Steep-spectrum AGN in eROSITA Final Equatorial-Depth Survey (eFEDS): Their host galaxies and multi-wavelength properties

We selected sources with a steep soft-X-ray-band spectrum with a photon index of Γ > 2.5 - measured by eROSITA on board the Spectrum-Röntgen-Gamma (SRG) - from the eFEDS AGN catalogue as candidates of highly accreting supermassive black holes, and investigated their multi-wavelength properties. A...

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Autores: Iwasawa, Kazushi, Liu, T., Boller, T., Buchner, J., Li, Jun, Kawaguchi, T., Nagao, T., Terashima, Y., Toba, Y., Silverman, John D., Arcodia, R., Dauser, T., Krumpe, M., Nandra, K., Wilms, J.
Tipo de documento: artigo
Estado:Versão publicada
Data de publicação:2024
País:España
Recursos:Universidad de Barcelona
Repositório:Dipòsit Digital de la UB
OAI Identifier:oai:diposit.ub.edu:2445/218260
Acesso em linha:https://hdl.handle.net/2445/218260
Access Level:Acceso aberto
Palavra-chave:Galàxies
Astronomia de raigs X
Aixecaments topogràfics
Galaxies
X-ray astronomy
Surveys
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spelling Steep-spectrum AGN in eROSITA Final Equatorial-Depth Survey (eFEDS): Their host galaxies and multi-wavelength propertiesIwasawa, KazushiLiu, T.Boller, T.Buchner, J.Li, JunKawaguchi, T.Nagao, T.Terashima, Y.Toba, Y.Silverman, John D.Arcodia, R.Dauser, T.Krumpe, M.Nandra, K.Wilms, J.GalàxiesAstronomia de raigs XAixecaments topogràficsGalaxiesX-ray astronomySurveysWe selected sources with a steep soft-X-ray-band spectrum with a photon index of Γ > 2.5 - measured by eROSITA on board the Spectrum-Röntgen-Gamma (SRG) - from the eFEDS AGN catalogue as candidates of highly accreting supermassive black holes, and investigated their multi-wavelength properties. Among 601 bright AGN with 0.2−5 keV counts of greater than 100, 83 sources (≈14%) are classified as steep-spectrum sources. These sources have typical 0.5−2 keV luminosities of LSX ≈ 1044 erg s−1 and the majority of them are found at redshifts below z = 1. In comparison with sources with flatter spectra, these sources have, on average, a UV (or optical) to 2 keV luminosity ratio that is larger by ∼0.3 dex and bluer optical-to-UV continuum emission. They also appear to be radio quiet based on the detection rate in the FIRST and VLASS surveys. Their host galaxies - at least in the redshift range of z = 0.2 − 0.8, where the AGN-galaxy decomposition results from the Subaru Hyper Suprime-Cam imaging are available - tend to be late-type and have smaller stellar masses (M⋆ ∼ 1010.5 M⊙) than those of sources with flatter spectra. These properties are similar to those found in nearby narrow-line Seyfert 1 galaxies, in agreement with the picture that they are AGN with elevated accretion rates and are in the early growth phase of black hole and galaxy co-evolution. However, the steep-spectrum sources are not exclusively narrow-line Seyfert 1 galaxies; indeed many are broad-line Seyfert 1 galaxies, as found by a catalogue search. This suggests that these steep-spectrum sources may be black holes generally with high accretion rates but of a wide mass range, including a few objects emitting at LSX ≥ 1045 erg s−1, of which black hole masses can be close to 109 M⊙.EDP Sciences2024info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionapplication/pdfhttps://hdl.handle.net/2445/218260Articles publicats en revistes (Institut de Ciències del Cosmos (ICCUB))reponame:Dipòsit Digital de la UBinstname:Universidad de BarcelonaInglésReproducció del document publicat a: https://doi.org/10.1051/0004-6361/202348311Journal of Astrophysics and Astronomy, 2024, vol. 684, A153https://doi.org/10.1051/0004-6361/202348311cc-by (c) Iwasawa, Kazushi et al., 2024info:eu-repo/semantics/openAccessoai:diposit.ub.edu:2445/2182602026-05-27T06:46:51Z
dc.title.none.fl_str_mv Steep-spectrum AGN in eROSITA Final Equatorial-Depth Survey (eFEDS): Their host galaxies and multi-wavelength properties
title Steep-spectrum AGN in eROSITA Final Equatorial-Depth Survey (eFEDS): Their host galaxies and multi-wavelength properties
spellingShingle Steep-spectrum AGN in eROSITA Final Equatorial-Depth Survey (eFEDS): Their host galaxies and multi-wavelength properties
Iwasawa, Kazushi
Galàxies
Astronomia de raigs X
Aixecaments topogràfics
Galaxies
X-ray astronomy
Surveys
title_short Steep-spectrum AGN in eROSITA Final Equatorial-Depth Survey (eFEDS): Their host galaxies and multi-wavelength properties
title_full Steep-spectrum AGN in eROSITA Final Equatorial-Depth Survey (eFEDS): Their host galaxies and multi-wavelength properties
title_fullStr Steep-spectrum AGN in eROSITA Final Equatorial-Depth Survey (eFEDS): Their host galaxies and multi-wavelength properties
title_full_unstemmed Steep-spectrum AGN in eROSITA Final Equatorial-Depth Survey (eFEDS): Their host galaxies and multi-wavelength properties
title_sort Steep-spectrum AGN in eROSITA Final Equatorial-Depth Survey (eFEDS): Their host galaxies and multi-wavelength properties
dc.creator.none.fl_str_mv Iwasawa, Kazushi
Liu, T.
Boller, T.
Buchner, J.
Li, Jun
Kawaguchi, T.
Nagao, T.
Terashima, Y.
Toba, Y.
Silverman, John D.
Arcodia, R.
Dauser, T.
Krumpe, M.
Nandra, K.
Wilms, J.
author Iwasawa, Kazushi
author_facet Iwasawa, Kazushi
Liu, T.
Boller, T.
Buchner, J.
Li, Jun
Kawaguchi, T.
Nagao, T.
Terashima, Y.
Toba, Y.
Silverman, John D.
Arcodia, R.
Dauser, T.
Krumpe, M.
Nandra, K.
Wilms, J.
author_role author
author2 Liu, T.
Boller, T.
Buchner, J.
Li, Jun
Kawaguchi, T.
Nagao, T.
Terashima, Y.
Toba, Y.
Silverman, John D.
Arcodia, R.
Dauser, T.
Krumpe, M.
Nandra, K.
Wilms, J.
author2_role author
author
author
author
author
author
author
author
author
author
author
author
author
author
dc.subject.none.fl_str_mv Galàxies
Astronomia de raigs X
Aixecaments topogràfics
Galaxies
X-ray astronomy
Surveys
topic Galàxies
Astronomia de raigs X
Aixecaments topogràfics
Galaxies
X-ray astronomy
Surveys
description We selected sources with a steep soft-X-ray-band spectrum with a photon index of Γ > 2.5 - measured by eROSITA on board the Spectrum-Röntgen-Gamma (SRG) - from the eFEDS AGN catalogue as candidates of highly accreting supermassive black holes, and investigated their multi-wavelength properties. Among 601 bright AGN with 0.2−5 keV counts of greater than 100, 83 sources (≈14%) are classified as steep-spectrum sources. These sources have typical 0.5−2 keV luminosities of LSX ≈ 1044 erg s−1 and the majority of them are found at redshifts below z = 1. In comparison with sources with flatter spectra, these sources have, on average, a UV (or optical) to 2 keV luminosity ratio that is larger by ∼0.3 dex and bluer optical-to-UV continuum emission. They also appear to be radio quiet based on the detection rate in the FIRST and VLASS surveys. Their host galaxies - at least in the redshift range of z = 0.2 − 0.8, where the AGN-galaxy decomposition results from the Subaru Hyper Suprime-Cam imaging are available - tend to be late-type and have smaller stellar masses (M⋆ ∼ 1010.5 M⊙) than those of sources with flatter spectra. These properties are similar to those found in nearby narrow-line Seyfert 1 galaxies, in agreement with the picture that they are AGN with elevated accretion rates and are in the early growth phase of black hole and galaxy co-evolution. However, the steep-spectrum sources are not exclusively narrow-line Seyfert 1 galaxies; indeed many are broad-line Seyfert 1 galaxies, as found by a catalogue search. This suggests that these steep-spectrum sources may be black holes generally with high accretion rates but of a wide mass range, including a few objects emitting at LSX ≥ 1045 erg s−1, of which black hole masses can be close to 109 M⊙.
publishDate 2024
dc.date.none.fl_str_mv 2024
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv https://hdl.handle.net/2445/218260
url https://hdl.handle.net/2445/218260
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv Reproducció del document publicat a: https://doi.org/10.1051/0004-6361/202348311
Journal of Astrophysics and Astronomy, 2024, vol. 684, A153
https://doi.org/10.1051/0004-6361/202348311
dc.rights.none.fl_str_mv cc-by (c) Iwasawa, Kazushi et al., 2024
info:eu-repo/semantics/openAccess
rights_invalid_str_mv cc-by (c) Iwasawa, Kazushi et al., 2024
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv EDP Sciences
publisher.none.fl_str_mv EDP Sciences
dc.source.none.fl_str_mv Articles publicats en revistes (Institut de Ciències del Cosmos (ICCUB))
reponame:Dipòsit Digital de la UB
instname:Universidad de Barcelona
instname_str Universidad de Barcelona
reponame_str Dipòsit Digital de la UB
collection Dipòsit Digital de la UB
repository.name.fl_str_mv
repository.mail.fl_str_mv
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score 15.198674

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