STUDY OF A DENSE, CORONAL THICK TARGET SOURCE WITH THE MICROWAVE DATA AND 3D MODELING Gregory Fleishman, Yan Xu, Gelu Nita, & Dale Gary 03/12/2015

Introduction A science question: where does the electron acceleration occur in solar flares? Does it happen in dense or tenuous loops? If the acceleration region is dense, it must be detectable in HXR via coronal thick-target emission. Do dense coronal loops exist?

Dense Flaring Loops Dense post-flare loops (e.g., Neupert 1971; Marsh & Hurford 1980; Feldman et al. 1982) Dense cold flaring loop in a small flare (White et al. 1992) Dense hot flaring loops (Veronig & Brown 2004) Dense cold flaring loop in a large flare (Bastian, Fleishman, Gary 2007) A subset of dense coronal flares (Xu et al. 2008)

Bastian et al. 2007: n 0 ~ cm -3 Acceleration region; turbulence-mediated transport of fast electrons

Veronig & Brown 2004

Implications (Xu et al. 2008)

Xu et al. 2008

This study OVSA 5.6 GHz

Work Flow

Compare with 21 May 2004 M2.6 flare

3D Model (our event: ) SoHO/MDIRHESSI keV OVSA 5.6 GHz B 0 = 140 G Density; thermal Density; nonthermal

Model-to-data Comparison: Images X-ray model on RHESSI keV OVSA image at 5.6 GHz on microwave model X-ray model on microwave model on RHESSI keV

Model-to-data Comparison: Spectra

Compare with 21 May 2004 M2.6 flare

Summary of the 3D Model

Conclusions