IRIS diagnostics of non-thermal particles in coronal loops heated by nanoflares

Friday, 19 December 2014: 3:23 PM
Paola Testa1, Bart De Pontieu2, Joel C Allred3, Mats Carlsson4, Fabio Reale5 and Adrian Nigel Daw3, (1)Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, United States, (2)Lockheed Martin Solar and Astrophysics Laboratory, Palo Alto, CA, United States, (3)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (4)University of Oslo, Oslo, Norway, (5)University of Palermo, Dipartimento di Fisica & Chimica, Palermo, Italy
The variability of emission of the "moss", i.e., the upper transition region (TR) layer of high pressure loops in active regions, provides stringent constraints on the characteristics of heating events. We will discuss the new coronal heating diagnostics provided by the Interface Region Imaging Spectrograph (IRIS) together with SDO/AIA. IRIS provides imaging and spectral observations of the solar chromosphere and transition region, at high spatial (0.166 arcsec/pix) and temporal (down to ~1s) resolution at FUV and NUV wavelengths. We discuss how simultaneous IRIS and AIA observations, together with loop modeling (with the RADYN code) including chromosphere, transition region and corona, allow us to study impulsive heating events (nanoflares) and the energy transport mechanism between the corona and the lower atmospheric layers (thermal conduction vs. beams of non-thermal particles). We will show how the modeling of rapid moss brightenings provides diagnostics for the presence and properties of non-thermal particles in nanoflares, which are below the detectability threshold of hard X-ray observations.