A revision of the X-ray absorption nature of BALQSOs

Aims. Broad absorption-line quasars (BALQSOs) are key objects for studying the structure and emission/absorption properties of AGN. However, despite their fundamental importance, the properties of BALQSOs remain poorly understood. To investigate the X-ray nature of these sources, as well as the corr...

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Authors: Streblyanska, Alina, Barcons Jaúregui, Francesc Xavier|||0000-0003-1081-8861, Carrera Troyano, Francisco Jesús|||0000-0003-2135-9023, Gil-Merino Rubio, Rodrigo
Format: article
Publication Date:2010
Country:España
Institution:Universidad de Cantabria (UC)
Repository:UCrea Repositorio Abierto de la Universidad de Cantabria
Language:English
OAI Identifier:oai:repositorio.unican.es:10902/27998
Online Access:https://hdl.handle.net/10902/27998
Access Level:Open access
Keyword:X-rays: general
Quasars: absorption lines
Quasars: general
Galaxies: active
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spelling A revision of the X-ray absorption nature of BALQSOsStreblyanska, AlinaBarcons Jaúregui, Francesc Xavier|||0000-0003-1081-8861Carrera Troyano, Francisco Jesús|||0000-0003-2135-9023Gil-Merino Rubio, RodrigoX-rays: generalQuasars: absorption linesQuasars: generalGalaxies: activeAims. Broad absorption-line quasars (BALQSOs) are key objects for studying the structure and emission/absorption properties of AGN. However, despite their fundamental importance, the properties of BALQSOs remain poorly understood. To investigate the X-ray nature of these sources, as well as the correlations between X-ray and rest-frame UV properties, we compile a large sample of BALQSOs observed by XMM-Newton. Methods. We collect information for 88 sources from the literature and existing catalogues, creating the largest BALQSO sample analysed optically and in X-ray to date. We performed a full X-ray spectral analysis (using unabsorbed and both neutral and ionized absorption models) on a sample of 39 sources with higher X-ray spectral quality, and an approximate hardness-ratio analysis on the remaining sources. Using available optical spectra, we calculate the BALnicity index and investigate the dependence of this optical parameter on different X-ray properties. Results. Using the neutral absorption model, we find that 36% of our BALQSOs have NnH < 5 × 1021 cm−2, lower than the expected X-ray absorption for these objects. However, when we used a physically-motivated model for the X-ray absorption in BALQSOs, i.e., ionized absorption, ∼90% of the objects are absorbed. The observed difference in ionized properties of sources with the BALnicity index (BI) =0 and BI > 0 might be explained by different physical conditions of the outflow and/or inclination effects. The absorption properties also suggest that LoBALs may be physically different objects from HiBALs. In addition, we report on a correlation between the ionized absorption column density and BAL parameters. There is evidence (at the 98% level) that the amount of X-ray absorption is correlated with the strength of high-ionization UV absorption. Not previously reported, this correlation can be naturally understood in virtually all BALQSO models, as being driven by the total amount of gas mass flowing towards the observer. We also find a hint of a correlation between the BI and the ionization level detected in X-rays.We thank the anonymous referee for helpful comments. The first author would like to thank the Spanish Ministerio de Ciencia e Innovación for a Juan de la Cierva contract. XB, FJC and RGM acknowledge financial support by the Spanish MICINN under project ESP2006-13608-C02-01.We also acknowledge the Sloan Digital Sky Survey (http://www.sdss.org/). Funding for the SDSS has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the U.S. Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England.EDP SciencesUniversidad de Cantabria20102010-06-01journal articlehttp://purl.org/coar/resource_type/c_6501NAhttp://purl.org/coar/version/c_be7fb7dd8ff6fe43info:eu-repo/semantics/articlehttps://hdl.handle.net/10902/27998Astronomy and Astrophysics, 2010, 515, A2reponame:UCrea Repositorio Abierto de la Universidad de Cantabriainstname:Universidad de Cantabria (UC)Inglésengopen accesshttp://purl.org/coar/access_right/c_abf2info:eu-repo/semantics/openAccessoai:repositorio.unican.es:10902/279982026-06-02T12:39:31Z
dc.title.none.fl_str_mv A revision of the X-ray absorption nature of BALQSOs
title A revision of the X-ray absorption nature of BALQSOs
spellingShingle A revision of the X-ray absorption nature of BALQSOs
Streblyanska, Alina
X-rays: general
Quasars: absorption lines
Quasars: general
Galaxies: active
title_short A revision of the X-ray absorption nature of BALQSOs
title_full A revision of the X-ray absorption nature of BALQSOs
title_fullStr A revision of the X-ray absorption nature of BALQSOs
title_full_unstemmed A revision of the X-ray absorption nature of BALQSOs
title_sort A revision of the X-ray absorption nature of BALQSOs
dc.creator.none.fl_str_mv Streblyanska, Alina
Barcons Jaúregui, Francesc Xavier|||0000-0003-1081-8861
Carrera Troyano, Francisco Jesús|||0000-0003-2135-9023
Gil-Merino Rubio, Rodrigo
author Streblyanska, Alina
author_facet Streblyanska, Alina
Barcons Jaúregui, Francesc Xavier|||0000-0003-1081-8861
Carrera Troyano, Francisco Jesús|||0000-0003-2135-9023
Gil-Merino Rubio, Rodrigo
author_role author
author2 Barcons Jaúregui, Francesc Xavier|||0000-0003-1081-8861
Carrera Troyano, Francisco Jesús|||0000-0003-2135-9023
Gil-Merino Rubio, Rodrigo
author2_role author
author
author
dc.contributor.none.fl_str_mv Universidad de Cantabria
dc.subject.none.fl_str_mv X-rays: general
Quasars: absorption lines
Quasars: general
Galaxies: active
topic X-rays: general
Quasars: absorption lines
Quasars: general
Galaxies: active
description Aims. Broad absorption-line quasars (BALQSOs) are key objects for studying the structure and emission/absorption properties of AGN. However, despite their fundamental importance, the properties of BALQSOs remain poorly understood. To investigate the X-ray nature of these sources, as well as the correlations between X-ray and rest-frame UV properties, we compile a large sample of BALQSOs observed by XMM-Newton. Methods. We collect information for 88 sources from the literature and existing catalogues, creating the largest BALQSO sample analysed optically and in X-ray to date. We performed a full X-ray spectral analysis (using unabsorbed and both neutral and ionized absorption models) on a sample of 39 sources with higher X-ray spectral quality, and an approximate hardness-ratio analysis on the remaining sources. Using available optical spectra, we calculate the BALnicity index and investigate the dependence of this optical parameter on different X-ray properties. Results. Using the neutral absorption model, we find that 36% of our BALQSOs have NnH < 5 × 1021 cm−2, lower than the expected X-ray absorption for these objects. However, when we used a physically-motivated model for the X-ray absorption in BALQSOs, i.e., ionized absorption, ∼90% of the objects are absorbed. The observed difference in ionized properties of sources with the BALnicity index (BI) =0 and BI > 0 might be explained by different physical conditions of the outflow and/or inclination effects. The absorption properties also suggest that LoBALs may be physically different objects from HiBALs. In addition, we report on a correlation between the ionized absorption column density and BAL parameters. There is evidence (at the 98% level) that the amount of X-ray absorption is correlated with the strength of high-ionization UV absorption. Not previously reported, this correlation can be naturally understood in virtually all BALQSO models, as being driven by the total amount of gas mass flowing towards the observer. We also find a hint of a correlation between the BI and the ionization level detected in X-rays.
publishDate 2010
dc.date.none.fl_str_mv 2010
2010-06-01
dc.type.none.fl_str_mv journal article
http://purl.org/coar/resource_type/c_6501
NA
http://purl.org/coar/version/c_be7fb7dd8ff6fe43
dc.type.openaire.fl_str_mv info:eu-repo/semantics/article
format article
dc.identifier.none.fl_str_mv https://hdl.handle.net/10902/27998
url https://hdl.handle.net/10902/27998
dc.language.none.fl_str_mv Inglés
eng
language_invalid_str_mv Inglés
language eng
dc.rights.none.fl_str_mv open access
http://purl.org/coar/access_right/c_abf2
dc.rights.openaire.fl_str_mv info:eu-repo/semantics/openAccess
rights_invalid_str_mv open access
http://purl.org/coar/access_right/c_abf2
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 Astronomy and Astrophysics, 2010, 515, A2
reponame:UCrea Repositorio Abierto de la Universidad de Cantabria
instname:Universidad de Cantabria (UC)
instname_str Universidad de Cantabria (UC)
reponame_str UCrea Repositorio Abierto de la Universidad de Cantabria
collection UCrea Repositorio Abierto de la Universidad de Cantabria
repository.name.fl_str_mv
repository.mail.fl_str_mv
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score 15,300719

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