Cargando…

Standard Cosmic Ray Energetics and Light Element Production

The recent observations of Be and B in metal poor stars has led to a reassessment of the origin of the light elements in the early Galaxy. At low it is metallicity ([O/H] < -1.75), it is necessary to introduce a production mechanism which is independent of the interstellar metallicity (primary)....

Descripción completa

Detalles Bibliográficos
Autores principales: Fields, Brian D., Olive, Keith A., Casse, Michel, Vangioni-Flam, Elisabeth
Lenguaje:eng
Publicado: 2000
Materias:
Acceso en línea:https://dx.doi.org/10.1051/0004-6361:20010251
http://cds.cern.ch/record/467662
_version_ 1780896487235911680
author Fields, Brian D.
Olive, Keith A.
Casse, Michel
Vangioni-Flam, Elisabeth
author_facet Fields, Brian D.
Olive, Keith A.
Casse, Michel
Vangioni-Flam, Elisabeth
author_sort Fields, Brian D.
collection CERN
description The recent observations of Be and B in metal poor stars has led to a reassessment of the origin of the light elements in the early Galaxy. At low it is metallicity ([O/H] < -1.75), it is necessary to introduce a production mechanism which is independent of the interstellar metallicity (primary). At higher metallicities, existing data might indicate that secondary production is dominant. In this paper, we focus on the secondary process, related to the standard Galactic cosmic rays, and we examine the cosmic ray energy requirements for both present and past epochs. We find the power input to maintain the present-day Galactic cosmic ray flux is about 1.5e41 erg/s = 5e50 erg/century. This implies that, if supernovae are the sites of cosmic ray acceleration, the fraction of explosion energy going to accelerated particles is about 30%, a value which we obtain consistently both from considering the present cosmic ray flux and confinement and from the present 9Be and 6Li abundances. Using the abundances of 9Be (and 6Li) in metal-poor halo stars, we extend the analysis to show the effect of the interstellar gas mass on the standard galactic cosmic ray energetic constraints on models of Li, Be, and B evolution. The efficiency of the beryllium production per erg may be enhanced in the past by a factor of about 10; thus the energetic requirement by itself cannot be used to rule out a secondary origin of light elements. Only a clear and undisputable observational determination of the O-Fe relation in the halo will discriminate between the two processes. (abridged)
id cern-467662
institution Organización Europea para la Investigación Nuclear
language eng
publishDate 2000
record_format invenio
spelling cern-4676622023-10-20T02:39:29Zdoi:10.1051/0004-6361:20010251http://cds.cern.ch/record/467662engFields, Brian D.Olive, Keith A.Casse, MichelVangioni-Flam, ElisabethStandard Cosmic Ray Energetics and Light Element ProductionAstrophysics and AstronomyThe recent observations of Be and B in metal poor stars has led to a reassessment of the origin of the light elements in the early Galaxy. At low it is metallicity ([O/H] < -1.75), it is necessary to introduce a production mechanism which is independent of the interstellar metallicity (primary). At higher metallicities, existing data might indicate that secondary production is dominant. In this paper, we focus on the secondary process, related to the standard Galactic cosmic rays, and we examine the cosmic ray energy requirements for both present and past epochs. We find the power input to maintain the present-day Galactic cosmic ray flux is about 1.5e41 erg/s = 5e50 erg/century. This implies that, if supernovae are the sites of cosmic ray acceleration, the fraction of explosion energy going to accelerated particles is about 30%, a value which we obtain consistently both from considering the present cosmic ray flux and confinement and from the present 9Be and 6Li abundances. Using the abundances of 9Be (and 6Li) in metal-poor halo stars, we extend the analysis to show the effect of the interstellar gas mass on the standard galactic cosmic ray energetic constraints on models of Li, Be, and B evolution. The efficiency of the beryllium production per erg may be enhanced in the past by a factor of about 10; thus the energetic requirement by itself cannot be used to rule out a secondary origin of light elements. Only a clear and undisputable observational determination of the O-Fe relation in the halo will discriminate between the two processes. (abridged)The recent observations of Be and B in metal poor stars has led to a reassessment of the origin of the light elements in the early Galaxy. At low it is metallicity ([O/H] < -1.75), it is necessary to introduce a production mechanism which is independent of the interstellar metallicity (primary). At higher metallicities, existing data might indicate that secondary production is dominant. In this paper, we focus on the secondary process, related to the standard Galactic cosmic rays, and we examine the cosmic ray energy requirements for both present and past epochs. We find the power input to maintain the present-day Galactic cosmic ray flux is about 1.5e41 erg/s = 5e50 erg/century. This implies that, if supernovae are the sites of cosmic ray acceleration, the fraction of explosion energy going to accelerated particles is about 30%, a value which we obtain consistently both from considering the present cosmic ray flux and confinement and from the present 9Be and 6Li abundances. Using the abundances of 9Be (and 6Li) in metal-poor halo stars, we extend the analysis to show the effect of the interstellar gas mass on the standard galactic cosmic ray energetic constraints on models of Li, Be, and B evolution. The efficiency of the beryllium production per erg may be enhanced in the past by a factor of about 10: thus the energetic requirement by itself cannot be used to rule out a secondary origin of light elements. Only a clear and undisputable observational determination of the O-Fe relation in the halo will discriminate between the two processes. (abridged)astro-ph/0010121UMN-TH-00-1924TPI-MINN-00-48CERN-TH-2000-288CERN-TH-2000-288UMN-TH-1924TPI-MINN-2000-48oai:cds.cern.ch:4676622000-10-05
spellingShingle Astrophysics and Astronomy
Fields, Brian D.
Olive, Keith A.
Casse, Michel
Vangioni-Flam, Elisabeth
Standard Cosmic Ray Energetics and Light Element Production
title Standard Cosmic Ray Energetics and Light Element Production
title_full Standard Cosmic Ray Energetics and Light Element Production
title_fullStr Standard Cosmic Ray Energetics and Light Element Production
title_full_unstemmed Standard Cosmic Ray Energetics and Light Element Production
title_short Standard Cosmic Ray Energetics and Light Element Production
title_sort standard cosmic ray energetics and light element production
topic Astrophysics and Astronomy
url https://dx.doi.org/10.1051/0004-6361:20010251
http://cds.cern.ch/record/467662
work_keys_str_mv AT fieldsbriand standardcosmicrayenergeticsandlightelementproduction
AT olivekeitha standardcosmicrayenergeticsandlightelementproduction
AT cassemichel standardcosmicrayenergeticsandlightelementproduction
AT vangioniflamelisabeth standardcosmicrayenergeticsandlightelementproduction