Despite the eurozone crisis, and the ambivalent attitudes ofthe Turkish public, Turkey still stands to benefit from EUaccession.by Blo

While the EU continues to work toward a solution to the eurozone crisis, Turkey has experienced a period of strong economic growth. Soli Özel argues that although Turkey’s interest in EU membership has declined in the wake of the crisis, the country could still gain substantial benefits from European integration. The crisis may also have a positive effect for Turkey if it produces a more flexible arrangement in the EU’s structure, potentially opening the door for the country’s accession

General Relativistic Effects on Magnetar Models of AXPs

General relativistic bending of light dramatically alters the variability of X-ray emission originating from the surfaces of ultramagnetic neutron stars. We construct radiative equilibrium models of such strongly magnetic cooling neutron stars with light-element atmospheres to compute the angle- and energy-dependent intensity emerging from their surfaces and find that the beaming of surface emission is predominantly non-radial. The combination of this radiation pattern with the calculations of light bending yields pulse amplitudes that vary non-monotonically with the neutron star compactness and the size of the emitting region. The significant suppression of the pulse amplitude for large emitting areas provides very strong constraints on the mechanisms that can simultaneously produce high periodic variability and X-ray luminosity. We apply these results to the thermally-emitting magnetar models of anomalous X-ray pulsars (AXPs), which are bright slowly-rotating X-ray sources with large pulse amplitudes. We use the observed fluxes and pulse amplitudes for all known AXPs and show that thermal emission from two antipodal regions on their surfaces, as predicted by some magnetar models, is inconsistent with these observed properties.Comment: 4 pages, 3 figs, to appear in the Proceedings of the 9th Marcel Grossman Meeting, Rome, 2000 (World Scientific

Spectral Lines from Rotating Neutron Stars

The line profiles from rotating neutron stars are affected by a number of relativistic processes such as Doppler boosts, strong self-lensing, frame-dragging, and the differential gravitational redshift arising from the stellar oblateness. In this Letter, we calculate line profiles taking into account the first two effects, which is accurate for rotation rates less than the breakup frequency. We show that the line profiles are not only broadened and weakened but are also significantly asymmetric, and allow for an independent measurement of both the mass and the radius of the neutron star. Furthermore, we investigate the case when a fraction of the neutron star surface contributes to the emission and find that the line profiles are typically doubly peaked. We discuss the implications of our results for searches for line features in the spectra of isolated neutron stars and X-ray bursters. We finally assess the systematic uncertainties introduced by the line asymmetry in inferring the compactness of neutron stars from the detection of redshifted lines.Comment: 8 pages, submitted to The Astrophysical Journal Letter