Medium scale anisotropy in the TeV cosmic ray flux observed by ARGO-YBJ

Bartoli, B.; Bernardini, P.; Bi, X. J.; Bolognino, I.; Branchini, P.; Budano, A.; Melcarne, A. K. Calabrese; Camarri, P.; Cao, Z.; Cardarelli, R.; Catalanotti, S.; Chen, S. Z.; Chen, T. L.; Creti, P.; Cui, S. W.; Dai, B. Z.; D’Amone, A.; Danzengluobu,; Mitri, I. De; Piazzoli, B. D’Ettorre; Girolamo, T. Di; Sciascio, G. Di; Feng, C. F.; Feng, Z.; Feng, Z. Y.; Gou, Q. B.; Guo, Y. Q.; He, H. H.; Hu, Haibing; Hu, Hongbo; Iacovacci, M.; Iuppa, R.; Jia, H. Y.; Labaciren,; Li, H. J.; Liguori, G.; Liu, C.; Liu, J.; Liu, M. Y.; Lü, H.; H., X.; Mancarella, G.; Mari, S. M.; Marsella, G.; Martello, D.; Mastroianni, S.; Montini, P.; Ning, C. C.; Panareo, M.; Panico, B.; Perrone, L.; Pistilli, P.; Ruggieri, F.; Salvini, P.; Santonico, R.; Sbano, S. N.; Shen, P. R.; Sheng, X. D.; Shi, Feng; Surdo, A.; Tan, Y. H.; Vallania, P.; Vernetto, S.; Vigorito, C.; Wang, H.; Wu, C. Y.; Wu, H. R.; Xue, L.; Yan, Y. X.; Yang, Q. Y.; Yang, Xiaoyu; Yao, Z. G.; Yuan, A. F.; Zha, M.; Zhang, H. M.; Zhang, L.; Zhang, X. Y.; Zhang, Y.; Zhaxiciren,; Zhaxisangzhu,; Zhou, X. X.; Zhu, F. R.; Zhu, Q. Q.; Zizzi, G.

doi:10.1103/physrevd.88.082001

Cited by 71 publications

(67 citation statements)

References 54 publications

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“…As it can be seen in (Bartoli et al, 2013). This result seems to exclude any effect of the solar activity on the MSA.…”

Section: Time Dependencesupporting

confidence: 62%

“…The importance of this observation lies in the unexpected confinement of a large flux of low rigidity particles in such narrow beams. Figure 3 shows the ARGO-YBJ sky map in equatorial coordinates as obtained with about 3.7 × 10 11 events reconstructed with a zenith angle ≤ 50 • (selecting the declination region δ ∼ −20 • ÷ 80 • ) (Bartoli et al, 2013). According to the simulation, the median energy of the isotropic CR proton flux is E 50 p ≈ 1.8 TeV (mode energy ≈ 0.7 TeV).…”

Section: Medium/small Scale Anisotropymentioning

confidence: 99%

“…The relative excess (e − b)/b is computed for each multiplicity interval. The horizontal axis reports the multiplicity, the vertical one the relative intensity (for details see Bartoli et al, 2013).…”

Section: The Multiplicity Spectrummentioning

confidence: 99%

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The cosmic ray anisotropy below 10<sup>15</sup> eV

Sciascio

2015

ASTRA Proc.

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Abstract. The measurement of the anisotropy in the cosmic ray (CR) arrival direction distribution provides important informations on the propagation mechanisms and on the identification of their sources. In the last decade the anisotropy came back to the attention of the scientific community, thanks to several new two-dimensional representations of the CR arrival direction distribution which clearly showed the existence of anisotropies at different angular scales in both hemispheres. The origin of the observed anisotropies is still unknown. So far, no theory of CRs in the Galaxy exists yet to explain the observations leaving the standard model of CRs and that of the local magnetic field unchanged at the same time. In this paper the observations of Galactic CR anisotropy will be briefly summarized, with particular attention to the results obtained by the ARGO-YBJ experiment in the Northern Hemisphere. IntroductionThe CR arrival direction distribution and its anisotropy has been a long-standing problem ever since the 1930s. In fact, the measurement of the anisotropy is a powerful tool to investigate the propagation mechanisms and the spatial source distribution determining the CR world as we know it.As CRs are mostly charged nuclei, their paths throughout the Galaxy are deflected and highly isotropized by the action of galactic magnetic field (GMF) they propagate through before reaching the Earth. The GMF is the superposition of a regular and a chaotic contribution. Although the strength of the non-regular component is still under debate, the local total intensity is supposed to be B = 2 ÷ 4 µG (Beck, 2001). In such a field, the gyroradius of CRs is given by r a.u. = 100 R TV , where r a.u. is in astronomic units and R TV is the particle rigidity in TeraVolt.The high degree of isotropy observed in the CR arrival direction distribution suggests that the propagation in the Galaxy of CRs trapped by the magnetic field can be described in terms of diffusion, at least up to 10 16−17 eV (Berezinskii, 1990).The measurement of the anisotropy is complementary to the study of the CR energy spectrum and elemental composition to understand the origin and propagation of the radiation and to probe the structure of the magnetic fields through which CRs travel. In fact, while the elemental composition of CRs observed at the Earth is a quantity averaged over all possible propagation trajectories and large time intervals, thus mainly probing the diffusive propagation mechanisms, the anisotropy, on the contrary, can give information on the structure of the magnetic field near the solar system.In principle any anisotropy reflects a motion. As an example, three different effects may lead to a CR anisotropy. The first effect is related to the motion of the Earth/Solar System with respect to the isotropic CRs rest frame (the so-called Compton-Getting effect, Compton and Getting, 1935). The second is due to nearby and recent CR sources (pulsars or SNRs). For an isotropic propagation, a CR source distribution in the Galaxy is expected to ...

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“…As it can be seen in (Bartoli et al, 2013). This result seems to exclude any effect of the solar activity on the MSA.…”

Section: Time Dependencesupporting

confidence: 62%

Section: Medium/small Scale Anisotropymentioning

confidence: 99%

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The cosmic ray anisotropy below 10<sup>15</sup> eV

Sciascio

2015

ASTRA Proc.

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“…There are 3 regions with an excess of cosmic-rays above 5 σ level. Region A and B were already reported by Milagro experiment, and region C was recently announced by the ARGO-YBJ collaboration [16]. The origin of the cosmic-ray anisotropy is unclear.…”

Section: Scientific Resultsmentioning

confidence: 95%

First year results from the HAWC observatory

Casanova

2017

EPJ Web Conf.

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Abstract. The High Altitude Water Cherenkov Observatory is an all-sky surveying instrument sensitive to gamma rays and cosmic rays from 100GeV to 100TeV. With its 2sr instantaneous field of view and a duty cycle of > 95%, HAWC is carrying out an unbiased survey of the Northern sky and is monitoring known flaring sources and searching for transients. HAWC operation began mid-2013 with a partially-completed detector. The array was terminated in 2015. We here summarize the status of the observatory, and highlight its first scientific results, resulting from the first year of data taking after completion of the detector. In particular, we will present the HAWC map of the sky at tens of TeV.

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“…• ARGO-YBJ has reported [11] the observation of anisotropic structures on a medium angular scale as wide as ∼ 10…”

Section: Introductionmentioning

confidence: 99%

The analog Resistive Plate Chamber detector of the ARGO-YBJ experiment

Bartoli

Bernardini

et al. 2015

Astroparticle Physics

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The ARGO-YBJ experiment has been in stable data taking from November 2007 till February 2013 at the YangBaJing Cosmic Ray Observatory (4300 m a.s.l.). The detector consists of a single layer of Resistive Plate Chambers (RPCs) (6700 m 2 ) operated in streamer mode. The signal pick-up is obtained by means of strips facing one side of the gas volume. The digital readout of 1 arXiv:1504.01510v1 [astro-ph.IM] 7 Apr 2015 the signals, while allows a high space-time resolution in the shower front reconstruction, limits the measurable energy to a few hundred TeV. In order to fully investigate the 1-10 PeV region, an analog readout has been implemented by instrumenting each RPC with two large size electrodes facing the other side of the gas volume. Since December 2009 the RPC charge readout has been in operation on the entire central carpet (∼ 5800 m 2 ). In this configuration the detector is able to measure the particle density at the core position where it ranges from tens to many thousands of particles per m 2 . Thus ARGO-YBJ provides a highly detailed image of the charge component at the core of air showers. In this paper we describe the analog readout of RPCs in ARGO-YBJ and discuss both the performance of the system and the physical impact on the EAS measurements.

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Medium scale anisotropy in the TeV cosmic ray flux observed by ARGO-YBJ

Cited by 71 publications

References 54 publications

The cosmic ray anisotropy below 10<sup>15</sup> eV

The cosmic ray anisotropy below 10<sup>15</sup> eV

First year results from the HAWC observatory

The analog Resistive Plate Chamber detector of the ARGO-YBJ experiment

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Medium scale anisotropy in the TeV cosmic ray flux observed by ARGO-YBJ

Cited by 71 publications

References 54 publications

The cosmic ray anisotropy below 10&lt;sup&gt;15&lt;/sup&gt; eV

The cosmic ray anisotropy below 10&lt;sup&gt;15&lt;/sup&gt; eV

First year results from the HAWC observatory

The analog Resistive Plate Chamber detector of the ARGO-YBJ experiment

Contact Info

Product

Resources

About

The cosmic ray anisotropy below 10<sup>15</sup> eV

The cosmic ray anisotropy below 10<sup>15</sup> eV