Discovery of Kilohertz Quasi-periodic Oscillations in 4U 1735-44

Autores
Wijnands, Rudy; van der Klis, Michiel; Méndez, Mariano R.; van Paradijs, Jan; Lewin, Walter H. G.; Lamb, Frederick K.; Vaughan, Brian A.; Kuulkers, Erik
Año de publicación
1998
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
We discovered a single kilohertz (kHz) quasi-periodic oscillation (QPO) near 1150 Hz in the Rossi X-Ray Timing Explorer X-ray light curve of the low-mass X-ray binary and atoll source 4U 1735-44. The rms amplitude of this peak was 2%-3%, and the FWHM was 6-40 Hz. There are indications that the kHz QPO frequency decreased from 1160 to 1145 Hz when the count rate increased, which would be quite different from what is observed in other atoll sources for which kHz QPOs have been discovered. In the X-ray color-color diagram and hardness-intensity diagram, the source traced out the curved branch (the so-called banana branch) that has been found by previous instruments. The kHz QPO was detected only when the source was at the lowest count rates during our observations, i.e., on the lower part of the banana branch. When 4U 1735-44 was at higher count rates, i.e., on the upper part of the banana branch and at a higher inferred mass accretion rate with respect to that on the lower part of the banana branch, the QPO was not detected. Besides the kHz QPO, we discovered a low-frequency QPO with a frequency near 67 Hz, together with a complex, broad-peaked noise component below 30 Hz. This 67 Hz QPO may be related to the magnetospheric beat-frequency QPO, which is observed on the horizontal branch of Z sources. This idea is supported by the (peaked) noise found in both 4U 1735-44 and Z sources at frequencies just below the QPO frequency.
Facultad de Ciencias Astronómicas y Geofísicas
Materia
Ciencias Astronómicas
Accretion disks
Stars: individual (4U 1735244)
Stars: neutron
X-rays: stars
Nivel de accesibilidad
acceso abierto
Condiciones de uso
http://creativecommons.org/licenses/by-nc-sa/4.0/
Repositorio
SEDICI (UNLP)
Institución
Universidad Nacional de La Plata
OAI Identificador
oai:sedici.unlp.edu.ar:10915/122871

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repository_id_str 1329
network_name_str SEDICI (UNLP)
spelling Discovery of Kilohertz Quasi-periodic Oscillations in 4U 1735-44Wijnands, Rudyvan der Klis, MichielMéndez, Mariano R.van Paradijs, JanLewin, Walter H. G.Lamb, Frederick K.Vaughan, Brian A.Kuulkers, ErikCiencias AstronómicasAccretion disksStars: individual (4U 1735244)Stars: neutronX-rays: starsWe discovered a single kilohertz (kHz) quasi-periodic oscillation (QPO) near 1150 Hz in the Rossi X-Ray Timing Explorer X-ray light curve of the low-mass X-ray binary and atoll source 4U 1735-44. The rms amplitude of this peak was 2%-3%, and the FWHM was 6-40 Hz. There are indications that the kHz QPO frequency decreased from 1160 to 1145 Hz when the count rate increased, which would be quite different from what is observed in other atoll sources for which kHz QPOs have been discovered. In the X-ray color-color diagram and hardness-intensity diagram, the source traced out the curved branch (the so-called banana branch) that has been found by previous instruments. The kHz QPO was detected only when the source was at the lowest count rates during our observations, i.e., on the lower part of the banana branch. When 4U 1735-44 was at higher count rates, i.e., on the upper part of the banana branch and at a higher inferred mass accretion rate with respect to that on the lower part of the banana branch, the QPO was not detected. Besides the kHz QPO, we discovered a low-frequency QPO with a frequency near 67 Hz, together with a complex, broad-peaked noise component below 30 Hz. This 67 Hz QPO may be related to the magnetospheric beat-frequency QPO, which is observed on the horizontal branch of Z sources. This idea is supported by the (peaked) noise found in both 4U 1735-44 and Z sources at frequencies just below the QPO frequency.Facultad de Ciencias Astronómicas y Geofísicas1998info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionArticulohttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdfL39-L42http://sedici.unlp.edu.ar/handle/10915/122871enginfo:eu-repo/semantics/altIdentifier/issn/0004-637Xinfo:eu-repo/semantics/altIdentifier/arxiv/astro-ph/9801018info:eu-repo/semantics/altIdentifier/doi/10.1086/311217info:eu-repo/semantics/openAccesshttp://creativecommons.org/licenses/by-nc-sa/4.0/Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)reponame:SEDICI (UNLP)instname:Universidad Nacional de La Platainstacron:UNLP2025-09-29T11:29:14Zoai:sedici.unlp.edu.ar:10915/122871Institucionalhttp://sedici.unlp.edu.ar/Universidad públicaNo correspondehttp://sedici.unlp.edu.ar/oai/snrdalira@sedici.unlp.edu.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:13292025-09-29 11:29:15.047SEDICI (UNLP) - Universidad Nacional de La Platafalse
dc.title.none.fl_str_mv Discovery of Kilohertz Quasi-periodic Oscillations in 4U 1735-44
title Discovery of Kilohertz Quasi-periodic Oscillations in 4U 1735-44
spellingShingle Discovery of Kilohertz Quasi-periodic Oscillations in 4U 1735-44
Wijnands, Rudy
Ciencias Astronómicas
Accretion disks
Stars: individual (4U 1735244)
Stars: neutron
X-rays: stars
title_short Discovery of Kilohertz Quasi-periodic Oscillations in 4U 1735-44
title_full Discovery of Kilohertz Quasi-periodic Oscillations in 4U 1735-44
title_fullStr Discovery of Kilohertz Quasi-periodic Oscillations in 4U 1735-44
title_full_unstemmed Discovery of Kilohertz Quasi-periodic Oscillations in 4U 1735-44
title_sort Discovery of Kilohertz Quasi-periodic Oscillations in 4U 1735-44
dc.creator.none.fl_str_mv Wijnands, Rudy
van der Klis, Michiel
Méndez, Mariano R.
van Paradijs, Jan
Lewin, Walter H. G.
Lamb, Frederick K.
Vaughan, Brian A.
Kuulkers, Erik
author Wijnands, Rudy
author_facet Wijnands, Rudy
van der Klis, Michiel
Méndez, Mariano R.
van Paradijs, Jan
Lewin, Walter H. G.
Lamb, Frederick K.
Vaughan, Brian A.
Kuulkers, Erik
author_role author
author2 van der Klis, Michiel
Méndez, Mariano R.
van Paradijs, Jan
Lewin, Walter H. G.
Lamb, Frederick K.
Vaughan, Brian A.
Kuulkers, Erik
author2_role author
author
author
author
author
author
author
dc.subject.none.fl_str_mv Ciencias Astronómicas
Accretion disks
Stars: individual (4U 1735244)
Stars: neutron
X-rays: stars
topic Ciencias Astronómicas
Accretion disks
Stars: individual (4U 1735244)
Stars: neutron
X-rays: stars
dc.description.none.fl_txt_mv We discovered a single kilohertz (kHz) quasi-periodic oscillation (QPO) near 1150 Hz in the Rossi X-Ray Timing Explorer X-ray light curve of the low-mass X-ray binary and atoll source 4U 1735-44. The rms amplitude of this peak was 2%-3%, and the FWHM was 6-40 Hz. There are indications that the kHz QPO frequency decreased from 1160 to 1145 Hz when the count rate increased, which would be quite different from what is observed in other atoll sources for which kHz QPOs have been discovered. In the X-ray color-color diagram and hardness-intensity diagram, the source traced out the curved branch (the so-called banana branch) that has been found by previous instruments. The kHz QPO was detected only when the source was at the lowest count rates during our observations, i.e., on the lower part of the banana branch. When 4U 1735-44 was at higher count rates, i.e., on the upper part of the banana branch and at a higher inferred mass accretion rate with respect to that on the lower part of the banana branch, the QPO was not detected. Besides the kHz QPO, we discovered a low-frequency QPO with a frequency near 67 Hz, together with a complex, broad-peaked noise component below 30 Hz. This 67 Hz QPO may be related to the magnetospheric beat-frequency QPO, which is observed on the horizontal branch of Z sources. This idea is supported by the (peaked) noise found in both 4U 1735-44 and Z sources at frequencies just below the QPO frequency.
Facultad de Ciencias Astronómicas y Geofísicas
description We discovered a single kilohertz (kHz) quasi-periodic oscillation (QPO) near 1150 Hz in the Rossi X-Ray Timing Explorer X-ray light curve of the low-mass X-ray binary and atoll source 4U 1735-44. The rms amplitude of this peak was 2%-3%, and the FWHM was 6-40 Hz. There are indications that the kHz QPO frequency decreased from 1160 to 1145 Hz when the count rate increased, which would be quite different from what is observed in other atoll sources for which kHz QPOs have been discovered. In the X-ray color-color diagram and hardness-intensity diagram, the source traced out the curved branch (the so-called banana branch) that has been found by previous instruments. The kHz QPO was detected only when the source was at the lowest count rates during our observations, i.e., on the lower part of the banana branch. When 4U 1735-44 was at higher count rates, i.e., on the upper part of the banana branch and at a higher inferred mass accretion rate with respect to that on the lower part of the banana branch, the QPO was not detected. Besides the kHz QPO, we discovered a low-frequency QPO with a frequency near 67 Hz, together with a complex, broad-peaked noise component below 30 Hz. This 67 Hz QPO may be related to the magnetospheric beat-frequency QPO, which is observed on the horizontal branch of Z sources. This idea is supported by the (peaked) noise found in both 4U 1735-44 and Z sources at frequencies just below the QPO frequency.
publishDate 1998
dc.date.none.fl_str_mv 1998
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
Articulo
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format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://sedici.unlp.edu.ar/handle/10915/122871
url http://sedici.unlp.edu.ar/handle/10915/122871
dc.language.none.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv info:eu-repo/semantics/altIdentifier/issn/0004-637X
info:eu-repo/semantics/altIdentifier/arxiv/astro-ph/9801018
info:eu-repo/semantics/altIdentifier/doi/10.1086/311217
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-sa/4.0/
Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)
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