Abstract
Abstract Solar wind plasma at the Earth’s orbit carries transient magnetic field structures including discontinuities. Their interaction with the Earth’s bow shock can significantly alter discontinuity configuration and stability. We investigate such an interaction for the most widespread type of solar wind discontinuities—rotational discontinuities (RDs). We use a set of in situ multispacecraft observations and perform kinetic hybrid simulations. We focus on the RD current density amplification that may lead to magnetic reconnection. We show that the amplification can be as high as two orders of magnitude and is mainly governed by three processes: the transverse magnetic field compression, global thinning of RD, and interaction of RD with low-frequency electromagnetic waves in the magnetosheath, downstream of the bow shock. The first factor is found to substantially exceed simple hydrodynamic predictions in most observed cases, the second effect has a rather moderate impact, while the third causes strong oscillations of the current density. We show that the presence of accelerated particles in the bow shock precursor highly boosts the current density amplification, making the postshock magnetic reconnection more probable. The pool of accelerated particles strongly affects the interaction of RDs with the Earth’s bow shock, as it is demonstrated by observational data analysis and hybrid code simulations. Thus, shocks should be distinguished not by the inclination angle, but rather by the presence of foreshocks populated with shock reflected particles. Plasma processes in the RD–shock interaction affect magnetic structures and turbulence in the Earth’s magnetosphere and may have implications for the processes in astrophysics.
Highlights
Solar wind flow carries a wide range of magnetic field structures that are large-amplitude Alfven waves, rotational (RD) and tangential discontinuities (TD, current sheets), and interplanetary shock waves (Smith 1973a,b; Neugebauer et al 1984; Neugebauer 2006; Tsurutani & Ho 1999; Vasquez et al 2007; Greco et al 2009b,a)
We focus on the rotational discontinuities (RDs) current density amplification that may lead to magnetic reconnection
We show that the amplification can be as high as two orders of magnitude and is mainly governed by three processes: the transverse magnetic field compression, global thinning of RD, and interaction of RD with low-frequency electromagnetic waves in the magnetosheath, downstream of the bow shock
Summary
Solar wind flow carries a wide range of magnetic field structures (solar wind transients) that are large-amplitude Alfven waves, rotational (RD) and tangential discontinuities (TD, current sheets), and interplanetary shock waves (Smith 1973a,b; Neugebauer et al 1984; Neugebauer 2006; Tsurutani & Ho 1999; Vasquez et al 2007; Greco et al 2009b,a). A dissipation of magnetic field contained in solar wind transients is believed to support proton and electron heating (Osman et al 2011, 2012) and acceleration (Tessein et al 2013) This dissipation can be due to magnetic field line reconnection that is driven by internal or externally driven instabilities of strong currents carried by solar wind transients (Phan et al 2006; Gosling 2012; Zank et al 2014; Drake et al 2020), e.g. solar wind RDs and TDs, that are plane layers of intense currents (Servidio et al 2015; Podesta 2017; Podesta & Roytershteyn 2017; Greco et al 2016). The most straightforward of such drivers are the interactions of RDs with each other or with larger-scale magnetic field structures, like planetary bow shocks (Nakanotani et al 2020)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.