Modeling the Excitation, Propagation and Damping of Quasi-Periodic Fast Magnetosonic Waves in Realistic Coronal Active Region Magnetic Field Structures

TL;DR

This paper advances QFP wave modeling by embedding quasi-periodic fast magnetosonic wave trains within a realistic coronal AR magnetic-field structure derived from AR 11166. Using a resistive 3D MHD framework with gravitational stratification and a potential-field extrapolation, it simulates excitation by localized velocity pulses and generates synthetic emission-measure maps to compare with SDO/AIA observations. Key findings show that realistic magnetic topology improves qualitative agreement with observed QFP properties, including directionality, propagation along funnel-like loops, and damping due to energy spreading and resistive effects, with implications for coronal seismology and flare energy transport. Overall, the work demonstrates that accurate 3D modeling of AR magnetic fields enhances our ability to diagnose coronal parameters from QFP wave behavior.

Abstract

Quasi-periodic fast propagating magnetosonic waves (QFPs) were discovered in the solar corona in EUV since the launch of SDO spacecraft more than a decade ago. The QFP waves are associated with flares and coronal mass ejections (CMEs) providing information on flare pulsations as well as on the magnetic field by MHD wave seismology. Previous models of QFP waves used primarily idealized magnetic active region structures. However, more realistic active region numerical models are needed to improve the application of coronal seismology to observations of waves in coronal structures. Here, we extend the previous models by including realistic magnetic configuration based on an observed coronal active region in a case study using AR 11166 observed on March 10, 2011 by SDO/AIA, using potential field extrapolation of photospheric magnetic field with realistic gravitationally stratified density structure { with typical coronal temperature} in our resistive 3D MHD model. We aim at reproducing the observed QFPs properties, such as directionality, propagation, reflection, nonlinearity, and damping of these waves. We model various forms of excitation of QFPs through time dependent boundary conditions, and localized pulses at the base of the corona. We produce synthetic emission measure (EM) maps from the 3D MHD modeling results to facilitate comparison to EUV observations. We find that the present more realistic model provides better qualitative agreement with observations compared to previous idealized models, improving the study of QFP wave excitation, propagation and damping in coronal ARs, with potential applications to coronal seismology.

Figures (11)

• Figure 1: The QFP wave event observed in AR 11166 on 2011 March 10 by SDO/AIA in (a) 171 Å, and (b) 193 Å channels. White arrows in (a) mark the AR, flare source, and fan loop associated with the event. Two white curves indicate the initial EUV wave fronts. The white box marks a region, where the propagating waves in the running difference images are shown in Figure \ref{['QFP_171_193_diff:fig']}.
• Figure 2: The difference images showing the QFP waves observed by AIA in 171Å (a1)$-$(c1) and 193Å (a2)$-$(c2) at a sequence of times in the range 06:40$-$06:50 UT on Mar-10-2011 following the onset of the C class flare. The green curves in each panel mark the wavefronts of EUV waves (or QFP wave trains in panel (c1)). Animations are available online. The accelerated animation shows the time-sequence of the difference images for the two AIA EUV wavelengths of 171Å (corresponding to the top panels) and the 193Å (corresponding to the lower panels) for the time interval 06:40$-$06:50 UT on Mar-10-2011.
• Figure 3: The potential magnetic field extrapolation using the HMI vector magnetogram of AR 11166, the source of the QFP waves observed by SDO/AIA on Mar-10-2011 at about 06:40 UT. The red (positive polarity) and blue (negative polarity) colors indicate the photospheric magnetic field in the range $\pm$1000 G. The ‘cylindrical equal area’ map projection (CEA) coordinates are used here Sun13
• Figure 4: The initial state of the 3D MHD model $(t=0)$. (a) The magnetic field lines reconstructed using potential field extrapolation with Green's function method of the radial magnetic field for AR 11166. (b) The gravitationally stratified density in the $x-z$ plane at $y={ -0.72}$, overlaid with several fieldlines that are calculated from the ($B_x$, $B_z$) components in this 2D plane. (c) The fast magnetosonic speed, $V_f$, in the $x-y$ plane at ${ z=1.42}$. The arrowheads mark the location of the QFP wave train source in the 3D MHD model: Source A at $(-0.71, -0.2)$ (yellow arrowhead), and Source B at $(-1.1, -0.5)$ (white arrowhead). (d) $V_f$ in the $x-z$ plane at ${ y=-0.72}$.
• Figure 5: The snapshot of the variables in the $x-y$ plane ('on disk') at $t=114\tau_A$, $z=1.42$ due to the QFP waves launched at Source A in the modeled AR 11166. (a) The relative 'running difference' density perturbation $\Delta\rho/\rho_0$, where $\Delta\rho=(\rho(t)-\rho(t-\Delta t)/\rho_0$; the yellow 'x' marks the location of the temporal evolution shown below. (b) the running difference of the emission measure, EM, computed from the 3D model AR. The online accelerated animation of this panel shows the modeled time interval $t=[42.1, 129]\tau_A$ (corresponding to $\sim$ 8:33 min. duration). (c) The velocity magnitude and direction. (d) The magnetic field magnitude and direction.