Characterising fast-time variations in the hard X-ray time profiles of solar flares using Solar Orbiter's STIX

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Hauptverfasser: Collier, Hannah, Hayes, Laura A., Battaglia, Andrea F., Harra, Louise K., Krucker, Säm
Format: Preprint
Veröffentlicht: 2023
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author Collier, Hannah
Hayes, Laura A.
Battaglia, Andrea F.
Harra, Louise K.
Krucker, Säm
author_facet Collier, Hannah
Hayes, Laura A.
Battaglia, Andrea F.
Harra, Louise K.
Krucker, Säm
contents Aims: The aim of this work is to develop a method to systematically detect and characterise fast-time variations ($\gtrsim 1$s) in the non-thermal hard X-ray (HXR) time profiles of solar flares using high-resolution data from Solar Orbiter's Spectrometer/Telescope for Imaging X-rays (STIX). Methods: The HXR time profiles were smoothed using Gaussian Process (GP) regression. The time profiles were then fitted with a linear combination of Gaussians to decompose the time profile. From the Gaussian decomposition, key characteristics such as the periodicity, full width at half maximum (FWHM), time evolution, and amplitude can be derived. Results: We present the outcome of applying this method to four M and X GOES-class flares from the first year of Solar Orbiter science operations. The HXR time profiles of these flares were decomposed into individual Gaussians and their periods were derived. The quality of fit is quantified by the standard deviation of the residuals (difference between observed and fitted curve, normalised by the error on the observed data), for which we obtain $\leq 1.8$ for all flares presented. In this work, the first detection of fast-time variations with Solar Orbiter's STIX instrument has been made on timescales across the range of 4-128s. Conclusions: A new method for identifying and characterising fast-time variations in the non-thermal HXR profiles of solar flares has been developed, in which the time profiles are fit with a linear combination of Gaussian bursts. The opportunity to study time variations in flares has greatly improved with the new observations from STIX on Solar Orbiter.
format Preprint
id arxiv_https___arxiv_org_abs_2301_08040
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Characterising fast-time variations in the hard X-ray time profiles of solar flares using Solar Orbiter's STIX
Collier, Hannah
Hayes, Laura A.
Battaglia, Andrea F.
Harra, Louise K.
Krucker, Säm
Solar and Stellar Astrophysics
Aims: The aim of this work is to develop a method to systematically detect and characterise fast-time variations ($\gtrsim 1$s) in the non-thermal hard X-ray (HXR) time profiles of solar flares using high-resolution data from Solar Orbiter's Spectrometer/Telescope for Imaging X-rays (STIX). Methods: The HXR time profiles were smoothed using Gaussian Process (GP) regression. The time profiles were then fitted with a linear combination of Gaussians to decompose the time profile. From the Gaussian decomposition, key characteristics such as the periodicity, full width at half maximum (FWHM), time evolution, and amplitude can be derived. Results: We present the outcome of applying this method to four M and X GOES-class flares from the first year of Solar Orbiter science operations. The HXR time profiles of these flares were decomposed into individual Gaussians and their periods were derived. The quality of fit is quantified by the standard deviation of the residuals (difference between observed and fitted curve, normalised by the error on the observed data), for which we obtain $\leq 1.8$ for all flares presented. In this work, the first detection of fast-time variations with Solar Orbiter's STIX instrument has been made on timescales across the range of 4-128s. Conclusions: A new method for identifying and characterising fast-time variations in the non-thermal HXR profiles of solar flares has been developed, in which the time profiles are fit with a linear combination of Gaussian bursts. The opportunity to study time variations in flares has greatly improved with the new observations from STIX on Solar Orbiter.
title Characterising fast-time variations in the hard X-ray time profiles of solar flares using Solar Orbiter's STIX
topic Solar and Stellar Astrophysics
url https://arxiv.org/abs/2301.08040