Confusing Head-On Collisions with Precessing Intermediate-Mass Binary Black Hole Mergers

We report a degeneracy between the gravitational-wave signals from quasi-circular precessing black-hole mergers and those from extremely eccentric mergers, namely head-on collisions. Performing model selection on numerically simulated signals of head-on collisions using models for quasi-circular binaries we find that, for signal-to-noise ratios of 15 and 25, typical of Advanced LIGO observations, head-on mergers with respective total masses of $M\in (125,300)M_\odot$ and $M\in (200,440)M_\odot$ would be identified as precessing quasi-circular intermediate-mass black hole binaries, located at a much larger distance. Ruling out the head-on scenario would require to perform model selection using currently nonexistent waveform models for head-on collisions, together with the application of astrophysically motivated priors on the (rare) occurrence of those events. We show that in situations where standard parameter inference of compact binaries may report component masses inside (outside) the pair-instability supernova gap, the true object may be a head-on merger with masses outside (inside) this gap. We briefly discuss the potential implications of these findings for the recent gravitational-wave detection GW190521, which we analyse in detail in [Phys. Rev. Lett. 126, 081101]

The Macroeconomic Consequences of Microeconomic Phenomena in the Housing and Labor Markets

This dissertation consists of three independent chapters, each of which use microeconomic data and methods to inform an analysis of macroeconomic models and questions. The first two chapters study the short-run dynamics of housing markets, while the last chapter studies fluctuations in labor markets.Economic

Spontaneous scalarization of charged Black Holes

Extended scalar-tensor Gauss-Bonnet (ESTGB) gravity has been recently argued to exhibit spontaneous scalarization of vacuum black holes (BAs). A similar phenomenon can be expected in a larger class of models, which includes, e.g., Einstein-Maxwell scalar (EMS) models, where spontaneous scalarization of electrovacuum BHs should occur. EMS models have no higher curvature corrections, a technical simplification over ESTGB models that allows us to investigate, fully nonlinearly, BH scalarization in two novel directions. First, numerical simulations in spherical symmetry show, dynamically, that Reissner-Nordstrom (RN) BHs evolve into a perturbatively stable scalarized BH. Second, we compute the nonspherical sector of static scalarized BH solutions bifurcating from the RN BH trunk. Scalarized BHs form an infinite (countable) number of branches and possess a large freedom in their multipole structure. Unlike the case of electrovacuum, the EMS model admits static, asymptotically flat, regular on and outside the horizon BHs without spherical symmetry and even without any spatial isometrics, which are thermodynamically preferred over the electrovacuum state. We speculate on a possible dynamical role of these nonspherical scalarized BHs.publishe

Liquid phase exfoliation of carbonate-intercalated layered double hydroxides

Direct exfoliation of a carbonate layered double hydroxide (LDHs) has been achieved by using a novel horn‐probe sonic tip, avoiding the development of time‐consuming anion‐exchange reactions. Most suitable solvents were chosen based on the Hildebrand solubility parameters and the thickness of the exfoliated nanosheets confirmed unambiguously the successful delamination

Reverse Semi-Combustion Driven by Titanium Dioxide-Ionic Liquid Hybrid Photocatalyst

EP/L015633/1 EP/K005138/1 CAPES (158804/2017/01-and 001 FAPERGS -16/2552-0000 18/2551-0000561-4 88887.195052/2018-00 CNPq :406260/2018-4 169462/2017-0 406750/2016-5 465454/2014-3 grant agreement No 810310Unprecedented metal-free photocatalytic CO2 conversion to CO (up to 228±48 μmol g−1 h−1) was displayed by TiO2@IL hybrid photocatalysts prepared by simple impregnation of commercially available P25-titanium dioxide with imidazolium-based ionic liquids (ILs). The high activity of TiO2@IL hybrid photocatalysts was mainly associated to (i) TiO2@IL red shift compared to the pure TiO2 absorption, and thus a modification of the TiO2 surface electronic structure; (ii) TiO2 with IL bearing imidazolate anions lowered the CO2 activation energy barrier. The reaction mechanism was postulated to occur via CO2 photoreduction to formate species by the imidazole/imidazole radical redox pair, yielding CO and water.publishersversionpublishe