Core Concepts
Using a warm-target model incorporating both kappa and power-law electron distributions to analyze X-ray spectra from two solar flares, this study finds that the kappa distribution provides a more physically realistic representation of accelerated electrons, yielding lower nonthermal energy estimates for similar photon spectra.
Stats
GOES-class M3.5 solar flare on 2011 February 24, peaking at βΌ07:35 UT.
First HXR peak at approximately 07:30 UT.
Preburst X-ray spectra analysis time frame: 07:29:52 to 07:30:00 UT.
Burst time interval for spectral analysis: 07:30:00 to 07:30:44 UT.
Plasma temperature before electron acceleration (πBπ0): 1.30 keV.
Emission measure before electron acceleration (πΈπ0): 0.127 Γ 10^49 cm^β3.
Loop-top source size: π = πβ2 = 3.7 Mm and π = 15.3 Mm.
Cross-sectional area of the loop-top source: π΄ = ππ^2 = 4.21 Γ 10^10 cm^2.
Volume of the loop-top source: π = π΄ Γ π = ππ^2π = 6.46 Γ 10^26 cm^3.
Thermal electron number density: πloop = β(πΈπ0βπ) = 4.4 Γ 10^10 cm^β3.
Half-loop length: πΏ = 15.8 Mm.
GOES-class M4.0 solar flare on 2022 March 28, peaking at βΌ11:29 UT.
HXR burst time: approximately 11:21 UT.
Selected burst time range: 11:21:24β11:21:44 UT.
Preburst time range: 11:21:12β11:21:17 UT.
Fit range for spectral analysis: 6β50 keV.
Preburst spectra temperature (πBπ0): 1.67 keV.
Preburst spectra emission measure (πΈπ0): 0.0532 Γ 10^49 cm^β3.
Northern loop-top source size: π1 = π1β2 = 3.4 Mm and π1 = 12.1 Mm.
Southern loop-top source size: π2 = π2β2 = 3.2 Mm and π2 = 9.6 Mm.
Cross-sectional area of the loop-top source (using the northern source): π΄ = ππ1^2 = 3.64 Γ 10^10 cm^2.
Volume of the loop-top source: π = ππ1^2π1 + ππ2^2π2 = 7.59 Γ 10^26 cm^3.
Half-loop length: πΏ = 18.4 Mm.