The distribution of stars around the Milky Way's central black hole: II. Diffuse light from sub-giants and dwarfs

Context. This is the second of three papers that search for the predicted stellar cusp around the Milky Way's central black hole, Sagittarius A∗, with new data and methods. Aims. We aim to infer the distribution of the faintest stellar population currently accessible through observations around...

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Autores: Schödel, Rainer, Gallego Cano, Eulalia, Dong, H., Nogueras Lara, Francisco, Gallego Calvente, Teresa, Amaro-Seoane, P., Baumgardt, Holger
Tipo de recurso: artículo
Estado:Versión publicada
Fecha de publicación:2018
País:España
Institución:Consejo Superior de Investigaciones Científicas (CSIC)
Repositorio:DIGITAL.CSIC. Repositorio Institucional del CSIC
OAI Identifier:oai:digital.csic.es:10261/183214
Acceso en línea:http://hdl.handle.net/10261/183214
Access Level:acceso abierto
Palabra clave:Galaxy: center
Galaxy: structure
Infrared: stars
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spelling The distribution of stars around the Milky Way's central black hole: II. Diffuse light from sub-giants and dwarfsSchödel, RainerGallego Cano, EulaliaDong, H.Nogueras Lara, FranciscoGallego Calvente, TeresaAmaro-Seoane, P.Baumgardt, HolgerGalaxy: centerGalaxy: structureInfrared: starsContext. This is the second of three papers that search for the predicted stellar cusp around the Milky Way's central black hole, Sagittarius A∗, with new data and methods. Aims. We aim to infer the distribution of the faintest stellar population currently accessible through observations around Sagittarius A∗. Methods. We used adaptive optics assisted high angular resolution images obtained with the NACO instrument at the ESO VLT. Through optimised PSF fitting we removed the light from all detected stars above a given magnitude limit. Subsequently we analysed the remaining, diffuse light density. Systematic uncertainties were constrained by the use of data from different observing epochs and obtained with different filters. We show that it is necessary to correct for the diffuse emission from the mini-spiral, which would otherwise lead to a systematically biased light density profile. We used a Paschen α map obtained with the Hubble Space Telescope for this purpose. Results. The azimuthally averaged diffuse surface light density profile within a projected distance of R ≲ 0.5 pc from Sagittarius A∗ can be described consistently by a single power law with an exponent of Γ = 0.26 ± 0.02 ± 0.05, similar to what has been found for the surface number density of faint stars in Paper I. Conclusions. The analysed diffuse light arises from sub-giant and main-sequence stars with K ≈ 19-22 with masses of 0.8-1.5 M. These stars can be old enough to be dynamically relaxed. The observed power-law profile and its slope are consistent with the existence of a relaxed stellar cusp around the Milky Way's central black hole. We find that a Nuker law provides an adequate description of the nuclear cluster's intrinsic shape (assuming spherical symmetry). The 3D power-law slope near Sgr A∗ is γ = 1.13 ± 0.03 ± 0.05. The stellar density decreases more steeply beyond a break radius of about 3 pc, which corresponds roughly to the radius of influence of the massive black hole. At a distance of 0.01 pc from the black hole, we estimate a stellar mass density of 2.6 ± 0.3 × 10 M pc and a total enclosed stellar mass of 180 ± 30 M. These estimates assume a constant mass-to-light ratio and do not take stellar remnants into account. The fact that a flat projected surface density is observed for old giants at projected distances R ≲ 0.3 pc implies that some mechanism may have altered their appearance or distribution.© ESO, 2017.The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement No [614922]. PAS acknowledges support from the Ramon y Cajal Programme of the Ministry of Economy, Industry and Competitiveness of Spain. This work has been partially supported by the CAS President's International Fellowship Initiative. F.N.L. acknowledges financial support from a predoctoral contract of the Spanish Ministerio de Educacion, Cultura y Deporte, code FPU14/01700.Peer ReviewedEDP SciencesEuropean Research CouncilMinisterio de Educación, Cultura y Deporte (España)Chinese Academy of SciencesMinisterio de Industria y Competitividad (España)Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]2019201920182019info:eu-repo/semantics/articlehttp://purl.org/coar/resource_type/c_6501Publisher's versioninfo:eu-repo/semantics/publishedVersionhttp://hdl.handle.net/10261/183214reponame:DIGITAL.CSIC. Repositorio Institucional del CSICinstname:Consejo Superior de Investigaciones Científicas (CSIC)Inglés#PLACEHOLDER_PARENT_METADATA_VALUE#info:eu-repo/grantAgreement/EC/FP7/614922Síinfo:eu-repo/semantics/openAccessoai:digital.csic.es:10261/1832142026-05-22T06:33:51Z
dc.title.none.fl_str_mv The distribution of stars around the Milky Way's central black hole: II. Diffuse light from sub-giants and dwarfs
title The distribution of stars around the Milky Way's central black hole: II. Diffuse light from sub-giants and dwarfs
spellingShingle The distribution of stars around the Milky Way's central black hole: II. Diffuse light from sub-giants and dwarfs
Schödel, Rainer
Galaxy: center
Galaxy: structure
Infrared: stars
title_short The distribution of stars around the Milky Way's central black hole: II. Diffuse light from sub-giants and dwarfs
title_full The distribution of stars around the Milky Way's central black hole: II. Diffuse light from sub-giants and dwarfs
title_fullStr The distribution of stars around the Milky Way's central black hole: II. Diffuse light from sub-giants and dwarfs
title_full_unstemmed The distribution of stars around the Milky Way's central black hole: II. Diffuse light from sub-giants and dwarfs
title_sort The distribution of stars around the Milky Way's central black hole: II. Diffuse light from sub-giants and dwarfs
dc.creator.none.fl_str_mv Schödel, Rainer
Gallego Cano, Eulalia
Dong, H.
Nogueras Lara, Francisco
Gallego Calvente, Teresa
Amaro-Seoane, P.
Baumgardt, Holger
author Schödel, Rainer
author_facet Schödel, Rainer
Gallego Cano, Eulalia
Dong, H.
Nogueras Lara, Francisco
Gallego Calvente, Teresa
Amaro-Seoane, P.
Baumgardt, Holger
author_role author
author2 Gallego Cano, Eulalia
Dong, H.
Nogueras Lara, Francisco
Gallego Calvente, Teresa
Amaro-Seoane, P.
Baumgardt, Holger
author2_role author
author
author
author
author
author
dc.contributor.none.fl_str_mv European Research Council
Ministerio de Educación, Cultura y Deporte (España)
Chinese Academy of Sciences
Ministerio de Industria y Competitividad (España)
Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]
dc.subject.none.fl_str_mv Galaxy: center
Galaxy: structure
Infrared: stars
topic Galaxy: center
Galaxy: structure
Infrared: stars
description Context. This is the second of three papers that search for the predicted stellar cusp around the Milky Way's central black hole, Sagittarius A∗, with new data and methods. Aims. We aim to infer the distribution of the faintest stellar population currently accessible through observations around Sagittarius A∗. Methods. We used adaptive optics assisted high angular resolution images obtained with the NACO instrument at the ESO VLT. Through optimised PSF fitting we removed the light from all detected stars above a given magnitude limit. Subsequently we analysed the remaining, diffuse light density. Systematic uncertainties were constrained by the use of data from different observing epochs and obtained with different filters. We show that it is necessary to correct for the diffuse emission from the mini-spiral, which would otherwise lead to a systematically biased light density profile. We used a Paschen α map obtained with the Hubble Space Telescope for this purpose. Results. The azimuthally averaged diffuse surface light density profile within a projected distance of R ≲ 0.5 pc from Sagittarius A∗ can be described consistently by a single power law with an exponent of Γ = 0.26 ± 0.02 ± 0.05, similar to what has been found for the surface number density of faint stars in Paper I. Conclusions. The analysed diffuse light arises from sub-giant and main-sequence stars with K ≈ 19-22 with masses of 0.8-1.5 M. These stars can be old enough to be dynamically relaxed. The observed power-law profile and its slope are consistent with the existence of a relaxed stellar cusp around the Milky Way's central black hole. We find that a Nuker law provides an adequate description of the nuclear cluster's intrinsic shape (assuming spherical symmetry). The 3D power-law slope near Sgr A∗ is γ = 1.13 ± 0.03 ± 0.05. The stellar density decreases more steeply beyond a break radius of about 3 pc, which corresponds roughly to the radius of influence of the massive black hole. At a distance of 0.01 pc from the black hole, we estimate a stellar mass density of 2.6 ± 0.3 × 10 M pc and a total enclosed stellar mass of 180 ± 30 M. These estimates assume a constant mass-to-light ratio and do not take stellar remnants into account. The fact that a flat projected surface density is observed for old giants at projected distances R ≲ 0.3 pc implies that some mechanism may have altered their appearance or distribution.© ESO, 2017.
publishDate 2018
dc.date.none.fl_str_mv 2018
2019
2019
2019
dc.type.none.fl_str_mv info:eu-repo/semantics/article
http://purl.org/coar/resource_type/c_6501
Publisher's version
info:eu-repo/semantics/publishedVersion
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://hdl.handle.net/10261/183214
url http://hdl.handle.net/10261/183214
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv #PLACEHOLDER_PARENT_METADATA_VALUE#
info:eu-repo/grantAgreement/EC/FP7/614922
Sí
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.publisher.none.fl_str_mv EDP Sciences
publisher.none.fl_str_mv EDP Sciences
dc.source.none.fl_str_mv reponame:DIGITAL.CSIC. Repositorio Institucional del CSIC
instname:Consejo Superior de Investigaciones Científicas (CSIC)
instname_str Consejo Superior de Investigaciones Científicas (CSIC)
reponame_str DIGITAL.CSIC. Repositorio Institucional del CSIC
collection DIGITAL.CSIC. Repositorio Institucional del CSIC
repository.name.fl_str_mv
repository.mail.fl_str_mv
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