Gaussian analysis of two hemisphere observations of galactic cosmic ray sidereal anisotropies

Hall, D. L.; Munakata, K.; Yasue, S.; Mori, S.; Kato, C.; Koyama, M.; Akahane, S.; Fujii, Z.; Fujimoto, K.; Humble, J. E.; Fenton, A. G.; Fenton, K. B.; Duldig, M. L.

doi:10.1029/1998ja900107

Cited by 47 publications

(48 citation statements)

References 39 publications

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“…Large-scale anisotropies and smaller scale excess regions have been detected in the distribution of CRs in this energy range (Nagashima et al 1998;Hall et al 1999;Abdo et al 2008;Abbasi et al 2011;Surdo & Argo-Ybj Collaboration 2011). It has been suggested that the Sun is located in a magnetic flux tube in the ISM, and that such a structure would be a conduit for GCRs (Frisch 1997).…”

Section: Galactic Cosmic Rays and The Local Ismfmentioning

confidence: 99%

“…The blue open circle gives the ISMF direction derived from the center of the IBEX Ribbon arc. The large blue circular region (light gray) shows the location of the tail-in anisotropy for ∼500 GeV GCRs modeled by Hall et al (1999), with the extent defined by the 68 • width from Nagashima et al (1998). The regions outlined by thick black lines show the observed heliotail that is deflected ∼44 • to the west of the downwind gas direction (red triangle) and is prominent in maps of the globally distributed ENAs (Schwadron et al 2011).…”

Section: Cmb Dipole Anisotropy and The Local Ismfmentioning

confidence: 99%

“…The tail-in excess was originally attributed to the heliotail because it is approximately opposite to the direction of the solar motion through the LSR. Hall et al (1999) Figure 11 shows the directions of the ISMF, tail-in excess compared to the ISMF direction, and the true heliotail corresponding to the ENA flux minimum centered ∼44 • west of the downwind gas flow (Schwadron et al 2011). …”

Section: Galactic Cosmic Rays and The Local Ismfmentioning

confidence: 99%

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The Interstellar Magnetic Field Close to the Sun. Ii.

Frisch

Andersson

Berdyugin

et al. 2012

ApJ

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The magnetic field in the local interstellar medium (ISM) provides a key indicator of the galactic environment of the Sun and influences the shape of the heliosphere. We have studied the interstellar magnetic field (ISMF) in the solar vicinity using polarized starlight for stars within 40 pc of the Sun and 90 • of the heliosphere nose. In Frisch et al. (Paper I), we developed a method for determining the local ISMF direction by finding the best match to a group of interstellar polarization position angles obtained toward nearby stars, based on the assumption that the polarization is parallel to the ISMF. In this paper, we extend the analysis by utilizing weighted fits to the position angles and by including new observations acquired for this study. We find that the local ISMF is pointed toward the • 25 pc −1 . This conclusion is conditioned on the small sample of stars available for defining this rotation. Variations from the ordered component suggest a turbulent component of ∼23 • . The ordered component and standard relations between polarization, color excess, and H o column density predict a reasonable increase of N(H) with distance in the local ISM. The similarity of the ISMF directions traced by the polarizations, the IBEX Ribbon, and pulsars inside the Local Bubble in the third galactic quadrant suggest that the ISMF is relatively uniform over spatial scales of 8-200 pc and is more similar to interarm than spiral-arm magnetic fields. The ISMF direction from the polarization data is also consistent with small-scale spatial asymmetries detected in GeV-TeV cosmic rays with a galactic origin. The peculiar geometrical relation found earlier between the cosmic microwave background dipole moment, the heliosphere nose, and the ISMF direction is supported by this study. The interstellar radiation field at ∼975 Å does not appear to play a role in grain alignment for the low-density ISM studied here.

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Section: Galactic Cosmic Rays and The Local Ismfmentioning

confidence: 99%

Section: Cmb Dipole Anisotropy and The Local Ismfmentioning

confidence: 99%

Section: Galactic Cosmic Rays and The Local Ismfmentioning

confidence: 99%

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The Interstellar Magnetic Field Close to the Sun. Ii.

Frisch

Andersson

Berdyugin

et al. 2012

ApJ

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“…Above the energy range where cosmic rays are directly affected by inner heliospheric processes (see, e.g., Florinski et al 2013;Manuel et al 2014;Florinski et al 2015), a statistically significant anisotropy has been observed by a variety of experiments, sensitive to different energy ranges (from tens of GeV to a few PeV), located on or below the Earth's surface in the northern hemisphere (Nagashima et al 1998;Hall et al 1999;Amenomori et al 2005Amenomori et al , 2006Guillian et al 2007;Abdo et al 2009;Aglietta et al 2009;Zhang et al 2009;Munakata et al 2010;Amenomori et al 2011;de Jong et al 2011;Cui et al 2011;Bartoli et al 2015) and in the southern hemisphere (Abbasi et al 2010a(Abbasi et al , 2011a(Abbasi et al , 2012bAartsen et al 2013b).…”

Section: Introductionmentioning

confidence: 99%

Cosmic-Ray Small-Scale Anisotropies and Local Turbulent Magnetic Fields

López-Barquero

Farber

Desiati

et al. 2016

ApJ

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Cosmic-ray anisotropy has been observed in a wide energy range and at different angular scales by a variety of experiments over the past decade. However, no comprehensive or satisfactory explanation has been put forth to date. The arrival distribution of cosmicrays at Earth is the convolution of the distribution of their sources and of the effects of geometry and properties of the magnetic field through which particles propagate. It is generally believed that the anisotropy topology at the largest angular scale is adiabatically shaped by diffusion in the structured interstellar magnetic field. On the contrary, the medium-and small-scale angular structure could be an effect of nondiffusive propagation of cosmicrays in perturbed magnetic fields. In particular, a possible explanation forthe observed small-scale anisotropy observed at theTeV energy scalemay be the effect of particle propagation in turbulent magnetized plasmas. We perform numerical integration of test particle trajectories in low-β compressible magnetohydrodynamic turbulence to study how the cosmicrays' arrival direction distribution is perturbed when they stream along the local turbulent magnetic field. We utilize Liouville's theorem for obtaining the anisotropy at Earth and provide the theoretical framework for the application of the theorem in the specific case of cosmic-ray arrival distribution. In this work, we discuss the effects on the anisotropy arising from propagation in this inhomogeneous and turbulent interstellar magnetic field.

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“…Mori et al, 1981Mori et al, , 1989Mori et al, , 1993 and at Poatina (42 • S), (Hall et al, 1998(Hall et al, , 1999. Fig.…”

Section: Ga and Ta Of Three Kinds Of Sidereal Anisotropy In The Hmsmentioning

confidence: 99%

The existence of cosmic ray sidereal anisotropies of galactic and solar origins with energies lower than 104 GeV and their modulation caused by the presumed behavior pattern of the heliomagnetosphere and of its neighboring gaseous matter in interstellar magnetic field

et al. 2012

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It is shown that the sidereal anisotropy (S i A) of cosmic rays (CRs) with energies smaller than 10 4 GeV consists of three kinds: one (GA) is of galactic origin from the direction G (α G = 0 hr; δ G = −20• ), and the other two (tail-in TA and nose-in HA) are of solar origin from the respective directions T (α T = 6 hr; δ T ∼ −24• ) and H (α H = 18 hr; δ H > 0• ) and supposed to be produced by the acceleration of CRs on the tail and nose boundaries of the heliomagnetosphere (HMS). This conclusion was arrived at in 1995 after a long-term delay since the beginning of CR observations in the early 20-th century. This delay was mainly due to the inconsistency among observations caused by the belief that the sidereal anisotropy must be unidirectional in space. The inconsistency has been solved at least qualitatively by the discovery of GA and TA. These anisotropies, including also HA, are subject, respectively, to their proper solar modulations in the HMS characterized by a polarity reversal every 11 years of the solar polar magnetic field and solar activity dependence with an 11-year periodicity. By using these modulation patterns, the origins of the three anisotropies have been determined. TA and HA thus determined inversely produce the following kinds of evidence and problems in the HMS: (1) the structure of the HMS, (2) acceleration of CRs on the boundary of the HMS, (3) CR Lens Effect of the HMS for the sharp concentration of TA and HA, (4) the proper motion (V HMS ) of the HMS relative to neighboring stars, (5) the proper motion of interstellar gaseous matter (including the magnetic field) relative to neighboring stars, and (6) the existence of the Subordinate HMS surrounding the HMS for the explanation of the duality of the motion of the HMS and also of the absence of the Compton-Getting (C-G) effect on the HMS. The present paper not only presents a brief summary of the studies of CR sidereal anisotropy made by many researchers during the 20th century leading to the present understanding, but also presents some problems to open up a new vista of the future.

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Gaussian analysis of two hemisphere observations of galactic cosmic ray sidereal anisotropies

Cited by 47 publications

References 39 publications

The Interstellar Magnetic Field Close to the Sun. Ii.

The Interstellar Magnetic Field Close to the Sun. Ii.

Cosmic-Ray Small-Scale Anisotropies and Local Turbulent Magnetic Fields

The existence of cosmic ray sidereal anisotropies of galactic and solar origins with energies lower than 104 GeV and their modulation caused by the presumed behavior pattern of the heliomagnetosphere and of its neighboring gaseous matter in interstellar magnetic field

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