The role of mass, equation of state and superfluid reservoir in large pulsar glitches

Observations of pulsar glitches may provide insights on the internal physics of neutron stars and recent studies show how it is in principle possible to constrain pulsar masses with timing observations. The reliability of these estimates depend on the current uncertainties about the structure of neutron stars and on our ability to model the dynamics of the superfluid neutrons in the internal layers. We assume a simplified model for the rotational dynamics of a neutron star and estimate an upper bound to the mass of 25 pulsars from their largest glitch and average activity: the aim is to understand to which extent the mass constraints are sensitive to the choice of the unknown structural properties of neutron stars, like the extension of the superfluid region and the equation of state. Reasonable values, within the range measured for neutron star masses, are obtained only if the superfluid domain extends for at least a small region inside the outer core, which is compatible with calculations of the neutron S-wave pairing gap. Moreover, the mass constraints stabilise when the superfluid domain extends to densities over nuclear saturation, irrespective of the equation of state tested.Comment: 11 pages, 6 figure

A universal formula for the relativistic correction to the mutual friction coupling time-scale in neutron stars

Vortex-mediated mutual friction governs the coupling between the superfluid and normal components in neutron star interiors. By, for example, comparing precise timing observations of pulsar glitches with theoretical predictions it is possible to constrain the physics in the interior of the star, but to do so an accurate model of the mutual friction coupling in general relativity is needed. We derive such a model directly from Carter's multifluid formalism, and study the vortex structure and coupling time-scale between the components in a relativistic star. We calculate how general relativity modifies the shape and the density of the quantized vortices and show that, in the quasi-Schwarzschild coordinates, they can be approximated as straight lines for realistic neutron star configurations. Finally, we present a simple universal formula (given as a function of the stellar compactness alone) for the relativistic correction to the glitch rise-time, which is valid under the assumption that the superfluid reservoir is in a thin shell in the crust or in the outer core. This universal relation can be easily employed to correct, a posteriori, any Newtonian estimate for the coupling time-scale, without any additional computational expense.Comment: 20 pages, 7 figure

Antitrust risk in EU manufacturing: A sector-level ranking. Bruegel Working Paper 2014/07, July 2014

The object of this paper is twofold: to provide a broad descriptive analysis of the risk of collusive behaviour throughout Europe in the manufacturing sector; and to identify those manufacturing sectors in which the European Commission has been more active in the past in its capacity of antitrust authority

The doping effect of Italian feed-in tariffs on the PV market

In less than six years, Italy has become one of the leading markets for PV power plants and one of the countries in the world with the largest number of installations and installed peak power. Such a quick and large growth is due to a series of feed-in tariff schemes that have been uncapped until 2012. As a matter of fact, any size or any number of PV power plants could be installed during a period of three years. Since the feed-in tariffs are not paid by national taxes but are charged on the electricity bills, Italian energy users are now due to pay each year a surcharge of 9 billion euros on their energy bills. This paper aims at discussing this development by highlighting the benefits but also some significant drawbacks that the application of uncontrolled feed-in tariffs has produced