Table of Contents
Overview
Definition and Composition
Cosmic rays are defined as high-energy particles or clusters of particles that travel through space at nearly the speed of light. These particles are primarily composed of protons and atomic nuclei, and they originate from various sources, including the Sun, our galaxy, and distant galaxies.[3.1] Initially thought to be electromagnetic radiation, subsequent research has clarified that cosmic rays are indeed high-energy particles.[2.1] Cosmic rays, also known as astroparticles, are high-energy particles or clusters of particles that travel through space at nearly the speed of light.[3.1] These particles are primarily composed of protons or atomic nuclei and originate from various sources, including the Sun, the galaxy, and distant galaxies.[3.1] When primary cosmic rays enter the Earth's atmosphere, they interact with the nuclei of atmospheric gases, leading to the production of secondary particles through a series of complex reactions known as particle showers.[3.1] These secondary cosmic rays are the resultant particles that reach the Earth's surface and play a crucial role in advancing our understanding of the cosmic environment and the fundamental processes occurring in the universe.[2.1]Types of Cosmic Rays
Cosmic rays are classified into two main categories: primary and secondary cosmic rays. Primary cosmic rays are high-energy particles originating from astrophysical sources, such as supernovae and other cosmic events. They are predominantly composed of protons and alpha particles, constituting about 99% of their composition, with a small fraction consisting of heavier nuclei and an extremely minor proportion of positrons and antiprotons.[31.1] Upon entering the Earth's atmosphere, these primary cosmic rays interact with atmospheric nuclei, initiating a series of complex nuclear reactions. When primary cosmic rays collide with atmospheric gases, they produce a cascade of secondary particles, known as secondary cosmic rays. A single primary proton with an energy of (10^{18}) eV can generate approximately (10^8) secondary charged particles at ground level.[7.1] These interactions lead to the formation of extensive air showers, characterized by a multiplicative process where secondary particles can reach the Earth's surface.[10.1] The study of these secondary particles is crucial, as they constitute the background counts detected by high-energy detectors at balloon and satellite altitudes.[9.1] Cosmic rays, traveling through the universe at nearly the speed of light, originate from outer space.[24.1] When primary cosmic rays, primarily composed of protons or light nuclei, enter the Earth's atmosphere, they collide with atmospheric gas nuclei, resulting in a cascade of secondary particles.[24.1] This cascade, known as an air shower, includes secondary, tertiary, and other particles produced during these interactions.[22.1] The development of extensive air showers in the atmosphere determines the composition and properties of the secondary radiation, which includes particles and electromagnetic radiation present at various altitudes.[22.1] Detecting and analyzing these secondary cosmic rays is crucial for understanding the nature and sources of cosmic rays.[24.1]History
Key Milestones in Cosmic Ray Research
Victor Franz Hess's discovery of cosmic rays in the early twentieth century represents a pivotal milestone in the field of physics. Initially investigating sources of radioactivity, Hess conducted a series of high-altitude balloon flights, which led him to encounter radiations originating from outside of Earth, later termed cosmic rays. His groundbreaking work culminated in the sharing of the 1936 Nobel Prize in Physics for this discovery, which has since proven invaluable in various physics experiments, including those conducted at CERN.[39.1] Hess's observations revealed that cosmic rays are high-energy particles that travel through the universe at nearly the speed of light. Initially misidentified as electromagnetic radiation due to their penetrating power, further research established that cosmic rays consist of various high-energy particles with intrinsic mass.[44.1] This misnomer highlights the evolving understanding of cosmic rays, which have been recognized as significant contributors to astrophysics and particle physics. In subsequent decades, research continued to advance, leading to the establishment of the Pierre Auger Observatory, inaugurated in 2008 in Malargüe, Argentina. This observatory was designed to study the highest energy cosmic rays with unprecedented precision and statistics. Notably, in 2007, the observatory's team discovered that the sources of the highest-energy particles are not uniformly distributed across the sky, marking another significant advancement in cosmic ray research.[41.1] Cosmic rays (CRs) are high-energy charged particles that primarily originate outside the solar system, consisting mainly of protons (approximately 89%), helium nuclei (around 10%), and about 1% of other heavier elements.[51.1] These particles reach the top of the Earth's atmosphere, where they interact with atmospheric constituents, leading to the production of secondary cosmic rays, also known as air showers.[51.1] Recent research has highlighted the effects of cosmic rays on various terrestrial processes, including electrical phenomena, cloud formation, and even human health.[49.1] The CLOUD (Cosmics Leaving OUtdoor Droplets) experiment at CERN has provided encouraging initial results regarding the potential influences of cosmic rays on cloud formation and Earth's climate.[49.1] As cosmic ray research progresses, it is anticipated that these particles may help address fundamental questions in physics, such as those related to dark matter and dark energy, marking the beginning of a new era in this field.[43.1]Mechanisms Of Cosmic Ray Production
Sources of Cosmic Rays
Cosmic rays primarily originate from various astrophysical processes, with the majority being classified as primary cosmic rays. These are predominantly composed of protons and alpha particles, accounting for approximately 99% of their composition, while heavier nuclei constitute about 1%, and an extremely small fraction consists of positrons and antiprotons.[74.1] The sources of cosmic rays can be categorized into galactic and extragalactic origins, with most cosmic rays being identified as galactic cosmic rays (GCRs), which are primarily produced within the Milky Way Galaxy.[76.1] One of the best candidates for a source of cosmic rays is supernova explosions, which signify the violent deaths of certain stars.[87.1] The material ejected by these explosions generates shock waves that travel through the interstellar medium, where charged particles can become trapped and bounce back and forth.[87.1] These shockwaves accelerate charged particles, such as protons, some of which eventually reach Earth as cosmic rays.[89.1] The first-order Fermi shock acceleration mechanism plays a significant role in this process, suggesting that supernovae with trans-relativistic outflows may accelerate cosmic rays to energies exceeding 10^18 eV, particularly within the first year following the explosion.[77.1] Thus, supernova remnants, characterized by expanding clouds of gas and magnetic fields, serve as crucial sites for the acceleration of cosmic rays.[89.1] In addition to supernovae, other astrophysical phenomena contribute to cosmic ray production. For instance, recent discoveries have indicated that high-energy neutrinos detected from the Milky Way may provide insights into the origins of high-energy cosmic rays.[80.1] Furthermore, the interactions between cosmic rays and potential dark matter candidates are being explored as a means to address fundamental questions in modern physics.[86.1]Acceleration Processes
Shocks generated by supernova remnants (SNRs) are recognized as a primary mechanism for the acceleration of charged particles, achieving energies up to approximately 100 TeV through a process known as diffusive shock acceleration (DSA).[93.1] These shocks are believed to be the main contributors to the pool of Galactic cosmic rays, which primarily consist of relativistic protons with energies less than (10^{15.5}) eV.[103.1] However, there remains ongoing debate regarding the capability of SNRs to accelerate particles to the "knee" energy, which is around (10^{15.5}) eV.[93.1] Considerable efforts have been devoted to theoretical works aimed at elucidating the details of particle acceleration in this context.[103.1] The acceleration of galactic cosmic rays (GCRs) in the interstellar medium (ISM) has been a subject of extensive research for many decades. Prevailing theories suggest that the processes by which GCRs are accelerated usually involve some form of diffusive shock acceleration at shocks generated by supernovae.[102.1] During their propagation, cosmic rays gain energy through stochastic re-acceleration, which occurs as they interact with turbulence in the medium.[101.1] Although cosmic rays constitute only about 10^-9 of interstellar particles by number, their collective energy density is comparable to that of thermal particles, underscoring their significance in the dynamics of the interstellar environment.[105.1] Furthermore, cosmic rays are confined and scattered by the Galactic magnetic field, which plays a crucial role in their propagation and acceleration.[105.1] The energy density of cosmic rays, along with components of the ISM and different phases of gas, are of similar order, highlighting the interconnectedness of these factors in cosmic ray dynamics.[104.1]Effects Of Cosmic Rays
Impact on Earth's Atmosphere
Cosmic rays, which are high-energy particles originating from outer space, have significant interactions with the Earth's atmosphere that can influence various environmental processes. When primary cosmic rays enter the Earth's atmosphere, they collide with atmospheric nuclei, resulting in a cascade of secondary particles. This interaction produces complex reactions known as particle showers, which contribute to the natural background radiation experienced on Earth.[113.1] The intensity of cosmic radiation varies with altitude, with higher altitudes experiencing greater exposure due to the reduced atmospheric shielding.[112.1] The average annual dose of cosmic radiation at sea level is approximately 0.33 mSv (33 mrem), highlighting the continuous presence of this natural radiation.[112.1] Research indicates that cosmic rays may play a role in climate dynamics by influencing cloud formation and atmospheric chemistry. Specifically, cosmic rays can ionize the air, which aids in the formation of aerosols that serve as cloud condensation nuclei (CCN). These nuclei are essential for the condensation of water droplets, leading to the development of low-altitude clouds.[138.1] Furthermore, cosmic rays have been suggested to seed clouds through radiation bursts, potentially affecting weather conditions and contributing to long-term climate change.[123.1] The modulation of cosmic ray flux by solar activity also plays a crucial role in this process. During periods of high solar activity, the solar wind deflects more cosmic rays, which can lead to variations in cloud cover and atmospheric conditions.[137.1] Although cosmic rays represent a minor component compared to other climatic drivers, their ability to modulate cloud cover and atmospheric chemistry signifies a subtle yet noteworthy influence on the Earth's climate system.[136.1]Health Implications for Humans
Cosmic radiation poses significant health risks, particularly for flight crews who are among the occupational groups most exposed to ionizing radiation. Their average annual effective dose of cosmic radiation exceeds that of other radiation-exposed workers in the United States, excluding astronauts, primarily due to the high levels of cosmic radiation encountered at flight altitudes.[116.1] This elevated exposure has raised concerns regarding long-term health implications, including an increased risk of radiation-induced cancer.[135.1] Research has indicated that exposure to cosmic radiation during critical periods, such as the first trimester of pregnancy, may be linked to adverse outcomes, including an increased risk of miscarriage among flight attendants.[115.1] Furthermore, studies like the Harvard Flight Attendant Study have highlighted that the combination of radiation exposure, disrupted sleep cycles, and exposure to onboard chemicals contributes to various occupational health issues within cabin crew.[134.1] In response to these health risks, national and international organizations, including the Federal Aviation Administration (FAA), have initiated programs to measure radiation exposure and assess its implications for flight crews.[133.1] The Basic Safety Standards (Directive 96/29/Euratom) mandate that member states ensure that undertakings operating aircraft account for the exposure of air crew to cosmic radiation, particularly for those likely to exceed 1 mSv per year.[114.1] In 2024, the aviation industry faces several evolving challenges, with cosmic radiation exposure for pilots and flight crews being one of the most critical issues. This area has gained increasing attention due to its potential long-term health risks, as many health and safety issues related to aviation are well understood, but cosmic radiation remains less clear.[132.1] To address these concerns, various national and international organizations have conducted studies, including analyses by the Office of Supersonic Transport Development and the Office of Aviation Medicine of the Federal Aviation Administration (FAA). These organizations have reviewed available information on cosmic radiation and have instituted a program for radiation measurement to enhance safety protocols in the industry.[133.1]In this section:
Recent Advancements
New Discoveries and Theories
Recent studies have significantly advanced our understanding of cosmic rays (CRs), particularly through direct measurements and theoretical developments. An international team of researchers has reported results from a direct measurement of the cosmic ray helium spectrum using data collected by the CALET instrument aboard the International Space Station. This analysis, covering the period from October 2015 to April 2022, revealed a complex energy distribution that deviates from the previously assumed single power-law model, indicating spectral hardening and softening trends across a broad energy range from approximately 40 GeV to 250 TeV.[159.1] Recent advances in the field of astrophysical feedback strongly suggest that cosmic rays (CRs) are crucial for understanding cosmological galaxy formation and evolution. The interstellar medium (ISM), which consists of gas, dust, and cosmic rays, plays a vital role in the formation and evolution of stars and galaxies, acting as both a reservoir for star formation and a medium for energy and matter exchange.[179.1] Cosmic rays influence various processes within the ISM, including star formation and the dynamics of supernovae, highlighting their importance in the overall evolution of galaxies.[155.1] Furthermore, advances in theoretical and numerical simulations have provided new insights into the transport coefficients of cosmic rays, which are essential for predicting their behavior in different astrophysical environments.[180.1] These developments enhance our understanding of the complex interactions between cosmic rays and the ISM, as well as their impact on galactic dynamics. Recent discoveries in cosmic ray research have revealed a softening in the total energy spectrum of cosmic rays at tens of TeV, raising significant questions about the physical origins of this phenomenon, which remain unknown.[160.1] These findings deviate from conventional models of cosmic ray acceleration and propagation that typically assume a "single power-law distribution," where the number of particles decreases with increasing energy.[162.1] Furthermore, a critical review of the standard paradigm for the origin of Galactic cosmic rays highlights unexpected behaviors observed in both local and distant cosmic rays, challenging the commonly accepted scenarios and addressing long-standing open issues in the field.[161.1] The role of collisionless shock waves, recognized as some of nature's most powerful particle accelerators, is crucial in this context, as they are believed to contribute significantly to the generation of high-energy cosmic rays.[167.1] Recent theoretical advancements in plasma physics have provided key insights into the mechanisms behind cosmic ray acceleration, suggesting that high-energy electrons can be produced through the complex interplay of various processes, including interactions with plasma waves and transient structures.[166.1]In this section:
Cosmic Rays In Astrophysics
Role in Galactic Processes
Cosmic rays play a crucial role in various galactic processes, particularly through their interactions with the interstellar medium (ISM), which comprises the matter and radiation found in the space between star systems in a galaxy.[228.1] These high-energy particles are capable of operating throughout both diffuse and dense interstellar clouds, serving as a mechanism for ionization that drives interstellar chemistry.[96.1] Furthermore, cosmic rays interact with the ISM by transferring energy to gas through ionization and excitation, as well as to free electrons via Coulomb interactions.[228.1] This energy transfer not only heats the ambient gas but also has significant implications for our understanding of cosmic ray propagation and the overall dynamics of the galaxy.[96.1] The interaction of cosmic rays with turbulent magnetic fields in the ISM generates nonthermal emissions, which are essential for understanding cosmic ray propagation.[94.1] Furthermore, cosmic rays are well-coupled to the ISM at larger scales, influencing stratification and driving outflows, although their impact on smaller scales remains less clear.[95.1] Galactic cosmic rays (GCRs) also affect the interstellar medium by transferring energy to gas through ionization and excitation processes, which can lead to significant changes in the physical state of the ISM.[228.1] The presence of cosmic rays in the ISM is not merely passive; they actively participate in heating the gas and altering its chemical composition, thereby playing a vital role in the overall dynamics of the galaxy.[96.1]Influence on Cosmic Structures
Cosmic rays, which are high-energy particles originating from outer space, play a significant role in understanding cosmic structures and their interactions with the Earth's atmosphere. These particles travel at nearly the speed of light and provide valuable data on high-energy processes in the universe, influencing both atmospheric chemistry and climate.[219.1] One of the notable effects of cosmic rays is their interaction with the Earth's atmosphere, where they produce ions that contribute to cloud formation. Specifically, cosmic rays help convert small aerosols into cloud condensation nuclei, which are essential for the formation of liquid water droplets that create clouds.[233.1] This process is further explored in the CLOUD experiment, which investigates the potential link between galactic cosmic rays and cloud formation using a specialized cloud chamber.[232.1] Cosmic rays are a fascinating aspect of our universe, with the potential to impact both technology and biological systems.[220.1] Their influence on cloud formation is an area of ongoing research, as cloud formation depends on various factors, including atmospheric temperature and the amount of water vapor present. Cosmic rays may contribute to this process by producing secondary particles in the atmosphere.[231.1] However, while some findings suggest that cosmic rays could play a role in cloud formation, it is crucial to consider these claims in the context of the more significant effects of greenhouse gases and other atmospheric factors on climate change. According to experts, in the climate of the last few thousand years, cosmic rays have made no appreciable difference to overall cloud-seeding particle concentrations in the atmosphere or to temperature.[231.1] Understanding cosmic rays is essential not only for our comprehension of the universe but also for addressing practical implications, particularly as humanity plans future space missions to the Moon, Mars, and beyond, where mitigating the risks from cosmic rays is a priority.[220.1] Additionally, understanding cosmic rays is crucial for future space exploration, as they pose risks to technology and biological systems during missions to the Moon, Mars, and beyond.[220.1] The ongoing study of cosmic rays not only enhances our comprehension of cosmic structures but also informs strategies to mitigate their potential hazards in both space and terrestrial environments.[219.1]Future Research Directions
Theoretical Developments in Cosmic Ray Physics
Recent advancements in theoretical and numerical simulations have significantly enhanced our understanding of cosmic ray (CR) propagation and its implications for astrophysics. A direct measurement of the cosmic ray helium spectrum, conducted by an international team using data from the CALET experiment, revealed a more complex energy distribution than the previously assumed single power-law, indicating the need for refined models in cosmic ray physics.[154.1] This complexity is further underscored by the role of cosmic rays in galaxy formation and evolution, where they interact with the interstellar medium (ISM) and influence star formation processes.[155.1] The development of new algorithms for simulating cosmic ray propagation has been pivotal in this field. These algorithms are designed to provide both phenomenological and self-consistent models based on numerical solutions of the Fokker-Planck equation, which is essential for accurately predicting cosmic ray behavior across galactic and larger scales.[251.1] Additionally, multimessenger astronomy has emerged as a crucial tool, allowing researchers to constrain cosmic ray sources and their propagation through various astrophysical environments.[250.1] Future research directions also include the establishment of a Global Cosmic Ray Observatory (GCOS), which aims to integrate high-energy physics with atmospheric studies, thereby broadening the scientific scope of cosmic ray research.[248.1] This initiative reflects a growing recognition of the interdisciplinary nature of cosmic ray studies, particularly in relation to their effects on climate and atmospheric dynamics.[258.1] The integration of machine learning and artificial intelligence in cosmic ray detection is exemplified by the Cosmic-CoNN framework, which serves as an end-to-end solution for addressing the challenges associated with cosmic ray (CR) detection in CCD-captured astronomical images. This framework includes a deep-learning architecture, high-performance CR detection models, a new dataset, and a suite of tools designed to utilize these models effectively.[254.1] Recent advancements in deep learning have shown promising results in training CR-detection models; however, it is important to note that instrument-specific models may experience performance degradation when applied to images from ground-based facilities that were not included in the training data. Cosmic-CoNN aims to overcome this limitation by producing generic CR-detection models that can be more broadly applicable.[255.1]In this section:
References
[2] Cosmic Rays Explained - Science Notes and Projects — Cosmic Rays Explained Cosmic rays are high-energy particles originating from outer space that travel through the universe at nearly the speed of light. Although initially thought to be electromagnetic radiation (hence the term “rays”), subsequent research revealed that cosmic rays are actually high-energy particles. Origin and Sources of Cosmic Rays When primary cosmic rays enter the Earth’s atmosphere, they collide with nuclei of atmospheric gases, producing a cascade of secondary particles. Secondary cosmic rays are the particles that result from these interactions and reach the Earth’s surface. When primary cosmic rays enter the Earth’s atmosphere they interact with atmospheric nuclei and produce a series of complex reactions known as particle showers. Detection of Cosmic Rays Are Cosmic Rays Dangerous? Cosmic rays are invaluable in astrophysics and particle physics:
[3] Cosmic ray - Wikipedia — Cosmic rays are high-energy particles or clusters of particles that move through space at nearly the speed of light. They originate from various sources, such as the Sun, the galaxy, and distant galaxies, and interact with Earth's atmosphere to produce secondary particles.
[7] Secondary Cosmic Rays | SpringerLink — High-energy cosmic rays produce a large number of charged particles when they induce an air shower in the atmosphere. A primary proton of \ (10^ {18}\) eV creates about \ (10^8\) secondary charged particles at ground level.
[9] [2112.08668] Simulation of Cosmic Rays in the Earth's Atmosphere and ... — The study of secondary particles produced by the cosmic-ray interaction in the Earth's atmosphere is very crucial as these particles mainly constitute the background counts produced in the high-energy detectors at balloon and satellite altitudes.
[10] "Soft" and "Hard" Components of Cosmic Rays - PhysicsOpenLab — Most cosmic rays arriving on Earth are secondary products of swarms formed in the atmosphere by primary cosmic rays, with interactions that typically produce a cascade of secondary particles starting from a single energetic particle.
[22] The Secondary Cosmic Radiation | SpringerLink — 10.1 Composition of the Secondary Radiation As we have discussed, the development of extensive air showers in the Earth's atmosphere, generated by the interaction of primary high-energy particles (mostly protons or light nuclei), determines the composition and properties of the secondary radiation, i.e., the set of particles and electromagnetic radiation present at any given altitude above
[24] Cosmic Rays Explained - Science Notes and Projects — Cosmic Rays Explained Cosmic rays are high-energy particles originating from outer space that travel through the universe at nearly the speed of light. Although initially thought to be electromagnetic radiation (hence the term “rays”), subsequent research revealed that cosmic rays are actually high-energy particles. Origin and Sources of Cosmic Rays When primary cosmic rays enter the Earth’s atmosphere, they collide with nuclei of atmospheric gases, producing a cascade of secondary particles. Secondary cosmic rays are the particles that result from these interactions and reach the Earth’s surface. When primary cosmic rays enter the Earth’s atmosphere they interact with atmospheric nuclei and produce a series of complex reactions known as particle showers. Detection of Cosmic Rays Are Cosmic Rays Dangerous? Cosmic rays are invaluable in astrophysics and particle physics:
[31] Cosmic ray - Wikipedia — Cosmic rays originate as primary cosmic rays, which are those originally produced in various astrophysical processes. Primary cosmic rays are composed mainly of protons and alpha particles (99%), with a small amount of heavier nuclei (≈1%) and an extremely minute proportion of positrons and antiprotons.
[39] Victor Hess discovers cosmic rays | timeline.web.cern.ch — High in the atmosphere, Hess had discovered a natural source of high-energy particles: cosmic rays. Hess shared the 1936 Nobel prize in physics for his discovery, and cosmic rays have proved useful in physics experiments - including several at CERN - since. Find out more: About cosmic rays (from the CERN courier) - A discovery of cosmic
[41] A Timeline of High-Energy Cosmic Rays History - Pierre Auger Observatory — An international group of researchers began design studies for a new cosmic ray observatory, the Pierre Auger Project, named in honor of the discoverer of air showers. The Pierre Auger Observatory is designed to study the highest energy cosmic rays with unprecedented statistics and precision. 2007 — Auger discovers extragalactic origin of highest-energy cosmic rays Using the Pierre Auger Observatory in Argentina, the largest cosmic-ray observatory in the world, a team of scientistsfrom 17 countries found that the sources of the highest-energy particles are not distributed uniformly across the sky. Scientists of the Pierre Auger Observatory, a project to study the highest-energy cosmic rays, celebrated the inauguration of the southern site of their observatory in Malargüe, Argentina, on November 14, 2008.
[43] The History of Cosmic Ray Studies after Hess - ScienceDirect — After 100 years of cosmic ray research we are again at the beginning of a new era, and cosmic rays may contribute to solve the many open questions, like dark matter and dark energy, by providing energies well beyond those of earth-bound accelerators. Keywords: cosmic rays, history, elementary particles, neutrinos 1.
[44] Cosmic ray - Wikipedia — The term ray (as in optical ray) seems to have arisen from an initial belief, due to their penetrating power, that cosmic rays were mostly electromagnetic radiation. Nevertheless, following wider recognition of cosmic rays as being various high-energy particles with intrinsic mass, the term "rays" is consistent with known particles such as cathode rays, canal rays, alpha rays, and beta rays.
[49] Impact of galactic cosmic rays on Earth's atmosphere and human health — In the present paper, we have reviewed and attempted to provide an overview of cosmic ray effects on terrestrial processes such as electrical phenomena, lightning discharges cloud formation and cloud coverage, temperature variation, space weather phenomena, Earth’s climate and the effects of GCRs on human health. The initial results of the CLOUD (Cosmics Leaving OUtdoor Droplets) experiment at CERN, Geneva, Switzerland is encouraging in the study of the possible influences of cosmic rays on cloud (Duplissy et al., 2009). Overall objectives of this paper are to discuss the present understanding of cosmic rays, their association with various physical processes related to the Earth’s atmosphere and its impact on human health. Impact of cosmic rays and solar energetic particles on the Earth's ionosphere and atmosphere Galactic cosmic rays and solar particles in Earth's atmosphere
[51] Impact of galactic cosmic rays on Earth's atmosphere and human health — Cosmic rays (CRs) are high energy charged particles mostly having origin outside solar system and contain protons (∼89%), helium nuclei (∼10%) and about 1% other heavier elements (Mewaldt, 2010).These charged particles reaching at the top of the Earth's atmosphere are known as primary and their interaction with atmospheric constituents give rise to secondary CRs (also called as air showers).
[74] Cosmic ray - Wikipedia — Cosmic rays originate as primary cosmic rays, which are those originally produced in various astrophysical processes. Primary cosmic rays are composed mainly of protons and alpha particles (99%), with a small amount of heavier nuclei (≈1%) and an extremely minute proportion of positrons and antiprotons. [ 10 ]
[76] Cosmic ray | Definition, Types, Effects, & Facts | Britannica — Cosmic ray, a high-speed particle—either an atomic nucleus or an electron—that travels through space. Most of these particles come from sources within the Milky Way Galaxy and are known as galactic cosmic rays (GCRs). ... It is accepted that these light nuclei are produced when heavier primaries (e.g., carbon and oxygen) are fragmented
[77] Cosmic Ray Production in Supernovae | Space Science Reviews - Springer — We give a brief review of the origin and acceleration of cosmic rays (CRs), emphasizing the production of CRs at different stages of supernova evolution by the first-order Fermi shock acceleration mechanism. We suggest that supernovae with trans-relativistic outflows, despite being rather rare, may accelerate CRs to energies above 10 18 eV $10^{18}\\mbox{ eV}$ over the first year of their
[80] The Milky Way shines in high-energy neutrinos - Nature — In 2023, the IceCube Neutrino Observatory discovered high-energy neutrinos from the Milky Way, an important clue towards understanding the origin of high-energy cosmic rays.
[86] Cosmic Rays and their Role in Understanding Fundamental Physics — The interactions between cosmic rays and potential dark matter candidates could yield valuable insights, helping to address some of the most profound questions in modern physics . Conclusion. Cosmic rays represent a fascinating and dynamic frontier in the study of fundamental physics, offering unique insights into high-energy astrophysical
[87] 11.4: Cosmic Rays - Physics LibreTexts — The best candidates for a source of cosmic rays are the supernova explosions, which mark the violent deaths of some stars (and which we will discuss in The Death of Stars). The material ejected by the explosion produces a shock wave, which travels through the interstellar medium. Charged particles can become trapped, bouncing back and forth
[89] Cosmic rays originate from supernova shockwaves | Nature — The shockwaves of supernova explosions accelerate charged particles such as protons, some of which end up raining on Earth as cosmic rays. ... McKee, M. Cosmic rays originate from supernova
[93] [2211.07417] Nonthermal processes and particle acceleration in ... — Shocks of supernova remnants (SNRs) accelerate charged particles up to 100 TeV range via diffusive shock acceleration (DSA) mechanism. It is believed that shocks of SNRs are the main contributors to the pool of Galactic cosmic rays, although it is still under debate whether they can accelerate particles up to the "knee" energy (10^15.5 eV) or not. In this chapter, we start with introducing
[94] Cosmic Ray Diffusion in the Turbulent Interstellar Medium: Effects of ... — Cosmic rays (CRs) interact with turbulent magnetic fields in the intestellar medium, generating nonthermal emission. After many decades of studies, the theoretical understanding of their diffusion in the ISM continues to pose a challenge. This study numerically explores a recent prediction termed "mirror diffusion" and its synergy with traditional diffusion mechanism based on gyroresonant
[95] Cosmic-Ray Feedback on Bistable Interstellar Medium Turbulence — While cosmic rays (E ≳ 1 GeV) are well coupled to a galaxy's interstellar medium (ISM) at scales of L > 100 pc, adjusting stratification and driving outflows, their impact on small scales is less clear. Based on calculations of the cosmic-ray diffusion coefficient from observations of the grammage in the Milky Way, cosmic rays have little time to dynamically impact the ISM on those small
[96] Cosmic-ray astrochemistry - PubMed — This, of course, demands a mechanism for ionization, and cosmic rays are the ideal candidate as they can operate throughout the majority of both diffuse and dense interstellar clouds. Aside from driving interstellar chemistry via ionization, cosmic rays also interact with the interstellar medium in ways that heat the ambient gas, produce gamma
[101] The Important Role of Cosmic-Ray Re-Acceleration - arXiv.org — The Important Role of Cosmic-Ray Re-Acceleration Martina Cardillo ... field, B0, and the medium density, rISM. During propagation, CRs gain energy through stochastic re-acceleration . This physical process was introduced in to explain low-energy secondary ... interstellar turbulence has to be damped by CRs to transfer them its
[102] Acceleration of Galactic Cosmic Rays in The Interstellar Medium — The acceleration of galactic cosmic rays (GCRs) in the interstellar medium has been a subject of interest and extensive research for many decades. Prevailing theories for the processes by which the GCRs are accelerated usually involve some form of diffusive shock acceleration at shocks generated by supernovae.
[103] The interstellar medium in young supernova remnants: key to the ... — Cosmic-ray acceleration in supernova remnants (SNRs) is the most promising mechanism for accelerating Galactic cosmic rays, which mainly comprise relativistic protons with energies less than 10 15.5 eV. Considerable efforts have been devoted to theoretical works to elucidate the details of particle acceleration (e.g., Bell 1978; Blandford and Ostriker 1978).
[104] Continuous solutions of cosmic-rays and waves in astrophysical ... - Nature — In the astrophysical environments the energy density of cosmic rays, components of the interstellar medium, different phases of gas (i.e., plasma) and magnetic field are of the same order of
[105] The microphysics and macrophysics of cosmic rays a) - AIP Publishing — This review paper commemorates a century of cosmic ray research, with emphasis on the plasma physics aspects. Cosmic rays comprise only ∼ 10 − 9 of interstellar particles by number, but collectively their energy density is about equal to that of the thermal particles. They are confined by the Galactic magnetic field and well scattered by small scale magnetic fluctuations, which couple them
[112] Facts About Radiation from Space (Cosmic Radiation) — Radiation dose due to cosmic radiation will vary with altitude. Higher altitudes mean greater exposure to cosmic radiation. Cosmic radiation is more intense in the upper atmosphere and most intense in deep space. Learn more about radiation from air travel. The average annual dose or exposure from cosmic radiation is 0.33 mSv (33 mrem).
[113] Cosmic Rays Explained - Science Notes and Projects — Cosmic Rays Explained Cosmic rays are high-energy particles originating from outer space that travel through the universe at nearly the speed of light. Although initially thought to be electromagnetic radiation (hence the term “rays”), subsequent research revealed that cosmic rays are actually high-energy particles. Origin and Sources of Cosmic Rays When primary cosmic rays enter the Earth’s atmosphere, they collide with nuclei of atmospheric gases, producing a cascade of secondary particles. Secondary cosmic rays are the particles that result from these interactions and reach the Earth’s surface. When primary cosmic rays enter the Earth’s atmosphere they interact with atmospheric nuclei and produce a series of complex reactions known as particle showers. Detection of Cosmic Rays Are Cosmic Rays Dangerous? Cosmic rays are invaluable in astrophysics and particle physics:
[114] PDF — Basic Safety Standards (Directive 96/29/Euratom) [BSS96]. The protection of air crew (Article 42) is therein formulated as "Each Member State shall make arrangements for undertakings operating aircraft to take account of exposure to cosmic radiation of air crew who are liable to be subject to exposure to more than 1 mSv per year.
[115] Aircrew and Cosmic Ionizing Radiation | Aviation | CDC — For flight attendants, a NIOSH study found that exposure to 0.36 millisieverts (mSv) or more of cosmic radiation in the first trimester may be linked to increased risk of miscarriage. NIOSH is looking more specifically at whether cosmic ionizing radiation is linked to cancer and reproductive problems.
[116] Flight Crews and Radiation Exposure - Versant Medical Physics and ... — Flight crews are among the occupational groups most exposed to ionizing radiation, with an average annual effective dose surpassing that of other radiation-exposed workers in the United States, excluding astronauts. 1 This elevated exposure is primarily due to the high levels of cosmic radiation encountered at flight altitudes, which can pose significant health risks to pilots and cabin crew
[123] These Scientists Say Cosmic Ray Radiation Has an Effect on Climate Change — New research suggests these rays are capable of seeding clouds with their radiation bursts, affecting weather conditions and even climate change in the long term. Scientists from the Technical University of Denmark (the Danmarks Tekniske Universitet or DTU) suggest that their experiments show varying radiation from the Sun and other supernovae
[132] The Importance of Monitoring Cosmic Radiation for Pilots in 2024 — In 2024, the aviation industry is dealing with several evolving challenges, and one of the most critical is cosmic radiation exposure for pilots and flight crews. While many health and safety issues are well understood, cosmic radiation is an area that has gained increasing attention due to its potential long-term health risks. With flights operating at altitudes where protection from the
[133] PDF — A number of national and international organizations carried out a variety of studies. The Office of Supersonic Transport Development and the Office of Aviation Medicine, both of the Federal Aviation Administration (FAA), analyzed avail-able information on cosmic radiation and decided to institute a program of radiation measurement.
[134] The little-known risk of cosmic radiation in air travel — Several studies have been carried out regarding the effects of cosmic radiation on flight crews. One example, the Harvard Flight Attendant Study, concluded that the risks of radiation exposure, coupled with the disruption of sleep cycles and on-board chemicals, all contribute to occupational health issues within cabin crew, and links factors to
[135] PDF — 4.1 The main concerns are the long-term risk of radiation-induced cancer (Friedberg et al) because of cosmic radiation; and, in the case of pregnant aircrew, possible harm to the foetus and mainly stochastic effects later in life and to a lesser extent, birth defects.
[136] Unveiling the impact of cosmic rays and solar activities on climate ... — Although cosmic rays represent a minor component compared to other climatic drivers, their potential to modulate cloud cover and atmospheric chemistry signifies a subtle yet noteworthy influence on the Earth's climate system (Kirkby, 2007).
[137] How Might Climate be Influenced by Cosmic Rays? — The idea that cosmic rays may affect climate through modulation of the cosmic ray ionization in the atmosphere goes back to Edward Ney in 1959. It was known that solar wind modulates the flux of cosmic rays reaching Earth—a high solar activity deflects more of the cosmic rays reaching the inner solar system, and with it reduces the
[138] PDF — Here, the surprising answer about those never ending natural changes of climate is that ga-lactic cosmic rays1, atomic particles coming from the supernova remnants left by explod-ed stars, appear to play a major part. By ionizing the air, cosmic rays help to form aerosols2 that may grow into cloud condensation nuclei (CCN), required for water droplets to condense and create low-altitude clouds
[154] Helium Nuclei Research Advances Our Understanding of Cosmic Ray Origin ... — In a new study, an international team of researchers report the results of a direct measurement of the cosmic ray helium spectrum using the data collected by CALET. In contrast to the single power-law that was previously believed to exist, analysis of the flux data collected between 2015 and 2022 reveals that the energy distribution of cosmic
[155] Cosmic ray feedback in galaxies and galaxy clusters — Recent advances in the field of astrophysical feedback strongly suggest that cosmic rays (CRs) may be crucially important for our understanding of cosmological galaxy formation and evolution. Here we present a review of the state-of-the-art of this field and provide a pedagogical introduction to cosmic ray plasma physics, including the physics of wave–particle interactions, acceleration processes, CR spatial and spectral transport, and important cooling processes. 3.1), stellar feedback and CR-driven winds (starting with one-dimensional models and moving on to progressively more sophisticated descriptions of the dynamical interactions of CR with the ISM including the role of CRs in the dynamics of SNe, CR interactions with cold clouds and multiphase ISM, impact of CRs on star formation, and the physics of galactic wind launching; Sect.
[159] [2304.14699] Direct Measurement of the Cosmic-Ray Helium Spectrum from ... — We present the results of a direct measurement of the cosmic-ray helium spectrum with the CALET instrument in operation on the International Space Station since 2015. The observation period covered by this analysis spans from October 13, 2015 to April 30, 2022 (2392 days). The very wide dynamic range of CALET allowed to collect helium data over a large energy interval, from ~40 GeV to ~250 TeV
[160] A measurement of the all-particle energy spectrum of cosmic rays from ... — The recent discovery of a softening 1 in the total energy spectrum of cosmic rays at tens of TeV by HAWC and NUCLEON has raised questions about the physical origin of this feature, which is still unknown.
[161] [1903.11584] The origin of Galactic cosmic rays: challenges to the ... — A critical review of the standard paradigm for the origin of Galactic cosmic rays is presented. Recent measurements of local and far-away cosmic rays reveal unexpected behaviours, which challenge the commonly accepted scenario. These recent findings are discussed, together with long-standing open issues. Despite the progress made thanks to ever-improving observational techniques and
[162] Helium nuclei research advances our understanding of cosmic ray origin ... — These results deviated from the conventional cosmic ray acceleration and propagation models that assume a "single power-law distribution," wherein the number of particles decrease with increasing
[166] New study unveils breakthrough in understanding cosmic particle ... — These shock waves are one of nature's most powerful particle accelerators and have long intrigued scientists for the role they play in producing cosmic rays -- high-energy particles that travel across vast distances in space. This new study provides key insights into the electron injection problem, showing that electrons can be accelerated to high energies through the interaction of various processes across multiple scales. This research suggests that these high-energy electrons were generated by the complex interplay of multiple acceleration mechanisms, including the interaction of electrons with various plasma waves, transient structures in the foreshock, and Earth's bow shock. By refining the shock acceleration model, this study provides new insight into the workings of space plasmas and the fundamental processes that govern energy transfer in the universe.
[167] Scientists Unravel Mystery of Cosmic Ray Acceleration — Scientists have made significant strides toward understanding how collisionless shock waves—phenomena found throughout the universe—can accelerate particles to extreme speeds. These shock waves, some of the most powerful natural particle accelerators, have captivated researchers due to their role in generating cosmic rays—high-energy particles that travel vast distances across space. The
[179] Interstellar Medium - (Astrophysics II) - Vocab, Definition ... - Fiveable — The interstellar medium (ISM) is the matter that exists in the space between stars in a galaxy, consisting of gas, dust, and cosmic rays. This material plays a crucial role in the formation and evolution of stars and galaxies, acting as both a reservoir for star formation and a medium through which energy and matter are exchanged. The ISM is influenced by galactic magnetic fields and has
[180] Cosmic Rays and Heliospheric Physics - Nature — Advances in theoretical and numerical simulations have provided new insights into the transport coefficients of cosmic rays, which are essential for predicting their behavior in different
[219] Cosmic Rays and Their Impact on Earth: Why It Matters — What Are Cosmic Rays? Cosmic rays are high-energy particles originating from outer space and traveling at nearly the speed of light. Studying cosmic rays helps scientists understand high-energy processes in the universe and their impact on our planet. Studying these interactions provides valuable data on the behavior of high-energy particles and helps scientists understand how cosmic rays influence atmospheric chemistry and climate. Ongoing research and technological advancements aim to enhance protection against cosmic rays, ensuring that space and ground-based systems can operate effectively in the face of these high-energy particles. They contribute to mapping the distribution and behavior of cosmic rays, helping scientists unravel the mysteries of these high-energy particles and their impact on both space and Earth.
[220] Cosmic Rays: Origins, Effects, and Impact on Earth - Info You Trust — Cosmic rays can impact both technology and biological systems. Some of the most notable effects include: ... Understanding cosmic rays is crucial for the future of space travel. As humanity plans missions to the Moon, Mars, and beyond, mitigating the risks from cosmic rays is a priority. ... Cosmic rays are a fascinating part of our universe
[228] Interstellar medium - Wikipedia — The interstellar medium (ISM) is the matter and radiation that exists in the space between the star systems in a galaxy. This matter includes gas in ionic, ... Cosmic rays transfer energy to gas through both ionization and excitation and to free electrons through Coulomb interactions. Low-energy cosmic rays (a few MeV)
[231] These Scientists Say Cosmic Ray Radiation Has an Effect on Climate ... — Cloud formation depends on a number of factors, including atmospheric temperature and the amount of water vapour in the air, but we might be able to add another influence to the mix: cosmic rays beaming down through space. While the findings suggest that cosmic rays could play at least some part in cloud formation, claims about effects on climate change must be weighed up against the evidence we have for the effect of greenhouse gases and other factors down here on the planet. "In the climate of the last few thousand years, [cosmic rays] can make no appreciable difference to overall cloud-seeding particle concentrations in the atmosphere or to temperature," Gordon told Ryan F.
[232] CLOUD: cosmic rays and cloud formation - CERN — CLOUD is an experiment that uses a cloud chamber to study the possible link between galactic cosmic rays and cloud formation. Based at the Proton Synchrotron at CERN, this is the first time a high-energy physics accelerator has been used to study atmospheric and climate science; the results could greatly modify our understanding of clouds and
[233] The missing link between exploding stars, clouds, and climate on Earth — Cosmic rays interacting with the Earth's atmosphere producing ions that helps turn small aerosols into cloud condensation nuclei -- seeds on which liquid water droplets form to make clouds.A
[248] The past and future 20-years endeavor for discovering origins of ultra ... — The concept of a Global Cosmic Ray Observatory (GCOS) poses a promising science case for high energy physics, fundamental physics, particle physics and solar, geo and atmospheric physics . The future objectives of UHECR science, outlined in the Snowmass paper [ 141 ] , were reported in the contributions [ 142 , 143 ] .
[250] PDF — • Two recent advances: • Multimessenger astronomy helps us constrain cosmic ray propagation and cosmic ray sources • "Live" galaxy evolution simulations with cosmic rays, spanning a range of galaxy types* Background *See e.g. Uhlig+ 2012, Hanasz+ 2013, Salem and Bryan 2014, Ruszkowski+ 2017, Farber+ 2018, Chan+ 2019, Buck+ 2020,
[251] Simulations of cosmic ray propagation - ResearchGate — We review numerical methods for simulations of cosmic ray (CR) propagation on galactic and larger scales. We present the development of algorithms designed for phenomenological and self-consistent
[254] Cosmic-CoNN: A Cosmic Ray Detection Deep Learning Framework, Dataset ... — Cosmic-CoNN is an end-to-end solution to help tackle the cosmic ray (CR) detection problem in CCD-captured astronomical images. It includes a deep-learning framework, high-performance CR detection models, a new dataset, and a suite of tools to use to the models, shown in the figure above:
[255] Cosmic-CoNN: A Cosmic Ray Detection Deep-Learning Framework, Dataset ... — Recent work using deep learning to train CR-detection models has demonstrated promising results. However, instrument-specific models suffer from performance loss on images from ground-based facilities not included in the training data. In this work, we present Cosmic-CoNN, a deep-learning framework designed to produce generic CR-detection models.
[258] Cosmic rays, aerosols, clouds, and climate: Recent findings from the ... — Cosmic rays, aerosols, clouds, and climate: Recent findings from the CLOUD experiment J. R. Pierce1 1Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado, USA Abstract The Cosmics Leaving OUtdoor Droplets (CLOUD) experiment was created to systematically test the link between galactic cosmic rays (GCR) and climate, speci fically, the connection of ions from GCR to