Cosmic-ray variations in the solar neighbourhood
| Autor: | Mn Mazziotta, Isabelle Grenier, François R. Kamal Youssef |
|---|---|
| Přispěvatelé: | Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS) |
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Physics
photon: production cosmic radiation: spectrum gas: mass Astrophysics::High Energy Astrophysical Phenomena gas: interaction nucleon Astronomy Cosmic ray Astrophysics::Cosmology and Extragalactic Astrophysics solar system solar GLAST helium: cosmic radiation gas: target gamma ray bremsstrahlung: emission cloud nucleus nucleus: interaction [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] Neighbourhood (mathematics) Astrophysics::Galaxy Astrophysics cosmic radiation: flux nucleus: interaction |
| Zdroj: | PoS 37th International Cosmic Ray Conference 37th International Cosmic Ray Conference, Jul 2021, Berlin, Germany. pp.616, ⟨10.22323/1.395.0616⟩ |
| DOI: | 10.22323/1.395.0616⟩ |
| Popis: | International audience; The $\gamma$ radiation produced in cosmic-ray and gas interactions has been used to probe the local cosmic-ray spectrum in several clouds to distances of about 1 kpc around the Sun. Early measurements made with Fermi LAT data were found in good agreement with the proton and helium cosmic-ray spectra reaching the Solar System, given the 10-15% uncertainty in target gas mass that is inherent to HI line observations. The local cosmic-ray uniformity has recently been challenged by the finding of a significant loss of particles in the nearby Eridu cirrus. We have revisited the $\gamma$-ray emissivity spectrum one would expect per gas nucleon from hadronic and bremsstrahlung emission using the latest cosmic-ray spectra inferred near the Sun, outside the heliosphere. We have also used improved photon production spectra in nucleus-nucleus interactions. We find that, because of the current uncertainty in the $\gamma$-ray yield per nuclear interaction, one cannot conclude whether the average cosmic-ray spectrum measured within $\sim$1 kpc from the Sun is comparable or superior to that inferred just outside the Solar System, nor whether the low cosmic-ray flux pervading the Eridu cirrus is consistent or not with the flux reaching the Sun. The Eridu cirrus and the Sun both lie in a hollow valley of the local interstellar medium. We show that the cosmic-ray flux in Eridu is about half that observed in two other more massive clouds that flank the valley. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|