Non-Thermal Emission From Astrophysical Shocks and Their Observational Implications
CitationWang, Xiawei. 2019. Non-Thermal Emission From Astrophysical Shocks and Their Observational Implications. Doctoral dissertation, Harvard University, Graduate School of Arts & Sciences.
AbstractThis thesis presents a series of studies on the non-thermal emission produced by collisionless shocks in various astrophysical systems and their observational implications. First, we discuss the hydrodynamics and multi-messengers from AGN outflows, which account for the missing component of the extragalactic gamma-ray background, cumulative neutrino background and ultra high energy cosmic rays. This is the first model that simultaneously accounts for all three messengers at their observed levels without parameters tuning. Next, we introduce a new model for the ignition of star formation in low-mass halos at high redshifts that otherwise do not form stars. A passing shock could trigger star formation and generate a self-sustaining starburst front. This model makes new predictions for illuminated cosmic filaments that can by tested by state-of-the-art instrumentation. In addition, we discuss star formation in AGN outflows in massive galaxies as a new mechanism for hypervelocity star production. Moreover, we show that non-thermal emission can be used to probe floating black holes in the Milky Way as well as gaseous halos at high redshifts. Finally, we branch out the application to planetary systems. The interaction between the planet's magnetoshpere and the stellar wind of the host star produces a bow shock that produces non-thermal emission detectable in multi-wavelengths. This opens a new window for the detection of exoplanet systems as well as provide constraints on their physical properties.
Citable link to this pagehttp://nrs.harvard.edu/urn-3:HUL.InstRepos:42029679
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