The Large Observatory for X-ray Timing (LOFT)

Abstract

M. Feroci et al.Abstract High-time-resolution X-ray observations of compact objects provide direct access to strong-field gravity, to the equation of state of ultradense 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 M3 candidate missions to undergo an assessment phase, will revolutionise the study of collapsed objects in our galaxy and of the brightest supermassive black holes in active galactic nuclei. Thanks to an innovative design and the development of large-area monolithic silicon drift detectors, the Large Area Detector (LAD) on board LOFT will achieve an effective area of ∼12 m 2 (more than an order of magnitude larger than any spaceborne predecessor) in the 2-30 keV range (up to 50 keV in expanded mode), yet still fits a conventional platform and small/medium-class launcher. With this large area and a spectral resolution of <260 eV, LOFT will yield unprecedented information on strongly curved spacetimes and matter under extreme conditions of pressure and magnetic field strength.

X-ray reverberation around accreting black holes

“…as suggested for use on the proposed Large Observatory for X-ray Timing, LOFT (Feroci et al 2012). This technology could affordably reach collecting areas two orders of magnitude larger than XMM-Newton at Fe K and harder energies, while maintaining CCD-like energy resolution.…”

Implications of the gravitational wave event GW150914

“…In turn, this would improve the prospects that analysis of gravitational waveforms from NS-NS or NS-BH binaries will inform us about the properties of those stars. In particular, if the radius of these stars as well as their masses can be inferred with precision and reliability, this will serve as a valuable input to nuclear physics theories (see [164,165,166] for a discussion of the current systematics-dominated estimates of radii, as well as of the good prospects for measuring radii using X-ray observations with the NASA mission NICER [167] and the planned European Space Agency (ESA) mission LOFT [168]). Plans are also being made for third-generation detectors such as the proposed Einstein Telescope [169], which would have 10-km underground arms and many other advances; this could reach ten times the sensitivity of Advanced LIGO and would thus greatly increase both the rates and precision of observations.…”

Multi-Wavelength Variability

“…The development of large-area silicon-drift detectors puts such detector areas within reach for launch in the 2020s, e.g. the proposed LOFT mission (Feroci et al 2012). Furthermore, in the soft X-ray band the ATHENA mission, which is now confirmed for launch in the late 2020s, will allow significant advances in studying lags of disc blackbody components and soft X-ray reverberation in AGN (Nandra et al 2013).…”