Patterns of Activity in a Global Model of a Solar Active Region

Abstract

In this work we investigate the global activity patterns predicted from a model active region heated by distributions of nanoflares that have a range of frequencies. What differs is the average frequency of the distributions. The activity patterns are manifested in time lag maps of narrow-band instrument channel pairs. We combine hydrodynamic and forward modeling codes with a magnetic field extrapolation to create a model active region and apply the time lag method to synthetic observations. Our aim is not to reproduce a particular set of observations in detail, but to recover some typical properties and patterns observed in active regions. Our key findings are the following. 1. cooling dominates the time lag signature and the time lags between the channel pairs are generally consistent with observed values. 2. shorter coronal loops in the core cool more quickly than longer loops at the periphery. 3. all channel pairs show zero time lag when the line-of-sight passes through coronal loop foot-points. 4. there is strong evidence that plasma must be re-energized on a time scale comparable to the cooling timescale to reproduce the observed coronal activity, but it is likely that a relatively broad spectrum of heating frequencies are operating across active regions. 5. due to their highly dynamic nature, we find nanoflare trains produce zero time lags along entire flux tubes in our model active region that are seen between the same channel pairs in observed active regions.

References in corpus (32)

• A Critical Assessment of Nonlinear Force-Free Field Modeling of the Solar Corona for Active Region 10953
• Highly Efficient Modeling of Dynamic Coronal Loops
• Key Aspects of Coronal Heating
• A Systematic Survey of High Temperature Emission in Solar Active Regions
• The influence of numerical resolution on coronal density in hydrodynamic models of impulsive heating
• Evidence for Widespread Cooling in an Active Region Observed with the SDO Atmospheric Imaging Assembly
• Constraints on the Heating of High Temperature Active Region Loops: Observations from Hinode and SDO
• Enthalpy-based Thermal Evolution of Loops: II. Improvements to the Model
• Using a Differential Emission Measure and Density Measurements in an Active Region Core to Test a Steady Heating Model
• Patterns of Nanoflare Storm Heating Exhibited by an Active Region Observed with SDO/AIA
• Hinode X-Ray Telescope Detection of Hot Emission from Quiescent Active Regions: A Nanoflare Signature?
• Comparing magnetic field extrapolations with measurements of magnetic loops
• Evidence of widespread hot plasma in a non-flaring coronal active region from Hinode/XRT
• The Role of Type II Spicules in the Upper Solar Atmosphere
• Diagnosing the time-dependence of active region core heating from the emission measure: I. Low-frequency nanoflares
• Temperature distribution of a non-flaring active region from simultaneous Hinode XRT and EIS observations
• Hinode/EIS spectroscopic validation of very hot plasma imaged with Solar Dynamics Observatory in non-flaring active region cores
• The Spatial and Temporal Dependence of Coronal Heating by Alfven Wave Turbulence
• Static and Dynamic Modeling of a Solar Active Region. I: Soft X-Ray Emission
• New Observations of the Solar 0.5-5 keV Soft X-ray Spectrum
• Diagnosing the time-dependence of active region core heating from the emission measure: II. Nanoflare trains
• Are Chromospheric Nanoflares a Primary Source of Coronal Plasma?
• Comparison of Hinode/XRT and RHESSI detection of hot plasma in the non-flaring solar corona
• Determining heating time scales in solar active region cores from AIA/SDO Fe XVIII images
• On the sensitivity of the GOES flare classification to properties of the electron beam in the thick target model
• A simple model for the evolution of multi-stranded coronal loops
• 2D cellular automaton model for the evolution of active region coronal plasmas
• Chromospheric Nanoflares as a Source of Coronal Plasma: II. Repeating Nanoflares
• Can a Long Nanoflare Storm Explain the Observed Emission Measure Distributions in Active Region Cores?
• X-raying hot plasma in solar active regions with the SphinX spectrometer
• Profiles of heating in turbulent coronal magnetic loops
• Thermal structure of hot non-flaring corona from Hinode/EIS

Cited by in corpus (21)

• Long-Period Intensity Pulsations in Coronal Loops Explained by Thermal Non-Equilibrium Cycles
• Multi-scale observations of thermal non-equilibrium cycles in coronal loops
• Modelling the solar transition region using an adaptive conduction method
• Data-Constrained Solar Modeling with GX Simulator
• Understanding Heating in Active Region Cores through Machine Learning I. Numerical Modeling and Predicted Observables
• Signatures of Steady Heating in Time Lag Analysis of Coronal Emission
• Identifying Observables that can Differentiate Between Impulsive and Footpoint Heating: Time Lags and Intensity Ratios
• The Magnetic Properties of Heating Events on High-Temperature Active Region Loops
• Towards a Quantitative Comparison of Magnetic Field Extrapolations and Observed Coronal Loops
• Hard X-Ray Constraints on Small-Scale Coronal Heating Events
• The First Flight of the Marshall Grazing Incidence X-ray Spectrometer (MaGIXS)
• A new approach for modelling chromospheric evaporation in response to enhanced coronal heating: II Non-uniform heating
• Signatures of the non-Maxwellian $\kappa$-distributions in optically thin line spectra. II. Synthetic Fe XVII--XVIII X-ray coronal spectra and predictions for the Marshall Grazing-Incidence X-ray Spectrometer (MaGIXS)
• Role of small-scale impulsive events in heating the X-ray bright points of the quiet Sun
• Observationally quantified reconnection providing a viable mechanism for active region coronal heating
• Coronal Heating Law Constrained by Microwave Gyroresonant Emission
• Quantifying the Influence of Key Physical Processes on the Formation of Emission Lines Observed by IRIS: I. Non-Equilibrium Ionization and Density-Dependent Rates
• Understanding Heating in Active Region Cores through Machine Learning II. Classifying Observations
• Transition region contribution to AIA observations in the context of coronal heating
• Temperature and Differential Emission Measure Profiles in Turbulent Solar Active Region Loops
• Nanoflare Diagnostics from Magnetohydrodynamic Heating Profiles