The Athena X-ray Observatory: Community Support Portal

  • Athena: revealing the Hot and Energetic Universe

    Athena: revealing the Hot and Energetic Universe

  • Where are the hot baryons and how do they evolve?

  • Reveal the causes and effects of cosmic feedback

  • Track obscured accretion through the epoch of galaxy formation

  • Understand the physics of accretion onto compact objects

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Search WHIM 15 02 17Abstract: "We present the results from the Suzaku satellite of the surrounding region of a galaxy cluster, A2744, at z = 0.3. To search for oxygen emission lines from the warm-hot intergalactic medium (WHIM), we analyzed X-ray spectra from two northeast regions 2.2–3.3 and 3.3– 4.4 Mpc from the center of the cluster, which offers the first test on the presence of a WHIM near the typical accretion shock radius (∼ 2r200) predicted by hydrodynamical simulations. For the 2.2–3.3 Mpc region, the spectral fit significantly (99.2% significance) improved when we include O VII and O VIII lines in the spectral model. A comparable WHIM surface brightness was obtained in the 3.3–4.4 Mpc region and the redshift of O VIII line is consistent with z = 0.3 within errors. The present results support that the observed soft X-ray emission originated from the WHIM. However, considering both statistical and systematic uncertainties, O VIII detection in the northeast regions was marginal. The surface brightness of the O VIII line in 10−7photons cm−2 s−1 arcmin−2 was measured to be 2.7 ± 1.0, 2.1 ± 1.2 for the 2.2–3.3, 3.3– 4.4 Mpc regions, giving the upper limit on the baryon overdensity of δ = 319(< 443), 283(< 446), respectively. This is comparable with previous observations of cluster outskirts and their theoretical predictions. The future prospect for WHIM detection using the Athena X-IFU microcalorimeter is briefly discussed here. In addition, we also derived the ICM temperature distribution of A2744 to detect a clear discontinuity at the location of the radio relic. This suggests that the cluster has undergone strong shock heating by mass accretion along the filament."

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Advanced Telescope for High Energy Astrophysics


Athena (Advanced Telescope for High ENergy Astrophysics) is the X-ray observatory mission selected by ESA, within its Cosmic Vision 2015-2025 programme, to address the Hot and Energetic Universe scientific theme. It is the second L(large)-class mission within that programme and is due for launch in 2028.

Athena will study how hot baryons assemble into groups and clusters of galaxies, determine their chemical enrichment across cosmic time, measure their mechanical energy and characterise the missing baryons which are expected to reside in intergalactic filamentary structures. At the same time, it will study the physics of accretion into compact objects, find the earliest accreting supermassive black holes and trace their growth even when in very obscured environment, and show how they influence the evolution of galaxies and clusters through feedback processes. Athena will also have a fast target of opportunity observational capability, enabling studies and usage of GRBs and other transient phenomena. As an observatory, Athena will offer vital information on high-energy phenomena on all classes of astrophysical objects, from solar system bodies to the most distant objects known. See Science chapter for more details.

Athena will consist of a single large-aperture grazing-incidence X-ray telescope, utilizing a novel technology (High-performance Si pore optics) developed in Europe, with 12m focal length and 5 arcsec HEW on-axis angular resolution. The focal plane contains two instruments. One is the Wide Field Imager (WFI) providing sensitive wide field imaging and spectroscopy and high count-rate capability. The other one is the X-ray Integral Field Unit (X-IFU) delivering spatially resolved high-resolution X-ray spectroscopy over a limited field of view. See Mission chapter for more details.

With its unparalleled capabilities, Athena will be a truly transformational observatory, operating in conjunction with other large observatories across the electromagnetic spectrum available in the late 2020s (like ALMA, E-ELT, JWST, SKA, CTA, etc).