Study of the Solar Magnetic Field influence on the cosmic ray Sun shadow

Nan Yuncheng Shandong University & Institute of High Energy Physics

Chen Songzhan, Feng Cunfeng and Jiang Chaowei

36th ICRC, 2019, Madison, WI, U.S.A

IHEP

Outline

1. Introduction

2. Sun Shadow Modeling and the Solar-terrestrial Magnetic Field affection

3. Influences of Different CMF’s Models on the Sun Shadow

4. Summary

Sun

1. Introduction

A probe to detect the Solar-terrestrial magnetic field.

-1-

Sun shadow

Interplanetary Magnetic Field: ARGO-YBJ probes the IMF using Sun shadow at 5 TeV.

ApJ, 729:113 (2011)

-2-

The structure of the IMF estimated using Sun shadow

is consistent with the satellite measurement.

The CSSS model is more consistent with the Sun shadow measurement.

Coronal Magnetic Field: Tibet ASγ evaluates two models using Sun shadow at 10 TeV.

PRL,111,011101(2013)

CSSS model is preferred.

-3-

Energy dependent：ARGO-YBJ’s Result

ARGO-YBJ have detected Yearly rigidity dependence of Sun shadow. Chen, et al. 35th ICRC

-4-

LHAASO’s expectation of 2-day Sun shadow observations

Wu, et al. Astroparticle Physics 103 (2018) 41–48

-5-

2. SUN SHADOW MODELING AND THE SOLAR-TERRESTRIAL MAGNETIC FIELD AFFECTION

Simulation of the Sun Shadow

• Back forward method

tracing the anti-particle from earth to Sun.

Earth

Sun

Anti-particle

-6-

• Component： proton

• Energy range：TeV - PeV

• Number of events：~ 107

The Solar-terrestrial Magnetic Field

IGRF model Rearth [T] Parker model θ =90°[nT] PFSS model[Gauss]

Large-scale magnetic field in the corona (CMF)

Interplanetary magnetic field (IMF)

Geomagnetic field

(GMF)

-7-

Influence of Large-scale CMF on the Sun Shadow

-8-

The CMF dominates the deficit ratio of the Sun shadow!

E=1TeV

West East(deg)

Sou

th

No

rth

(deg

)

E=10TeV

West East(deg)

Sou

th

No

rth

(deg

)

E=100TeV

Sou

th

No

rth

(deg

)

West East(deg)

Solar minimum

Influence of Large-scale CMF on the Sun Shadow

-9-

How?

E=1TeV

E=10TeV

E=100TeV

X(R⊙ )

Z(R⊙

)

X(R⊙ )

Z(R⊙

)

X(R⊙ )

Z(R⊙

)

SUN

SS Solar minimum

Influence of IMF on the Sun Shadow

-10-

Spring Equinox Summer Solstice Autumnal Equinox

we expect the seasonal dependence of the extension of the Sun shadow.

Seasonal dependence

A year

Solar minimum

3. INFLUENCES OF DIFFERENT CMF’S MODELS ON THE SUN SHADOW

Influences of Different CMF’s Models on the Sun Shadow

-11-

Solar minimum

E< 10TeV, the CSSS and low height of Rss of the PFSS increase the extension!

At 10TeV, the deficit ratios of different models are the same! Different results from ASγ.

Influences of Different CMF’s Models on the Sun Shadow

-12-

Solar maximum

To explore more about the CMF, we need the experimental data and more simulation!

• The CMF and the IMF affect the deficit and the extension of the Sun shadow, respectively.

• From our simulation, we expect the seasonal dependence of the extension of the Sun shadow.

• Also, current models and parameters give a different expectations on Sun shadow. Both of them need data to confirm.

-13-

THANK YOU!

4. Summary