GW190814: gravitational waves from the coalescence of a 23 solar mass black hole with a 2.6 solar mass compact object

We report the observation of a compact binary coalescence involving a 22.2–24.3 Me black hole and a compact object with a mass of 2.50–2.67 Me (all measurements quoted at the 90% credible level). The gravitational-wave signal, GW190814, was observed during LIGO’s and Virgo’s third observing run on 2019 August 14 at 21:10:39 UTC and has a signal-to-noise ratio of 25 in the three-detector network. The source was localized to 18.5 deg2 at a distance of - + 241 45 41 Mpc; no electromagnetic counterpart has been confirmed to date. The source has the most unequal mass ratio yet measured with gravitational waves, - + 0.112 0.009 0.008, and its secondary component is either the lightest black hole or the heaviest neutron star ever discovered in a double compact-object system. The dimensionless spin of the primary black hole is tightly constrained to �0.07. Tests of general relativity reveal no measurable deviations from the theory, and its prediction of higher-multipole emission is confirmed at high confidence. We estimate a merger rate density of 1–23 Gpc−3 yr−1 for the new class of binary coalescence sources that GW190814 represents. Astrophysical models predict that binaries with mass ratios similar to this event can form through several channels, but are unlikely to have formed in globular clusters. However, the combination of mass ratio, component masses, and the inferred merger rate for this event challenges all current models of the formation and mass distribution of compact-object binaries

Predicting current and future distribution of Hovenia dulcis Thunb. (Rhamnaceae) worldwide

Biological invasions are increasingly recognized as one of the major threats to biodiversity. The Japanese raisin tree (Hovenia dulcis) is native to East Asia, however, in southeastern South America this species has become one of the most pervasive invaders. Hovenia dulcis has many biological characteristics that favor the process of invasion and few studies have indicated changes in the structure and composition of native plant communities where this species has become invader. Given the invasiveness shown in southeastern South America, our main goal was to identify the potentially suitable habitats for this invasive species at a global scale. In this sense, we modeled the potential distribution of H. dulcis along the terrestrial areas worldwide using an ensemble forecasting approach. Additionally, the percentage of overlapping biodiversity hotspot areas with the currently suitable areas for this species was calculated. Our results revealed that the current potential H. dulcis range is equivalent to 7.88% (12,719,365 km2) of the terrestrial area worldwide. For the future scenarios of climate change, the potential distribution area tends to have a small reduction. However, significant suitable areas were identified for H. dulcis range in the northern limits of the boreal distribution. Currently, around 17% of biodiversity hotspot areas overlap with the suitable areas for H. dulcis occurrence. In summary, given that the prevention is well-recognized as a more effective management action against invasive alien species, it is essential to implement policies to prevent H. dulcis introduction in suitable areas worldwide, as well as local population control, especially in biodiversity hotspots