Emission Measure Distribution and Heating of Two Active Region Cores

TL;DR

This study analyzes the coronal plasma in active region cores using Hinode data, finding emission measure distributions consistent with nanoflare heating models but also compatible with steady heating, highlighting the challenge in distinguishing heating mechanisms.

Contribution

It provides observational evidence supporting nanoflare heating models in active region cores and compares these with steady heating scenarios.

Findings

Emission measure distribution follows EM∝T^{2.4} from log T=5.5 to 6.55

Observations align with nanoflare-heated loop strand models

Steady heating remains a plausible alternative without additional constraints.

Abstract

Using data from the Extreme-ultraviolet Imaging Spectrometer aboard Hinode, we have studied the coronal plasma in the core of two active regions. Concentrating on the area between opposite polarity moss, we found emission measure distributions having an approximate power-law form EM$\propto T^{2.4}$ from $\log\,T = 5.5$ up to a peak at $\log\,T = 6.55$. We show that the observations compare very favorably with a simple model of nanoflare-heated loop strands. They also appear to be consistent with more sophisticated nanoflare models. However, in the absence of additional constraints, steady heating is also a viable explanation.