Soft X-ray background fluctuations and large-scale structure in the Universe

We have studied the fluctuations of the soft (0.9-2 keV) X-ray background intensity for ∼10 and ∼2 arcmin beam sizes, using 80 high galactic latitude medium-deep images from the ROSAT position sensitive proportional counter (PSPC). These fluctuations are dominated (and well reproduced) by confusion...

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Detalles Bibliográficos
Autores: Carrera, Francisco J., Fabian, Andrew C., Barcons, Xavier
Tipo de recurso: artículo
Estado:Versión publicada
Fecha de publicación:1997
País:España
Institución:Consejo Superior de Investigaciones Científicas (CSIC)
Repositorio:DIGITAL.CSIC. Repositorio Institucional del CSIC
OAI Identifier:oai:digital.csic.es:10261/170082
Acceso en línea:http://hdl.handle.net/10261/170082
Access Level:acceso abierto
Palabra clave:Methods: statistical
Large-scale structure of the universe
X-ray general
Diffuse radiation
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spelling Soft X-ray background fluctuations and large-scale structure in the UniverseCarrera, Francisco J.Fabian, Andrew C.Barcons, XavierMethods: statisticalLarge-scale structure of the universeX-ray generalDiffuse radiationWe have studied the fluctuations of the soft (0.9-2 keV) X-ray background intensity for ∼10 and ∼2 arcmin beam sizes, using 80 high galactic latitude medium-deep images from the ROSAT position sensitive proportional counter (PSPC). These fluctuations are dominated (and well reproduced) by confusion noise produced by sources unresolved with the beam sizes we used. We find no evidence for any excess fluctuations which could be attributed to source clustering. The 95 per cent confidence upper limits on excess fluctuations ΔIclus are: (ΔIclus/I)10arcmin≲0.12, (ΔIclus/I)2arcmin≲0.07. We have checked the possibility that low surface brightness extended objects (like groups or clusters of galaxies) may have a significant contribution to excess fluctuations, finding that they are not necessary to fit the distribution of fluctuations, and obtaining an upper limit on the surface density for this type of source. Standard cold dark matter models would produce ΔI/I larger than the above limits for any value of the density of the Universe Ω = 0.1 - 1, unless the bias parameter of the X-ray emitting matter is smaller than unity, or an important fraction of the sources of the soft X-ray background (∼ 30 per cent) is at redshifts z > 1. Limits on the 2-10 keV excess fluctuations are also considered, showing that X-ray sources in that band have to be at redshifts z > 1 unless Ω > 0.4. Finally, if the spatial correlation function of the sources that produce these excess fluctuations is instead a power law, the density contrast δρ/ρ implied by the excess s luctuations reveals that the Universe is smooth and linear on scales of tens of Mpc, while it can be highly non-linear on scales of ∼ 1 Mpc.FJC and XB thank the DGICYT for financial support, under project PB92-00501. ACF thanks the Royal Society for support.Peer ReviewedRoyal Astronomical SocietyOxford University PressRoyal Society (UK)Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]2018201819972018info:eu-repo/semantics/articlehttp://purl.org/coar/resource_type/c_6501Publisher's versioninfo:eu-repo/semantics/publishedVersionhttp://hdl.handle.net/10261/170082reponame:DIGITAL.CSIC. Repositorio Institucional del CSICinstname:Consejo Superior de Investigaciones Científicas (CSIC)Ingléshttps://doi.org/10.1093/mnras/285.4.820Síinfo:eu-repo/semantics/openAccessoai:digital.csic.es:10261/1700822026-05-22T06:33:51Z
dc.title.none.fl_str_mv Soft X-ray background fluctuations and large-scale structure in the Universe
title Soft X-ray background fluctuations and large-scale structure in the Universe
spellingShingle Soft X-ray background fluctuations and large-scale structure in the Universe
Carrera, Francisco J.
Methods: statistical
Large-scale structure of the universe
X-ray general
Diffuse radiation
title_short Soft X-ray background fluctuations and large-scale structure in the Universe
title_full Soft X-ray background fluctuations and large-scale structure in the Universe
title_fullStr Soft X-ray background fluctuations and large-scale structure in the Universe
title_full_unstemmed Soft X-ray background fluctuations and large-scale structure in the Universe
title_sort Soft X-ray background fluctuations and large-scale structure in the Universe
dc.creator.none.fl_str_mv Carrera, Francisco J.
Fabian, Andrew C.
Barcons, Xavier
author Carrera, Francisco J.
author_facet Carrera, Francisco J.
Fabian, Andrew C.
Barcons, Xavier
author_role author
author2 Fabian, Andrew C.
Barcons, Xavier
author2_role author
author
dc.contributor.none.fl_str_mv Royal Society (UK)
Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]
dc.subject.none.fl_str_mv Methods: statistical
Large-scale structure of the universe
X-ray general
Diffuse radiation
topic Methods: statistical
Large-scale structure of the universe
X-ray general
Diffuse radiation
description We have studied the fluctuations of the soft (0.9-2 keV) X-ray background intensity for ∼10 and ∼2 arcmin beam sizes, using 80 high galactic latitude medium-deep images from the ROSAT position sensitive proportional counter (PSPC). These fluctuations are dominated (and well reproduced) by confusion noise produced by sources unresolved with the beam sizes we used. We find no evidence for any excess fluctuations which could be attributed to source clustering. The 95 per cent confidence upper limits on excess fluctuations ΔIclus are: (ΔIclus/I)10arcmin≲0.12, (ΔIclus/I)2arcmin≲0.07. We have checked the possibility that low surface brightness extended objects (like groups or clusters of galaxies) may have a significant contribution to excess fluctuations, finding that they are not necessary to fit the distribution of fluctuations, and obtaining an upper limit on the surface density for this type of source. Standard cold dark matter models would produce ΔI/I larger than the above limits for any value of the density of the Universe Ω = 0.1 - 1, unless the bias parameter of the X-ray emitting matter is smaller than unity, or an important fraction of the sources of the soft X-ray background (∼ 30 per cent) is at redshifts z > 1. Limits on the 2-10 keV excess fluctuations are also considered, showing that X-ray sources in that band have to be at redshifts z > 1 unless Ω > 0.4. Finally, if the spatial correlation function of the sources that produce these excess fluctuations is instead a power law, the density contrast δρ/ρ implied by the excess s luctuations reveals that the Universe is smooth and linear on scales of tens of Mpc, while it can be highly non-linear on scales of ∼ 1 Mpc.
publishDate 1997
dc.date.none.fl_str_mv 1997
2018
2018
2018
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/10261/170082
url http://hdl.handle.net/10261/170082
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv https://doi.org/10.1093/mnras/285.4.820
Sí
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.publisher.none.fl_str_mv Royal Astronomical Society
Oxford University Press
publisher.none.fl_str_mv Royal Astronomical Society
Oxford University Press
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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