Evaluation of the Interplanetary Magnetic Field Strength Using the Cosmic-Ray Shadow of the Sun

Amenomori, M.; Bi, X. J.; Chen, D; Chen, T L; Chen, W Y; Cui, S. W.; Danzengluobu,; Ding, L. K.; Feng, C.; Feng, Z.; Feng, Z. Y.; Gou, Q. B.; Guo, Y. Q.; He, Han; He, Ze; Hibino, K.; Hotta, N.; Hu, Haibing; Hu, Hongbo; Huang, J.; Jia, H. Y.; Jiang, L.; Kajino, F.; Kasahara, K.; Katayose, Y.; Kato, C.; Kawata, K.; Kozai, M.; Labaciren,; Le, G. M.; Li, A F; Li, H J; Li, W J; Liu, C; Liu, J S; Liu, M Y; Lü, H.; Meng, X. R.; Miyazaki, Tetsuya; Mizutani, K.; Munakata, K.; Nakajima, T.; Nakamura, Yuya; Nanjo, H.; Nakamura, Masaki; Niwa, T.; Ohnishi, M.; Ohta, I.; Ozawa, S.; Qian, X. L.; Qu, X. B.; Saito, T.; Saito, Takayuki; Sakata, M.; Sako, T. K.; Shao, J.; Shibata, M.; Shirai, T.; Sugimoto, H.; Takita, M.; Tan, Y. H.; Tateyama, N.; Torii, Shoji; Tsuchiya, H.; Udo, S.; Wang, H; Wu, H. R.; Xue, L.; Yamamoto, Y.; Yamauchi, K.; Yang, Zhongwei; Yuan, A. F.; Yuda, T.; Zhai, L. M.; Zhang, H M; Zhang, J L; Zhang, X Y; Zhang, Y; Zhang, Yi; Zhang, Ying; Zhaxisangzhu,; Zhou, X. X.

doi:10.1103/physrevlett.120.031101

Cited by 12 publications

(7 citation statements)

References 15 publications

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“…Compared to the Moon shadow observed by HAWC, the Sun shadow at low energies (∼1 TeV) is less significant due to the effect of the solar magnetic fields [64,65]. The Sun shadow is more pronounced at higher energies, at which the cosmic rays are less deflected by the coronal and interplanetary magnetic fields [71][72][73]. The evolution of the shadow size with energy is also an illustration of the angular resolution of the detector to cosmic rays, which has been modeled and verified in Refs.…”

Section: Sky Maps and Background Estimationmentioning

confidence: 97%

“…Another limitation of this analysis comes from an incomplete understanding of the shadow on short time scales. In low energy bins, the shadow is weak because the cosmic-ray flux is smeared out by the Sun's magnetic field [79]. A potential gamma-ray excess would be easier to detect over a weak shadow.…”

Section: Gamma-hadron Separation and The Sun Shadowmentioning

confidence: 99%

“…If the gamma-ray spectrum measured in the last solar minimum continues into the TeV range without a cutoff during the minimum of cycle 25, HAWC will be able to detect it with high significance. Long term monitoring from HAWC on the Sun shadow will also allow us to understand the effect of solar magnetic fields on TeV cosmic rays [71][72][73]. Finally, hadronic cosmic rays interacting in the solar atmosphere will also produce solar atmospheric neutrinos [48][49][50], which are being searched for in IceCube [82].…”

Section: B Implications and Future Workmentioning

confidence: 99%

See 2 more Smart Citations

First HAWC observations of the Sun constrain steady TeV gamma-ray emission

Albert¹,

Alfaro²,

Álvarez³

et al. 2018

Phys. Rev. D

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Steady gamma-ray emission up to at least 200 GeV has been detected from the solar disk in the Fermi-LAT data, with the brightest, hardest emission occurring during solar minimum. The likely cause is hadronic cosmic rays undergoing collisions in the Sun's atmosphere after being redirected from ingoing to outgoing in magnetic fields, though the exact mechanism is not understood. An important new test of the gamma-ray production mechanism will follow from observations at higher energies. Only the High Altitude Water Cherenkov (HAWC) Observatory has the required sensitivity

show abstract

Section: Sky Maps and Background Estimationmentioning

confidence: 97%

Section: Gamma-hadron Separation and The Sun Shadowmentioning

confidence: 99%

Section: B Implications and Future Workmentioning

confidence: 99%

See 1 more Smart Citation

First HAWC observations of the Sun constrain steady TeV gamma-ray emission

Albert¹,

Alfaro²,

Álvarez³

et al. 2018

Phys. Rev. D

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show abstract

“…The gamma-ray data by Fermi-LAT [9][10][11][12] provide a rich set of phenomena that is not touched nor explained in this work, including time variations, spectral features, and gamma-ray morphology. Furthermore, cosmic-ray Sun shadows [45][46][47][48][49] should be intimately related to the production of the disk gamma rays [50]. We anticipate that once the relevant magnetic fields are identified or included in the calculation, these features and observations will be important for verifying or differentiating competing models.…”

Section: B Outlookmentioning

confidence: 99%

Simulating gamma-ray production from cosmic rays interacting with the solar atmosphere in the presence of coronal magnetic fields

Li,

Ng,

Chen

et al. 2020

Preprint

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Cosmic rays can interact with the solar atmosphere and produce a slew of secondary messengers, making the Sun a bright gamma-ray source in the sky. Detailed observations with Fermi-LAT have shown that these interactions must be strongly affected by solar magnetic fields in order to produce the wide range of observational features, such as high flux and hard spectrum. However, the detailed mechanisms behind these features are still a mystery. In this work, we tackle this problem by performing particle-interaction simulations in the solar atmosphere in the presence of coronal magnetic fields modeled using the potential field source surface (PFSS) model. We find that the low-energy (∼ GeV) gamma-ray production is significantly enhanced by the coronal magnetic fields, but the enhancement decreases rapidly with energy. The enhancement is directly correlated with the production of gamma rays with large deviation angles relative to the input cosmic-ray direction. We conclude that coronal magnetic fields are essential for correctly modeling solar disk gamma rays below 10 GeV, but above that the effect of coronal magnetic fields diminishes. Other magnetic field structures are needed to explain the high-energy disk emission.

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“…On the other hand, the center of the Sun shadow is displaced from the optical center of the Sun, since the interplanetary magnetic field (IMF) between the Sun and the Earth deflects TeV cosmic rays following the simple Lorentz force law. This displacement of the Sun shadow can be used to measure the strength/direction of the IMF [309,310]. Recently, the experimental evidence of Earth-directed CMEs affecting the Sun shadow was found in a few TeV energy region [311].…”

Section: Space Weather and Heliospheric Physicsmentioning

confidence: 99%

Science Case for a Wide Field-of-View Very-High-Energy Gamma-ray Observatory in the Southern Hemisphere

Albert

Harding

2019

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We outline the science motivation for SGSO, the Southern Gamma-Ray Survey Observatory. SGSO will be a next-generation wide field-of-view gamma-ray survey instrument, sensitive to gamma-rays in the energy range from 100 GeV to hundreds of TeV. Its science topics include unveiling galactic and extragalactic particle accelerators, monitoring the transient sky at very high energies, probing particle physics beyond the Standard Model, and the characterization of the cosmic ray flux. SGSO will consist of an air shower detector array, located in South America. Due to its location and large field of view, SGSO will be complementary to other current and planned gamma-ray observatories such as HAWC, LHAASO, and CTA.

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Evaluation of the Interplanetary Magnetic Field Strength Using the Cosmic-Ray Shadow of the Sun

Cited by 12 publications

References 15 publications

First HAWC observations of the Sun constrain steady TeV gamma-ray emission

First HAWC observations of the Sun constrain steady TeV gamma-ray emission

Simulating gamma-ray production from cosmic rays interacting with the solar atmosphere in the presence of coronal magnetic fields

Science Case for a Wide Field-of-View Very-High-Energy Gamma-ray Observatory in the Southern Hemisphere

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