Chaotic Effects on Cosmic Ray Anisotropy in a Heliosphere-inspired Model

López-Barquero, Vanessa; Desiati, P.

doi:10.22323/1.358.1109

Cited by 4 publications

(6 citation statements)

References 13 publications

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“…3.3). With such a method, it is possible to derive the density gradient and pitch angle distribution of TeV CRs in the local ISM while accounting for particle trajectory chaotic behavior 21 , and the residual experimental systematic biases 22 affecting the CR anisotropy sky maps.…”

Section: Methodsmentioning

confidence: 99%

“…A simple dimensional consideration provides a useful hint: 10 TeV protons have a gyroradius of about 500-800 AU in a 3-5 µG local interstellar magnetic field. This is about the transverse size of the heliosphere, which implies that some sort of spacial resonance must occur when CR particles pass through the heliosphere [12][13][14][15][16][17][18][19][20][21][22][23] . CR pitch angle distribution in the ISM is modified by the presence of the heliosphere when particles are collected on Earth.…”

Section: Contextmentioning

confidence: 99%

“…All-sky CR arrival direction distribution maps yields a powerful tool to explore the origin of the observed CR anisotropy. In particular, they make it possible to investigate how the outer heliosphere influences CR particle trajectories coming from the ISM [12][13][14][17][18][19][20][21]23 .…”

Section: Cosmic Ray Anisotropymentioning

confidence: 99%

See 2 more Smart Citations

Using TeV Cosmic Rays to probe the Heliosphere's Boundary with the Local Interstellar Medium

Desiati¹,

Díaz-Vélez²,

Giacinti³

et al. 2022

Preprint

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The heliosphere is the magnetic structure formed by the Sun's atmosphere extending into the local interstellar medium (ISM). The heliopause, the boundary separating the heliosphere from the ISM, is a still largely unexplored region of space. Even though the Voyager spacecraft officially entered the local ISM in 2012 (V1) and 2018 (V2) and are delivering data on the outer space environment, they are just two points piercing a vast region of space at specific times. The heliospheric boundary regulates the penetration of MeV-GeV galactic cosmic rays (CR) into the inner heliosphere, where the solar system is located. Interstellar keV neutral atoms are crucial to the outer heliosphere since they can penetrate unperturbed and transfer energy into the solar wind. Missions such as NASA's Interstellar Boundary EXplorer (IBEX) and Cassini are designed to detect neutral atoms and monitor charge exchange processes at the heliospheric boundary. The heliosphere does not modulate the intensity of TeV CR particles coming from the ISM, but it does influence their arrival direction distribution. Ground-based CR observatories have provided statistically accurate maps of CR anisotropy as a function of energy over the last couple of decades. Combining such observations to produce all-sky coverage makes it possible to investigate the impact that the heliosphere has on TeV CR particles. We can numerically calculate the pristine TeV CR pitch angle distribution in the local ISM using state-of-the-art heliosphere models. Only with the heliospheric influence subtracted is it possible to use TeV CR observations to infer propagation properties and the characteristics of magnetic turbulence in the ISM. Numerical calculations of CR particle trajectories through heliospheric models, therefore, provide a complementary tool to probe into the global properties of the boundary region, such as its size, length, and the scale of the local interstellar magnetic field draping around the heliosphere. A program boosting heliospheric modeling with emphasis on the boundary region, and promoting combined CR experimental data analyses from multiple ground-based experiments, will benefit CR astrophysics and, in reverse, will provide additional data and complementary tools to explore the interaction between the heliosphere and the local ISM.

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Section: Methodsmentioning

confidence: 99%

Section: Contextmentioning

confidence: 99%

See 1 more Smart Citation

Using TeV Cosmic Rays to probe the Heliosphere's Boundary with the Local Interstellar Medium

Desiati¹,

Díaz-Vélez²,

Giacinti³

et al. 2022

Preprint

Self Cite

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show abstract

“…Generally speaking, the observed cosmic-ray anisotropy (CRA) is due to a combination of extra-terrestrial and local effects. The extra-terrestrial contribution includes the distribution of the cosmic ray sources in the Milky Way, and the properties of the galactic and interstellar magnetic field, such as turbulence and the number and characteristics of coherent magnetic structures, including the heliosphere [4][5][6]. It is possible that the Compton-Getting effect due to the galactic rotation may be contributing to the observations [7], however, no evidence was found yet.…”

Section: Introductionmentioning

confidence: 99%

Harmonic Interference of Earth's Orbital Velocity and the Sidereal Cosmic Ray Anisotropy

Díaz-Vélez¹,

Desiati²,

Abbasi³

et al. 2021

Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021)

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When cosmic-ray arrival directions are observed in celestial coordinates, they appear to have a small anisotropy whose origin is still largely unknown. In addition to this celestial anisotropy, the Earth's revolution around the Sun produces a faint Compton-Getting dipole anisotropy with an excess oriented towards the direction of motion in solar coordinates. The relative rotation of the celestial and solar reference frames over a calendar year causes interference between the two sources of anisotropy. It is possible to characterize the resulting yearly modulations by studying the side-bands to the diurnal and sidereal frequencies in anti-and extended-sidereal time frames. This work provides a numerical simulation of the interference between anisotropies in sidereal and solar reference frames to predict the distributions in anti-sidereal and extended-sidereal frames.

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“…Using a Liouville mapping technique, which takes into account the detailed heliospheric magnetic field structure, is employed. With such a method, it is possible to derive the density gradient and pitch angle distribution of TeV CRs in the LISM while accounting for particle trajectory chaotic behavior 69 , and the residual experimental systematic biases 53 affecting the CR anisotropy sky maps. With such results, we will be able to probe the global CR propagation through the ISM.…”

mentioning

confidence: 99%

Snowmass 2021 LoI: Determination of cosmic ray properties in the local interstellar medium with all-sky anisotropy observations

Desiati,

Vélez,

Pogorelov

et al. 2020

Preprint

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Propagation of Galactic cosmic rays (CR) in the interstellar medium (ISM) is among the unsolved problems in particle astrophysics. Interpretation of CR spectrum and composition measurements and their possible link to dark matter crucially relies on our understanding of CR propagation in the Galaxy. Several air shower experiments have measured a significant anisotropy of CRs in the TeV to PeV energy range. These observations hint to a complicated overlap of more than one cause: from the distribution of the CR sources in the Milky Way to the nature of such sources, from the turbulence properties of interstellar plasmas to the inhomogeneous nature of the interstellar medium. Coherent magnetic structures such as the heliosphere greatly influence the CR arrival direction distribution. It is necessary to account for and remove the heliosphere's distortion effects if we want to determine the pristine CR arrival direction distribution in the local interstellar medium (LISM), the environment surrounding the solar system up to the distance of particle mean free path. The recent availability of accurate all-sky maps of CR arrival direction distribution and the latest advancements in heliospheric modeling, make it possible to infer the CR pitch angle distribution in the LISM using a Liouville mapping technique. With the interstellar CR distribution, we can study the global characteristics of CR diffusion, tap into the properties of interstellar plasma turbulence, test the recent and local CR source hypothesis, and whether clumps of dark matter have a role in the observed CR observations. The study can lead to developments aiming to a better understanding of the heliosphere, particularly the boundary region with the ISM, and additional constraints on the LISM properties.

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Chaotic Effects on Cosmic Ray Anisotropy in a Heliosphere-inspired Model

Cited by 4 publications

References 13 publications

Using TeV Cosmic Rays to probe the Heliosphere's Boundary with the Local Interstellar Medium

Using TeV Cosmic Rays to probe the Heliosphere's Boundary with the Local Interstellar Medium

Harmonic Interference of Earth's Orbital Velocity and the Sidereal Cosmic Ray Anisotropy

Snowmass 2021 LoI: Determination of cosmic ray properties in the local interstellar medium with all-sky anisotropy observations

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