An HST/COS legacy survey of high-velocity ultraviolet absorption in the Milky Way's circumgalactic medium and the Local Group

Autores
Richter, Philipp; Nuza, Sebastian Ernesto; Fox, A. J.; Wakker, B. P.; Lehner, N.; Ben Bekhti, N.
Año de publicación
2017
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
Context. The Milky Way is surrounded by large amounts of diffuse gaseous matter that connects the stellar body of our Galaxy with its large-scale Local Group (LG) environment. Aims. To characterize the absorption properties of this circumgalactic medium (CGM) and its relation to the LG we present the so-far largest survey of metal absorption in Galactic high-velocity clouds (HVCs) using archival ultraviolet (UV) spectra of extragalactic background sources. The UV data are obtained with the Cosmic Origins Spectrograph (COS) onboard the Hubble Space Telescope (HST) and are supplemented by 21 cm radio observations of neutral hydrogen. Methods. Along 270 sightlines we measure metal absorption in the lines of Si ii, Si iii, Cii, and Civ and associated Hi 21 cm emission in HVCs in the velocity range jvLSRj = 100-500 km s-1. With this unprecedented large HVC sample we were able to improve the statistics on HVC covering fractions, ionization conditions, small-scale structure, CGM mass, and inflow rate. For the first time, we determine robustly the angular two point correlation function of the high-velocity absorbers, systematically analyze antipodal sightlines on the celestial sphere, and compare the HVC absorption characteristics with that of damped Lyman α absorbers (DLAs) and constrained cosmological simulations of the LG (CLUES project). Results. The overall sky-covering fraction of high-velocity absorption is 77 ± 6 percent for the most sensitive ion in our survey, Si iii, and for column densities log N(Si iii) ≥ 12.1. This value is ∼4-5 times higher than the covering fraction of 21 cm neutral hydrogen emission at log N(H i) ≥ 18.7 along the same lines of sight, demonstrating that the Milky Way's CGM is multi-phase and predominantly ionized. The measured equivalent-width ratios of Si ii, Si iii, Cii, and C iv are inhomogeneously distributed on large and small angular scales, suggesting a complex spatial distribution of multi-phase gas that surrounds the neutral 21 cm HVCs. We estimate that the total mass and accretion rate of the neutral and ionized CGM traced by HVCs is MHVC ≥ 3.0 × 109 M⊙ and dMHVC=dt ≥ 6.1 M⊙ yr-1, where the Magellanic Stream (MS) contributes with more than 90 percent to this mass/mass-flow. If seen from an external vantage point, the Milky Way disk plus CGM would appear as a DLA that would exhibit for most viewing angles an extraordinary large velocity spread of Δv ≈ 400-800 km s-1, a result of the complex kinematics of the Milky Way CGM that is dominated by the presence of the MS. We detect a velocity dipole of high-velocity absorption at low/high galactic latitudes that we associate with LG gas that streams to the LG barycenter. This scenario is supported by the gas kinematics predicted from the LG simulations. Conclusions. Our study confirms previous results, indicating that the Milky Way CGM contains sufficient gaseous material to feed the Milky Way disk over the next Gyr at a rate of a few solar masses per year, if the CGM gas can actually reach the MW disk. We demonstrate that the CGM is composed of discrete gaseous structures that exhibit a large-scale kinematics together with small-scale variations in physical conditions. The MS clearly dominates both the cross section and mass flow of high-velocity gas in the Milky Way's CGM. The possible presence of high-velocity LG gas underlines the important role of the local cosmological environment in the large-scale gas-circulation processes in and around the Milky Way.
Fil: Richter, Philipp. Universitat Potsdam. Mathematisch Nautrwissenschaften Fakultat; Alemania
Fil: Nuza, Sebastian Ernesto. Leibniz Institut Fuer Astrophysik Potsdam; Alemania. 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. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina
Fil: Fox, A. J.. Space Telescope Science Institute; Estados Unidos
Fil: Wakker, B. P.. University of Wisconsin; Estados Unidos
Fil: Lehner, N.. University of Notre Dame; Estados Unidos
Fil: Ben Bekhti, N.. Research Establishment For Applied Science (fgan);
Materia
GALAXY: EVOLUTION
GALAXY: HALO
GALAXY: STRUCTURE
ISM: KINEMATICS AND DYNAMICS
TECHNIQUES: SPECTROSCOPIC
ULTRAVIOLET: ISM
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:11336/92530

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network_name_str CONICET Digital (CONICET)
spelling An HST/COS legacy survey of high-velocity ultraviolet absorption in the Milky Way's circumgalactic medium and the Local GroupRichter, PhilippNuza, Sebastian ErnestoFox, A. J.Wakker, B. P.Lehner, N.Ben Bekhti, N.GALAXY: EVOLUTIONGALAXY: HALOGALAXY: STRUCTUREISM: KINEMATICS AND DYNAMICSTECHNIQUES: SPECTROSCOPICULTRAVIOLET: ISMhttps://purl.org/becyt/ford/1.3https://purl.org/becyt/ford/1Context. The Milky Way is surrounded by large amounts of diffuse gaseous matter that connects the stellar body of our Galaxy with its large-scale Local Group (LG) environment. Aims. To characterize the absorption properties of this circumgalactic medium (CGM) and its relation to the LG we present the so-far largest survey of metal absorption in Galactic high-velocity clouds (HVCs) using archival ultraviolet (UV) spectra of extragalactic background sources. The UV data are obtained with the Cosmic Origins Spectrograph (COS) onboard the Hubble Space Telescope (HST) and are supplemented by 21 cm radio observations of neutral hydrogen. Methods. Along 270 sightlines we measure metal absorption in the lines of Si ii, Si iii, Cii, and Civ and associated Hi 21 cm emission in HVCs in the velocity range jvLSRj = 100-500 km s-1. With this unprecedented large HVC sample we were able to improve the statistics on HVC covering fractions, ionization conditions, small-scale structure, CGM mass, and inflow rate. For the first time, we determine robustly the angular two point correlation function of the high-velocity absorbers, systematically analyze antipodal sightlines on the celestial sphere, and compare the HVC absorption characteristics with that of damped Lyman α absorbers (DLAs) and constrained cosmological simulations of the LG (CLUES project). Results. The overall sky-covering fraction of high-velocity absorption is 77 ± 6 percent for the most sensitive ion in our survey, Si iii, and for column densities log N(Si iii) ≥ 12.1. This value is ∼4-5 times higher than the covering fraction of 21 cm neutral hydrogen emission at log N(H i) ≥ 18.7 along the same lines of sight, demonstrating that the Milky Way's CGM is multi-phase and predominantly ionized. The measured equivalent-width ratios of Si ii, Si iii, Cii, and C iv are inhomogeneously distributed on large and small angular scales, suggesting a complex spatial distribution of multi-phase gas that surrounds the neutral 21 cm HVCs. We estimate that the total mass and accretion rate of the neutral and ionized CGM traced by HVCs is MHVC ≥ 3.0 × 109 M⊙ and dMHVC=dt ≥ 6.1 M⊙ yr-1, where the Magellanic Stream (MS) contributes with more than 90 percent to this mass/mass-flow. If seen from an external vantage point, the Milky Way disk plus CGM would appear as a DLA that would exhibit for most viewing angles an extraordinary large velocity spread of Δv ≈ 400-800 km s-1, a result of the complex kinematics of the Milky Way CGM that is dominated by the presence of the MS. We detect a velocity dipole of high-velocity absorption at low/high galactic latitudes that we associate with LG gas that streams to the LG barycenter. This scenario is supported by the gas kinematics predicted from the LG simulations. Conclusions. Our study confirms previous results, indicating that the Milky Way CGM contains sufficient gaseous material to feed the Milky Way disk over the next Gyr at a rate of a few solar masses per year, if the CGM gas can actually reach the MW disk. We demonstrate that the CGM is composed of discrete gaseous structures that exhibit a large-scale kinematics together with small-scale variations in physical conditions. The MS clearly dominates both the cross section and mass flow of high-velocity gas in the Milky Way's CGM. The possible presence of high-velocity LG gas underlines the important role of the local cosmological environment in the large-scale gas-circulation processes in and around the Milky Way.Fil: Richter, Philipp. Universitat Potsdam. Mathematisch Nautrwissenschaften Fakultat; AlemaniaFil: Nuza, Sebastian Ernesto. Leibniz Institut Fuer Astrophysik Potsdam; Alemania. 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. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Fox, A. J.. Space Telescope Science Institute; Estados UnidosFil: Wakker, B. P.. University of Wisconsin; Estados UnidosFil: Lehner, N.. University of Notre Dame; Estados UnidosFil: Ben Bekhti, N.. Research Establishment For Applied Science (fgan); EDP Sciences2017-06info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionhttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdfapplication/pdfhttp://hdl.handle.net/11336/92530Richter, Philipp; Nuza, Sebastian Ernesto; Fox, A. J.; Wakker, B. P.; Lehner, N.; et al.; An HST/COS legacy survey of high-velocity ultraviolet absorption in the Milky Way's circumgalactic medium and the Local Group; EDP Sciences; Astronomy and Astrophysics; 607; A48; 6-2017; 1-370004-6361CONICET DigitalCONICETenginfo:eu-repo/semantics/altIdentifier/url/https://arxiv.org/pdf/1611.07024.pdfinfo:eu-repo/semantics/altIdentifier/doi/10.1051/0004-6361/201630081info:eu-repo/semantics/openAccesshttps://creativecommons.org/licenses/by-nc-sa/2.5/ar/reponame:CONICET Digital (CONICET)instname:Consejo Nacional de Investigaciones Científicas y Técnicas2025-09-29T10:07:39Zoai:ri.conicet.gov.ar:11336/92530instacron: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 10:07:39.944CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicasfalse
dc.title.none.fl_str_mv An HST/COS legacy survey of high-velocity ultraviolet absorption in the Milky Way's circumgalactic medium and the Local Group
title An HST/COS legacy survey of high-velocity ultraviolet absorption in the Milky Way's circumgalactic medium and the Local Group
spellingShingle An HST/COS legacy survey of high-velocity ultraviolet absorption in the Milky Way's circumgalactic medium and the Local Group
Richter, Philipp
GALAXY: EVOLUTION
GALAXY: HALO
GALAXY: STRUCTURE
ISM: KINEMATICS AND DYNAMICS
TECHNIQUES: SPECTROSCOPIC
ULTRAVIOLET: ISM
title_short An HST/COS legacy survey of high-velocity ultraviolet absorption in the Milky Way's circumgalactic medium and the Local Group
title_full An HST/COS legacy survey of high-velocity ultraviolet absorption in the Milky Way's circumgalactic medium and the Local Group
title_fullStr An HST/COS legacy survey of high-velocity ultraviolet absorption in the Milky Way's circumgalactic medium and the Local Group
title_full_unstemmed An HST/COS legacy survey of high-velocity ultraviolet absorption in the Milky Way's circumgalactic medium and the Local Group
title_sort An HST/COS legacy survey of high-velocity ultraviolet absorption in the Milky Way's circumgalactic medium and the Local Group
dc.creator.none.fl_str_mv Richter, Philipp
Nuza, Sebastian Ernesto
Fox, A. J.
Wakker, B. P.
Lehner, N.
Ben Bekhti, N.
author Richter, Philipp
author_facet Richter, Philipp
Nuza, Sebastian Ernesto
Fox, A. J.
Wakker, B. P.
Lehner, N.
Ben Bekhti, N.
author_role author
author2 Nuza, Sebastian Ernesto
Fox, A. J.
Wakker, B. P.
Lehner, N.
Ben Bekhti, N.
author2_role author
author
author
author
author
dc.subject.none.fl_str_mv GALAXY: EVOLUTION
GALAXY: HALO
GALAXY: STRUCTURE
ISM: KINEMATICS AND DYNAMICS
TECHNIQUES: SPECTROSCOPIC
ULTRAVIOLET: ISM
topic GALAXY: EVOLUTION
GALAXY: HALO
GALAXY: STRUCTURE
ISM: KINEMATICS AND DYNAMICS
TECHNIQUES: SPECTROSCOPIC
ULTRAVIOLET: ISM
purl_subject.fl_str_mv https://purl.org/becyt/ford/1.3
https://purl.org/becyt/ford/1
dc.description.none.fl_txt_mv Context. The Milky Way is surrounded by large amounts of diffuse gaseous matter that connects the stellar body of our Galaxy with its large-scale Local Group (LG) environment. Aims. To characterize the absorption properties of this circumgalactic medium (CGM) and its relation to the LG we present the so-far largest survey of metal absorption in Galactic high-velocity clouds (HVCs) using archival ultraviolet (UV) spectra of extragalactic background sources. The UV data are obtained with the Cosmic Origins Spectrograph (COS) onboard the Hubble Space Telescope (HST) and are supplemented by 21 cm radio observations of neutral hydrogen. Methods. Along 270 sightlines we measure metal absorption in the lines of Si ii, Si iii, Cii, and Civ and associated Hi 21 cm emission in HVCs in the velocity range jvLSRj = 100-500 km s-1. With this unprecedented large HVC sample we were able to improve the statistics on HVC covering fractions, ionization conditions, small-scale structure, CGM mass, and inflow rate. For the first time, we determine robustly the angular two point correlation function of the high-velocity absorbers, systematically analyze antipodal sightlines on the celestial sphere, and compare the HVC absorption characteristics with that of damped Lyman α absorbers (DLAs) and constrained cosmological simulations of the LG (CLUES project). Results. The overall sky-covering fraction of high-velocity absorption is 77 ± 6 percent for the most sensitive ion in our survey, Si iii, and for column densities log N(Si iii) ≥ 12.1. This value is ∼4-5 times higher than the covering fraction of 21 cm neutral hydrogen emission at log N(H i) ≥ 18.7 along the same lines of sight, demonstrating that the Milky Way's CGM is multi-phase and predominantly ionized. The measured equivalent-width ratios of Si ii, Si iii, Cii, and C iv are inhomogeneously distributed on large and small angular scales, suggesting a complex spatial distribution of multi-phase gas that surrounds the neutral 21 cm HVCs. We estimate that the total mass and accretion rate of the neutral and ionized CGM traced by HVCs is MHVC ≥ 3.0 × 109 M⊙ and dMHVC=dt ≥ 6.1 M⊙ yr-1, where the Magellanic Stream (MS) contributes with more than 90 percent to this mass/mass-flow. If seen from an external vantage point, the Milky Way disk plus CGM would appear as a DLA that would exhibit for most viewing angles an extraordinary large velocity spread of Δv ≈ 400-800 km s-1, a result of the complex kinematics of the Milky Way CGM that is dominated by the presence of the MS. We detect a velocity dipole of high-velocity absorption at low/high galactic latitudes that we associate with LG gas that streams to the LG barycenter. This scenario is supported by the gas kinematics predicted from the LG simulations. Conclusions. Our study confirms previous results, indicating that the Milky Way CGM contains sufficient gaseous material to feed the Milky Way disk over the next Gyr at a rate of a few solar masses per year, if the CGM gas can actually reach the MW disk. We demonstrate that the CGM is composed of discrete gaseous structures that exhibit a large-scale kinematics together with small-scale variations in physical conditions. The MS clearly dominates both the cross section and mass flow of high-velocity gas in the Milky Way's CGM. The possible presence of high-velocity LG gas underlines the important role of the local cosmological environment in the large-scale gas-circulation processes in and around the Milky Way.
Fil: Richter, Philipp. Universitat Potsdam. Mathematisch Nautrwissenschaften Fakultat; Alemania
Fil: Nuza, Sebastian Ernesto. Leibniz Institut Fuer Astrophysik Potsdam; Alemania. 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. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina
Fil: Fox, A. J.. Space Telescope Science Institute; Estados Unidos
Fil: Wakker, B. P.. University of Wisconsin; Estados Unidos
Fil: Lehner, N.. University of Notre Dame; Estados Unidos
Fil: Ben Bekhti, N.. Research Establishment For Applied Science (fgan);
description Context. The Milky Way is surrounded by large amounts of diffuse gaseous matter that connects the stellar body of our Galaxy with its large-scale Local Group (LG) environment. Aims. To characterize the absorption properties of this circumgalactic medium (CGM) and its relation to the LG we present the so-far largest survey of metal absorption in Galactic high-velocity clouds (HVCs) using archival ultraviolet (UV) spectra of extragalactic background sources. The UV data are obtained with the Cosmic Origins Spectrograph (COS) onboard the Hubble Space Telescope (HST) and are supplemented by 21 cm radio observations of neutral hydrogen. Methods. Along 270 sightlines we measure metal absorption in the lines of Si ii, Si iii, Cii, and Civ and associated Hi 21 cm emission in HVCs in the velocity range jvLSRj = 100-500 km s-1. With this unprecedented large HVC sample we were able to improve the statistics on HVC covering fractions, ionization conditions, small-scale structure, CGM mass, and inflow rate. For the first time, we determine robustly the angular two point correlation function of the high-velocity absorbers, systematically analyze antipodal sightlines on the celestial sphere, and compare the HVC absorption characteristics with that of damped Lyman α absorbers (DLAs) and constrained cosmological simulations of the LG (CLUES project). Results. The overall sky-covering fraction of high-velocity absorption is 77 ± 6 percent for the most sensitive ion in our survey, Si iii, and for column densities log N(Si iii) ≥ 12.1. This value is ∼4-5 times higher than the covering fraction of 21 cm neutral hydrogen emission at log N(H i) ≥ 18.7 along the same lines of sight, demonstrating that the Milky Way's CGM is multi-phase and predominantly ionized. The measured equivalent-width ratios of Si ii, Si iii, Cii, and C iv are inhomogeneously distributed on large and small angular scales, suggesting a complex spatial distribution of multi-phase gas that surrounds the neutral 21 cm HVCs. We estimate that the total mass and accretion rate of the neutral and ionized CGM traced by HVCs is MHVC ≥ 3.0 × 109 M⊙ and dMHVC=dt ≥ 6.1 M⊙ yr-1, where the Magellanic Stream (MS) contributes with more than 90 percent to this mass/mass-flow. If seen from an external vantage point, the Milky Way disk plus CGM would appear as a DLA that would exhibit for most viewing angles an extraordinary large velocity spread of Δv ≈ 400-800 km s-1, a result of the complex kinematics of the Milky Way CGM that is dominated by the presence of the MS. We detect a velocity dipole of high-velocity absorption at low/high galactic latitudes that we associate with LG gas that streams to the LG barycenter. This scenario is supported by the gas kinematics predicted from the LG simulations. Conclusions. Our study confirms previous results, indicating that the Milky Way CGM contains sufficient gaseous material to feed the Milky Way disk over the next Gyr at a rate of a few solar masses per year, if the CGM gas can actually reach the MW disk. We demonstrate that the CGM is composed of discrete gaseous structures that exhibit a large-scale kinematics together with small-scale variations in physical conditions. The MS clearly dominates both the cross section and mass flow of high-velocity gas in the Milky Way's CGM. The possible presence of high-velocity LG gas underlines the important role of the local cosmological environment in the large-scale gas-circulation processes in and around the Milky Way.
publishDate 2017
dc.date.none.fl_str_mv 2017-06
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/11336/92530
Richter, Philipp; Nuza, Sebastian Ernesto; Fox, A. J.; Wakker, B. P.; Lehner, N.; et al.; An HST/COS legacy survey of high-velocity ultraviolet absorption in the Milky Way's circumgalactic medium and the Local Group; EDP Sciences; Astronomy and Astrophysics; 607; A48; 6-2017; 1-37
0004-6361
CONICET Digital
CONICET
url http://hdl.handle.net/11336/92530
identifier_str_mv Richter, Philipp; Nuza, Sebastian Ernesto; Fox, A. J.; Wakker, B. P.; Lehner, N.; et al.; An HST/COS legacy survey of high-velocity ultraviolet absorption in the Milky Way's circumgalactic medium and the Local Group; EDP Sciences; Astronomy and Astrophysics; 607; A48; 6-2017; 1-37
0004-6361
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://arxiv.org/pdf/1611.07024.pdf
info:eu-repo/semantics/altIdentifier/doi/10.1051/0004-6361/201630081
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dc.publisher.none.fl_str_mv EDP Sciences
publisher.none.fl_str_mv EDP Sciences
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reponame_str CONICET Digital (CONICET)
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repository.name.fl_str_mv CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicas
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