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Rankin JS, Bindi V, Bykov AM, Cummings AC, Della Torre S, Florinski V, Heber B, Potgieter MS, Stone EC, Zhang M. Galactic Cosmic Rays Throughout the Heliosphere and in the Very Local Interstellar Medium. SPACE SCIENCE REVIEWS 2022; 218:42. [PMID: 35855211 PMCID: PMC9287243 DOI: 10.1007/s11214-022-00912-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Accepted: 06/15/2022] [Indexed: 06/15/2023]
Abstract
We review recent observations and modeling developments on the subject of galactic cosmic rays through the heliosphere and in the Very Local Interstellar Medium, emphasizing knowledge that has accumulated over the past decade. We begin by highlighting key measurements of cosmic-ray spectra by Voyager, PAMELA, and AMS and discuss advances in global models of solar modulation. Next, we survey recent works related to large-scale, long-term spatial and temporal variations of cosmic rays in different regimes of the solar wind. Then we highlight new discoveries from beyond the heliopause and link these to the short-term evolution of transients caused by solar activity. Lastly, we visit new results that yield interesting insights from a broader astrophysical perspective.
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Affiliation(s)
- Jamie S. Rankin
- Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 USA
| | - Veronica Bindi
- Physics and Astronomy Department, University of Hawaii, Honolulu, HI 96822 USA
| | | | | | | | - Vladimir Florinski
- Center for Space Plasma and Aeronomic Research (CSPAR) and Department of Space Science, University of Alabama in Huntsville, Huntsville, AL 35805 USA
| | - Bernd Heber
- Institute for Experimental and Applied Physics, Christian Albrechts University in Kiel, Kiel, Germany
| | - Marius S. Potgieter
- Institute for Experimental and Applied Physics, Christian Albrechts University in Kiel, Kiel, Germany
| | | | - Ming Zhang
- Department of Physics and Space Sciences, Florida Institute of Technology, Melbourn, FL 32901 USA
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Kleimann J, Dialynas K, Fraternale F, Galli A, Heerikhuisen J, Izmodenov V, Kornbleuth M, Opher M, Pogorelov N. The Structure of the Large-Scale Heliosphere as Seen by Current Models. SPACE SCIENCE REVIEWS 2022; 218:36. [PMID: 35664863 PMCID: PMC9156516 DOI: 10.1007/s11214-022-00902-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 05/06/2022] [Indexed: 05/23/2023]
Abstract
This review summarizes the current state of research aiming at a description of the global heliosphere using both analytical and numerical modeling efforts, particularly in view of the overall plasma/neutral flow and magnetic field structure, and its relation to energetic neutral atoms. Being part of a larger volume on current heliospheric research, it also lays out a number of key concepts and describes several classic, though still relevant early works on the topic. Regarding numerical simulations, emphasis is put on magnetohydrodynamic (MHD), multi-fluid, kinetic-MHD, and hybrid modeling frameworks. Finally, open issues relating to the physical relevance of so-called "croissant" models of the heliosphere, as well as the general (dis)agreement of model predictions with observations are highlighted and critically discussed.
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Affiliation(s)
- Jens Kleimann
- Theoretische Physik IV, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | | | - Federico Fraternale
- Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, Huntsville, AL 35899 USA
| | | | - Jacob Heerikhuisen
- Department of Mathematics and Statistics, University of Waikato, Hamilton, 3240 New Zealand
| | - Vladislav Izmodenov
- Moscow Center of Fundamental and Applied Mathematics, Lomonosov Moscow State University, Moscow, Russia
- Space Research Institute (IKI) of Russian Academy of Sciences, Moscow, Russia
| | - Marc Kornbleuth
- Astronomy Department, Boston University, Boston, MA 02215 USA
| | - Merav Opher
- Astronomy Department, Boston University, Boston, MA 02215 USA
- Radcliffe Institute for Advanced Study at Harvard University, Cambridge, MA USA
| | - Nikolai Pogorelov
- Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, Huntsville, AL 35899 USA
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3
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Interpretation of the Spectra and Anisotropy of Galactic Cosmic Rays. UNIVERSE 2022. [DOI: 10.3390/universe8060307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Recent measurements of the spectra and anisotropy of cosmic rays (CRs) show a fine structure that reflects the spectral hardenings of CRs nuclei at the rigidity R ∼ 200 GV followed by softenings at R ∼ 10 TV, and reveal complicated energy dependence of the amplitude and phase of anisotropy from 100 GeV to PeV. Numerous studies have shown that the existence of nearby CR sources and a local interstellar magnetic field (LIMF) near the solar system are crucial for such CR spectral and anisotropic patterns. In this work, we analyze the CR spectra of different CR components and the anisotropy considering the nearby Geminga supernova remnants (SNRs) source. In the calculation process, we also introduce the anisotropic diffusion of CRs induced by the LIMF based on the spatial-dependent propagation (SDP) model. As a result, our model can simultaneously account for the CR spectra and the anisotropy from 100 GeV to PeV. Future high-precision measurements of the CR anisotropy, for example, by the LHAASO experiment, would be of the essence in the assessment of our proposed model.
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Galli A, Baliukin II, Bzowski M, Izmodenov VV, Kornbleuth M, Kucharek H, Möbius E, Opher M, Reisenfeld D, Schwadron NA, Swaczyna P. The Heliosphere and Local Interstellar Medium from Neutral Atom Observations at Energies Below 10 keV. SPACE SCIENCE REVIEWS 2022; 218:31. [PMID: 35673597 PMCID: PMC9165285 DOI: 10.1007/s11214-022-00901-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 05/05/2022] [Indexed: 05/08/2023]
Abstract
As the heliosphere moves through the surrounding interstellar medium, a fraction of the interstellar neutral helium, hydrogen, and heavier species crossing the heliopause make it to the inner heliosphere as neutral atoms with energies ranging from few eV to several hundred eV. In addition, energetic neutral hydrogen atoms originating from solar wind protons and from pick-up ions are created through charge-exchange with interstellar atoms. This review summarizes all observations of heliospheric energetic neutral atoms and interstellar neutrals at energies below 10 keV. Most of these data were acquired with the Interstellar Boundary Explorer launched in 2008. Among many other IBEX breakthroughs, it provided the first ever all-sky maps of energetic neutral atoms from the heliosphere and enabled the science community to measure in-situ interstellar neutral hydrogen, oxygen, and neon for the first time. These observations have revolutionized and keep challenging our understanding of the heliosphere shaped by the combined forces of the local interstellar flow, the local interstellar magnetic field, and the time-dependent solar wind.
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Affiliation(s)
- André Galli
- Physics Institute, University of Bern, Bern, Switzerland
| | - Igor I. Baliukin
- Space Research Institute of Russian Academy of Sciences, Moscow, Russia
- Moscow Center for Fundamental and Applied Mathematics, Lomonosov Moscow State University, Moscow, Russia
| | - Maciej Bzowski
- Space Research Centre, Polish Academy of Sciences, Warsaw, Poland
| | - Vladislav V. Izmodenov
- Space Research Institute of Russian Academy of Sciences, Moscow, Russia
- Moscow Center for Fundamental and Applied Mathematics, Lomonosov Moscow State University, Moscow, Russia
| | | | | | | | | | | | | | - Paweł Swaczyna
- Department of Astrophysical Sciences, Princeton University, Princeton, NJ USA
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Wu H, Tan HL, Toe CY, Scott J, Wang L, Amal R, Ng YH. Photocatalytic and Photoelectrochemical Systems: Similarities and Differences. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1904717. [PMID: 31814196 DOI: 10.1002/adma.201904717] [Citation(s) in RCA: 89] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 09/17/2019] [Indexed: 05/10/2023]
Abstract
Photocatalytic and photoelectrochemical processes are two key systems in harvesting sunlight for energy and environmental applications. As both systems are employing photoactive semiconductors as the major active component, strategies have been formulated to improve the properties of the semiconductors for better performances. However, requirements to yield excellent performances are different in these two distinctive systems. Although there are universal strategies applicable to improve the performance of photoactive semiconductors, similarities and differences exist when the semiconductors are to be used differently. Here, considerations on selected typical factors governing the performances in photocatalytic and photoelectrochemical systems, even though the same type of semiconductor is used, are provided. Understanding of the underlying mechanisms in relation to their photoactivities is of fundamental importance for rational design of high-performing photoactive materials, which may serve as a general guideline for the fabrication of good photocatalysts or photoelectrodes toward sustainable solar fuel generation.
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Affiliation(s)
- Hao Wu
- Particles and Catalysis Research Group, School of Chemical Engineering, The University of New South Wales, Sydney, NSW, 2052, Australia
- School of Energy and Environment, City University of Hong Kong, Kowloon, 999077, Hong Kong SAR
| | - Hui Ling Tan
- Particles and Catalysis Research Group, School of Chemical Engineering, The University of New South Wales, Sydney, NSW, 2052, Australia
- Department of Applied Chemistry, Faculty of Engineering, Kyushu University, Nishi-Ku, Fukuoka, 8190395, Japan
| | - Cui Ying Toe
- Particles and Catalysis Research Group, School of Chemical Engineering, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - Jason Scott
- Particles and Catalysis Research Group, School of Chemical Engineering, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - Lianzhou Wang
- School of Chemical Engineering, Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Queensland, 4072, Australia
| | - Rose Amal
- Particles and Catalysis Research Group, School of Chemical Engineering, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - Yun Hau Ng
- Particles and Catalysis Research Group, School of Chemical Engineering, The University of New South Wales, Sydney, NSW, 2052, Australia
- School of Energy and Environment, City University of Hong Kong, Kowloon, 999077, Hong Kong SAR
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Zirnstein EJ, McComas DJ, Schwadron NA, Dayeh MA, Heerikhuisen J, Swaczyna P. Strong Scattering of ~keV Pickup Ions in the Local Interstellar Magnetic Field Draped Around Our Heliosphere: Implications for the IBEX Ribbon's Source and IMAP. THE ASTROPHYSICAL JOURNAL 2019; 876:247. [PMID: 31359881 DOI: 10.3847/1538-4357/ab5b91] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The leading hypothesis for the origin of the Interstellar Boundary Explorer (IBEX) "ribbon" of enhanced energetic neutral atoms (ENAs) from the outer heliosphere is the secondary ENA mechanism, whereby neutralized solar wind ions escape the heliosphere and, after several charge-exchange processes, may propagate back toward Earth primarily in directions perpendicular to the local interstellar magnetic field (ISMF). However, the physical processes governing the parent protons outside of the heliopause are still unconstrained. In this study, we compute the "spatial retention" model proposed by Schwadron & McComas (2013) in a 3D simulated heliosphere. In their model, pickup ions outside the heliopause that originate from the neutral solar wind are spatially-retained in a region of space via strong pitch angle scattering before becoming ENAs. We find that the ribbon's intensity and shape can vary greatly depending on the pitch angle scattering rate both inside and outside the spatial retention region, potentially contributing to the globally distributed flux. The draping of the ISMF around the heliopause creates an asymmetry in the average distance to the ribbon's source as well as an asymmetry in the ribbon's shape, i.e., radial cross section of ENA flux through the circular ribbon. The spatial retention model adds an additional asymmetry to the ribbon's shape due to the enhancement of ions in the retention region close to the heliopause. Finally, we demonstrate how the ribbon's structure observed at 1 au is affected by different instrument capabilities, and how the Interstellar Mapping and Acceleration Probe (IMAP) may observe the ribbon.
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Affiliation(s)
- E J Zirnstein
- Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA
| | - D J McComas
- Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA
| | | | - M A Dayeh
- Southwest Research Institute, San Antonio, TX 78228, USA
| | - J Heerikhuisen
- Department of Space Science, University of Alabama in Huntsville, Huntsville, AL 35899, USA
| | - P Swaczyna
- Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA
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Ahlers M. Deciphering the Dipole Anisotropy of Galactic Cosmic Rays. PHYSICAL REVIEW LETTERS 2016; 117:151103. [PMID: 27768328 DOI: 10.1103/physrevlett.117.151103] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Indexed: 06/06/2023]
Abstract
Recent measurements of the dipole anisotropy in the arrival directions of Galactic cosmic rays (CRs) indicate a strong energy dependence of the dipole amplitude and phase in the TeV-PeV range. We argue here that these observations can be well understood within standard diffusion theory as a combined effect of (i) one or more local sources at Galactic longitude 120°≲l≲300° dominating the CR gradient below 0.1-0.3 PeV, (ii) the presence of a strong ordered magnetic field in our local environment, (iii) the relative motion of the solar system, and (iv) the limited reconstruction capabilities of ground-based observatories. We show that an excellent candidate of the local CR source responsible for the dipole anisotropy at 1-100 TeV is the Vela supernova remnant.
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Affiliation(s)
- Markus Ahlers
- WIPAC & Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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A FOUR-FLUID MHD MODEL OF THE SOLAR WIND/INTERSTELLAR MEDIUM INTERACTION WITH TURBULENCE TRANSPORT AND PICKUP PROTONS AS SEPARATE FLUID. ACTA ACUST UNITED AC 2016. [DOI: 10.3847/0004-637x/820/1/17] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Mertsch P, Funk S. Solution to the cosmic ray anisotropy problem. PHYSICAL REVIEW LETTERS 2015; 114:021101. [PMID: 25635539 DOI: 10.1103/physrevlett.114.021101] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Indexed: 06/04/2023]
Abstract
In the standard diffusive picture for transport of cosmic rays (CRs), a gradient in the CR density induces a typically small, dipolar anisotropy in their arrival directions. This is being widely advertised as a tool for finding nearby sources. However, the predicted dipole amplitude at TeV and PeV energies exceeds the measured one by almost 2 orders of magnitude. Here, we critically examine the validity of this prediction, which is based on averaging over an ensemble of turbulent magnetic fields. We focus on (1) the deviations of the dipole in a particular random realization from the ensemble average, and (2) the possibility of a misalignment between the regular magnetic field and the CR gradient. We find that if the field direction and the gradient direction are close to ∼90°, the dipole amplitude is considerably suppressed and can be reconciled with observations, which sheds light on a long-standing problem. Furthermore, we show that the dipole direction in general does not coincide with the gradient direction, thus hampering the search for nearby sources.
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Affiliation(s)
- Philipp Mertsch
- Kavli Institute for Particle Astrophysics & Cosmology, 2575 Sand Hill Road, M/S 29, Menlo Park, California 94025, USA
| | - Stefan Funk
- Kavli Institute for Particle Astrophysics & Cosmology, 2575 Sand Hill Road, M/S 29, Menlo Park, California 94025, USA
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