  We conduct forward-modeling analysis based on our 2.5 dimensional
magnetohydrodynamics (MHD) simulation of magnetic flux rope (MFR) formation and
eruption driven by photospheric converging motion. The current sheet (CS)
evolution during the MFR formation and eruption process in our MHD simulation
can be divided into four stages. The current sheet (CS) evolution during the
MFR formation and eruption process in our MHD simulation can be divided into
four stages. The first stage shows the CS forming and gradually lengthening.
Resistive instabilities that disrupt the CS mark the beginning of the second
stage. Magnetic islands disappear in the third stage and reappear in the fourth
stage. Synthetic images and light curves of the seven Solar Dynamics
Observatory/Atmospheric Imaging Assembly (AIA) channels, i.e., 9.4 nm, 13.1 nm,
17.1 nm, 19.3 nm, 21.1 nm, 30.4 nm, and 33.5 nm, and the 3-25 keV thermal X-ray
are obtained with forward-modeling analysis. The loop-top source and the
coronal sources of the soft X-ray are reproduced in forward modeling. The light
curves of the seven SDO/AIA channels start to rise once resistive instabilities
develop. The light curve of the 3-25 keV thermal X-ray starts to go up when the
reconnection rate reaches one of its peaks. Quasiperiodic pulsations (QPPs)
appear twice in the SDO/AIA 17.1 nm, 21.1 nm, and 30.4 nm channels,
corresponding to the period of chaotic (re)appearance and CS-guided
displacements of the magnetic islands. QPPs appear once in the SDO/AIA 9.4 nm
and 33.5 nm channels after the disruption of the CS by resistive instabilities
and in the 19.3 nm channel when the chaotic motion of the magnetic islands
reappears.
