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A systematic analysis of the phase lags associated with the type-C quasi-periodic oscillation in GRS 1915+105

A systematic analysis of the phase lags associated with the type-C quasi-periodic oscillation in GRS 1915+105
A systematic analysis of the phase lags associated with the type-C quasi-periodic oscillation in GRS 1915+105
We present a systematic analysis of the phase lags associated with the type-C QPOs in GRS1915+105 using RXTE data. Our sample comprises of 620RXTE observations with type-CQPOs ranging from ∼0.4Hz to ∼6.3Hz. Based on our analysis, we confirm that the QPO phase lags decrease with QPO frequency, and change sign from positive to negative at a QPO frequency of ∼2Hz. In addition, we find that the slope of this relation is significantly different between QPOs below and above 2 Hz. The relation between the QPO lags and QPO rms can be well fitted with a broken line: as the QPO lags go from negative to positive, the QPO rms first increases, reaching its maximum at around zero lag, and then decreases. The phase-lag behaviour of the subharmonic of the QPO is similar to that of the QPO fundamental, where the subharmonic lags decrease with subharmonic frequency and change sign from positive to negative at a subharmonic frequency of ∼1Hz; on the contrary, the second harmonic of the QPO shows a quite different phase-lag behaviour, where all the second harmonics show hard lags that remain more or less constant. For both the QPO and its (sub)harmonics, the slope of the lag-energy spectra shows a similar evolution with frequency as the average phase lags. This suggests that the lag-energy spectra drives the average phase lags. We discuss the possibility for the change in lag sign, and the physical origin of the QPO lags.
0035-8711
Zhang, Liang
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Méndez, Mariano
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Altamirano, Diego
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Qu, Jinlu
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Chen, Li
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Karpouzas, Konstantinos
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Belloni, Tomaso M.
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Bu, Qingcui
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Huang, Yue
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Ma, Xiang
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Tao, Lian
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Wang, Yanan
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Zhang, Liang
77199a72-9bb0-4336-bbff-15c8e1b790cb
Méndez, Mariano
8e1ca225-c1bc-45ef-a572-6d1b4032cbe7
Altamirano, Diego
d5ccdb09-0b71-4303-9538-05b467be075b
Qu, Jinlu
f062632f-d68b-474a-bf6e-a73860fbe41f
Chen, Li
90472886-55fe-42d6-8e97-1e20d5b79802
Karpouzas, Konstantinos
4e7447e5-6991-4cd9-8c2f-1c0e6c9763db
Belloni, Tomaso M.
e0d2fe61-a28e-4f18-b836-b0993a3ba17b
Bu, Qingcui
fae2b254-8ba9-43f8-90c1-f7275c1b0281
Huang, Yue
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Ma, Xiang
e00054e2-db8d-44c6-be6c-7cf807f0f6d3
Tao, Lian
75749bbb-a4e9-4734-8325-6180e5dad82b
Wang, Yanan
9a02a8fa-8381-49f4-b045-de72e6ab6f83

Zhang, Liang, Méndez, Mariano, Altamirano, Diego, Qu, Jinlu, Chen, Li, Karpouzas, Konstantinos, Belloni, Tomaso M., Bu, Qingcui, Huang, Yue, Ma, Xiang, Tao, Lian and Wang, Yanan (2020) A systematic analysis of the phase lags associated with the type-C quasi-periodic oscillation in GRS 1915+105. Monthly Notices of the Royal Astronomical Society. (In Press)

Record type: Article

Abstract

We present a systematic analysis of the phase lags associated with the type-C QPOs in GRS1915+105 using RXTE data. Our sample comprises of 620RXTE observations with type-CQPOs ranging from ∼0.4Hz to ∼6.3Hz. Based on our analysis, we confirm that the QPO phase lags decrease with QPO frequency, and change sign from positive to negative at a QPO frequency of ∼2Hz. In addition, we find that the slope of this relation is significantly different between QPOs below and above 2 Hz. The relation between the QPO lags and QPO rms can be well fitted with a broken line: as the QPO lags go from negative to positive, the QPO rms first increases, reaching its maximum at around zero lag, and then decreases. The phase-lag behaviour of the subharmonic of the QPO is similar to that of the QPO fundamental, where the subharmonic lags decrease with subharmonic frequency and change sign from positive to negative at a subharmonic frequency of ∼1Hz; on the contrary, the second harmonic of the QPO shows a quite different phase-lag behaviour, where all the second harmonics show hard lags that remain more or less constant. For both the QPO and its (sub)harmonics, the slope of the lag-energy spectra shows a similar evolution with frequency as the average phase lags. This suggests that the lag-energy spectra drives the average phase lags. We discuss the possibility for the change in lag sign, and the physical origin of the QPO lags.

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A systematic analysis of the phase lags associated with the type-C quasi-periodic oscillation in GRS 1915+105 - Accepted Manuscript
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Accepted/In Press date: 18 March 2020
Additional Information: arxiv copy is AM

Identifiers

Local EPrints ID: 441915
URI: http://eprints.soton.ac.uk/id/eprint/441915
ISSN: 0035-8711
PURE UUID: 440247eb-b100-40a6-ba80-f95b9a37ecc8
ORCID for Diego Altamirano: ORCID iD orcid.org/0000-0002-3422-0074

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Date deposited: 02 Jul 2020 16:31
Last modified: 07 Oct 2020 02:05

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Contributors

Author: Liang Zhang
Author: Mariano Méndez
Author: Jinlu Qu
Author: Li Chen
Author: Konstantinos Karpouzas
Author: Tomaso M. Belloni
Author: Qingcui Bu
Author: Yue Huang
Author: Xiang Ma
Author: Lian Tao
Author: Yanan Wang

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