The Athena X-ray Integral Field Unit: a consolidated design for the system requirement review of the preliminary definition phase

Abstract

The Athena X-ray Integral Unit (X-IFU) is the high resolution X-ray spectrometer studied since 2015 for flying in the mid-30s on the Athena space X-ray Observatory. Athena is a versatile observatory designed to address the Hot and Energetic Universe science theme, as selected in November 2013 by the Survey Science Committee. Based on a large format array of Transition Edge Sensors (TES), X-IFU aims to provide spatially resolved X-ray spectroscopy, with a spectral resolution of 2.5 eV (up to 7 keV) over a hexagonal field of view of 5 arc minutes (equivalent diameter). The X-IFU entered its System Requirement Review (SRR) in June 2022, at about the same time when ESA called for an overall X-IFU redesign (including the X-IFU cryostat and the cooling chain), due to an unanticipated cost overrun of Athena. In this paper, after illustrating the breakthrough capabilities of the X-IFU, we describe the instrument as presented at its SRR (i.e. in the course of its preliminary definition phase, so-called B1), browsing through all the subsystems and associated requirements. We then show the instrument budgets, with a particular emphasis on the anticipated budgets of some of its key performance parameters, such as the instrument efficiency, spectral resolution, energy scale knowledge, count rate capability, non X-ray background and target of opportunity efficiency. Finally, we briefly discuss the ongoing key technology demonstration activities, the calibration and the activities foreseen in the X-IFU Instrument Science Center, touch on communication and outreach activities, the consortium organisation and the life cycle assessment of X-IFU aiming at minimising the environmental footprint, associated with the development of the instrument. Thanks to the studies conducted so far on X-IFU, it is expected that along the design-to-cost exercise requested by ESA, the X-IFU will maintain flagship

Evidence of a Massive Stellar Disruption in the X-Ray Spectrum of ASASSN-14li

“…Given that long observations are needed to perform detailed spectroscopic and variability studies in bright TDEs and Seyferts using Chandra, XMM-Newton, and NuSTAR, it is clear that additional progress will require more sensitive instruments. The Athena/X-IFU will provide a resolution of 2 eV across the 0.3-10.0 keV passband, and an effective area nearly 2 orders of magnitude higher than that of the RGS in the 0.3-0.5 keV band where the crucial N and C lines are found (Barret et al 2023). The proposed Arcus Probe mission will deliver even higher resolution at long wavelengths, and simultaneous UV coverage (Smith et al 2022).…”

Development of the microcalorimeter and anticoincidence detector for the Line Emission Mapper x-ray probe

“…The design of LMS instrument takes advantage of decades of development of microcalorimeter detector systems for spaceflight and relies heavily on heritage from the microcalorimeter instrument on Hitomi's soft x-ray spectrometer (SXS), 8 and from the twice flown microcalorimeter sounding rocket experiment, Micro-X, 9 which was the first instance of TES detectors being flown in space. TES microcalorimeters and TDM SQUID readouts are baselined for the X-ray Integral Field Unit (X-IFU) on the Athena x-ray observatory, 10 and TES microcalorimeters are also baselined for the Lynx x-ray microcalorimeter instrument on the Lynx observatory. 11,12 Details of the full LMS architecture, including the cooling system, focal plane assembly, and detector chain architecture, can be found in Ref.…”

Development of space-flight room-temperature electronics for the Line Emission Mapper Microcalorimeter Spectrometer

“…[11][12][13] The AwaXe ASIC is currently under development at the Astroparticle and Cosmology Laboratory in Paris and was initially designed for the European Space Agency's Athena X-IFU. 14 Within the ASIC is an LNA to amplify the output signal coming from the SSA. The amplified error signal is interfaced to the column PCB of the DEEP, digitized using a high-speed digitizer ADC, and then processed in an FPGA to generate feedback signals for the SQ1 mux and the SSA at two high-speed DACs.…”