Electron Agyrotropy and Anisotropy: how to interpret signatures from MMS observations?

In this work we explore via fully kinetic simulations the agyrotropic and anisotropic behavior of electrons during asymmetric magnetic reconnection. Two different configurations with the same asymmetry degree are compared. The first configuration represents the traditional steady asymmetric reconnection with a single isolated reconnection site. The second configuration instead considers the same asymmetric evolution from an initial tangential discontinuity. Being intrinsically unstable, this latter configuration soon causes the formation of several randomly distributed reconnection points, eventually leading to rapid magnetic island growth and coalescence. We identify three different reconnection regions, marked as X-, D- and M-regions, according to their different behaviour. For each region we identify unique signatures in terms of anisotropy, agyrotropy and electron distribution functions. We search and identify the physical mechanisms responsible for these signatures. The results of our study is a table of signature where a given crossing can be readily identified as pertaining a X-, D- or M- reconnection region. Our table is invaluable in the interpretation of events with multiple reconnection sites encountered by the MMS NASA mission.