The University of Southampton
University of Southampton Institutional Repository

Assessing quasi-periodicities in Jovian x-ray emissions: techniques and heritage survey

Assessing quasi-periodicities in Jovian x-ray emissions: techniques and heritage survey
Assessing quasi-periodicities in Jovian x-ray emissions: techniques and heritage survey

Jupiter's auroral X-rays are rather mysterious, with an unknown driver, and several previous reports of individual cases of quasi-periodic emission. In this work we revisit heritage X-ray data sets from the 1990s to 2015 and apply robust significance testing of emerging quasi-periodicities, seeking to understand the robustness and regularity of previously reported quasi-periodic emissions. Our analysis incorporates the use of the Rayleigh test as an alternative to Lomb-Scargle analysis or Fast Fourier Transforms, where Rayleigh is particularly suited to a time-tagged data set of sparse counts such as is common for jovian X-ray data. Furthermore, the analysis techniques that we present (including Rayleigh testing and Monte Carlo simulation) can be applied to any time-tagged data set. The code to conduct such analysis is released as supplementary information to accompany this paper. The five most significant (p value <0.01) quasi-periods from Jupiter's northern auroral region have periods ranging from ~8.0 to 45.96 min, and the two most significant (p value <0.01) quasi-periods from the south have periods of ~14.1 and ~34.9 min. The selection of a restrictive hot spot source region seems to be critical for detecting quasi-periodic emission, suggesting that the site of pulsations may be spatially localized. Periods vary from one Jupiter rotation to the next in one long observation, and the north and south are shown to pulse independently in another conjugate observation. These results have important implications for understanding the driver of jovian X-ray emission.

Chandra, Jupiter, periodicities, Rayleigh testing, timing analysis, X-rays
2169-9380
9204-9221
Jackman, C. M.
9bc3456c-b254-48f1-ade0-912c5b8b4529
Knigge, C.
ac320eec-631a-426e-b2db-717c8bf7857e
Altamirano, D.
d5ccdb09-0b71-4303-9538-05b467be075b
Gladstone, R.
6a2011bf-2561-4956-9928-46e6b927ba6d
Dunn, W.
6d4b6d4f-3a63-423f-9f6a-4213952a69e7
Elsner, R.
8bd02ac2-399b-458f-ada3-5eb91b17a9ad
Kraft, R.
9b3235bb-bc6e-4014-98e6-97a4c28238c3
Branduardi-Raymont, G.
36295f98-922c-47dc-879b-063a8ab190a5
Ford, P.
6344cb0c-9606-4496-9d8b-74d8f4bd679f
Jackman, C. M.
9bc3456c-b254-48f1-ade0-912c5b8b4529
Knigge, C.
ac320eec-631a-426e-b2db-717c8bf7857e
Altamirano, D.
d5ccdb09-0b71-4303-9538-05b467be075b
Gladstone, R.
6a2011bf-2561-4956-9928-46e6b927ba6d
Dunn, W.
6d4b6d4f-3a63-423f-9f6a-4213952a69e7
Elsner, R.
8bd02ac2-399b-458f-ada3-5eb91b17a9ad
Kraft, R.
9b3235bb-bc6e-4014-98e6-97a4c28238c3
Branduardi-Raymont, G.
36295f98-922c-47dc-879b-063a8ab190a5
Ford, P.
6344cb0c-9606-4496-9d8b-74d8f4bd679f

Jackman, C. M., Knigge, C., Altamirano, D., Gladstone, R., Dunn, W., Elsner, R., Kraft, R., Branduardi-Raymont, G. and Ford, P. (2018) Assessing quasi-periodicities in Jovian x-ray emissions: techniques and heritage survey. Journal of Geophysical Research: Space Physics, 123 (11), 9204-9221. (doi:10.1029/2018JA025490).

Record type: Article

Abstract

Jupiter's auroral X-rays are rather mysterious, with an unknown driver, and several previous reports of individual cases of quasi-periodic emission. In this work we revisit heritage X-ray data sets from the 1990s to 2015 and apply robust significance testing of emerging quasi-periodicities, seeking to understand the robustness and regularity of previously reported quasi-periodic emissions. Our analysis incorporates the use of the Rayleigh test as an alternative to Lomb-Scargle analysis or Fast Fourier Transforms, where Rayleigh is particularly suited to a time-tagged data set of sparse counts such as is common for jovian X-ray data. Furthermore, the analysis techniques that we present (including Rayleigh testing and Monte Carlo simulation) can be applied to any time-tagged data set. The code to conduct such analysis is released as supplementary information to accompany this paper. The five most significant (p value <0.01) quasi-periods from Jupiter's northern auroral region have periods ranging from ~8.0 to 45.96 min, and the two most significant (p value <0.01) quasi-periods from the south have periods of ~14.1 and ~34.9 min. The selection of a restrictive hot spot source region seems to be critical for detecting quasi-periodic emission, suggesting that the site of pulsations may be spatially localized. Periods vary from one Jupiter rotation to the next in one long observation, and the north and south are shown to pulse independently in another conjugate observation. These results have important implications for understanding the driver of jovian X-ray emission.

Text
Jackman_et_al-2018-Journal_of_Geophysical_Research__Space_Physics - Version of Record
Available under License Creative Commons Attribution.
Download (853kB)

More information

e-pub ahead of print date: 6 October 2018
Published date: 1 November 2018
Keywords: Chandra, Jupiter, periodicities, Rayleigh testing, timing analysis, X-rays

Identifiers

Local EPrints ID: 427227
URI: https://eprints.soton.ac.uk/id/eprint/427227
ISSN: 2169-9380
PURE UUID: f59aff90-0311-4005-a86c-194cedf691f5
ORCID for D. Altamirano: ORCID iD orcid.org/0000-0002-3422-0074

Catalogue record

Date deposited: 09 Jan 2019 17:30
Last modified: 08 Nov 2019 01:31

Export record

Altmetrics

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of https://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×