Study of Current Sheet formation and Forced Reconnection based on the Newton Challenge.

Current sheet formation and intensification can be studied by compressing a initially uniform or weakly stratified plasma. Recently, the community has been challenged to conduct a common test, the so-called Newton challenge. In the Newton challenge, a small localized perturbation in space is applied at the boundary of a 2D simulation box and is first slowly turned on and eventually slowly turned off. Current sheet intensification is produced by this gentle push, eventually leading to reconnection in the sheet. We revisit the gentle push approach, trying also stronger and more sudden pushes leading to shock compression. We investigate the relationship between the properties and evolution of the intensified current sheet with the type of boundary perturbation and particularly its temporal variation. The importance of the study is that of course, in reality, the perturbation is self-consistently created by the overall Sun-Earth system itself, often with temporally and spatially localized events (e.g. FTE). We report a number of simulations conducted with kinetic and fluid codes documenting the evolution of different properties of the forming current sheet. While the same final thickness can be obtained in different ways, the path followed to reach a certain thickness and the key properties of the sheet formed depend strongly on the push.