Science instruments

The science is feasible using existing technology combined with innovative instrumental capabilities on a single satellite comprising four instruments:

EDGE satellite and payload

• Wide Field Spectrometer (WFS): effective area 1000 cm², 3 eV resolution, 0.7 x 0.7 deg² Field of View (FoV, optics with 2/4 reflections and TES calorimeter as detector

• Wide Field Imager (WFI): effective area 1000 cm², 15” angular resolution constant over the full 1.4^o diameter FoV, CCD detectors

• Wide Field Monitor (WFM): FoV ¼ of the sky, consistent with requirement for follow up measurements of 80 bright bursts per year

• Gamma-Ray Burst Detector (GRBD): extension of energy range of the instruments to 3 MeV

Mission profile

EDGE is feasible as a truly ESA mission within the cost cap of an ESA medium class mission. Its fast repointing (1 deg/s) requires a compact satellite. With a densely packed payload this is compatible with the VEGA launcher. Its low background requires a low Earth equatorial orbit. We have adopted a lifetime of 3 years, appropriate to realize the major goals of the mission with a modest guest observer program. An extension to 5 years is feasible within the budget constraints.

Timeliness of EDGE

EDGE is highly complementary to operational and planned missions:

• the only mission with high spectral resolution (< 3 eV), large GRASP (> 400 cm²deg²) and fast repointing

• 2 orders of magnitude improvement in line detection sensitivity for extended sources compared to existing and planned X-ray missions

• point source sensitivity better than the XMM/Lockman Hole observation for a sky coverage of >10 deg² (XMM/Lockman Hole: 0.25 deg²)

• 1 order of magnitude lower instrumental background than current missions and future observatory X-ray missions (XEUS, Con-X)

• vast increase in redshift coverage through high resolution spectroscopy up to the formation epoch for clusters of galaxies and earliest star formation

• first time high spectral resolution for transient sources (minutes)

The technology is well developed in Europe (Technical Readiness Level ≥ 4) and little risk is involved.

The EDGE collaboration

The EDGE collaboration includes national agencies and major institutions from Italy, Japan, Netherlands, Denmark, France, Germany, Switzerland, UK and the USA. The payload will be provided by institutes from ESA member states, Japan and the USA.