Abstract

We report the detection of high-energy gamma-rays from the quiescent Sun with the Large Area Telescope on board the Fermi Gamma-Ray Space Telescope (Fermi) during the first 18 months of the mission. These observations correspond to the recent period of low solar activity when the emission induced by cosmic rays (CRs) is brightest. For the first time, the high statistical significance of the observations allows clear separation of the two components: the point-like emission from the solar disk due to CR cascades in the solar atmosphere and extended emission from the inverse Compton (IC) scattering of CR electrons on solar photons in the heliosphere. The observed integral flux (>= 100 MeV) from the solar disk is (4.6 +/- 0.2inverted right perpendicularstatistical errorinverted left perpendicular(-0.08)(+1.0)inverted right perpendicularsystematic errorinverted left perpendicular) x 10(-7) cm(-2) s(-1), which is similar to 7 times higher than predicted by the "nominal" model of Seckel et al. In contrast, the observed integral flux (>= 100 MeV) of the extended emission from a region of 20 degrees radius centered on the Sun, but excluding the disk itself, (6.8 +/- 0.7[stat.](-0.4)(+0.5)[syst.]) x 10(-7) cm(-2) s(-1), along with the observed spectrum and the angular profile, is in good agreement with the theoretical predictions for the IC emission.

Autore Pugliese

• Loparco Francesco , Giordano Francesco , Spinelli Paolo , Fusco Piergiorgio , Raino' Silvia

Tutti gli autori

• LOPARCO F.;GIORDANO F.;SPINELLI P.;FUSCO P.;RAINO' S.

Titolo volume/Rivista

Non Disponibile

Anno di pubblicazione

2011

ISSN

0004-637X

ISBN

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Numero di citazioni Wos

50

Ultimo Aggiornamento Citazioni

Non Disponibile

Numero di citazioni Scopus

61

Ultimo Aggiornamento Citazioni

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Settori ERC

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Codici ASJC

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