Matched-filtering and parameter estimation of ringdown waveforms

Using recent results from numerical relativity simulations of non-spinning binary black hole mergers we revisit the problem of detecting ringdown waveforms and of estimating the source parameters, considering both LISA and Earth-based interferometers. We find that Advanced LIGO and EGO could detect intermediate-mass black holes of mass up to about 1000 solar masses out to a luminosity distance of a few Gpc. For typical multipolar energy distributions, we show that the single-mode ringdown templates presently used for ringdown searches in the LIGO data stream can produce a significant event loss (> 10% for all detectors in a large interval of black hole masses) and very large parameter estimation errors on the black hole's mass and spin. We estimate that more than 10^6 templates would be needed for a single-stage multi-mode search. Therefore, we recommend a "two stage" search to save on computational costs: single-mode templates can be used for detection, but multi-mode templates or Prony methods should be used to estimate parameters once a detection has been made. We update estimates of the critical signal-to-noise ratio required to test the hypothesis that two or more modes are present in the signal and to resolve their frequencies, showing that second-generation Earth-based detectors and LISA have the potential to perform no-hair tests.Comment: 19 pages, 9 figures, matches version in press in PR

Homicide Rates in Fragile Democracies : Reflections on the Paradoxes of Latin America

This article analyzes the relationship between the quality of democracy and homicide rates in Latin America Our hypothesis is that governments with authoritarian tendencies in Latin America do not necessarily have higher homicide rates than those without these tendencies Our research focuses analyzing the quality of democracy in four countries Brazil and Colombia categorized as weak democracies and Peru and Bolivia considered hybrid regimes Secondary data obtained from the Economist Intelligence Unit Our World in Data and the World Bank Group websites were used for this analysis Findings indicate that weakening of institutions is an important contributor to homicide rates in weak democracies Brazil and Colombia However this factor has less of an impact on homicide rates in hybrid regime countries Peru and Bolivia where the fragility of democracy coexists with lower homicide rate