AUTHOR=Polito Vanessa , Peterson Marianne , Glesener Lindsay , Testa Paola , Yu Sijie , Reeves Katharine K. , Sun Xudong , Duncan Jessie TITLE=Multi-wavelength observations and modeling of a microflare: constraining non-thermal particle acceleration JOURNAL=Frontiers in Astronomy and Space Sciences VOLUME=10 YEAR=2023 URL=https://www.frontiersin.org/journals/astronomy-and-space-sciences/articles/10.3389/fspas.2023.1214901 DOI=10.3389/fspas.2023.1214901 ISSN=2296-987X ABSTRACT=

In this work we analyze a small B-class flare that occurred on 29 April 2021 and was observed simultaneously by the Interface Region Imaging Spectrograph (IRIS) and the Nuclear Spectroscopic Telescope Array (NuSTAR) X-ray instrument. The IRIS observations of the ribbon of the flare show peculiar spectral characteristics that are typical signatures of energy deposition by non-thermal electrons in the lower atmosphere. The presence of the non-thermal particles is also confirmed directly by fitting the NuSTAR spectral observations. We show that, by combining IRIS and NuSTAR multi-wavelength observations from the corona to the lower atmosphere with hydrodynamic simulations using the RADYN code, we can provide strict constraints on electron-beam heated flare models. This work presents the first NuSTAR, IRIS and RADYN joint analysis of a non-thermal microflare, and presents a self-consistent picture of the flare-accelerated electrons in the corona and the chromospheric response to those electrons.