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

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dc.citation.issueNumber1en_US
dc.citation.journalTitleThe Astrophysical Journalen_US
dc.citation.volumeNumber864en_US
dc.contributor.authorMarsh, Andrew J.en_US
dc.contributor.authorSmith, David M.en_US
dc.contributor.authorGlesener, Lindsayen_US
dc.contributor.authorKlimchuk, James A.en_US
dc.contributor.authorBradshaw, Stephen J.en_US
dc.contributor.authorVievering, Julianaen_US
dc.contributor.authorHannah, Iain G.en_US
dc.contributor.authorChriste, Stevenen_US
dc.contributor.authorIshikawa, Shin-nosukeen_US
dc.contributor.authorKrucker, Sämen_US
dc.date.accessioned2018-11-09T14:59:57Zen_US
dc.date.available2018-11-09T14:59:57Zen_US
dc.date.issued2018en_US
dc.description.abstractMuch 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 H 0, durations τ, delay times between events t N , 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 <H 0 < 13 erg cm−3 s−1 and a wide range of delay times and durations. We exclude delays between events shorter than ~900 s at the 90% confidence level for this region. Three of five regions observed by NuSTAR on 2014 November 1 are well fit by homogeneous nanoflare models, while two regions with higher fluxes are not. Generally, the NuSTAR count spectra are well fit by nanoflare sequences with smaller heating amplitudes, shorter delays, and shorter durations than the allowed FOXSI-2 models. These apparent discrepancies are likely due to differences in spectral coverage between the two instruments and intrinsic differences among the regions. Steady heating (t N  = τ) was ruled out with >99% confidence for all regions observed by either instrument.en_US
dc.identifier.citationMarsh, Andrew J., Smith, David M., Glesener, Lindsay, et al.. "Hard X-Ray Constraints on Small-scale Coronal Heating Events." <i>The Astrophysical Journal,</i> 864, no. 1 (2018) IOP Publishing: https://doi.org/10.3847/1538-4357/aad380.en_US
dc.identifier.digitalMarsh-2018en_US
dc.identifier.doihttps://doi.org/10.3847/1538-4357/aad380en_US
dc.identifier.urihttps://hdl.handle.net/1911/103294en_US
dc.language.isoengen_US
dc.publisherIOP Publishingen_US
dc.rightsArticle is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.en_US
dc.titleHard X-Ray Constraints on Small-scale Coronal Heating Eventsen_US
dc.typeJournal articleen_US
dc.type.dcmiTexten_US
dc.type.publicationpublisher versionen_US
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