eXTP overall concept & updated design Yongwei DONG IHEP, CAS

Scientific requirements on payload Scientific Objectives of XTP –One singularity (BH), Two stars (NS or magnetar), Three extremes (gravity, density, magnetism) Core sciences of LOFT –Strong Field Gravity; Dense Matter –LOFT payloads: ~8 m 2 LAD; 4 WFM pairs ItemRequirementScientific driver Effective area~1 m 2 EOS, BH spins, GR effect Energy range keV broadband spectrum multi- wavelength variability Energy resolution180 keVbroad Iron line measurement Time resolution< 100 μssub-millisecond variability MDP~1% B, emission mechanism; emission geometry Detecting area for polarimeter >1000 cm 2 2/11

XTP payload configuration (Before Roma meeting) eXTP configurationBasic configuration Upper part of XTP (Fixed OB, 2 kinds of FL) 3/11

Payload configuration of eXTP (new) 10 LFAs: FL=4.5 m, Aperture=450mm 5 HFAs: Same FL and same aperture as the LFA. –Reason: enabling more LADs; reducing complexity in mirror development –Multi-layer coating in the center region? –Decision: same optical design as LFA 40 LAD modules (~3 m 2 ) 2 WFM units –Trade-off between number of HFAs and WFMs 4/11

Payload layout of eXTP PayloadConfiguration High energy Focusing Array (HFA) 5 telescopes SGO optics SDD detectors Low energy Focusing Array (LFA) 10 telescopes SGO/Nickel optics CCD (8/10); GPD(2/10) High energy Collimating Array (HCA) 40 LAD modules LIGA collimator (Pb glass) SDD Wide Field Camera (WFC)2 PAIRs of WFM Sunshade layout for LAD modules, WFM pairs and mirrors is crucial. 5/11

FPD of eXTP CCD for LFASDD for HFAGPD on LFA Effective area8*8 mm 2 (+/-3’)26*26 mm 2 (+/-8 ‘)15*15mm 2 (+/-5.8’) Pixel0.5 mm(0.4 ‘)Hexagon(3.2mm,2’)0.1mm(0.078’) Number of pixels16*1619- Energy range0.5~10 keV1-30 keV2-10 keV Energy resolution<180 Time resolution< 100 μs< 10 μs< 500μs SDD layout CCD readout GPD 6/11

Effective area (1) 7/11

Effective area (2) 8/11

Requirements on satellite ItemRequirements Orbit 550km, 28°(14°backup) Lifetime 5 years (expected 10 years ） Attitude Avoid the sun Observation mode Pointing Accuracy of attitude pointing < 0.01° (3σ) Accuracy of attitude measurement < 0.002° (3σ) Attitude stabilization 0.005°/s(3σ) Attitude maneuver <10min in +/-30degree, 20 times/year Data volume3 Tb/day Timing accuracy from platform1 μs 9/11

Orbit & sky visibility Circular orbit –550 km, inclination angle of 28 degree (14 degree) TC&TM at Malindi –Pros: Lower background especially for LAD; lower launching cost –Cons: no long & continuous pointed observation of AGNs, etc Sun avoiding angle –+/-30 degree –To be checked with layout of WFM pairs and thermal design of LAD & FPD Sky visibility (Incli. 20 degree) 10/11

Launcher for eXTP Current choice is CZ-3C, 4200× fairing CZ-7 SERIES –Pros: longer fairing which enables longer FL. –Cons: drop in effective area in soft X-ray; higher launching cost More shells needed for longer FL 11/11

Memorabilia - Collaboration between XTP & LOFT , 1 st XTP-LOFT collaboration meeting in Beijing ~09, 2 nd XTP-LOFT collaboration meeting in Geneva , the president of CNSA, Mr. Dazhe Xu, visited ASI , Marco Feroci (LOFT PI) visited CAST and was received by CNSA officials ~04, eXTP Roma meeting ~27, mini workshop on eXTP science and eXTP international workshop in Beijing 12/11