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Radio frequency timing analysis of the compact jet in the black hole X-ray binary Cygnus X-1

Radio frequency timing analysis of the compact jet in the black hole X-ray binary Cygnus X-1
Radio frequency timing analysis of the compact jet in the black hole X-ray binary Cygnus X-1
We present simultaneous multiband radio and X-ray observations of the black hole X-ray binary Cygnus X-1, taken with the Karl G. Jansky Very Large Array and the Nuclear Spectroscopic Telescope Array. With these data, we detect clear flux variability consistent with emission from a variable compact jet. To probe how the variability signal propagates down the jet flow, we perform detailed timing analyses of our data. We find that the radio jet emission shows no significant power at Fourier frequencies f ≳ 0.03 Hz (below ∼30 s time-scales), and that the higher frequency radio bands (9/11 GHz) are strongly correlated over a range of time-scales, displaying a roughly constant time lag with Fourier frequency of a few tens of seconds. However, in the lower frequency radio bands (2.5/3.5 GHz), we find a significant loss of coherence over the same range of time-scales. Further, we detect a correlation between the X-ray/radio emission, measuring time lags between the X-ray/radio bands on the order of tens of minutes. We use these lags to solve for the compact jet speed, finding that the Cyg X-1 jet is more relativistic than usually assumed for compact jets, where β=0.92+0.03−0.06 and (⁠Γ=2.59+0.79−0.61⁠). Lastly, we constrain how the jet size scale changes with frequency, finding a shallower relation (∝ν−0.4) than predicted by simple jet models (∝ν−1), and estimate a jet opening angle of ϕ ∼ 0.4–1.8 deg. With this study we have developed observational techniques designed to overcome the challenges of radio timing analyses and created the tools needed to connect rapid radio jet variability properties to internal jet physics.
0035-8711
2987-3003
Tetarenko, A.J.
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Casella, P.
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Miller-Jones, J.C. A.
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Sivakoff, G. R.
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Tetarenko, B. E.
b62ce163-46fb-4989-b805-b6b2b5a78121
Maccarone, T. J.
c2f1d87b-e2ef-4e33-b09f-a2861d917ea8
Gandhi, P.
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Eikenberry, S.
1e439ded-8c26-4664-809a-e817020237c3
Tetarenko, A.J.
dfa769cf-9270-4af0-ab89-d8a01fb2cd94
Casella, P.
c254f195-d43d-4385-98ef-d33600fb7f81
Miller-Jones, J.C. A.
3f659cec-bbb3-447c-b94e-4f170af560a6
Sivakoff, G. R.
78946fc0-c772-46ea-8c7b-85e99b6e8844
Tetarenko, B. E.
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Maccarone, T. J.
c2f1d87b-e2ef-4e33-b09f-a2861d917ea8
Gandhi, P.
5bc3b5af-42b0-4dd8-8f1f-f74048d4d4a9
Eikenberry, S.
1e439ded-8c26-4664-809a-e817020237c3

Tetarenko, A.J., Casella, P., Miller-Jones, J.C. A., Sivakoff, G. R., Tetarenko, B. E., Maccarone, T. J., Gandhi, P. and Eikenberry, S. (2019) Radio frequency timing analysis of the compact jet in the black hole X-ray binary Cygnus X-1. Monthly Notices of the Royal Astronomical Society, 484 (3), 2987-3003. (doi:10.1093/mnras/stz165).

Record type: Article

Abstract

We present simultaneous multiband radio and X-ray observations of the black hole X-ray binary Cygnus X-1, taken with the Karl G. Jansky Very Large Array and the Nuclear Spectroscopic Telescope Array. With these data, we detect clear flux variability consistent with emission from a variable compact jet. To probe how the variability signal propagates down the jet flow, we perform detailed timing analyses of our data. We find that the radio jet emission shows no significant power at Fourier frequencies f ≳ 0.03 Hz (below ∼30 s time-scales), and that the higher frequency radio bands (9/11 GHz) are strongly correlated over a range of time-scales, displaying a roughly constant time lag with Fourier frequency of a few tens of seconds. However, in the lower frequency radio bands (2.5/3.5 GHz), we find a significant loss of coherence over the same range of time-scales. Further, we detect a correlation between the X-ray/radio emission, measuring time lags between the X-ray/radio bands on the order of tens of minutes. We use these lags to solve for the compact jet speed, finding that the Cyg X-1 jet is more relativistic than usually assumed for compact jets, where β=0.92+0.03−0.06 and (⁠Γ=2.59+0.79−0.61⁠). Lastly, we constrain how the jet size scale changes with frequency, finding a shallower relation (∝ν−0.4) than predicted by simple jet models (∝ν−1), and estimate a jet opening angle of ϕ ∼ 0.4–1.8 deg. With this study we have developed observational techniques designed to overcome the challenges of radio timing analyses and created the tools needed to connect rapid radio jet variability properties to internal jet physics.

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Accepted/In Press date: 11 January 2019
e-pub ahead of print date: 16 January 2019
Published date: 11 April 2019

Identifiers

Local EPrints ID: 430176
URI: http://eprints.soton.ac.uk/id/eprint/430176
ISSN: 0035-8711
PURE UUID: 49f937b7-b906-44d8-813b-1ad681aa4ed6
ORCID for P. Gandhi: ORCID iD orcid.org/0000-0003-3105-2615

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Date deposited: 16 Apr 2019 16:30
Last modified: 07 Oct 2020 02:06

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Contributors

Author: A.J. Tetarenko
Author: P. Casella
Author: J.C. A. Miller-Jones
Author: G. R. Sivakoff
Author: B. E. Tetarenko
Author: T. J. Maccarone
Author: P. Gandhi ORCID iD
Author: S. Eikenberry

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