Forward Modeling of Active Region Coronal Emissions. I. Methods and Testing

Details Forward Modeling of Active Region Coronal Emissions. I. Methods and Testing Forward Modeling of Active Region Coronal Emissions. I. Methods and Testing

Dec 2008

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008apjs..179..509l&link_type=abstract

The Astrophysical Journal Supplement Series, Volume 179, Issue 2, pp. 509-533.

Astronomy and Astrophysics

Astronomy

13

Sun: Corona, Sun: Magnetic Fields, Sun: X-Rays, Gamma Rays

Scientific paper

We present a method for simulating coronal emissions from solar active regions using observed photospheric magnetograms and an assumption about the coronal heating mechanism as input. The method invokes a ``quasi-force-free'' (minimized Lorentz force) coronal magnetic solution and a steady state energy balance model solved along field lines. Coronal heating is included using parameterized approximations relating the heat deposited to properties of the magnetic field. We use calculated temperatures and densities to predict emissions and compare to observations from the Yohkoh Soft X-ray satellite. We use NOAA active region 8210 to test the model's sensitivities. We find predicted intensities and emission morphologies change little with different assumptions for the coronal magnetic field. We test methods for calculating the proportionality constant in a heating scale relationship and find filling factors of ~(1-5)×10-2 are needed to match temperature in the cases considered. We investigate the effect of heating scale height, finding that loop-top heating improves temperature predictions but decreases success of the emission morphology prediction. Footpoint heating has the opposite effect. Overall, our model produces relatively robust results for a wide range of assumptions. Yet the results are highly sensitive to the input coronal heating parameterization, making our method a powerful approach for discriminating between heating mechanisms. Nevertheless, we find substantial discrepancies between our synthetic emissions and observed emissions. We investigate sources of discrepancy and suggest that improved magnetic field extrapolations and dynamic heating are necessary to improve simulations.

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