Found 6 talks width keyword neutron stars

We introduce the strong CP problem and the existence of the Axion as a possible solution. 

We discuss the possibility that axions are the dark matter of the Universe and the possible ways to

detect it or disprove it using: direct laboratory experiments as well as astrophysical and cosmological

The matter within a few Schwarzschild radii of accreting neutron stars and black holes is moving under the influence of a strong gravitational field, and, in stellar mass compact objects, through strongly curved spacetime. The X-rays emitted in the accretion process can be used to diagnose this motion, using both spectroscopy and rapid time variability. Similarly, X-rays emitted from the surface of accreting neutron stars can be used to diagnose neutron star mass, radius and even internal structure. I discuss these ways to probe strong gravitational fields and ultradense matter from an empirical perspective and in the context of proposed future X-ray observatories, in particular, LOFT.

Neutron stars in low-mass X-ray binaries (NS-LMXBs) are unique laboratories of accretion physics, strong gravity and ultra-dense matter. I will give an overview of what we have learned in recent years by studying accretion flows and thermonuclear bursts in these systems.

I will first present and discuss the main result of a systematic study of their different accretion states: the discovery of a correlation between luminosity and spectral hardness. I will also show ongoing work on the connection between active (1-100% of the Eddington luminosity) and quiescent (down to 10^-6 times Eddington) phases of NS-LMXBs.

In the second part I will focus on the relation between mass accretion rate and the recurrence time of thermonuclear bursts (explosive nuclear burning on the neutron star surface), presenting results at the lowest and highest mass accretion rates. In particular, I will argue that rotation plays a larger role than we thought in setting the nuclear burning regimes on an accreting neutron star.

I will review what we know about Type I Bursts (thermonuclear explosions on the surface of accreting Neutron Stars) and burst oscillations (fluctuations in the intensity of the burst lightcurves). I will describe the known problems in burst oscillation models and the various solutions that have been proposed. I will report recent progress made in the case of the pulsar IGR J17480-2446 in the Globular Cluster Terzan 5, where we were able to pin point the most likely mechanism responsible for the oscillations. I will explain whether this might be applicable to the other bursters and discuss future perspectives including current efforts to develop magneto-hydrodynamical simulations of the bursting process.

According to Quantum Chromodynamics, which is the well established theory of strong interactions, quark and gluons are forced to live inside hadrons because of the property of confinement. However, under extreme conditions of temperature and pressure, a new phase called quark-gluon plasma is possible, where quarks and gluons became basically free. In the last years it has been possible to study this phase experimentally by using new facilities called Heavy Ion Colliders like the RHIC (Brookhaven) or the LHC (CERN).

In this talk I will summarise the events that led to the discovery of the first four pulsars, recount several instances where pulsars were almost discovered and reflect on what lessons we might draw from these stories.