0000000000471825
AUTHOR
T. Belloni
The Large Observatory for X-ray Timing (LOFT)
High-time-resolution X-ray observations of compact objects provide direct access to strong-field gravity, to the equation of state of ultra-dense matter and to black hole masses and spins. A 10 m^2-class instrument in combination with good spectral resolution is required to exploit the relevant diagnostics and answer two of the fundamental questions of the European Space Agency (ESA) Cosmic Vision Theme "Matter under extreme conditions", namely: does matter orbiting close to the event horizon follow the predictions of general relativity? What is the equation of state of matter in neutron stars? The Large Observatory For X-ray Timing (LOFT), selected by ESA as one of the four Cosmic Vision M…
The NHXM observatory
Exploration of the X-ray sky has established X-ray astronomy as a fundamental astrophysical discipline. While our knowledge of the sky below 10 keV has increased dramatically (∼8 orders of magnitude) by use of grazing incidence optics, we still await a similar improvement above 10 keV, where to date only collimated instruments have been used. Also ripe for exploration is the field of X-ray polarimetry, an unused fundamental tool to understand the physics and morphology of X-ray sources. Here we present a novel mission, the New Hard X-ray Mission (NHXM) that brings together for the first time simultaneous high-sensitivity, hard-X-ray imaging, broadband spectroscopy and polarimetry. NHXM will…
LOFT - A large observatory for x-ray timing
The high time resolution observations of the X-ray sky hold the key to a number of diagnostics of fundamental physics, some of which are unaccessible to other types of investigations, such as those based on imaging and spectroscopy. Revealing strong gravitational field effects, measuring the mass and spin of black holes and the equation of state of ultradense matter are among the goals of such observations. At present prospects for future, non-focused X-ray timing experiments following the exciting age of RXTE/PCA are uncertain. Technological limitations are unavoidably faced in the conception and development of experiments with effective area of several square meters, as needed in order to…
X-ray bursts and burst oscillations from the slowly spinning X-ray pulsar IGR J17480-2446 (Terzan 5)
The newly discovered 11-Hz accreting pulsar, IGR J17480-2446, located in the globular cluster Terzan 5, has shown several bursts with a recurrence time as short as a few minutes. The source shows the shortest recurrence time ever observed from a neutron star. Here we present a study of the morphological, spectral and temporal properties of 107 bursts observed by the Rossi X-ray Timing Explorer. The recurrence time and the fluence of the bursts clearly anticorrelate with the increase in the persistent X-ray flux. The ratio between the energy generated by the accretion of mass and that liberated during bursts indicates that helium is ignited in a hydrogen-rich layer. Therefore, we conclude th…