Building up the spectrum of cosmic rays in star-forming regions

Autores
Torres, Diego F.; Cillis, Analia Nilda; Lacki, Brian; Rephaeli, Joel
Año de publicación
2012
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
The common approach to compute the cosmic ray distribution in a starburst galaxy or region is equivalent to assuming that at any point within that environment, there is an accelerator inputting cosmic rays at a reduced rate. This rate should be compatible with the overall volume-average injection, given by the total number of accelerators that were active during the starburst age. These assumptions seem reasonable, especially under the supposition of a homogeneous and isotropic distribution of accelerators. However, in this approach the temporal evolution of the superposed spectrum is not explicitly derived; rather, it is essentially assumed ab initio. Here, we test the validity of this approach by following the temporal evolution and spatial distribution of the superposed cosmic ray spectrum and compare our results with those from theoretical models that treat the starburst region as a single source. In the calorimetric limit (with no cosmic ray advection), homogeneity is reached (typically within 20 per cent) across most of the starburst region. However, values of centre-to-edge intensity ratios can amount to a factor of several. Differences between the common homogeneous assumption for the cosmic ray distribution and our models are larger in the case of two-zone geometries, such as a central nucleus with a surrounding disc. We have also found that the decay of the cosmic ray density following the duration of the starburst process is slow, and even approximately 1 Myr after the burst ends (for a gas density of 35 cm-3) it may still be within an order of magnitude of its peak value. Based on our simulations, it seems that the detection of a relatively hard spectrum up to the highest gamma-ray energies from nearby starburst galaxies favours a relatively small diffusion coefficient (i.e. long diffusion time) in the region where most of the emission originates.
Fil: Torres, Diego F.. Institució Catalana de Recerca i Estudis Avancats; España
Fil: Cillis, Analia Nilda. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina
Fil: Lacki, Brian. Institute for Advanced Study; Estados Unidos
Fil: Rephaeli, Joel. University of California; Estados Unidos
Materia
radiation mechanisms: non-thermal
cosmic rays
supernova remnants
starburst
Nivel de accesibilidad
acceso abierto
Condiciones de uso
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
Repositorio
CONICET Digital (CONICET)
Institución
Consejo Nacional de Investigaciones Científicas y Técnicas
OAI Identificador
oai:ri.conicet.gov.ar:11336/19309

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spelling Building up the spectrum of cosmic rays in star-forming regionsTorres, Diego F.Cillis, Analia NildaLacki, BrianRephaeli, Joelradiation mechanisms: non-thermalcosmic rayssupernova remnantsstarbursthttps://purl.org/becyt/ford/1.3https://purl.org/becyt/ford/1The common approach to compute the cosmic ray distribution in a starburst galaxy or region is equivalent to assuming that at any point within that environment, there is an accelerator inputting cosmic rays at a reduced rate. This rate should be compatible with the overall volume-average injection, given by the total number of accelerators that were active during the starburst age. These assumptions seem reasonable, especially under the supposition of a homogeneous and isotropic distribution of accelerators. However, in this approach the temporal evolution of the superposed spectrum is not explicitly derived; rather, it is essentially assumed ab initio. Here, we test the validity of this approach by following the temporal evolution and spatial distribution of the superposed cosmic ray spectrum and compare our results with those from theoretical models that treat the starburst region as a single source. In the calorimetric limit (with no cosmic ray advection), homogeneity is reached (typically within 20 per cent) across most of the starburst region. However, values of centre-to-edge intensity ratios can amount to a factor of several. Differences between the common homogeneous assumption for the cosmic ray distribution and our models are larger in the case of two-zone geometries, such as a central nucleus with a surrounding disc. We have also found that the decay of the cosmic ray density following the duration of the starburst process is slow, and even approximately 1 Myr after the burst ends (for a gas density of 35 cm-3) it may still be within an order of magnitude of its peak value. Based on our simulations, it seems that the detection of a relatively hard spectrum up to the highest gamma-ray energies from nearby starburst galaxies favours a relatively small diffusion coefficient (i.e. long diffusion time) in the region where most of the emission originates.Fil: Torres, Diego F.. Institució Catalana de Recerca i Estudis Avancats; EspañaFil: Cillis, Analia Nilda. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Lacki, Brian. Institute for Advanced Study; Estados UnidosFil: Rephaeli, Joel. University of California; Estados UnidosOxford University Press2012-06info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionhttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdfapplication/pdfapplication/pdfhttp://hdl.handle.net/11336/19309Torres, Diego F.; Cillis, Analia Nilda; Lacki, Brian; Rephaeli, Joel; Building up the spectrum of cosmic rays in star-forming regions; Oxford University Press; Monthly Notices of the Royal Astronomical Society; 423; 1; 6-2012; 822-8300035-8711CONICET DigitalCONICETenginfo:eu-repo/semantics/altIdentifier/url/https://academic.oup.com/mnras/article-lookup/doi/10.1111/j.1365-2966.2012.20920.xinfo:eu-repo/semantics/altIdentifier/doi/10.1111/j.1365-2966.2012.20920.xinfo:eu-repo/semantics/openAccesshttps://creativecommons.org/licenses/by-nc-sa/2.5/ar/reponame:CONICET Digital (CONICET)instname:Consejo Nacional de Investigaciones Científicas y Técnicas2025-09-29T09:42:02Zoai:ri.conicet.gov.ar:11336/19309instacron:CONICETInstitucionalhttp://ri.conicet.gov.ar/Organismo científico-tecnológicoNo correspondehttp://ri.conicet.gov.ar/oai/requestdasensio@conicet.gov.ar; lcarlino@conicet.gov.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:34982025-09-29 09:42:03.129CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicasfalse
dc.title.none.fl_str_mv Building up the spectrum of cosmic rays in star-forming regions
title Building up the spectrum of cosmic rays in star-forming regions
spellingShingle Building up the spectrum of cosmic rays in star-forming regions
Torres, Diego F.
radiation mechanisms: non-thermal
cosmic rays
supernova remnants
starburst
title_short Building up the spectrum of cosmic rays in star-forming regions
title_full Building up the spectrum of cosmic rays in star-forming regions
title_fullStr Building up the spectrum of cosmic rays in star-forming regions
title_full_unstemmed Building up the spectrum of cosmic rays in star-forming regions
title_sort Building up the spectrum of cosmic rays in star-forming regions
dc.creator.none.fl_str_mv Torres, Diego F.
Cillis, Analia Nilda
Lacki, Brian
Rephaeli, Joel
author Torres, Diego F.
author_facet Torres, Diego F.
Cillis, Analia Nilda
Lacki, Brian
Rephaeli, Joel
author_role author
author2 Cillis, Analia Nilda
Lacki, Brian
Rephaeli, Joel
author2_role author
author
author
dc.subject.none.fl_str_mv radiation mechanisms: non-thermal
cosmic rays
supernova remnants
starburst
topic radiation mechanisms: non-thermal
cosmic rays
supernova remnants
starburst
purl_subject.fl_str_mv https://purl.org/becyt/ford/1.3
https://purl.org/becyt/ford/1
dc.description.none.fl_txt_mv The common approach to compute the cosmic ray distribution in a starburst galaxy or region is equivalent to assuming that at any point within that environment, there is an accelerator inputting cosmic rays at a reduced rate. This rate should be compatible with the overall volume-average injection, given by the total number of accelerators that were active during the starburst age. These assumptions seem reasonable, especially under the supposition of a homogeneous and isotropic distribution of accelerators. However, in this approach the temporal evolution of the superposed spectrum is not explicitly derived; rather, it is essentially assumed ab initio. Here, we test the validity of this approach by following the temporal evolution and spatial distribution of the superposed cosmic ray spectrum and compare our results with those from theoretical models that treat the starburst region as a single source. In the calorimetric limit (with no cosmic ray advection), homogeneity is reached (typically within 20 per cent) across most of the starburst region. However, values of centre-to-edge intensity ratios can amount to a factor of several. Differences between the common homogeneous assumption for the cosmic ray distribution and our models are larger in the case of two-zone geometries, such as a central nucleus with a surrounding disc. We have also found that the decay of the cosmic ray density following the duration of the starburst process is slow, and even approximately 1 Myr after the burst ends (for a gas density of 35 cm-3) it may still be within an order of magnitude of its peak value. Based on our simulations, it seems that the detection of a relatively hard spectrum up to the highest gamma-ray energies from nearby starburst galaxies favours a relatively small diffusion coefficient (i.e. long diffusion time) in the region where most of the emission originates.
Fil: Torres, Diego F.. Institució Catalana de Recerca i Estudis Avancats; España
Fil: Cillis, Analia Nilda. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina
Fil: Lacki, Brian. Institute for Advanced Study; Estados Unidos
Fil: Rephaeli, Joel. University of California; Estados Unidos
description The common approach to compute the cosmic ray distribution in a starburst galaxy or region is equivalent to assuming that at any point within that environment, there is an accelerator inputting cosmic rays at a reduced rate. This rate should be compatible with the overall volume-average injection, given by the total number of accelerators that were active during the starburst age. These assumptions seem reasonable, especially under the supposition of a homogeneous and isotropic distribution of accelerators. However, in this approach the temporal evolution of the superposed spectrum is not explicitly derived; rather, it is essentially assumed ab initio. Here, we test the validity of this approach by following the temporal evolution and spatial distribution of the superposed cosmic ray spectrum and compare our results with those from theoretical models that treat the starburst region as a single source. In the calorimetric limit (with no cosmic ray advection), homogeneity is reached (typically within 20 per cent) across most of the starburst region. However, values of centre-to-edge intensity ratios can amount to a factor of several. Differences between the common homogeneous assumption for the cosmic ray distribution and our models are larger in the case of two-zone geometries, such as a central nucleus with a surrounding disc. We have also found that the decay of the cosmic ray density following the duration of the starburst process is slow, and even approximately 1 Myr after the burst ends (for a gas density of 35 cm-3) it may still be within an order of magnitude of its peak value. Based on our simulations, it seems that the detection of a relatively hard spectrum up to the highest gamma-ray energies from nearby starburst galaxies favours a relatively small diffusion coefficient (i.e. long diffusion time) in the region where most of the emission originates.
publishDate 2012
dc.date.none.fl_str_mv 2012-06
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
http://purl.org/coar/resource_type/c_6501
info:ar-repo/semantics/articulo
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://hdl.handle.net/11336/19309
Torres, Diego F.; Cillis, Analia Nilda; Lacki, Brian; Rephaeli, Joel; Building up the spectrum of cosmic rays in star-forming regions; Oxford University Press; Monthly Notices of the Royal Astronomical Society; 423; 1; 6-2012; 822-830
0035-8711
CONICET Digital
CONICET
url http://hdl.handle.net/11336/19309
identifier_str_mv Torres, Diego F.; Cillis, Analia Nilda; Lacki, Brian; Rephaeli, Joel; Building up the spectrum of cosmic rays in star-forming regions; Oxford University Press; Monthly Notices of the Royal Astronomical Society; 423; 1; 6-2012; 822-830
0035-8711
CONICET Digital
CONICET
dc.language.none.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv info:eu-repo/semantics/altIdentifier/url/https://academic.oup.com/mnras/article-lookup/doi/10.1111/j.1365-2966.2012.20920.x
info:eu-repo/semantics/altIdentifier/doi/10.1111/j.1365-2966.2012.20920.x
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
eu_rights_str_mv openAccess
rights_invalid_str_mv https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
dc.format.none.fl_str_mv application/pdf
application/pdf
application/pdf
dc.publisher.none.fl_str_mv Oxford University Press
publisher.none.fl_str_mv Oxford University Press
dc.source.none.fl_str_mv reponame:CONICET Digital (CONICET)
instname:Consejo Nacional de Investigaciones Científicas y Técnicas
reponame_str CONICET Digital (CONICET)
collection CONICET Digital (CONICET)
instname_str Consejo Nacional de Investigaciones Científicas y Técnicas
repository.name.fl_str_mv CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicas
repository.mail.fl_str_mv dasensio@conicet.gov.ar; lcarlino@conicet.gov.ar
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