Determining the Heating Rate in Reconnection Formed Flare Loops Wenjuan Liu 1, Jiong Qiu 1, Dana W. Longcope 1, Amir Caspi 2, Courtney Peck 2, Jennifer O'Hara 3 1.Department of Physics, Montana State University 2.LASP, University of Colorado 3.School of Mathematics and Statistics, University of St Andrews 1

Outline  Motivation How much energy is used to heat individual flare loops?  Methods (a few thousand loops)  Constructing heating rate from UV light curves at foot points  Modeling plasma evolution in each flare Loop with EBTEL  Results  synthetic soft X-ray and EUV emissions from the loops  synthetic UV emissions from the foot points during the decay phase  Discussions and Conclusions The synthetic light curves and spectra agree well with the obs. 2

Motivation -from reconnection to flare emission 3 flare foot points and loops (observable) Magnetic reconnection energy release/transport (not known in details) Link: heating rate in individual loops

Methods - constructing the heating rate For each flare loop, the heating rate (H) is proportional to the impulsive rise of UV 1600 emission at its foot point 4 cooling heating

Methods -calculating plasma evolution 5 EBTEL (Klimchuk 2008, Cargill 2012) model plasma properties in a few thousand loops coronal DEM (>1 MK) pressure gauge (Fisher 1987) transition region DEM (0.1~1 MK) during the decay

6 Methods - Comparing with observed total radiation InstrumentTemperature (MK) RHESSI>10 EVE2~10 AIA (EUV bands)2~10 AIA (UV bands) TRACE (UV bands) ~0.1

Application May 13 flare Overview of the flare M8.0 flare, obs. by RHESSI and TRACE 5127 loops with cross section area of 1” x 1” 7 Length of half-loop (Mm): 33 – 65 Max heating rate in individual loops (ergs/s): 2.4x10 24 – 5.7x10 25 Duration of heating (s): 13 – 131 Total heating energy (erg): 1.22×10 31

Results- Comparison with RHESSI 8 Obs. Model light curves in 3-6, 6-12, keV (details see Liu et al ApJ, 770,111 )

Application March 7 flare 9 Length of half-loop (Mm): Max heating rate in individual loops (ergs/s): 7.4x10 23 – 1.3x10 25 Duration of heating (s): 13 – 131 Total heating energy (erg): 4.64x10 30 Overview of the flare M1.7 flare, obs. by AIA and EUV 3057 loops with cross section area of 1” x 1”

Results- Comparison of EUV emissions 10 T~10 MKT~6.5 MK AIA 131AIA 94 EVE 133 Fe XX Fe XX III EVE 94 Fe XVIII Obs. Model

Results- Comparison of EUV emissions 11 T~2.7 MK T~1.9 MK AIA 335 AIA 211 EVE 335 Fe XVI EVE 211 Fe XIV Obs. Model

UV 1600 bands is dominated by C IV emission C IV line is optically thin transition region line The transition region DEM is given from the “pressure gauge” (Fisher 1987),when  In the transition region, the conduction is balanced by radiation  the pressure does not vary with height Results- Comparison with UV light curves at the decay phase 12 The calculated CIV flux decays at the same rate as observed

Discussions and Conclusions  We use the impulsive rise of UV light curves at the foot points to construct the heating rates in a few thousand loops, and calculate plasma properties of these loops  The synthetic coronal emission and decay-phase C IV emission from the model agree with the obs. very well  The method gives an estimate of total energy (lower limits): 1.22×10 31 for the M8.0 flare and 4.64x10 30 for the M1.7 flare 13

Reference Fisher, G. H. 1987, ApJ, 317, 502 Fletcher, L., Pollock, J., Potts, H. E., 2004, Solar Physics, 222, 279 Hawley, S. L., & Fisher, G. H. 1992, ApJS, 78, 565 Klimchuk, J. A., Patsourakos S., and Cargill P. J. 2008, ApJ, 682, 1351 Liu, W-J, Qiu, J., Longcope, D. W., Caspi, A. 2013, ApJ, 770, 111 Longcope, D.W., DesJardins, A. C., Carranza-Fulmer, T., Qiu, J., 2010, Solar Physics, 267, 107 Qiu, J., Liu, W.-J., Longcope, D. W ApJ, 752, 124 Qiu, J., Liu, W-J., Hill, N., Kazachenko, M. 2010, ApJ, 565,

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Results- Distribution of peak temperature and density for over 5000 flux tubes 18

Methods - Construct the heating rate  Temporally and spatially resolved  Determined by UV and HXR observations 19

Methods- loop evolution with EBTEL model 20

Methods- loop evolution with EBTEL model 21

AIA response function vs. EVE line contribution function 22

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