@article{60482213be7f41eeb0a82b59cabd687e,
title = "Studying the Transfer of Magnetic Helicity in Solar Active Regions with the Connectivity-based Helicity Flux Density Method",
abstract = "In the solar corona, magnetic helicity slowly and continuously accumulates in response to plasma flows tangential to the photosphere and magnetic flux emergence through it. Analyzing this transfer of magnetic helicity is key for identifying its role in the dynamics of active regions (ARs). The connectivity-based helicity flux density method was recently developed for studying the 2D and 3D transfer of magnetic helicity in ARs. The method takes into account the 3D nature of magnetic helicity by explicitly using knowledge of the magnetic field connectivity, which allows it to faithfully track the photospheric flux of magnetic helicity. Because the magnetic field is not measured in the solar corona, modeled 3D solutions obtained from force-free magnetic field extrapolations must be used to derive the magnetic connectivity. Different extrapolation methods can lead to markedly different 3D magnetic field connectivities, thus questioning the reliability of the connectivity-based approach in observational applications. We address these concerns by applying this method to the isolated and internally complex AR 11158 with different magnetic field extrapolation models. We show that the connectivity-based calculations are robust to different extrapolation methods, in particular with regard to identifying regions of opposite magnetic helicity flux. We conclude that the connectivity-based approach can be reliably used in observational analyses and is a promising tool for studying the transfer of magnetic helicity in ARs and relating it to their flaring activity.",
keywords = "Sun: corona, Sun: flares, Sun: photosphere, magnetic fields",
author = "K. Dalmasse and Pariat and G. Valori and Ju Jing and P. D{\'e}moulin",
note = "Funding Information: E.P. acknowledges the support of the French Agence Nationale pour la Recherche through the HELISOL project, contract No. ANR-15-CE31-0001. G.V. acknowledges the support of the Leverhulme Trust Research Project Grant 2014-051. J.J. is supported by NASA grant NNX16AF72G and 80NSSC17K0016. The data used here are courtesy of the NASA/SDO and the HMI science team. This work used the DAVE4VM code written and developed by P. Schuck at the Naval Research Laboratory. The helicity flux calculations were performed partly on the high-performance computing system Yellowstone (ark:/85065/d7wd3xhc) provided by NCAR's Computational and Information Systems Laboratory, sponsored by the National Science Foundation, and partly on the multiprocessor TRU64 computer of LESIA. The National Center for Atmospheric Research is sponsored by the National Science Foundation. Funding Information: acknowledges the support of the Leverhulme Trust Research Project Grant 2014-051. J.J. is supported by NASA grant NNX16AF72G and 80NSSC17K0016. The data used here are courtesy of the NASA/SDO and the HMI science team. This work used the DAVE4VM code written and developed by P. Schuck at the Naval Research Laboratory. The helicity flux calculations were performed partly on the high-performance computing system Yellowstone (ark:/85065/d7wd3xhc) provided by NCAR{\textquoteright}s Computational and Information Systems Laboratory, sponsored by the National Science Foundation, and partly on the multiprocessor TRU64 computer of LESIA. The National Center for Atmospheric Research is sponsored by the National Science Foundation. Funding Information: We thank the anonymous referee for helpful comments that improved the paper. K.D. thanks D. Nychka for his help on the Monte Carlo experiment and R. Centeno Elliott and A. Gri{\~n}{\'o}n Mar{\'i}n for their insights on HMI noise characterization. K.D. acknowledges funding from the Advanced Study Program, the High Altitude Observatory, and the Computational and Information Systems Laboratory. E.P. acknowledges the support of the French Agence Nationale pour la Recherche through the HELISOL project, contract No. ANR-15-CE31-0001. G.V. Publisher Copyright: {\textcopyright} 2018. The American Astronomical Society. All rights reserved.",
year = "2018",
month = jan,
day = "10",
doi = "10.3847/1538-4357/aaa1e1",
language = "English (US)",
volume = "852",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "2",
}