Physics of the Neupert Effect: Estimates of the Effects of Source Energy, Mass Transport, and Geometry Using RHESSI and GOES Data
Physics of the Neupert Effect: Estimates of the Effects of Source Energy, Mass Transport, and Geometry Using RHESSI and GOES Data
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DOI：
10.1086/427274
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发表时间：
2005-03
期刊：
影响因子：
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通讯作者：
A. Veronig;John C. Brown;B. R. Dennis;Richard A. Schwartz;L. Sui;A. Tolbert
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文献类型：
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作者：
A. Veronig;John C. Brown;B. R. Dennis;Richard A. Schwartz;L. Sui;A. Tolbert
“经验纽珀特效应”（ENE）是在许多耀斑中观测到的硬X射线（HXR）通量FHXR（t）与软X射线（SXR）通量时间导数FHXR（t）的时间相关性。这被广泛认为意味着厚靶碰撞韧致辐射产生FHXR（t）的高能电子是SXR发射热日冕等离子体的主要加热和质量供应源（通过色球蒸发）。如果这种解释是正确的，人们将期望从HXR光谱推断出的束电源Pbeam（t）与解释SXR通量和光谱所需的实际功率Pin（t）之间的更好的相关性，允许发射测量（EM）和温度T两者的变化，辐射和传导冷却损失，以及几何形状的复杂性，如多个环路。我们称之为“理论纽珀特效应”（TNE）。为了检验从数据中推断出的Pbeam（t）和Pin（t）是否比FHXR（t）和PINSXR（t）具有更好的相关性，我们使用了一个简单的单圈几何的近似方法和对粒子和能量输运的粗略估计，并将该模型应用于四个耀斑的RHESSI和GOES数据。我们发现，当束流低截止能量E1为常数时，Pbeam（t），Pin（t）的相关性并不比FHXR（t），FHSXR（t）好。虽然我们的模型包含了许多近似的冷却和其他物理，完全忽略了ENE数据的考虑，似乎没有理由为什么他们的数量级包含应该使TNE更糟，而不是更好，虽然这应该通过更准确的模拟检查。这些结果表明，以下一个或多个必须是真实的：（1）快电子不是SXR等离子体供应和加热的主要来源，（2）束低截止能量随时间变化，或（3）TNE是强烈的影响源的几何形状。这些选项进行了讨论TNE研究的未来可能的方向。
The "empirical Neupert effect" (ENE) is the observed temporal correlation of the hard X-ray (HXR) flux FHXR(t) with the time derivative of the soft X-ray (SXR) flux ḞSXR(t) in many flares. This is widely taken to mean that the energetic electrons responsible for FHXR(t) by thick-target collisional bremsstrahlung are the main source of heating and mass supply (via chromospheric evaporation) of the SXR-emitting hot coronal plasma. If this interpretation were correct, one would expect better correlation between the beam power supply Pbeam(t), inferred from the HXR spectrum, and the actual power Pin(t) required to explain the SXR flux and spectrum, allowing for variations in both emission measure (EM) and temperature T, for radiative and conductive cooling losses, and for complexities of geometry like multiple loops. We call this the "theoretical Neupert effect" (TNE). To test if it is true that Pbeam(t) and Pin(t) inferred from data are better correlated than FHXR(t) and ḞSXR(t), we use an approximate approach for a simple single-loop geometry and rough estimates of the particle and energy transport and apply the model to RHESSI and GOES data on four flares. We find that if the beam low cutoff energy E1 is taken as constant, the correlation of Pbeam(t), Pin(t) is no better than that of FHXR(t), ḞSXR(t). While our modeling contains many approximations to cooling and other physics, ignored entirely from ENE data considerations, there seems to be no reason why their order-of-magnitude inclusion should make the TNE worse rather than better, although this should be checked by more accurate simulations. These results suggest that one or more of the following must be true: (1) fast electrons are not the main source of SXR plasma supply and heating, (2) the beam low cutoff energy varies with time, or (3) the TNE is strongly affected by source geometry. These options are discussed in relation to possible future directions for TNE research.