The ATHENA x-ray integral field unit (X-IFU)

Abstract

The X-ray Integral Field Unit (X-IFU) is the high resolution X-ray spectrometer of the ESA Athena X-ray observatory. Over a field of view of 5' equivalent diameter, it will deliver X-ray spectra from 0.2 to 12 keV with a spectral resolution of 2.5 eV up to 7 keV on ∼ 5" pixels. The X-IFU is based on a large format array of super-conducting molybdenum-gold Transition Edge Sensors cooled at ∼ 90 mK, each coupled with an absorber made of gold and bismuth with a pitch of 249 µm. A cryogenic anti-coincidence detector located underneath the prime TES array enables the non X-ray background to be reduced. A bath temperature of ∼ 50 mK is obtained by a series of mechanical coolers combining 15K Pulse Tubes, 4K and 2K Joule-Thomson coolers which pre-cool a sub Kelvin cooler made of a 3 He sorption cooler coupled with an Adiabatic Demagnetization Refrigerator. Frequency domain multiplexing enables to read out 40 pixels in one single channel. A photon interacting with an absorber leads to a current pulse, amplified by the readout electronics and whose shape is reconstructed on board to recover its energy with high accuracy. The defocusing capability offered by the Athena movable mirror assembly enables the X-IFU to observe the brightest X-ray sources of the sky (up to Crab-like intensities) by spreading the telescope point spread function over hundreds of pixels. Thus the X-IFU delivers low pile-up, high throughput (> 50%), and typically 10 eV spectral resolution at 1 Crab intensities, i.e. a factor of 10 or more better than Silicon based X-ray detectors. In this paper, the current X-IFU baseline is presented, together with an assessment of its anticipated performance in terms of spectral resolution, background, and count rate capability. The X-IFU baseline configuration will be subject to a preliminary requirement review that is scheduled at the end of 2018.The X-IFU will be provided by an international consortium led by France, the Netherlands and Italy, with further ESA member state contributions from Belgium,

X-ray study of spatial structures in Tycho’s supernova remnant using unsupervised deep learning

“…Developing such methods is important for making the best use of the currently available data and for addressing the growing quality and quantity of future observational data. Model fitting of spectra is generally time-intensive; thus, the difficulty of spectral analysis is expected to increase steeply with successful implementation of an X-ray microcalorimeter (such as Athena; Barret et al 2018). The suggested unsupervised method can reveal characteristic features directly from raw observational data without spectral model fitting.…”

“…Because of this complexity, conventional analyses can be prone to human bias and oversight. In the near future, a dramatic improvement in the energy resolution of X-ray observations is expected; e.g., XRISM will have an energy resolution of several electron volts (Tashiro et al 2018), and Athena will have a spectral resolution of 2.5 eV up to 7 keV at a spatial resolution of ∼5 arcsec with ∼4000 pixels (Barret et al 2018). Detailed analysis of such data may require excessive human resources.…”

The abundance and physical properties of O vii and O viii X-ray absorption systems in the EAGLE simulations

“…For the O vii resonant line, we use values consistent with theirs: λ = 21.6019Å and f osc = 0.696, but ours come from a data compilation by Kaastra (2018). The other O vii He-like lines (forbidden and intercombination) have wavelengths sufficiently far from the resonant line (e.g., Bertone et al 2010a) that these should be clearly separated from each other at the resolutions achieved by instruments aboard Arcus (Smith et al 2016;Brenneman et al 2016), Athena (Lumb et al 2017Barret et al 2018), and Lynx (The Lynx Team 2018) (see Sections 3.2 and 4.1 for further discussion of the telescopes and instruments). Therefore, we only discuss the resonant line here, and note that for lines at the detection limits of these instruments, the lines are not blended.…”

Building a cluster: shocks, cavities, and cooling filaments in the group–group merger NGC 6338

“…The Athena X-ray observatory (Nandra et al 2013), expected to launch in the mid 2030s, may offer a opportunity to resolve this issue. In addition to a very large collecting area (1.4 m 2 at 1 keV), Athena will carry an X-ray Integral Field Unit (X-IFU Barret et al 2018), a cryogenically cooled imaging spectrograph with a ∼5diameter field of view, 5 pixels, and 2.5 eV spectral resolution. This unprecedented combination of spatial and spectral resolution offers the opportunity to map the velocity structure of the IGM by measuring the redshift of X-ray emission lines.…”