Electron-only Reconnection in an Ion-scale Current Sheet at the Magnetopause

In the standard model of magnetic reconnection, both ions and electrons couple to the newly reconnected magnetic field lines and are ejected away from the reconnection diffusion region in the form of bidirectional burst ion/electron jets. Recent observations propose a new model: electron-only magnetic reconnection without ion coupling in an electron-scale current sheet. Based on the data from the Magnetospheric Multiscale (MMS) mission, we observe a long-extension inner electron diffusion region (EDR) at least 40 d i away from the X-line at the Earth’s magnetopause, implying that the extension of EDR is much longer than the prediction of the theory and simulations. This inner EDR is embedded in an ion-scale current sheet (the width of ∼4 d i, d i is ion inertial length). However, such ongoing magnetic reconnection was not accompanied with burst ion outflow, implying the presence of electron-only reconnection in an ion-scale current sheet. Our observations present a new challenge for understanding the model of standard magnetic reconnection and the electron-only reconnection model in an electron-scale current sheet.

Observations of a Quickly Flapping Interplanetary Magnetic Reconnection Exhaust

On the basis of the Petschek reconnection model and the characteristics of reconnection, hundreds of reconnection exhausts were reported in the solar wind. Many multi-spacecraft observations also indicated that interplanetary magnetic reconnection is a quasi–steady-state plasma process and the reconnection X-line can extend hundreds of Earth radii. In this study, we report an interplanetary flapping reconnection exhaust observed by Wind on April 1, 2003 at one AU. The magnetic reconnection event has two adjacent accelerated flows. We compared the plasma and magnetic characteristics of the two accelerated flows and found that the second accelerated flow was due to the back-and-forth movement of the reconnection exhaust. Our observations reveal that not all interplanetary reconnections operate in a quasi–steady-state manner; some reconnection current sheets can move rapidly back and forth.

Exploring Flaring Behaviour on Low Mass Stars, Solar-type Stars and the Sun

We report on our project to study the activity in both the Sun and low mass stars. Utilising high cadence, Hα observations of a filament eruption made using the CRISP spectropolarimeter mounted on the Swedish Solar Telescope has allowed us to determine 3D velocity maps of the event. To gain insight into the physical mechanism which drives the event we have qualitatively compared our observation to a 3D MHD reconnection model. Solar-type and low mass stars can be highly active producing flares with energies exceeding erg. Using K2 and TESS data we find no correlation between the number of flares and the rotation phase which is surprising. Our solar flare model can be used to aid our understanding of the origin of flares in other stars. By scaling up our solar model to replicate observed stellar flare energies, we investigate the conditions needed for such high energy flares.

Forward backward multiplicity correlations: a tool to study properties of the proton-proton collisions

Forward-backward multiplicity correlations have been used to study hadron production mechanisms in electron-positron, proton-proton and more recently in leadlead collisions. The experimental results on this correlations and its comparison to different models reveals an incomplete agreement. In this work, we present an study of forward backward multiplicity correlations in proton-proton collisions using PYTHIA event generator, at LHC energies. Detailed analysis is presented in the case of soft and hard QCD processes, incorporating color reconnection model as part of hadronization mechanism and multiple parton interactions effects in the correlations. Our results and its comparison to available experimental data suggest that this kind of correlations are great tools to characterize the events and gives the possibility to disentangle phenomena in hard and soft QCD processes.