Forward Modeling of Simulated Transverse Oscillations in Coronal Loops and the Influence of Background Emission

Shi, Mijie, Van Doorsselaere, Tom, Antolin, Patrick and Li, Bo (2021) Forward Modeling of Simulated Transverse Oscillations in Coronal Loops and the Influence of Background Emission. The Astrophysical Journal, 922 (1). p. 60. ISSN 0004-637X

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We simulate transverse oscillations in radiatively cooling coronal loops and forward-model their spectroscopic and imaging signatures, paying attention to the influence of background emission. The transverse oscillations are driven at one footpoint by a periodic velocity driver. A standing kink wave is subsequently formed and the loop cross section is deformed due to the Kelvin–Helmholtz instability, resulting in energy dissipation and heating at small scales. Besides the transverse motions, a long-period longitudinal flow is also generated due to the ponderomotive force induced slow wave. We then transform the simulated straight loop to a semi-torus loop and forward-model their spectrometer and imaging emissions, mimicking observations of Hinode/EIS and SDO/AIA. We find that the oscillation amplitudes of the intensity are different at different slit positions, but are roughly the same in different spectral lines or channels. X-t diagrams of both the Doppler velocity and the Doppler width show periodic signals. We also find that the background emission dramatically decreases the Doppler velocity, making the estimated kinetic energy two orders of magnitude smaller than the real value. Our results show that background subtraction can help recover the real oscillation velocity. These results are helpful for further understanding transverse oscillations in coronal loops and their observational signatures. However, they cast doubt on the spectroscopically estimated energy content of transverse waves using the Doppler velocity.

Item Type: Article
Additional Information: Funding information: This work is supported by the National Natural Science Foundation of China (41904150, 11761141002, 41974200) and the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement No. 724326). P.A. acknowledges funding from his STFC Ernest Rutherford Fellowship (No. ST/ R004285/2). M.S. is supported by the international postdoctoral exchange fellowship from China Postdoctoral Council.
Uncontrolled Keywords: Magnetohydrodynamical, Solar coronal loops, Solar extreme ultraviolet emission, Solar coronal waves
Subjects: F300 Physics
F500 Astronomy
Department: Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Depositing User: Rachel Branson
Date Deposited: 14 Dec 2021 11:18
Last Modified: 19 Nov 2022 08:00

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