Hard X-Ray Constraints on Small-scale Coronal Heating Events

Much evidence suggests that the solar corona is heated impulsively, meaning that nanoflares may be ubiquitous in quiet and active regions (ARs). Hard X-ray (HXR) observations with unprecedented sensitivity >3 keV are now enabled by focusing instruments. We analyzed data from the Focusing Optics X...

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Bibliographic Details
Published in:The Astrophysical journal 2018-09, Vol.864 (1), p.5
Main Authors: Marsh, Andrew J., Smith, David M., Glesener, Lindsay, Klimchuk, James A., Bradshaw, Stephen J., Vievering, Juliana, Hannah, Iain G., Christe, Steven, Ishikawa, Shin-nosuke, Krucker, Säm
Format: Article
Language:English
Subjects:
Amplitudes
Astrophysics
Computational fluid dynamics
Computer simulation
Confidence intervals
Corona
Coronal heating
Delay time
Differential thermal analysis
Emission measurements
Emission spectra
Fluid flow
Fluxes
Heating
Hydrodynamics
Optics
Sensitivity analysis
Solar corona
Spacecraft
Spectroscopic telescopes
Sun: corona
Sun: flares
Sun: X-rays, gamma rays
X ray spectra
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Summary:Much evidence suggests that the solar corona is heated impulsively, meaning that nanoflares may be ubiquitous in quiet and active regions (ARs). Hard X-ray (HXR) observations with unprecedented sensitivity >3 keV are now enabled by focusing instruments. We analyzed data from the Focusing Optics X-ray Solar Imager (FOXSI) rocket and the Nuclear Spectroscopic Telescope Array (NuSTAR) spacecraft to constrain properties of AR nanoflares simulated by the EBTEL field-line-averaged hydrodynamics code. We generated model X-ray spectra by computing differential emission measures for homogeneous nanoflare sequences with heating amplitudes H0, durations τ, delay times between events tN, and filling factors f. The single quiescent AR observed by FOXSI-2 on 2014 December 11 is well fit by nanoflare sequences with heating amplitudes 0.02 erg cm−3 s−1 99% confidence for all regions observed by either instrument.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/aad380