The structure and signals of neutron stars, from birth to death

Abstract

Neutron stars (NSs) represent an active area of research: from their birth following the collapse of massive stars in supernova explosions, through their lives as hot thermal sources, radio pulsars and/or magnetars, up to their catastrophic demise (when they reside in compact binaries) following gravitational wave-driven coalescence. Progress in understanding the structure and signals of neutron stars demands expertise across a wide range of disciplines: from theoretical and observational astrophysics to nuclear and particle physics, computational relativity and gravitational wave (GW) physics. Several recent developments suggested that the time was ripe for a workshop focusing on all facets of NS science. These include: the recent discovery of a 2 solar mass neutron star; evidence for cooling of the NS in Cas A, suggesting a possible transition to neutron superfluidity; ‘advanced’ generation GW detectors LIGO and Virgo coming online in 2015; new observations challenging traditional models for gamma-ray bursts; new lab experiments which aim to probe the conditions of matter at ultrahigh densities and temperatures (e.g. NICA - Dubna); and new or planned electromagnetic observatories at radio (LOFAR/ASKAP/MeerKAT/SKA), optical (e.g. LSST), X-ray (NICER/LOFT/AXTAR/Athena+), and gamma-ray (e.g. CTA) wavelengths. This workshop brought together theoretical and observational astrophysicists from across the electromagnetic and GW spectrum, as well as nuclear physicists interested in the behavior of matter under extreme conditions. The goal was to explore what has been learned from current observations, to review what is expected from new facilities and to assess what exploratory work is required to lay the groundwork for these new capabilities. Throughout the workshop, senior researchers delivered lectures to PhD students, young postdoctoral researchers, and to other senior researchers wishing to expand their own knowledge. Lectures covered topics in high density matter, superfluidity, cooling of neutron stars, explosive phenomena, analysis of data from x-ray satellites, and gravitational wave emission. A general conference was also organized during the workshop and about 150 people took part.