Mission analysis and preliminary spacecraft design of the enhanced x-ray timing and polarimetry observatory

Abstract

The enhanced X-ray Timing and Polarimetry Observatory (eXTP) is a flagship international collaboration mission led by Chinese Academy of Sciences, with a large contribution from more than 20 European institutes. eXTP mission is designed to study the equation of state of ultra-dense matter under extreme conditions of strong density, gravity and magnetic field. The satellite carries four main instruments, including the Spectroscopy Focusing Array (SFA), the Large Area Detector (LAD), the Polarimetry Focusing array (PFA) and the Wide Field Monitor (WFM), enabling simultaneous spectral-timing-polarimetry studies of celestial sources in the energy range from 0.5-30 keV. The satellite will fly at a near-zero-inclination Low Earth Orbit, and is featured with long-time steady high-precision coaxial pointing, near realtime burst alert distribution, and follow-up maneuver capabilities. This paper describes the primary mission requirements and constraints, and presents an overall mission analysis including orbit analysis, pointing strategy, and board-ground communications, etc. The preliminary design of eXTP satellite is also introduced, including satellite overall configuration, observation modes, avionics architecture and development plan.

Electromagnetic signatures of strong-field gravity from accreting black holes

“…A critical point emerges specifically due to the effect of light bending, and it results in a transition from wobbling to continuous rotation of Ψ at a certain distance of the source. The polarization properties have been employed in NIR spectral band from ground based observations, but not yet in the X-ray domain to constrain the parameters of the central black hole; this should be possible with several upcoming satellite missions in the near future (Krawczynski et al, 2019;Zhang et al, 2019a;Chen et al, 2020). Much as interesting the theoretical possibility appears to be, its practical use will be very challenging because the effect of polarization changes tends to reduce the overall polarization degree of the source in comparison with the case when strong gravity is not present.…”

Experimental dielectronic recombination rate coefficients for lithium-like 40Ca17+

“…After the great success of these projects, the space-based x-ray observations limits is now being pushed towards the investigations of more far off cosmos and to the faint sources with new missions which have hundred times higher resolution power than that of the Chandra and XMM-Newton [21]. These new x-ray space missions includes the Spectrum Roentgen Gamma (eRosita and ART-XC telescopes) [22], x-ray Imaging and Spectroscopy Mission [23], enhanced x-ray Timing and Polarimetry Mission [24], and Advanced Telescope for High ENergy Astrophysics [25] etc. Owing to the large range of observation which consists of soft x-ray energy band-pass of ∼0.1-10 keV, these missions will be capable to observe very high-resolution x-ray spectra of L-shell and M-shell from several astrophysical abundant elements.…”

The wide field monitor onboard the Chinese-European x-ray mission eXTP

“…But it is also aimed to be a powerful X-ray observatory, acting as a discovery machine of the transient and variable X-ray sky. Its scientific payload includes four instruments: SFA (Spectroscopy Focusing Array), PFA (Polarimetry Focusing Array), LAD (Large Area Detector) and WFM (Wide Field Monitor); see Figure 1 for an artist's impression of the eXTP satellite with all its instruments onboard (see W. Chen et al 2 ). The set of eXTP instruments offers an unprecedented simultaneous wide-band X-ray timing and polarimetry sensitivity.…”

“…These detectors work in the (0.5-10) keV energy range, with an energy resolution better than 180 eV at 6 keV. Each one of the 4 PFA focal planes include a Gas Pixel Detector, designed in Italy, working in the (2)(3)(4)(5)(6)(7)(8) keV energy range, with an energy resolution better than 25% at 6 keV and polarimetric capability.…”