Distinguishing spin-aligned and isotropic black hole populations with gravitational waves.

The direct detection of gravitational waves from merging binary black holes opens up a window into the environments in which binary black holes form. One signature of such environments is the angular distribution of the black hole spins. Binary systems that formed through dynamical interactions between already-compact objects are expected to have isotropic spin orientations (that is, the spins of the black holes are randomly oriented with respect to the orbit of the binary system), whereas those that formed from pairs of stars born together are more likely to have spins that are preferentially aligned with the orbit.

Formation of the first three gravitational-wave observations through isolated binary evolution.

During its first four months of taking data, Advanced LIGO has detected gravitational waves from two binary black hole mergers, GW150914 and GW151226, along with the statistically less significant binary black hole merger candidate LVT151012. Here we use the rapid binary population synthesis code COMPAS to show that all three events can be explained by a single evolutionary channel-classical isolated binary evolution via mass transfer including a common envelope phase. We show all three events could have formed in low-metallicity environments (Z=0.

Socioeconomic variation in incidence of epilepsy: prospective community based study in south east England.

Objective: To determine the incidence of epilepsy in a general practice population and its variation with socioeconomic deprivation.

Design: Prospective surveillance for new cases over an 18 or 24 month period.

Participants: All patients on practice registers categorised for deprivation with the Carstairs score of their postcode.