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Integrated Activities for the High Energy Astrophysics Domain

Periodic Reporting for period 3 - AHEAD (Integrated Activities for the High Energy Astrophysics Domain)

Reporting period: 2018-09-01 to 2019-02-28

High energy (HE) astrophysics investigates the most extreme phenomena in the hot and energetic Universe. Most of the normal matter resides in a very hot gas. Black holes form in explosions at the edge of the Universe or harbour in the centre of normal galaxies, including our own. All these sources shine in X- and gamma-rays and can be best studied by HE astrophysics. Such studies are necessary to gather a more complete view of how our Universe works. Because our atmosphere is opaque to X-rays and gamma-rays, HE telescopes have to be placed above it. Thus space-based technology is needed to enable the study of the Universe at high energies. Access to space requires a strong level of coordination and long- term planning. The objective achieved by AHEAD is to integrate national efforts in HE astrophysics and to promote the domain at the European level, keeping its community at the cutting edge of science and technology and ensuring that space observatories for high-energy astrophysics are at the state of the art. AHEAD integrated key research infrastructures for on-ground test of space-based technology and made the best facilities for data analysis of high-energy astrophysical observatories available to the European community. It supported the scientific community via grants for collaborative studies, dissemination of results, and promotion of workshops. The technological development has focussed on the improvement of selected critical technologies for enhancing the science return of future high energy missions, in particular Athena, the large X-ray telescope by ESA, to be launched at the end of the next decade. Such a longstanding effort is also built upon the best exploitation of existing observatories. Feasibility studies for the more energetic gamma-ray missions have successfully led to mission concepts being currently studied by ESA.
AHEAD has shown that the technology employed to collect the faintest X-ray signals emitted by sources at the edge of the Universe, can also be profitably applied in applications for biology, medicine, fine art, environment. Finally, a strong public outreach package has ensuredthat the domain is well publicized at national, European and International level.
AHEAD encompassed a broad range of activities and their links are visualized in Fig.1. A fundamental heritage by AHEAD is the high level of collaborating attitude developed by the institutes and the high level of sustainability, whereby most of the AHEAD results will continue to be exploited by our community throughout other collaborative projects.
"Overall, all the objectives targeted by AHEAD have been successfully met. Joint research activities (JRA) provided the expected results. Many technology developments aimed at improving the scientific performances of the Athena mission. This goal has been successfully achieved in critical areas encompassing optics, detector and mission profile. Moreover, the innovation JRA has identified a promising innovative concept for application of the high resolution detectors developed in AHEAD outside the HE astronomy domain. The gamma-ray WP has been successful in clustering the gamma-ray community in focussing the scientific priorities and selected profiles for future mission concepts, now being developed by ESA and other agencies.
Networking activities (NA) concluded successfully. We have delivered a strong visiting programme, overbooked by the community. The numerous workshops and schools were based on issues of interest on a community that extend beyond the field, including the multimessenger Universe. They have provided young astronomers with the theoretical and practical skills to exploit current and future generation of facilities for large X-ray surveys and high resolution spectroscopy, in particular those close to launch: E-Rosita (2019) and XRISM (2022). The AHEAD public outreach programme has delivered excellent products with an exceedingly broad audience: video for planetaria, virtual reality videos (that can be watched by smartphone), social channels, press releases and educational material. The dome video on HE astrophysics received an international prize (Fig.3) and is being played in hundreds of planetaria worldwide. It has currently been viewed by ~25 millions people.
The two transnational access (TA) workpackages have offered access to 23 installations, of which 10 for data analysis and 13 for test and calibration, in 6 Announcements of Opportunity (AO). The data analysis program has been exploited by the community in line with planning. Access to experimental facilities ramped up and reached a broader community, thanks to the implementation of more flexible procedures and wider dissemination: 50% of the approved proposal were received by SMEs and 50% of the projects encompassed fields such as astro-particle, Earth observations and space debris. In summary the organisation of a joint AO call for all transnational and visiting programmes supported 143 persons for a total of 1108 days.
Dissemination of the AHEAD project results was very effective, this including spreading info via web pages, presentations to conferences, and about 110 articles published in journals, including a special issue of the journal “Experimental Astronomy"" (Fig.2).
One of the main goal of AHEAD was to improve the performance of Athena, the main observatory infrastructure in the field, beyond the baseline. The related activities proved to be very successful. An improved physical understanding of the sensor devices and their readout has been achieved and different prototypes produced and tested; same for the optical filters. The anti-coincidence (AC) detector, which has the prime goal to suppress background signals from cosmic rays, can extend the Athena response to higher energies; and the implementation of a passive layer reduce the background. A similar study of the other instrument, the WFI, has identified a similar design to reduce its background. X-ray mirrors developments have identified a procedure for improving the calibration and accommodation of the mirror modules of Athena. All these results are now incorporated in the Athena project. Other mirror configurations include the Lobster-eye technique, that allows wide-field X-ray observations with a sensitivity two orders of magnitude better than present instrumentation for X-ray all sky monitoring. Such studies are used for the benefit of missions several space gamma-ray missions focusing on the transient and multimessenger, further strengthening the link between X-ray and gamma-ray communities. The gamma-ray mission concept e-ASTROGAM has been recently revised and is now being evaluated for selection as an F-mission by ESA. Theseus has been selected for an assessment phase as a medium size ESA mission, with a down-selection in 2021 and launch in 2032. Overall AHEAD studies will enhance the science return of the major X-ray facilities which will become operational by the end of the next decade.
Finally, AHEAD has explored a range of applications of the same innovative technology used in astrophysics, showing the power of high spectral resolution X-ray for non-invasive analysis on biology, fine art, environmental measurements. For this concept a detailed system engineering study has been performed with two design options, providing a concrete initial step for a future application for the benefit of our society.
Figure 1. The AHEAD Management structure
Figure 3. The AHEAD dome video title-page
"Figure 2. Cover of the special issue of Experimental Astronomy on the topic ""Particle background in"