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Online harassment and content moderation have been well-documented in online communities. However, new contexts and systems always bring new ways of harassment and need new moderation mechanisms. This study focuses on hate raids, a form of group attack in real-time in live streaming communities. Through a qualitative analysis of hate raids discussion in the Twitch subreddit (r/Twitch), we found that (1) hate raids as a human-bot coordinated group attack leverages the live stream system to attack marginalized streamers and other potential groups with(out) breaking the rules, (2) marginalized streamers suffer compound harms with insufficient support from the platform, (3) moderation strategies are overwhelmingly technical, but streamers still struggle to balance moderation and participation considering their marginalization status and needs. We use affordances as a lens to explain how hate raids happens in live streaming systems and propose moderation-by-design as a lens when developing new features or systems to mitigate the potential abuse of such designs. 

Abstract Mercury possesses a miniature but dynamic magnetosphere driven primarily by the solar wind through magnetic reconnection. A prominent feature of the dayside magnetopause reconnection that has been frequently observed is flux transfer events (FTEs), which are thought to be an important player in driving the global convection at Mercury. Using the BATSRUS Hall magnetohydrodynamics model with coupled planetary interior, we have conducted a series of global simulations to investigate the generation and characteristics of FTEs under different solar wind Alfvénic Mach numbers (M_A) and interplanetary magnetic field (IMF) orientations. An automated algorithm was also developed to consistently identify FTEs and extract their key properties from the simulations. In all simulations driven by steady upstream conditions, FTEs are formed quasi‐periodically with recurrence time ranging from 2 to 9 s, and their characteristics vary in time as they evolve and interact with the surrounding plasma and magnetic field. Our statistical analysis of the simulated FTEs reveals that the key properties of FTEs, including spatial size, traveling speed and core field strength, all exhibit notable dependence on the solar windM_Aand IMF orientation, and the trends identified from the simulations are generally consistent with previous MErcury Surface Space ENvironment, GEochemistry, and Ranging observations. It is also found that FTEs formed in the simulations contribute about 3%–13% of the total open flux created at the dayside magnetopause that participates in the global circulation, suggesting that FTEs indeed play an important role in driving the Dungey cycle at Mercury. 

Abstract Mercury possesses a miniature yet dynamic magnetosphere driven primarily by magnetic reconnection occurring regularly at the magnetopause and in the magnetotail. Using the newly developed Magnetohydrodynamics with Adaptively Embedded Particle‐in‐Cell (MHD‐AEPIC) model coupled with planetary interior, we have performed a series of global simulations with a range of upstream conditions to study in detail the kinetic signatures, asymmetries, and flux transfer events (FTEs) associated with Mercury's dayside magnetopause reconnection. By treating both ions and electrons kinetically, the embedded PIC model reveals crescent‐shaped phase‐space distributions near reconnection sites, counter‐streaming ion populations in the cusp region, and temperature anisotropies within FTEs. A novel metric and algorithm are developed to automatically identify reconnection X‐lines in our 3D simulations. The spatial distribution of reconnection sites as modeled by the PIC code exhibits notable dawn‐dusk asymmetries, likely due to such kinetic effects as X‐line spreading and Hall effects. Across all simulations, simulated FTEs occur quasi‐periodically every 4–9 s. The properties of simulated FTEs show clear dependencies on the upstream solar wind Alfvénic Mach number (M_A) and the interplanetary magnetic field orientation, consistent with MESSENGER observations and previous Hall‐MHD simulations. FTEs formed in our MHD‐AEPIC model tend to carry a large amount of open flux, contributing ∼3%–36% of the total open flux generated at the dayside. Taken together, our MHD‐AEPIC simulations provide new insights into the kinetic processes associated with Mercury's magnetopause reconnection that should prove useful for interpreting spacecraft observations, such as those from MESSENGER and BepiColombo. 

Abstract Rapid plasma eruptions explosively release energy within Earth’s magnetosphere, at the Sun and at other planets. At Earth, these eruptions, termed plasmoids, occur in the magnetospheric nightside and are associated with sudden brightening of the aurora. The chain of events leading to the plasmoid is one of the longest-standing unresolved questions in space physics. Two competing paradigms have been proposed to explain the course of events. The first asserts that magnetic reconnection changes the magnetic topology in the tail, severing a part of the magnetosphere as plasmoid. The second employs kinetic instabilities that first disrupt the current sheet supporting the magnetotail and launch waves that trigger the topological change to eject the plasmoid. Here we numerically simulate Earth’s magnetosphere at realistic scales using a model that captures the physics underlying both paradigms. We show that both magnetic reconnection and kinetic instabilities are required to induce a global topological reconfiguration of the magnetotail, thereby combining the seemingly contradictory paradigms. Our results help to understand how plasma eruptions may take place, guide spacecraft constellation mission design to capture these ejections in observations and lead to improved understanding of space weather by improving the predictability of the plasmoids.