Urban Conflicts

Three sources of urban conflicts are identified: (1) changing state-city relationships; (2) the relationship between the dynamics of capitalist development and cities and (3) the specific dynamics of urban life and the urban environment where the city itself is seen as a causal variable. Two sets of questions cross-cut all three strands. The first addresses how violent conflicts can be regulated, transformed and rendered into more constructive non-violent conflicts through the processes of urban civil society. The second concerns how, why, and where urban conflicts turn violent and with what consequences. In summary cities now rival states as arenas and stakes in political conflict and urban conflicts have increasing transnational and transcultural salience which underlines the necessity for sustained comparative analyis

The peculiar Type Ia supernova iPTF14atg: Chandrasekhar-mass explosion or violent merger?

iPTF14atg, a subluminous peculiar Type Ia supernova (SN Ia) similar to SN 2002es, is the first SN Ia for which a strong UV flash was observed in the early-time light curves. This has been interpreted as evidence for a single-degenerate (SD) progenitor system, where such a signal is expected from interactions between the SN ejecta and the non-degenerate companion star. Here, we compare synthetic observables of multidimensional state-of-the-art explosion models for different progenitor scenarios to the light curves and spectra of iPTF14atg. From our models, we have difficulties explaining the spectral evolution of iPTF14atg within the SD progenitor channel. In contrast, we find that a violent merger of two carbon-oxygen white dwarfs with 0.9 and 0.76 M⊙, respectively, provides an excellent match to the spectral evolution of iPTF14atg from 10 d before to several weeks after maximum light. Our merger model does not naturally explain the initial UV flash of iPTF14atg. We discuss several possibilities like interactions of the SN ejecta with the circumstellar medium and surface radioactivity from an He-ignited merger that may be able to account for the early UV emission in violent merger models.