Articles de revues : « Astrophysics - High Energy Astrophysical Phenomena »

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Murase, Kohta, et Imre Bartos. « High-Energy Multimessenger Transient Astrophysics ». Annual Review of Nuclear and Particle Science 69, n^o 1 (19 octobre 2019) : 477–506. http://dx.doi.org/10.1146/annurev-nucl-101918-023510.

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The recent discoveries of high-energy cosmic neutrinos and gravitational waves from astrophysical objects have led to a new era of multimessenger astrophysics. In particular, electromagnetic follow-up observations triggered by these cosmic signals have proved to be highly successful and have brought about new opportunities in time-domain astronomy. We review high-energy particle production in various classes of astrophysical transient phenomena related to black holes and neutron stars, and discuss how high-energy emission can be used to reveal the underlying physics of neutrino and gravitational-wave sources.

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Ayala Solares, Hugo A. « The Astrophysical Multimessenger Observatory Network : a Summary ». Journal of Physics : Conference Series 2429, n^o 1 (1 février 2023) : 012034. http://dx.doi.org/10.1088/1742-6596/2429/1/012034.

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Abstract The Astrophysical Multimessenger Observatory Network (AMON) aims to connect the world’s leading high-energy and multimessenger observatories. AMON’s objective are to evoke the discovery of new multimessenger phenomena, exploit these phenomena as tools for fundamental physics and astrophysics, and explore archival datasets in search of multimessenger activity. Present projects include distributing low-latency multimessenger alerts from the Neutrino-Electromagnetic (NuEM) channel, as well as distrubting alerts from individual detectors including IceCube and HAWC. Looking ahead, AMON will continue providing useful real-time analyses of a wide variety of high-energy and multimessenger data streams, including coincidences between gravitational-wave data and gamma-ray data. It will also start using the SCiMMA-standard cyberinfrastructure, and keep strengthening its ties with the theoretical and time domain astrophysics communities.

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Learned, John G., et Karl Mannheim. « High-Energy Neutrino Astrophysics ». Annual Review of Nuclear and Particle Science 50, n^o 1 (décembre 2000) : 679–749. http://dx.doi.org/10.1146/annurev.nucl.50.1.679.

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▪ Abstract High-energy (>100 MeV) neutrino astrophysics enters an era of opportunity and discovery as the sensitivity of detectors approaches astrophysically relevant flux levels. We review the major challenges for this emerging field, among which the nature of dark matter, the origin of cosmic rays, and the physics of extreme objects such as active galactic nuclei, gamma-ray bursts, pulsars, and supernova remnants are of prime importance. Variable sources at cosmological distances allow the probing of neutrino propagation properties over baselines up to about 20 orders of magnitude larger than those probed by terrestrial long-baseline experiments. We review the possible astrophysical sources of high-energy neutrinos, which also act as an irreducible background to searches for phenomena at the electroweak and grand-unified-theory symmetry-breaking scales related to possible supersymmetric dark matter and topological defects. Neutrino astronomy also has the potential to discover previously unimagined high-energy sources invisible in other channels and provides the only means for direct observations of the early universe prior to the era of decoupling of photons and matter. We conclude with a discussion of experimental approaches and a short report on present projects and prospects. We look forward to the day when it will be possible to see the universe through a new window in the light of what may be its most numerous particle, the elusive neutrino.

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Longair, Malcolm. « Radio astronomy and the rise of high-energy astrophysics two anniversaries ». International Journal of Modern Physics D 28, n^o 02 (janvier 2019) : 1930004. http://dx.doi.org/10.1142/s0218271819300040.

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This paper celebrates the 100th anniversary of the birth of Martin Ryle and the 50th anniversary of the discovery of pulsars by Jocelyn Bell and Antony Hewish. Ryle and Hewish received the 1974 Nobel Prize in Physics, the first in the area of astrophysics. Their interests strongly overlapped, one of the key papers on the practical implementation of the technique of aperture synthesis being co-authored by Ryle and Hewish. The discovery of pulsars and the roles played by Hewish and Bell are described. These key advances were at the heart of the dramatic rise of high-energy astrophysics in the 1960s and led to the realization that general relativity is central to the understanding of high-energy astrophysical phenomena.

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Blandford, R. D. « The Phenomena of High Energy Astrophysics ». Symposium - International Astronomical Union 214 (2003) : 3–20. http://dx.doi.org/10.1017/s0074180900194124.

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A brief summary of some highlights in the study of high energy astrophysical sources over the past decade is presented. It is argued that the great progress that has been made derives largely from the application of new technology to observation throughout all of the electromagnetic and other spectra and that, on this basis, the next decade should be even more exciting. However, it is imperative to observe cosmic sources throughout these spectra in order to obtain a full understanding of their properties. In addition, it is necessary to learn the universal laws that govern the macroscopic and the microscopic behavior of cosmic plasma over a great range of physical conditions by combining observations of different classes of source. These two injunctions are illustrated by discussions of cosmology, hot gas, supernova remnants and explosions, neutron stars, black holes and ultrarelativistic outflows. New interpreations of the acceleration of Galactic cosmic rays, the cooling of hot gas in rich clusters and the nature of ultrarelativistic outflows are outlined. The new frontiers of VHE γ-ray astronomy, low frequency radio astronomy, neutrino astronomy, UHE cosmic ray physics and gravitational wave astronomy are especially promising.

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DE RÚJULA, A. « A UNIFIED MODEL OF HIGH-ENERGY ASTROPHYSICAL PHENOMENA ». International Journal of Modern Physics A 20, n^o 29 (20 novembre 2005) : 6562–83. http://dx.doi.org/10.1142/s0217751x05029617.

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I outline a unified model of high-energy astrophysics, in which the gamma background radiation, cluster "cooling flows", gamma-ray bursts, X-ray flashes and cosmic-ray electrons and nuclei of all energies — share a common origin. The mechanism underlying these phenomena is the emission of relativistic "cannonballs" by ordinary supernovae, analogous to the observed ejection of plasmoids by quasars and microquasars. I concentrate on Cosmic Rays: the longest-lasting conundrum in astrophysics. The distribution of Cosmic Rays in the Galaxy, their total "luminosity", the broken power-law spectra with their observed slopes, the position of the knee(s) and ankle(s), and the alleged variations of composition with energy are all explained in terms of simple and "standard" physics. The model is only lacking a satisfactory theoretical understanding of the "cannon" that emits the cannonballs in catastrophic episodes of accretion onto a compact object.

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Stehlé, C., A. Ciardi, J. P. Colombier, M. González, T. Lanz, A. Marocchino, M. Kozlova et B. Rus. « Scaling stellar jets to the laboratory : The power of simulations ». Laser and Particle Beams 27, n^o 4 (décembre 2009) : 709–17. http://dx.doi.org/10.1017/s0263034609990449.

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AbstractAdvances in laser and Z-pinch technology, coupled with the development of plasma diagnostics, and the availability of high-performance computers, have recently stimulated the growth of high-energy density laboratory astrophysics. In particular, a number of experiments have been designed to study radiative shocks and jets with the aim of shedding new light on physical processes linked to the ejection and accretion of mass by newly born stars. Although general scaling laws are powerful tools to link laboratory experiments with astrophysical plasmas, the phenomena modeled are often too complicated for simple scaling to remain relevant. Nevertheless, the experiments can still give important insights into the physics of astrophysical systems and can be used to provide the basic experimental validation of numerical simulations in regimes of interest to astrophysics. We will illustrate the possible links between laboratory experiments, numerical simulations, and astrophysics in the context of stellar jets. First we will discuss the propagation of stellar jets in a cross-moving interstellar medium and the scaling to Z-pinch produced jets. Our second example focuses on slab-jets produced at the Prague Asterix Laser System laser installation and their practical applications to astrophysics. Finally, we illustrate the limitations of scaling for radiative shocks, which are found at the head of the most rapid stellar jets.

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Tranchant, V., N. Charpentier, L. Van Box Som, A. Ciardi et É. Falize. « New Class of Laboratory Astrophysics Experiments : Application to Radiative Accretion Processes around Neutron Stars ». Astrophysical Journal 936, n^o 1 (25 août 2022) : 14. http://dx.doi.org/10.3847/1538-4357/ac81b8.

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Abstract Extreme radiative phenomena, where the radiation energy density and flux strongly influence the medium, are common in the universe. Nevertheless, because of limited or nonexistent observational and experimental data, the validity of theoretical and numerical models for some of these radiation-dominated regimes remains to be assessed. Here, we present the theoretical framework of a new class of laboratory astrophysics experiments that can take advantage of existing high-power laser facilities to study supersonic radiation-dominated waves. Based on an extension of Lie symmetry theory we show that the stringent constraints imposed on the experiments by current scaling theories can in fact be relaxed, and that astrophysical phenomena can be studied in the laboratory even if the ratio of radiation energy density to thermal energy and systems’ microphysics are different. The validity of this approach holds until the hydrodynamic response of the studied system starts to play a role. These equivalence symmetries concepts are demonstrated using a combination of simulations for conditions relevant to Type I X-ray burst and of equivalent laboratory experiments. These results constitute the starting point of a new general approach expanding the catalog of astrophysical systems that can be studied in the laboratory.

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Chen, Hui, et Frederico Fiuza. « Perspectives on relativistic electron–positron pair plasma experiments of astrophysical relevance using high-power lasers ». Physics of Plasmas 30, n^o 2 (février 2023) : 020601. http://dx.doi.org/10.1063/5.0134819.

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The study of relativistic electron–positron pair plasmas is both of fundamental physics interest and important to understand the processes that shape the magnetic field dynamics, particle acceleration, and radiation emission in high-energy astrophysical environments. Although it is highly desirable to study relativistic pair plasmas in the laboratory, their generation and control constitutes a critical challenge. Significant experimental and theoretical progress has been made over recent years to explore the use of intense lasers to produce dense relativistic pair plasma in the laboratory and study the basic collective plasma processes associated with these systems. Important challenges remain in terms of improving the number of pairs, system size, and control over the charge neutrality required to establish laboratory platforms that can expand our understanding of relativistic pair plasma and help validate underlying models in conditions relevant to high-energy astrophysical phenomena. We highlight recent progress in this field, discuss the main challenges, and the exciting prospects for studying relativistic pair plasmas and astrophysics relevant instabilities in the laboratory in the near future.

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Ryutov, D. D., et B. A. Remington. « Scaling astrophysical phenomena to high-energy-density laboratory experiments ». Plasma Physics and Controlled Fusion 44, n^o 12B (20 novembre 2002) : B407—B423. http://dx.doi.org/10.1088/0741-3335/44/12b/328.

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Hoang, Thiem. « Rotational Disruption of Astrophysical Dust and Ice—Theory and Applications ». Galaxies 8, n^o 3 (6 juillet 2020) : 52. http://dx.doi.org/10.3390/galaxies8030052.

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Dust is an essential component of the interstellar medium (ISM) and plays an important role in many different astrophysical processes and phenomena. Traditionally, dust grains are known to be destroyed by thermal sublimation, Coulomb explosions, sputtering, and shattering. The first two mechanisms arise from the interaction of dust with intense radiation fields and high-energy photons (extreme UV), which work in a limited astrophysical environment. The present review is focused on a new destruction mechanism present in the dust-radiation interaction that is effective in a wide range of radiation fields and has ubiquitous applications in astrophysics. We first describe this new mechanism of grain destruction, namely rotational disruption induced by Radiative Torques (RATs) or RAdiative Torque Disruption (RATD). We then discuss rotational disruption of nanoparticles by mechanical torques due to supersonic motion of grains relative to the ambient gas, which is termed MEchanical Torque Disruption (METD). These two new mechanisms modify properties of dust and ice (e.g., size distribution and mass), which affects observational properties, including dust extinction, thermal and nonthermal emission, and polarization. We present various applications of the RATD and METD mechanisms for different environments, including the ISM, star-forming regions, astrophysical transients, and surface astrochemistry.

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MATT, GIORGIO. « HIGH-ENERGY PHENOMENA STUDIED WITH X–RAY POLARIMETRY ». International Journal of Modern Physics D 19, n^o 06 (juin 2010) : 723–28. http://dx.doi.org/10.1142/s0218271810016889.

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After more than 30 years since the last X–ray polarimetric measurements, performed in the 70's by the OSO-8 satellite, thanks to recent technological advances, polarimetry is considered again as a viable technique for studing X–ray sources. In this contribution the author briefly discusses a couple of astrophysical situations, related to the topics of this conference, where X–ray polarimetry can be extremely useful. The author also discusses the observational perspectives, listing the main future space missions (proposed or even already approved) carrying on-board an X–ray polarimeter.

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de Gouveia Dal Pino, Elisabete M., et Alex C. Raga. « JD7 -Astrophysical Outflows and Associated Accretion Phenomena ». Proceedings of the International Astronomical Union 5, H15 (novembre 2009) : 235–36. http://dx.doi.org/10.1017/s1743921310009002.

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Highly collimated supersonic jets and outflows are very frequent in several astrophysical environments. They are seen in young stellar objects (YSOs), proto-planetary nebulae, compact objects (like galactic black holes or microquasars, and X-ray binary stars), active galactic nuclei, and are also possibly associated to gamma-ray bursts (GRBs) and to ultra-high energy cosmic rays sources (UHECRs). Despite their different physical scales, all these outflow classes have strong morphological similarities, but questions such as - what physics do they share? - or - can we find a universal mechanism of acceleration and collimation that operates in all classes? - remain matters of debate. The most accepted mechanism for their origin relies on a rotating accretion disk threaded by perpendicular large-scale magnetic fields and, though most of the systems producing jets contain an accretion disk around the central source, the real role that rotation and magnetic fields play in these processes is still not fully understood, nor are the highly non-linear physical processes connected to these jet-disk systems in the large parameter space involved.

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Tursunov, Arman, et Naresh Dadhich. « Fifty Years of Energy Extraction from Rotating Black Hole : Revisiting Magnetic Penrose Process ». Universe 5, n^o 5 (22 mai 2019) : 125. http://dx.doi.org/10.3390/universe5050125.

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Magnetic Penrose process (MPP) is not only the most exciting and fascinating process mining the rotational energy of black hole but it is also the favored astrophysically viable mechanism for high energy sources and phenomena. It operates in three regimes of efficiency, namely low, moderate and ultra, depending on the magnetization and charging of spinning black holes in astrophysical setting. In this paper, we revisit MPP with a comprehensive discussion of its physics in different regimes, and compare its operation with other competing mechanisms. We show that MPP could in principle foot the bill for powering engine of such phenomena as ultra-high-energy cosmic rays, relativistic jets, fast radio bursts, quasars, AGNs, etc. Further, it also leads to a number of important observable predictions. All this beautifully bears out the promise of a new vista of energy powerhouse heralded by Roger Penrose half a century ago through this process, and it has today risen in its magnetically empowered version of mid 1980s from a purely thought experiment of academic interest to a realistic powering mechanism for various high-energy astrophysical phenomena.

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Jacobson, Ted, Stefano Liberati et David Mattingly. « Lorentz violation at high energy : Concepts, phenomena, and astrophysical constraints ». Annals of Physics 321, n^o 1 (janvier 2006) : 150–96. http://dx.doi.org/10.1016/j.aop.2005.06.004.

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MOCIOIU, IRINA. « VERY HIGH ENERGY NEUTRINOS ». International Journal of Modern Physics A 20, n^o 30 (10 décembre 2005) : 7079–105. http://dx.doi.org/10.1142/s0217751x05028843.

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Galloway, D. K., Z. Johnston, A. Goodwin et A. Heger. « High-Energy Transients : Thermonuclear (Type-I) X-Ray Bursts ». Proceedings of the International Astronomical Union 14, S339 (novembre 2017) : 121–26. http://dx.doi.org/10.1017/s1743921318002363.

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AbstractMany distinct classes of high-energy variability have been observed in astrophysical sources, and over a range of time-scales. The widest range, spanning microseconds to decades, is found in accreting, compact, stellar-mass objects, including neutron stars and black holes. Neutron stars are of particular observational interest as they exhibit surface effects giving rise to phenomena – such as thermonuclear bursts and pulsations – not seen in black holes.This talk reviewed briefly the present understanding of thermonuclear (Type-I) X-ray bursts – events that are powered by an extensive chain of nuclear reactions which in many cases are unique to the environments. Thermonuclear bursts have been exploited over the last few years as an avenue to measure a neutron star’s mass and radius, although the contribution of systematic errors to the measurements remains contentious. We described recent efforts to match burst models to observations better, with a view to resolving some of the astrophysical uncertainties relating to those events. Our efforts have good prospects for providing information that is complementary to nuclear experiments.

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Weber, Fridolin, Gustavo A. Contrera, Milva G. Orsaria, William Spinella et Omair Zubairi. « Properties of high-density matter in neutron stars ». Modern Physics Letters A 29, n^o 23 (24 juillet 2014) : 1430022. http://dx.doi.org/10.1142/s0217732314300225.

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This short review aims at giving a brief overview of various states of matter that have been suggested to exist in the ultra-dense centers of neutron stars. Particular emphasis is put on the role of quark deconfinement in neutron stars and on the possible existence of compact stars made of absolutely stable strange quark matter (strange stars). Astrophysical phenomena, which distinguish neutron stars from quark stars, are discussed and the question of whether or not quark deconfinement may occur in neutron stars is investigated. Combined with observed astrophysical data, such studies are invaluable to delineate the complex structure of compressed baryonic matter and to put firm constraints on the largely unknown equation of state of such matter.

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WESTERHOFF, STEFAN. « ULTRA–HIGH-ENERGY COSMIC RAYS ». International Journal of Modern Physics A 21, n^o 08n09 (10 avril 2006) : 1950–61. http://dx.doi.org/10.1142/s0217751x06032897.

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One of the most striking astrophysical phenomena today is the existence of cosmic ray particles with energies in excess of 1020 eV. While their presence has been confirmed by a number of experiments, it is not clear where and how these particles are accelerated to these energies and how they travel astronomical distances without substantial energy loss. We are entering an exciting new era in cosmic ray physics, with instruments now producing data of unprecedented quality and quantity to tackle the many open questions. This paper reviews the current experimental status of cosmic ray physics and summarizes recent results on the energy spectrum and arrival directions of ultra-high-energy cosmic rays.

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SHAO, LIJING, et BO-QIANG MA. « LORENTZ VIOLATION EFFECTS ON ASTROPHYSICAL PROPAGATION OF VERY HIGH ENERGY PHOTONS ». Modern Physics Letters A 25, n^o 39 (21 décembre 2010) : 3251–66. http://dx.doi.org/10.1142/s0217732310034572.

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Lorentz violation (LV) is predicted by some quantum gravity (QG) candidates, wherein the canonical energy–momentum dispersion relation, E2 = p2+m2, is modified. Consequently, new phenomena beyond the standard model are predicted. In particular, the presence of LV highly affects the propagation of astrophysical photons with very high energies from distant galaxies. In this paper, we review the updating theoretical and experimental results on this topic. We classify the effects into three categories: (i) time lags between photons with different energies; (ii) a cutoff of photon flux above the threshold energy of photon decay, γ→e++e-; (iii) new patterns in the spectra of multi-TeV photons and EeV photons, due to the absorption of background lights. As we can see, the details of LV effects on astrophysical photons depend heavily on the "phase space" of LV parameters. From observational aspects, available and upcoming instruments can study these phenomena hopefully, and shed light onto LV issues and QG theories. The most recent progresses and constraints on the ultra-high energy cosmic rays (UHECRs) are also discussed.

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Trimble, Virginia. « IAU Symposium 214 : High‐Energy Processes and Phenomena in Astrophysics ». Publications of the Astronomical Society of the Pacific 115, n^o 803 (janvier 2003) : 142. http://dx.doi.org/10.1086/374186.

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Parkinson, W. H. « Commission 14 : Atomic and Molecular Data (Donnees Atomiques et Moleculaires) ». Transactions of the International Astronomical Union 21, n^o 1 (1991) : 105–36. http://dx.doi.org/10.1017/s0251107x00009949.

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Since its creation, the Commission has been keen on activating the cross-discipline interaction between astrophysics and atomic and molecular physics. The need for a variety of atomic and molecular data has become more and more important for the recent past years. This need will certainly increase still more in the next years, due to the creation of new ground based instruments and to the launch of new space missions : they will produce large amounts of high resolution spectra from the X-rays to the infrared and millimeter wavelengths involving many atoms, ions and molecules. At the 1988 Baltimore meeting there was a general consensus that the aim of the Commission is to watch over the atomic and molecular spectral and structure data, together with the energy exchange processes in atomic and molecular physics relevant for astrophysics. In particular, the Commission is concerned by the interactions between photons and atoms (or ions or molecules), including wavelengths and line transition probabilities data, and by the interactions between particles, including atomic, molecular, ionic and electronic collision cross-sections, and by related phenomena, such as line broadening, collisional redistribution of radiation and line polarization. All these informations are essential for the interpretation of astronomical observations, such as spectroscopic diagnosis and theoretical modelling of astrophysical media.

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Gehrels, Neil, et John K. Cannizzo. « High-energy transients ». Philosophical Transactions of the Royal Society A : Mathematical, Physical and Engineering Sciences 371, n^o 1992 (13 juin 2013) : 20120270. http://dx.doi.org/10.1098/rsta.2012.0270.

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We present an overview of high-energy transients in astrophysics, highlighting important advances over the past 50 years. We begin with early discoveries of γ-ray transients, and then delve into physical details associated with a variety of phenomena. We discuss some of the unexpected transients found by Fermi and Swift, many of which are not easily classifiable or in some way challenge conventional wisdom. These objects are important insofar as they underscore the necessity of future, more detailed studies.

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Bosch-Ramon, Valentí. « Nonthermal processes in microquasars ». Proceedings of the International Astronomical Union 6, S275 (septembre 2010) : 215–23. http://dx.doi.org/10.1017/s1743921310016066.

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AbstractMicroquasars are X-ray binaries that show extended radio jets. These jets can accelerate particles up to relativistic energies that produce non-thermal emission from radio to TeV, and could also make a non-negligible contribution to the galactic CRs in some energy ranges. The orbital motion and compactness of these sources allow the study of high-energy astrophysical phenomena in extreme conditions that change in accessible timescales. In this work, I briefly discuss the production of broadband non-thermal emission in microquasars, putting special emphasis on the high- and the very high-energy bands.

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Courvoisier, T. J. L., et V. Trimble. « Introduction ». Highlights of Astronomy 11, n^o 2 (1998) : 749–50. http://dx.doi.org/10.1017/s1539299600018682.

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Over the last few decades phenomena involving high energy particles (mostly electrons) and/or photons have become increasingly part of the astronomical work. Opening new spectral windows has revealed many phenomena that have deeply changed our perception of the Universe. High energy astrophysics, as this field of astronomy is known, is now very well integrated in the astronomical research. This is shown by the fact that the high energy astrophysics results are published in the leading astronomy and astrophysics journals of the world rather than anywhere else. Nonetheless, this still young field has not yet quite found its way in the structure and working of the IAU.

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Krastev, Plamen G. « Translating Neutron Star Observations to Nuclear Symmetry Energy via Deep Neural Networks ». Galaxies 10, n^o 1 (18 janvier 2022) : 16. http://dx.doi.org/10.3390/galaxies10010016.

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One of the most significant challenges involved in efforts to understand the equation of state of dense neutron-rich matter is the uncertain density dependence of the nuclear symmetry energy. In particular, the nuclear symmetry energy is still rather poorly constrained, especially at high densities. On the other hand, detailed knowledge of the equation of state is critical for our understanding of many important phenomena in the nuclear terrestrial laboratories and the cosmos. Because of its broad impact, pinning down the density dependence of the nuclear symmetry energy has been a long-standing goal of both nuclear physics and astrophysics. Recent observations of neutron stars, in both electromagnetic and gravitational-wave spectra, have already constrained significantly the nuclear symmetry energy at high densities. The next generation of telescopes and gravitational-wave observatories will provide an unprecedented wealth of detailed observations of neutron stars, which will improve further our knowledge of the density dependence of nuclear symmetry energy, and the underlying equation of state of dense neutron-rich matter. Training deep neural networks to learn a computationally efficient representation of the mapping between astrophysical observables of neutron stars, such as masses, radii, and tidal deformabilities, and the nuclear symmetry energy allows its density dependence to be determined reliably and accurately. In this work, we use a deep learning approach to determine the nuclear symmetry energy as a function of density directly from observational neutron star data. We show, for the first time, that artificial neural networks can precisely reconstruct the nuclear symmetry energy from a set of available neutron star observables, such as masses and radii as measured by, e.g., the NICER mission, or masses and tidal deformabilities as measured by the LIGO/VIRGO/KAGRA gravitational-wave detectors. These results demonstrate the potential of artificial neural networks to reconstruct the symmetry energy and the equation of state directly from neutron star observational data, and emphasize the importance of the deep learning approach in the era of multi-messenger astrophysics.

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de Wasseige, G. « KM3NeT sensitivity to low energy astrophysical neutrinos ». Journal of Instrumentation 16, n^o 12 (1 décembre 2021) : C12003. http://dx.doi.org/10.1088/1748-0221/16/12/c12003.

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Abstract KM3NeT, a new generation of neutrino telescope, is currently being deployed in the Mediterranean Sea. While its two sites, ORCA and ARCA, were respectively designed for the determination of neutrino mass hierarchy and high-energy neutrino astronomy, this contribution presents a study of the detection potential of KM3NeT in the MeV-GeV energy range. At these low energies, the data rate is dominated by low-energy atmospheric muons and environmental noise due to bioluminescence and K-40 decay. The goal of this study is to characterize the environmental noise in order to optimize the selection of low-energy neutrino interactions and increase the sensitivity of KM3NeT to transient astrophysical phenomena, such as close-by core-collapse supernovae, solar flares, and extragalactic transients. In this contribution, we will study how using data science tools might improve the sensitivity of KM3NeT in these low-energy neutrino searches. We will first introduce the data sets and the different variables used to characterize KM3NeT’s response to the environmental noise. We will then compare the efficiency of various tools in identifying different components in the environmental noise and in disentangling low-energy neutrino interactions from the background events. We will conclude with the implication of low-energy neutrinos for future astrophysical transient searches.

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Wang, Q. Daniel. « Studying the Nearby Universe with Chandra ». Symposium - International Astronomical Union 214 (2003) : 32–45. http://dx.doi.org/10.1017/s0074180900194148.

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I highlight results from Chandra observations of nearby galaxies, including the Milky Way. These observations have offered insights into old mysteries and indications of new high energy astrophysical phenomena and processes that are yet to be understood.

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VAN ELEWYCK, VERONIQUE, S. ANDO, Y. ASO, B. BARET, M. BARSUGLIA, I. BARTOS, E. CHASSANDE-MOTTIN et al. « JOINT SEARCHES BETWEEN GRAVITATIONAL-WAVE INTERFEROMETERS AND HIGH-ENERGY NEUTRINO TELESCOPES : SCIENCE REACH AND ANALYSIS STRATEGIES ». International Journal of Modern Physics D 18, n^o 10 (octobre 2009) : 1655–59. http://dx.doi.org/10.1142/s0218271809015655.

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Many of the astrophysical sources and violent phenomena observed in our Universe are potential emitters of gravitational waves (GWs) and high-energy neutrinos (HENs). A network of GW detectors such as LIGO and Virgo can determine the direction/time of GW bursts while the IceCube and ANTARES neutrino telescopes can also provide accurate directional information for HEN events. Requiring the consistency between both, totally independent, detection channels shall enable new searches for cosmic events arriving from potential common sources, of which many extra-galactic objects.

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Pretzl, Klaus. « Cryogenic detectors exploring new phenomena in physics and astrophysics ». Europhysics News 52, n^o 3 (2021) : 18–21. http://dx.doi.org/10.1051/epn/2021303.

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The potential to measure small energy transfers with very high energy resolutions motivated the development of cryogenic detectors to search for dark matter in the universe, the neutrino mass, neutrinoless double beta decay, and new phenomena in astrophysics. Other fields like material and life sciences also benefited from these developments.

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Colgate, Stirling A. « Relationship between high-energy physical phenomena on the sun and in astrophysics ». Solar Physics 118, n^o 1-2 (1988) : 1–15. http://dx.doi.org/10.1007/bf00148586.

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Berti, Emanuele, Vitor Cardoso, Luis C. B. Crispino, Leonardo Gualtieri, Carlos Herdeiro et Ulrich Sperhake. « Numerical relativity and high energy physics : Recent developments ». International Journal of Modern Physics D 25, n^o 09 (août 2016) : 1641022. http://dx.doi.org/10.1142/s0218271816410224.

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We review recent progress in the application of numerical relativity techniques to astrophysics and high-energy physics. We focus on recent developments regarding the spin evolution in black hole binaries, high-energy black hole collisions, compact object solutions in scalar–tensor gravity, superradiant instabilities, hairy black hole solutions in Einstein’s gravity coupled to fundamental fields, and the possibility to gain insight into these phenomena using analog gravity models.

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LEE, HYUN KYU, et YONGSUNG YOON. « FERMION PRODUCTION IN STRONG MAGNETIC FIELD AND ITS ASTROPHYSICAL IMPLICATIONS ». Modern Physics Letters A 22, n^o 25n28 (14 septembre 2007) : 2081–90. http://dx.doi.org/10.1142/s0217732307025327.

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We calculate the effective potential of a strong magnetic field induced by fermions with anomalous magnetic moments which couple to the electromagnetic field in the form of the Pauli interaction. For a uniform magnetic field, we find the explicit form of the effective potential. It is found that the non-vanishing imaginary part develops for a magnetic field stronger than a critical field and has a quartic form which is quite different from the exponential form of the Schwinger process. We also consider a linear magnetic field configuration as an example of inhomogeneous magnetic fields. We find that the imaginary part of the effective potential is nonzero even below the critical field and shows an exponentially decreasing behavior with respect to the inverse of the magnetic field gradient, which is the non-perturbative characteristics analogous to the Schwinger process. These results imply the instability of the strong magnetic field to produce fermion pairs as a purely magnetic effect. The possible applications to the astrophysical phenomena with strong magnetic field are also discussed.

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Trimble, Virginia. « Conference Summary : What is High Energy Astrophyics ? » Symposium - International Astronomical Union 214 (2003) : 411–23. http://dx.doi.org/10.1017/s0074180900194811.

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The original intent of the conference was to focus, first, on the physical processes (accretion, collimation, and all the rest) shared by two or more of the kinds of sources generally thought of as belonging to high energy astrophysics and, second, on the full range of phenomena, at all wavelengths, exhibited by those sources. This summary therefore addresses some of these issues as well as some new results presented at the symposium and some of the still-unanswered questions that were raised.

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Bellenghi, C., T. Glauch, C. Haack, T. Kontrimas, H. Niederhausen, R. Reimann et M. Wolf. « A new and improved IceCube point source analysis ». Journal of Instrumentation 16, n^o 11 (1 novembre 2021) : C11002. http://dx.doi.org/10.1088/1748-0221/16/11/c11002.

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Abstract The IceCube Neutrino Observatory, a cubic kilometer scale Cherenkov detector deployed in the deep ice at the geographic South Pole, investigates extreme astrophysical phenomena by studying the corresponding high-energy neutrino signal. Its discovery of a diffuse flux of astrophysical neutrinos with energies up to the PeV scale in 2013 has triggered a vast effort to identify the mostly unknown sources of these high energy neutrinos. Here, we present a new IceCube point-source search that improves the accuracy of the statistical analysis, especially at energies of a few TeV and below. The new approach is based on multidimensional kernel density estimation for the probability density functions and new estimators for the observables, namely the reconstructed energy and the estimated angular uncertainty on the reconstructed arrival direction. The more accurate analysis provides an improvement in discovery potential up to ∼30% over previous works for hard spectrum sources.

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RAZZAQUE, SOEBUR, PETER MÉSZÁROS et ELI WAXMAN. « HIGH ENERGY NEUTRINOS FROM A SLOW JET MODEL OF CORE COLLAPSE SUPERNOVAE ». Modern Physics Letters A 20, n^o 31 (10 octobre 2005) : 2351–67. http://dx.doi.org/10.1142/s0217732305018414.

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It has been hypothesized recently that core collapse supernovae are triggered by mildly relativistic jets following observations of radio properties of these explosions. Association of a jet, similar to a gamma-ray burst jet but only slower, allows shock acceleration of particles to high energy and non-thermal neutrino emission from a supernova. Detection of these high energy neutrinos in upcoming kilometer scale Cherenkov detectors may be the only direct way to probe inside these astrophysical phenomena as electromagnetic radiation is thermal and contains little information. Calculation of high energy neutrino signal from a simple and slow jet model buried inside the pre-supernova star is reviewed here. The detection prospect of these neutrinos in water or ice detector is also discussed in this brief review. Jetted core collapse supernovae in nearby galaxies may provide the strongest high energy neutrino signal from point sources.

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Bojičić, I. S., M. D. Filipović, D. Urošević, Q. A. Parker et T. J. Galvin. « Determination of Planetary Nebulae angular diameters from radio continuum spectral energy distribution modelling ». Monthly Notices of the Royal Astronomical Society 503, n^o 2 (10 mars 2021) : 2887–98. http://dx.doi.org/10.1093/mnras/stab687.

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ABSTRACT Powerful new, high-resolution, high-sensitivity, multifrequency, wide-field radio surveys such as the Australian Square Kilometre Array Pathfinder (ASKAP) Evolutionary Map of the Universe are emerging. They will offer fresh opportunities to undertake new determinations of useful parameters for various kinds of extended astrophysical phenomena. Here, we consider specific application to angular-size determinations of Planetary Nebulae (PNe) via a new radio continuum spectral energy distribution fitting technique. We show that robust determinations of angular size can be obtained, comparable to the best optical and radio observations but with the potential for consistent application across the population. This includes unresolved and/or heavily obscured PNe that are extremely faint or even non-detectable in the optical.

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Haggard, Daryl, et Gregory R. Sivakoff. « The Future of X-Ray Time-Domain Surveys ». Proceedings of the International Astronomical Union 7, S285 (septembre 2011) : 199–206. http://dx.doi.org/10.1017/s1743921312000609.

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AbstractModern X-ray observatories yield unique insight into the astrophysical time domain. Each X-ray photon can be assigned an arrival time, an energy and a sky position, yielding sensitive, energy-dependent light curves and enabling time-resolved spectra down to millisecond time-scales. Combining those with multiple views of the same patch of sky (e.g., in the Chandra and XMM-Newton deep fields) so as to extend variability studies over longer baselines, the spectral timing capacity of X-ray observatories then stretch over 10 orders of magnitude at spatial resolutions of arcseconds, and 13 orders of magnitude at spatial resolutions of a degree. A wealth of high-energy time-domain data already exists, and indicates variability on timescales ranging from microseconds to years in a wide variety of objects, including numerous classes of AGN, high-energy phenomena at the Galactic centre, Galactic and extra-Galactic X-ray binaries, supernovæ, gamma-ray bursts, stellar flares, tidal disruption flares, and as-yet unknown X-ray variables. This workshop explored the potential of strategic X-ray surveys to probe a broad range of astrophysical sources and phenomena. Here we present the highlights, with an emphasis on the science topics and mission designs that will drive future discovery in the X-ray time domain.

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Beall, J. H., J. Guillory, D. V. Rose et Michael T. Wolff. « MODELING JET INTERACTIONS WITH THE AMBIENT MEDIUM ». Acta Polytechnica 53, A (18 décembre 2013) : 683–86. http://dx.doi.org/10.14311/ap.2013.53.0683.

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Recent high-resolution (see, e.g., [13]) observations of astrophysical jets reveal complex structures apparently caused by ejecta from the central engine as the ejecta interact with the surrounding interstellar material. These observations include time-lapsed “movies” of both AGN and microquasars jets which also show that the jet phenomena are highly time-dependent. Such observations can be used to inform models of the jet–ambient-medium interactions. Based on an analysis of these data, we posit that a significant part of the observed phenomena come from the interaction of the ejecta with prior ejecta as well as interstellar material. In this view, astrophysical jets interact with the ambient medium through which they propagate, entraining and accelerating it. We show some elements of the modeling of these jets in this paper, including energy loss and heating via plasma processes, and large scale hydrodynamic and relativistic hydrodynamic simulations.

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Lagouri, Theodota. « Review on Higgs Hidden–Dark Sector Physics at High-Energy Colliders ». Symmetry 14, n^o 7 (22 juin 2022) : 1299. http://dx.doi.org/10.3390/sym14071299.

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The presence of a hidden or dark sector of phenomena that relates either weakly or in a particular way to Standard Model (SM) fields has theoretical as well as experimental support. Many extensions of SM use hidden or dark sector states to propose a specific candidate for dark matter (DM) in the universe or to explain astrophysical findings. If such a family of Beyond the Standard Model (BSM) particles and interactions exists, it is possible that they will be discovered experimentally at CERN’s Large Hadron Collider (LHC, √s≅14 TeV) and future High Energy Colliders. The primary emphasis is on a few examples of searches undertaken at the LHC that are relevant to Higgs Hidden–Dark Sector Physics. These studies’ existing constraints and prospects are also reported.

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Lang, Rodrigo Guedes, Humberto Martínez-Huerta et Vitor de Souza. « Ultra-High-Energy Astroparticles as Probes for Lorentz Invariance Violation ». Universe 8, n^o 8 (22 août 2022) : 435. http://dx.doi.org/10.3390/universe8080435.

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Compelling evidence for Lorentz invariance violation (LIV) would demand a complete revision of modern physics. Therefore, searching for a signal or extending the validity of the invariance is fundamental for building our understanding of the extreme phenomena in the Universe. In this paper, we review the potential of ultra-high-energy astroparticles in setting limits on LIV. The standard framework of LIV studies in astroparticle physics is reviewed and its use on the electromagnetic and hadronic sectors are discussed. In particular, the current status of LIV tests using experimental data on ultra-high-energy photons and cosmic rays is addressed. A detailed discussion with improved argumentation about the LIV kinematics of the relevant interactions is shown. The main previous results are presented together with new calculations based on recently published astrophysical models.

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Calucci, Giorgio. « Production of monopole–antimonopole pairs in very intense but slowly varying magnetic field ». International Journal of Modern Physics A 35, n^o 21 (27 juillet 2020) : 2050116. http://dx.doi.org/10.1142/s0217751x2050116x.

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The production of pairs of monopole–antimonopole in presence of extremely intense magnetic fields, is briefly investigated in the case where the magnetic field undergoes also a time variation. The possibility that similar conditions are realized, with a production of ordinary particles, was already considered for astrophysical phenomena, e.g. some phases of evolution of neutron stars.

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Lipunov, Vladimir M., Viktor G. Kornilov, Kirill Zhirkov, Artem Kuznetsov, Evgenii Gorbovskoy, Nikolai M. Budnev, David A. H. Buckley et al. « MASTER Real-Time Multi-Message Observations of High Energy Phenomena ». Universe 8, n^o 5 (5 mai 2022) : 271. http://dx.doi.org/10.3390/universe8050271.

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This review considers synchronous and follow-up MASTER Global Robotic Net optical observations of high energy astrophysical phenomena such as fast radio bursts (FRB), gamma-ray bursts (including prompt optical emission polarization discovery), gravitational-wave events, detected by LIGO/VIRGO (including GW170817 and independent Kilonova discovery), high energy neutrino sources (including the detection of IC-170922A progenitor) and others. We report on the first large optical monitoring campaign of the closest at that moment radio burster FRB 180916.J0158+65 simultaneously with a radio burst. We obtained synchronous limits on the optical flux of the FRB 180916.J0158+65 and FRB 200428 (soft gamma repeater SGR 1935+2154)(The CHIME/FRB Collaboration, Nature 2020, 587) at 155093 MASTER images with the total exposure time equal to 2,705,058 s, i.e., 31.3 days. It follows from these synchronous limitations that the ratio of the energies released in the optical and radio ranges does not exceed 4 × 105. Our optical monitoring covered a total of 6 weeks. On 28 April 2020, MASTER automatically following up on a Swift alert began to observe the galactic soft gamma repeater SGR 1935+2154 experienced another flare. On the same day, radio telescopes detected a short radio burst FRB 200428 and MASTER-Tavrida telescope determined the best prompt optical limit of FRB/SGR 1935+2154. Our optical limit shows that X-ray and radio emissions are not explained by a single power-law spectrum. In the course of our observations, using special methods, we found a faint extended afterglow in the FRB 180916.J0158+65 direction associated with the extended emission of the host galaxy.

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Huth, Sabrina, Peter T. H. Pang, Ingo Tews, Tim Dietrich, Arnaud Le Fèvre, Achim Schwenk, Wolfgang Trautmann et al. « Constraining neutron-star matter with microscopic and macroscopic collisions ». Nature 606, n^o 7913 (8 juin 2022) : 276–80. http://dx.doi.org/10.1038/s41586-022-04750-w.

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AbstractInterpreting high-energy, astrophysical phenomena, such as supernova explosions or neutron-star collisions, requires a robust understanding of matter at supranuclear densities. However, our knowledge about dense matter explored in the cores of neutron stars remains limited. Fortunately, dense matter is not probed only in astrophysical observations, but also in terrestrial heavy-ion collision experiments. Here we use Bayesian inference to combine data from astrophysical multi-messenger observations of neutron stars1–9 and from heavy-ion collisions of gold nuclei at relativistic energies10,11 with microscopic nuclear theory calculations12–17 to improve our understanding of dense matter. We find that the inclusion of heavy-ion collision data indicates an increase in the pressure in dense matter relative to previous analyses, shifting neutron-star radii towards larger values, consistent with recent observations by the Neutron Star Interior Composition Explorer mission5–8,18. Our findings show that constraints from heavy-ion collision experiments show a remarkable consistency with multi-messenger observations and provide complementary information on nuclear matter at intermediate densities. This work combines nuclear theory, nuclear experiment and astrophysical observations, and shows how joint analyses can shed light on the properties of neutron-rich supranuclear matter over the density range probed in neutron stars.

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LI, BAO-AN, et PLAMEN G. KRASTEV. « IMPRINTS OF THE NUCLEAR SYMMETRY ENERGY ON GRAVITATIONAL WAVES FROM DEFORMED PULSARS ». International Journal of Modern Physics E 19, n^o 08n09 (septembre 2010) : 1694–704. http://dx.doi.org/10.1142/s0218301310016119.

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The density dependence of nuclear symmetry energy is a critical input for understanding many interesting phenomena in astrophysics and cosmology. We report here effects of the nuclear symmetry energy partially constrained by terrestrial laboratory experiments on the strength of gravitational waves (GWs) from deformed pulsars at both low and high rotational frequencies.

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Dainotti, Maria, Delina Levine, Nissim Fraija, Donald Warren, Peter Veres et Shashwat Sourav. « The Closure Relations in High-Energy Gamma-ray Bursts Detected by Fermi-LAT ». Galaxies 11, n^o 1 (2 février 2023) : 25. http://dx.doi.org/10.3390/galaxies11010025.

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Gamma-ray bursts (GRBs) are brief, intense pulses of high-energy emission associated with extreme astrophysical phenomena, e.g. the death of massive stars or the coalescence of compact objects. They have been observed at high energies by the Fermi Large Area Telescope (LAT), which detects GRBs in the 20 MeV–300 GeV energy range. The Fermi-LAT Second GRB Catalog (2FLGC) presents information on 186 GRBs observed from 2008 to 2018. We consider the GRBs that have been fitted in the 2FLGC with a broken (21 GRBs) or simple power law (65 GRBs), compiling a total sample of 86 GRBs. We analyze the relationship between the spectral and temporal indices using closure relations according to the synchrotron forward-shock model evolving in stratified environments (n∝r−k). We find that the model without energy injection is preferred over the one with energy injection. There is a clear preference for the cooling conditions ν> max{νc,νm} and νm<ν<νc (where νc and νm are the cooling and characteristic frequencies, namely the frequency at the spectral break). Within these cooling conditions, density profiles r−k with values of k=1.5 and 2 generally have a higher rate of occurrence when considering relations with and without energy injection.

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Abarzhi, S. I., et K. R. Sreenivasan. « Turbulent mixing and beyond ». Philosophical Transactions of the Royal Society A : Mathematical, Physical and Engineering Sciences 368, n^o 1916 (13 avril 2010) : 1539–46. http://dx.doi.org/10.1098/rsta.2010.0021.

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Turbulence is a supermixer. Turbulent mixing has immense consequences for physical phenomena spanning astrophysical to atomistic scales under both high- and low-energy-density conditions. It influences thermonuclear fusion in inertial and magnetic confinement systems; governs dynamics of supernovae, accretion disks and explosions; dominates stellar convection, planetary interiors and mantle-lithosphere tectonics; affects premixed and non-premixed combustion; controls standard turbulent flows (wall-bounded and free—subsonic, supersonic as well as hypersonic); as well as atmospheric and oceanic phenomena (which themselves have important effects on climate). In most of these circumstances, the mixing phenomena are driven by non-equilibrium dynamics. While each article in this collection dwells on a specific problem, the purpose here is to seek a few unified themes amongst diverse phenomena.

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Viotti, Roberto F., Lucio Angelo Antonelli, Sonja Rebecchi et Corinne Rossi. « High energy phenomena in eta carinae ». Journal of Astrophysics and Astronomy 23, n^o 1-2 (mars 2002) : 19–22. http://dx.doi.org/10.1007/bf02702459.

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YAMADA, SHOICHI. « GRAVITATIONAL COLLAPSE OF MASSIVE STARS AS A PROBE INTO HOT DENSE MATTER ». Modern Physics Letters A 23, n^o 27n30 (30 septembre 2008) : 2443–50. http://dx.doi.org/10.1142/s0217732308029551.

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Nuclear physics is an indispensable input for the investigation of high energy astrophysical phenomena involving compact objects. In this paper I take a gravitational collapse of massive stars as an example and show how the macroscopic dynamics is influenced by the properties of nuclei and nuclear matter. I will discuss two topics that are rather independent of each other. The first one is the interplay of neutrino-nuclei inelastic scatterings and the standing accretion shock instability in the core of core collapse supernovae and the second is concerning the neutrino emissions from black hole formations and their dependence on the equation of state at very high densities. In the latter, I will also demonstrate that future astronomical observations might provide us with valuable information on the equation of state of hot dense matter.

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Dewan, Himani, R. Uma et R. P. Sharma. « Nonlinear evolution of Kinetic Alfvén Wave and the associated turbulence spectra in laser produced plasmas and laboratory simulation of astrophysical phenomena ». Plasma Physics and Controlled Fusion 63, n^o 12 (16 novembre 2021) : 125034. http://dx.doi.org/10.1088/1361-6587/ac35a4.

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Abstract This investigation presents the nonlinear interplay between pump wave (Kinetic Alfvén Wave (KAW)) and low-frequency ion acoustic wave (IAW) in the magnetized plasma. The model is developed by taking into account the ponderomotive nonlinearity associated due to the pump KAW. The coupled dimensionless equations (pump and IAW) are solved by adopting numerical simulation technique. The deduced results give the localization and filamentary structures of KAW, which eventually become chaotic with the evolution of time. The fundamental physics governing the dynamics of these two waves is influenced by the plasma beta ( β ) parameter; thereby affecting the nature of nonlinearity, dispersive properties and magnetic field amplification. The saturated spectra are analogous to that observed for many astrophysical scenarios for low (Chatterjee et al 2017 Nat. Commun. 8 15970) and high beta (White et al 2019 Nat. Commun. 10 1758; Tzeferacos et al 2017 Phys. Plasmas 24 041404) plasma. This theoretical model outlining the nonlinear interaction can be imperative in understanding the dynamics of magnetic field amplification in various astrophysical scenarios.

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