Caption: Broad band throughput of the Athena/X-IFU for high-resolution events (2.5 eV) as a function of the point source flux expressed in mCrab. 1 mCrab generates 66 counts/s over the full detector array. The blue curve represents the throughput for a point source on focus, while the red curve corresponds to the case where the mirror is out of focus by 35 mm. The performance of the current detector configuration exceeds the goal specification by about a factor of 3. The driving science case for the 2.5 eV throughput is the detection of the Warm Hot Intergalactic Medium, using bright gamma-ray burst afterglows, as background sources.

Additional comments: The Crab spectrum assumed in the simulation is a power law with a photon index of 2.1, a normalization of 9.5 and an N_H of 3x10²¹ cm^-2. A high-resolution event is defined as an event for which the time since the previous event is ≥ 3.2 ms and the time to the next event is ≥ 52.4 ms, and for which the crosstalk error is below 0.2 eV.

Reference: The X-IFU throughput budget, P. Peille, T. Dauser, R. den Hartog, C. Kirsch, E. Cucchetti, M. Lorenz, 2018, X-IFU internal note, XIFU-TN-SYS-00175-CNES, version 2.1.

Creation date: 15/11/2018 09:01:07. Version #: 2.

Credits: X-IFU Consortium. Copyrights: © DB/X-IFU.