Search for eccentric black hole coalescences during the third observing run of LIGO and Virgo

Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass M>70 M⊙) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities 0<e≤0.3 at 0.33 Gpc−3 yr−1 at 90\% confidence level

Ultralight vector dark matter search using data from the KAGRA O3GK run

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U(1)B−L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM

Domestic and transnational perspectives on democratization

The disciplinary separation between comparative politics and international relations is regularly challenged but persists as a result of institutional inertia and hiring practices. This essay uses the issue of democratization in an attempt to go beyond rhetoric and to develop a framework that integrates the role of transnational activism into the analysis of domestic regime change. Comparative research on democratization confirms that underlying socioeconomic conditions affect the long-term sustainability of democratic reforms. The initiation of such reforms, as well as the process they take, can best be understood using an agency-based framework that links domestic and transnational forces. Outside interventions are a potent factor in challenging authoritarian practices, but they do not simply displace existing domestic practices and conditions. Although transnational activists and scholars often celebrate the empowering role of networking and mobilization, the long-term effects of such interventions are still poorly understood. Transnational ties may distract domestic activists from building effective coalitions at home or undermine their legitimacy overall. Transnational scholars and activists can learn from comparative research how different domestic groups use outside interventions to promote their interests at home