Melania Del Santo

ESTREMO/WFXRT: Extreme phySics in the TRansient and Evolving COsmos

We present a mission designed to address two main themes of the ESA Cosmic Vision Programme: the Evolution of the Universe and its Violent phenomena. ESTREMO/WFXRT is based on innovative instrumental and observational approaches, out of the mainstream of observatories of progressively increasing area, i.e.: Observing with fast reaction transient sources, like GRB, at their brightest levels, thus allowing high resolution spectroscopy. Observing and surveying through a X-ray telescope with a wide field of view and with high sensitivity extended sources, like cluster and Warm Hot Intragalactic Medium (WHIM). ESTREMO/WFXRT will rely on two cosmological probes: GRB and large scale X-ray structures. This will allow measurements of the dark energy, of the missing baryon mass in the local universe, thought to be mostly residing in outskirts of clusters and in hot filaments (WHIM) accreting onto dark matter structures, the detection of first objects in the dark Universe, the history of metal formation. The key asset of ESTREMO/WFXRT with regard to the study of Violent Universe is the capability to observe the most extreme objects of the Universe during their bursting phases. The large flux achieved in this phase allows unprecedented measurements with high resolution spectroscopy. The mission is based on a wide field X-ray/hard X-ray monitor, covering >1/4 of the sky, to localize transients; fast (min) autonomous follow-up with X-ray telescope (2000 cm2) equipped with high resolution spectroscopy transition edge (TES) microcalorimeters (2eV resolution below 2 keV) and with a wide field (1°) for imaging with 10 resolution (CCD) extended faint structures and for cluster surveys. A low background is achieved by a 600 km equatorial orbit. The performances of the mission on GRB and their use as cosmological beacons are presented and discussed.

Dense matter with eXTP

In this White Paper we present the potential of the Enhanced X-ray Timing and Polarimetry (eXTP) mission for determining the nature of dense matter; neutron star cores host an extreme density regime which cannot be replicated in a terrestrial laboratory. The tightest statistical constraints on the dense matter equation of state will come from pulse profile modelling of accretion-powered pulsars, burst oscillation sources, and rotation-powered pulsars. Additional constraints will derive from spin measurements, burst spectra, and properties of the accretion flows in the vicinity of the neutron star. Under development by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Sciences, the eXTP mission is expected to be launched in the mid 2020s.

Sub‐luminous X‐ray Bursters Unveiled with INTEGRAL

In 2005 March 22nd, the INTEGRAL satellite caught a type‐I X‐ray burst from the unidentified source XMMU J174716.1–281048, serendipitously discovered with XMM‐Newton in 2003. Based on the type‐I X‐ray burst properties, we derived the distance of the object and suggested that the system is undergoing a prolonged accretion episode of many years. We present new data from a Swift/XRT campaign which strengthen this suggestion. AX J1754.2–2754 was an unclassified source reported in the ASCA catalogue of the Galactic Centre survey. INTEGRAL observed a type‐I burst from it in 2005, April 16th. Recently, a Swift ToO allowed us to refine the source position and establish its persistent nature.