift that redirected particles upstream. The distribution approached the escapeless limit dN/d gamma proportional to gamma(-1) when particles reached the confinement limit determined by the finite system size. The cylindrical field configuration resembled that expected for jets launched by the Blandford & Znajek mechanism, implying the potential of active galactic nuclei and gamma-ray bursts as sites for the production of ultra-high-energy cosmic rays.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
R. Battiston, B. Bertucci, O. Adriani, G. Ambrosi, B. Baudouy, P. Blasi, M. Boezio, D. Campana, L. Derome, I. De Mitri, V. Di Felice, F. Donato, M. Duranti, V. Formato, D. Grasso, I. Gebauer, R. Iuppa, N. Masi, D. Maurin, M. N. Mazziotta, R. Musenich, F. Nozzoli, P. Papini, P. Picozza, M. Pearce, S. Pospisil, L. Rossi, N. Tomassetti, V. Vagelli, X. Wu
Summary: Multimessenger astrophysics relies on precise detection of cosmic radiation, such as through space-borne magnetic spectrometers. These tools have enabled advancements in high-energy astrophysics, addressing fundamental questions like matter-antimatter asymmetry and indirect detection of Dark Matter.
EXPERIMENTAL ASTRONOMY
(2021)
Article
Astronomy & Astrophysics
G. Morlino, P. Blasi, E. Peretti, P. Cristofari
Summary: The origins of cosmic rays in our Galaxy remain a subject of ongoing debate, with supernova remnant shocks considered as possible sites of acceleration. However, it is widely accepted that reaching PeV energies from such sources is challenging. Accelerated particles escaping remnants have complex spectra not matching with those observed at Earth. Diffusive shock acceleration at the termination shock of star clusters is investigated, where maximum energy may reach the PeV region for powerful clusters. Energy dissipation in the wind to magnetic perturbations plays a crucial role in shaping the spectrum of accelerated particles. The possibility of a power-law spectrum with a slope of 4/4.3 is found, in agreement with standard models of cosmic ray transport in the Galaxy.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Benedikt Schroer, Oreste Pezzi, Damiano Caprioli, Colby Haggerty, Pasquale Blasi
Summary: Cosmic rays excite both resonant and nonresonant modes, leading to enhanced scattering and the formation of bubbles of gas, CRs, and self-generated magnetic fields. By suppressing diffusivity in the source's vicinity, this phenomenon invalidates the widely adopted flux-tube assumption and is expected to occur around any powerful CR source in the Galaxy, explaining suppressed CR diffusion claims around various Galactic sources.
ASTROPHYSICAL JOURNAL LETTERS
(2021)
Correction
Astronomy & Astrophysics
R. Battiston, B. Bertucci, O. Adriani, G. Ambrosi, B. Baudouy, P. Blasi, M. Boezio, D. Campana, L. Derome, I. De Mitri, V. Di Felice, F. Donato, M. Duranti, V. Formato, D. Grasso, I. Gebauer, R. Iuppa, N. Masi, D. Maurin, M. N. Mazziotta, R. Musenich, F. Nozzoli, P. Papini, P. Picozza, M. Pearce, S. Pospisil, L. Rossi, N. Tomassetti, V. Vagelli, X. Wu
EXPERIMENTAL ASTRONOMY
(2021)
Correction
Physics, Multidisciplinary
Carmelo Evoli, Pasquale Blasi, Elena Amato, Roberto Aloisio
PHYSICAL REVIEW LETTERS
(2021)
Article
Astronomy & Astrophysics
Alessandro Retino, Yuri Khotyaintsev, Olivier Le Contel, Maria Federica Marcucci, Ferdinand Plaschke, Andris Vaivads, Vassilis Angelopoulos, Pasquale Blasi, Jim Burch, Johan De Keyser, Malcolm Dunlop, Lei Dai, Jonathan Eastwood, Huishan Fu, Stein Haaland, Masahiro Hoshino, Andreas Johlander, Larry Kepko, Harald Kucharek, Gianni Lapenta, Benoit Lavraud, Olga Malandraki, William Matthaeus, Kathryn McWilliams, Anatoli Petrukovich, Jean-Louis Pincon, Yoshifumi Saito, Luca Sorriso-Valvo, Rami Vainio, Robert Wimmer-Schweingruber
Summary: This White Paper highlights the importance of addressing the fundamental science theme of particle energization in space plasmas through a future ESA mission, presenting five compelling science questions and the need for a multi-point, multi-scale Plasma Observatory for in situ measurements. This mission aims to enable a paradigm shift in our comprehension of particle energization and space plasma physics, with significant impacts on solar and astrophysical plasmas, further enhancing European leadership in this field.
EXPERIMENTAL ASTRONOMY
(2022)
Article
Astronomy & Astrophysics
Enrico Peretti, Giovanni Morlino, Pasquale Blasi, Pierre Cristofari
Summary: The intense star-forming activity in starburst galaxies leads to strong galactic winds and potential particle acceleration at the termination shock. The accelerated cosmic rays escape into extragalactic space, producing gamma-rays and neutrinos. The diffuse flux of cosmic rays from starburst bubbles is compared with existing data to study their impact on cosmological scales.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
B. Schroer, O. Pezzi, D. Caprioli, C. C. Haggerty, P. Blasi
Summary: The study investigates the formation of cosmic ray bubbles around sources and their diffusion properties and morphology, through simulations.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Oreste Pezzi, Pasquale Blasi, William H. Matthaeus
Summary: This paper discusses the energization of relativistic charged particles in three-dimensional incompressible MHD turbulence and the diffusive properties of their motion. The results show that turbulent plasma motion induces a random electric field, leading to stochastic acceleration of test particles in a simulated box, developing a second-order Fermi process. Some particles are trapped in large-scale structures and experience exponential acceleration if certain conditions are met.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Pierre Cristofari, Pasquale Blasi, Damiano Caprioli
Summary: Diffusive shock acceleration is the most likely process for accelerating particles in various astrophysical sources. However, several phenomena can affect the spectrum of accelerated particles, making it steeper or harder than the standard prediction. Magnetic field amplification leads to a steeper spectrum, while the excitation of the non-resonant streaming instability affects the spectral deformations.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Pasquale Blasi, Giovanni Morlino
Summary: We investigate the acceleration of cosmic rays at the termination shock resulting from the interaction of star cluster wind with the interstellar medium. The solution of the transport equation for accelerated particles in the wind-excavated cavity reveals interesting properties, including energy losses due to CR interactions with neutral gas. The maximum energy of the accelerated particles is discussed in relation to the origin of Galactic cosmic rays. Gamma-ray emission and the diffusion of accelerated particles downstream of the termination shock are also analyzed, with a comparison to observations in the Cygnus OB2 region.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Enrico Peretti, Alessandra Lamastra, Francesco Gabriele Saturni, Markus Ahlers, Pasquale Blasi, Giovanni Morlino, Pierre Cristofari
Summary: Active galactic nuclei can produce powerful winds known as ultra-fast outflows (UFOs), which may accelerate ultra-high energy cosmic rays and high-energy neutrinos. Our study suggests that obscured UFOs, such as those observed in NGC1068, could play a significant role in the observed gamma-ray flux while contributing less to the associated neutrino flux.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Carmelo Evoli, Elena Amato, Pasquale Blasi, Roberto Aloisio
Summary: Recent precision measurements of cosmic ray nuclei and leptons have revealed multiple features, suggesting the occasional presence of local cosmic ray sources reshaping the expected spectra. Researchers quantitatively address the likelihood of such sources existing by studying the statistical properties of source distribution in space and time, and the impact of our Galaxy's spiral structure on the spectra of different energy regions.
Article
Astronomy & Astrophysics
Benedikt Schroer, Carmelo Evoli, Pasquale Blasi
Summary: Recent measurements of cosmic-ray fluxes by the AMS-02 experiment have provided a comprehensive set of data, showing that parameters derived from lighter elements can effectively describe heavier nuclei data. The only anomaly is observed in iron nuclei at rigidity less than 100 GV, contradicting the standard model and previous data collections.
Article
Astronomy & Astrophysics
Carmelo Evoli, Elena Amato, Pasquale Blasi, Roberto Aloisio
Summary: This study presents a novel calculation method for evaluating the spectrum of electrons and positrons from random sources, supernova remnants, and pulsars within the spiral arms of the Galaxy, with pulsars considered as time-dependent sources of electron-positron pairs. The research shows that the electron spectrum exhibits a feature at greater than or similar to 50 GeV, while the positron spectrum is well described by contributions from pulsars, leading to a natural rise in the positron fraction.
