The key capabilities of X-IFU lie in its unprecedented spectral resolution, better than 2.5 eV up to 7 keV, combined with a large effective area, over a 5 arcminute (the equivalent diameter) hexagonal field of view and a low instrumental background. In addition, thanks to the defocussing capability of the telescope, the X-IFU will be able to observe the brightest X-ray sources of the sky, with micro-second time resolution, and yet keeping its excellent spectral resolution.
Before Athena and the X-IFU spectrometer, the Japanese mission XRISM and its instrument Resolve will open the window of spatially-resolved high-resolution X-ray spectroscopy. Resolve may be considered as a pathfinder to the Athena X-IFU. The main performance parameters of the two instruments are shown in the table below:
|Athena X-IFU||XRISM Resolve|
|Spectral resolution||2.5 eV||5 eV|
|Pixel size||5 arcsec||1 arcmin|
|1 keV effective area||~8200 cm2||~220 cm2|
|7 keV effective area||~970 cm2||~230 cm2|
|Maximum source intensity||1 Crab||0.2 Crab|
The X-IFU combines unprecedented capabilities, that are compared below with that of the Resolve spectrometer:
- an improved spectral resolution, around 2 times better;
- a better spatial resolution, around 10 times smaller pixel size for imaging versus Resolve;
- an effective area around 40 times higher at 1 keV and 4 times at 7 keV;
- and the ability to observe very bright sources with intensities about 5 times larger (expressed in units of the X-ray flux of the Crab Nebulae).
Thanks to the spacecraft agility, X-IFU will also have the capability to respond quickly, within a few hours, to target of opportunities, discovered with other facilities on the ground or in space.
For more information, check out this publication.