Search for gamma-ray emission from the Sun during solar minimum with the ARGO-YBJ experiment

Abstract

The hadronic interaction of cosmic rays with solar atmosphere can produce high energy gamma rays. The gamma-ray luminosity is correlated both with the flux of primary cosmic rays and the intensity of the solar magnetic field. The gamma rays below 200 GeV have been observed by $Fermi$ without any evident energy cutoff. The bright gamma-ray flux above 100 GeV has been detected only during solar minimum. The only available data in TeV range come from the HAWC observations, however outside the solar minimum. The ARGO-YBJ dataset has been used to search for sub-TeV/TeV gamma rays from the Sun during the solar minimum from 2008 to 2010, the same time period covered by the Fermi data. A suitable model containing the Sun shadow, solar disk emission and inverse-Compton emission has been developed, and the chi-square minimization method was used to quantitatively estimate the disk gamma-ray signal. The result shows that no significant gamma-ray signal is detected and upper limits to the gamma-ray flux at 0.3$-$7 TeV are set at 95\% confidence level. In the low energy range these limits are consistent with the extrapolation of the Fermi-LAT measurements taken during solar minimum and are compatible with a softening of the gamma-ray spectrum below 1 TeV. They provide also an experimental upper bound to any solar disk emission at TeV energies. Models of dark matter annihilation via long-lived mediators predicting gamma-ray fluxes > $10^{-7}$ GeV $c{m}^{-2}$ $s^{-1}$ below 1 TeV are ruled out by the ARGO-YBJ limits.

References in corpus (7)

• On Polar Magnetic Field Reversal and Surface Flux Transport During Solar Cycle 24
• Fermi-LAT Observations of Two Gamma-Ray Emission Components from the Quiescent Sun
• Gamma-ray emission from the solar halo and disk: a study with EGRET data
• Identification of the TeV Gamma-ray Source ARGO J2031+4157 with the Cygnus Cocoon
• Long-term Monitoring on Mrk 501 for Its VHE gamma Emission and a Flare in October 2011
• Crab Nebula: five-year observation with ARGO-YBJ
• Observation of TeV gamma-rays from the unidentified source HESS J1841-055 with the ARGO-YBJ experiment

Cited by in corpus (8)

• The TeV Sun Rises: Discovery of Gamma rays from the Quiescent Sun with HAWC
• A search for dark matter cosmic-ray electrons and positrons from the Sun with the Fermi Large Area Telescope
• Solar constraints on captured electrophilic dark matter
• Gravitational lensing of massive particles by a black-bounce-Schwarzschild black hole
• StellarICS: Inverse Compton Emission from the Quiet Sun and Stars from keV to TeV
• A New Component from the Quiet Sun: Synchrotron Radiation from Galactic Cosmic-Ray Electrons
• The influence of the Sun and Moon on the observation of very high energy gamma-ray sources using EAS arrays
• Strong field gravitational lensing of particles by a black-bounce-Schwarzschild black hole