Advanced Telescope for High-ENergy Astrophysics (''Athena'') is an X-ray observatory mission selected by

European Space Agency , owners = , headquarters = Paris, Île-de-France, France , coordinates = , spaceport = Guiana Space Centre , seal = File:ESA emblem seal.png , seal_size = 130px , image = Views in the Main Control Room (1205 ...

(ESA) within its Cosmic Vision program to address the Hot and Energetic Universe scientific theme. ''Athena'' will operate in the energy range of 0.2–12

keV Kev can refer to: Given name * Kev Adams, French comedian, actor, screenwriter and film producer born Kevin Smadja in 1991 * Kevin Kev Carmody (born 1946), Indigenous Australian singer-songwriter * Kev Coghlan (born 1988), Scottish Grand Prix motor ...

and will offer spectroscopic and imaging capabilities exceeding those of currently operating

X-ray astronomy satellite An X-ray astronomy satellite studies X-ray emissions from celestial objects, as part of a branch of space science known as X-ray astronomy. Satellites are needed because X-radiation is absorbed by the Earth's atmosphere, so instruments to detect ...

s – e.g. the

Chandra X-ray Observatory The Chandra X-ray Observatory (CXO), previously known as the Advanced X-ray Astrophysics Facility (AXAF), is a Flagship-class space telescope launched aboard the during STS-93 by NASA on July 23, 1999. Chandra is sensitive to X-ray sources 1 ...

and

XMM-Newton ''XMM-Newton'', also known as the High Throughput X-ray Spectroscopy Mission and the X-ray Multi-Mirror Mission, is an X-ray space observatory launched by the European Space Agency in December 1999 on an Ariane 5 rocket. It is the second cornerst ...

– by at least one order of magnitude on several parameter spaces simultaneously.

Mission

The primary goals of the mission are to map hot gas structures, determine their physical properties, and search for

supermassive black hole A supermassive black hole (SMBH or sometimes SBH) is the largest type of black hole, with its mass being on the order of hundreds of thousands, or millions to billions of times the mass of the Sun (). Black holes are a class of astronomical obj ...

History and development

The mission has its roots in two concepts from the early 2000s,

XEUS XEUS (X-ray Evolving Universe Spectroscopy) was a space observatory plan developed by the European Space Agency (ESA) as a successor to the successful XMM-Newton X-ray satellite telescope. It was merged to the International X-ray Observatory ...

of ESA and

Constellation-X Observatory The Constellation-X Observatory (Con-X or HTXS) was a mission concept for an X-ray space observatory to be operated by NASA; in 2008 it was merged with ESA and JAXA efforts in the same direction to produce the International X-ray Observatory pro ...

(Con-X) of

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...

. Around 2008, these two proposals were merged into the joint NASA/ESA/JAXA

International X-ray Observatory The International X-ray Observatory (IXO) is a cancelled X-ray telescope that was to be launched in 2021 as a joint effort by NASA, the European Space Agency (ESA), and the Japan Aerospace Exploration Agency (JAXA). In May 2008, ESA and NASA est ...

(IXO) proposal. In 2011, IXO was withdrawn and then ESA decided to proceed with a cost-reduced modification, which became known as ATHENA. ''Athena'' was selected in 2014 to become the second (L2) L-class Cosmic Vision mission, addressing the Hot and Energetic Universe science theme. The scientific advice for the ''Athena'' mission is provided by the ''Athena'' Science Study Team (ASST) composed of expert scientists from the community. The ASST was appointed by ESA on 16 July 2014. The ESA Study Scientist and Study Manager are Dr Matteo Guainazzi and Dr Mark Ayre respectively. ''Athena'' completed successfully its Phase A with the Mission Formulation Review on 12 November 2019. The next key milestone will be the mission adoption by ESA's Science Programme Committee (SPC) expected in 2023, leading to launch in 2035.

Orbit

In 2035, an

Ariane 64 Ariane 6 is a European expendable launch system currently under development since the early 2010s by ArianeGroup on behalf of the European Space Agency (ESA). It is intended to replace the Ariane 5, as part of the Ariane launch vehicle family ...

launch vehicle A launch vehicle or carrier rocket is a rocket designed to carry a payload (spacecraft or satellites) from the Earth's surface to outer space. Most launch vehicles operate from a launch pad, launch pads, supported by a missile launch contro ...

will lift ''Athena'' into a large amplitude

halo orbit A halo orbit is a periodic, three-dimensional orbit near one of the L1, L2 or L3 Lagrange points in the three-body problem of orbital mechanics. Although a Lagrange point is just a point in empty space, its peculiar characteristic is that it ca ...

around the point of the Sun-Earth system. The orbit around was selected due to its stable thermal environment, good sky visibility, high observing efficiency, and stable particle background. ''Athena'' will perform pre-planned scheduled observations of up to 300 celestial locations per year. A special

Target of Opportunity A target of opportunity is a target "visible to a surface or air sensor or observer, which is within range of available weapons and against which fire has not been scheduled or requested." A target of opportunity comes in two forms; "unplanned" and ...

mode will allow a re-point manoeuvre within 4 hours for 50% of any randomly occurring events in the sky.

Optics and instruments

The ''Athena'' X-ray observatory consists of a single X-ray telescope with a 12 m

focal length The focal length of an optical system is a measure of how strongly the system converges or diverges light; it is the inverse of the system's optical power. A positive focal length indicates that a system converges light, while a negative foca ...

, with an effective area of approx. 1.4 m² (at 1 keV) and a spatial resolution of 5

arcseconds A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The na ...

on-axis, degrading gracefully to less than 10 arcseconds at 30 arcminutes off-axis. The mirror is based on ESA's Silicon Pore Optics (SPO) technology. SPO provides an excellent ratio of collecting area to mass, while still offering a good angular resolution. It also benefits from a high

technology readiness level Technology readiness levels (TRLs) are a method for estimating the maturity of technologies during the acquisition phase of a program. TRLs enable consistent and uniform discussions of technical maturity across different types of technology. TR ...

and a modular design highly amenable to mass production necessary to achieve the unprecedented telescope collecting area. A movable mirror assembly can focus X-rays onto either one of ''Athena'' two instruments (WFI and X-IFU, see below) at any given time. Both the WFI and X-IFU successfully passed their Preliminary Requirements Reviews, on 31 October 2018 and 11 April 2019 respectively.

Wide Field Imager (WFI)

The Wide Field Imager (WFI) is a large field of view spectral-imaging camera based on the uniqu
Silicon DEPFET technology
developed in the semiconductor laboratory of the

Max Planck Society The Max Planck Society for the Advancement of Science (german: Max-Planck-Gesellschaft zur Förderung der Wissenschaften e. V.; abbreviated MPG) is a formally independent non-governmental and non-profit association of German research institutes. ...

. The DEPFETs provide an excellent energy resolution (<170eV at 7keV), low noise, fast readout and high time resolution, with good radiation hardness. The instrument combines the Large Detector Array, which is optimized for a wide field of view observations over a 40' x 40' instantaneous sky area, with a separate Fast Detector tailored to observe the brightest point sources of the X-ray sky with high throughput and low pile-up. These capabilities, in combination with the unprecedented effective area and wide field of the ''Athena'' telescope, will provide breakthrough capabilities in X-ray imaging spectroscopy. The WFI is developed by an international consortium composed of ESA member states. It is led by the

Max Planck Institute for Extraterrestrial Physics The Max Planck Institute for Extraterrestrial Physics is a Max Planck Institute, located in Garching, near Munich, Germany. In 1991 the Max Planck Institute for Physics and Astrophysics split up into the Max Planck Institute for Extraterrestrial Ph ...

(DEU) with partners in Germany (ECAP, IAA Tübingen), Austria (

University of Vienna The University of Vienna (german: Universität Wien) is a public research university located in Vienna, Austria. It was founded by Duke Rudolph IV in 1365 and is the oldest university in the German-speaking world. With its long and rich histor ...

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(DTU), France ( CEA Saclay,

Strasbourg Strasbourg (, , ; german: Straßburg ; gsw, label=Bas Rhin Alsatian, Strossburi , gsw, label=Haut Rhin Alsatian, Strossburig ) is the prefecture and largest city of the Grand Est region of eastern France and the official seat of the Eu ...

), Italy (

INAF The National Institute for Astrophysics ( it, Istituto Nazionale di Astrofisica, or INAF) is an Italian research institute in astronomy and astrophysics, founded in 1999. INAF funds and operates twenty separate research facilities, which in turn e ...

Bologna Bologna (, , ; egl, label= Emilian, Bulåggna ; lat, Bononia) is the capital and largest city of the Emilia-Romagna region in Northern Italy. It is the seventh most populous city in Italy with about 400,000 inhabitants and 150 different nat ...

Palermo Palermo ( , ; scn, Palermu , locally also or ) is a city in southern Italy, the capital (political), capital of both the autonomous area, autonomous region of Sicily and the Metropolitan City of Palermo, the city's surrounding metropolitan ...

), Poland (SRC PAS, NCAC PAS), the United Kingdom (

University of Leicester , mottoeng = So that they may have life , established = , type = public research university , endowment = £20.0 million , budget = £326 million , chancellor = David Willetts , vice_chancellor = Nishan Canagarajah , head_labe ...

Open University The Open University (OU) is a British public research university and the largest university in the United Kingdom by number of students. The majority of the OU's undergraduate students are based in the United Kingdom and principally study off- ...

), the United States (

Pennsylvania State University The Pennsylvania State University (Penn State or PSU) is a Public university, public Commonwealth System of Higher Education, state-related Land-grant university, land-grant research university with campuses and facilities throughout Pennsylvan ...

(Penn State), SLAC,

Massachusetts Institute of Technology The Massachusetts Institute of Technology (MIT) is a private land-grant research university in Cambridge, Massachusetts. Established in 1861, MIT has played a key role in the development of modern technology and science, and is one of the ...

(MIT), SAO), Switzerland (

University of Geneva The University of Geneva (French: ''Université de Genève'') is a public research university located in Geneva, Switzerland. It was founded in 1559 by John Calvin as a theological seminary. It remained focused on theology until the 17th centu ...

), Portugal (IA), and

Greece Greece,, or , romanized: ', officially the Hellenic Republic, is a country in Southeast Europe. It is situated on the southern tip of the Balkans, and is located at the crossroads of Europe, Asia, and Africa. Greece shares land borders with ...

(Athens Observatory,

University of Crete The University of Crete (UoC; Greek: Πανεπιστήμιο Κρήτης) is a multi-disciplinary, research-oriented institution in Crete, Greece, located in the cities of Rethymno (official seat) and Heraklion, and one of the country's most aca ...

). The principal investigator is Prof. Kirpal Nandra, Director of the High-Energy Group at MPE.

X-ray Integral Field Unit (X-IFU)

The X-ray Integral Field Unit is the cryogenic X-ray spectrometer of ''Athena'' X-IFU will deliver spatially resolved

X-ray spectroscopy X-ray spectroscopy is a general term for several spectroscopic techniques for characterization of materials by using x-ray radiation. Characteristic X-ray spectroscopy When an electron from the inner shell of an atom is excited by the energy o ...

, with a spectral resolution requirement of 2.5 eV up to 7 keV over a hexagonal field of view of 5 arc minutes (equivalent diameter). The prime detector of X-IFU is made of a large format array of Molybdenum Gold

transition-edge sensor A transition-edge sensor (TES) is a type of cryogenic energy sensor or cryogenic particle detector that exploits the strongly temperature-dependent resistance of the superconducting phase transition. History The first demonstrations of the supe ...

s coupled to absorbers made of Au and Bi to provide the required stopping power. The pixel size corresponds to slightly less than 5 arc seconds on the sky, thus matching the angular resolution of the X-ray optics. A large part of the X-IFU related ''Athena'' science objectives relies on the observation of faint extended sources (e.g. hot gas in

cluster of galaxies A galaxy cluster, or a cluster of galaxies, is a structure that consists of anywhere from hundreds to thousands of galaxies that are bound together by gravity, with typical masses ranging from 1014 to 1015 solar masses. They are the second-lar ...

to measure bulk motions and turbulence or its chemical composition), imposing the lowest possible instrumental background. This is achieved by the addition of a second cryogenic detector underneath the prime focal plane array. This way non-X-ray events such as particles can be vetoed using the temporal coincidence of detecting energy in both detectors simultaneously. The focal plane array, the sensors and the cold front end electronics are cooled at a stable temperature less than 100 mK by a multi-stage cryogenic chain, assembled by a series of mechanical coolers, with interface temperatures at 15 K, 4 K and 2 K and 300 mK, pre-cooling a sub Kelvin cooler made of a 3He adsorption cooler coupled with a
Adiabatic Demagnetization Refrigerator
Calibration data are acquired along with each observation from modulated X-ray sources to enable the energy calibration required to reach the targeted spectral resolution. Although an integral field unit where each and every pixel delivers a high resolution X-ray spectrum, the defocussing capability of the ''Athena'' mirror will enable the focal beam to be spread over hundreds of sensors. The X-IFU will thus be able to observe very bright X-ray sources. It will do so either with the nominal resolution, e.g. for detecting the baryons thought to reside in the Warm Hot Intergalactic Medium, using bright gamma-ray burst afterglows, as background sources shining through the cosmic web, or with a spectral resolution of 3–10 eV, e.g. for measuring the spins and characterizing the winds and outflows of bright

X-ray binaries X-ray binaries are a class of binary stars that are luminous in X-rays. The X-rays are produced by matter falling from one component, called the ''donor'' (usually a relatively normal star), to the other component, called the ''accretor'', which ...

at energies where their spectral signatures are the strongest (above 5 keV). As of December 2018, when the X-IFU consortium was formally endorsed by ESA as being responsible for the procurement of the instrument to ''Athena'', the X-IFU consortium gathered 11 European countries (

Belgium Belgium, ; french: Belgique ; german: Belgien officially the Kingdom of Belgium, is a country in Northwestern Europe. The country is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeast, France to th ...

Czech Republic The Czech Republic, or simply Czechia, is a landlocked country in Central Europe. Historically known as Bohemia, it is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the southeast. The ...

Finland Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of B ...

, France, Germany, Ireland, Italy, Netherlands, Poland, Spain, Switzerland), plus Japan and the United States. More than 50 research institutes are involved in the X-IFU consortium. The principal investigator of X-IFU is Dr Didier Barret, Director of research at the research institute in astrophysics and planetology of

Toulouse Toulouse ( , ; oc, Tolosa ) is the prefecture of the French department of Haute-Garonne and of the larger region of Occitania. The city is on the banks of the River Garonne, from the Mediterranean Sea, from the Atlantic Ocean and from Par ...

( IRAP-OMP,

CNRS The French National Centre for Scientific Research (french: link=no, Centre national de la recherche scientifique, CNRS) is the French state research organisation and is the largest fundamental science agency in Europe. In 2016, it employed 31,637 ...

UT3-Paul Sabatier/

CNES The (CNES; French: ''Centre national d'études spatiales'') is the French government space agency (administratively, a "public administration with industrial and commercial purpose"). Its headquarters are located in central Paris and it is und ...

, France). Dr Jan-Willem den Herder ( SRON, The Netherlands) and Dr Luigi Piro (

-IAPS, Italy) are co-principal investigators of the X-IFU.

manages the project, and on behalf of the X-IFU consortium, is responsible for the delivery of the instrument to ESA.

''Athena'' science goals

The "Hot and Energetic Universe" science theme revolves around two fundamental questions in

astrophysics Astrophysics is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. As one of the founders of the discipline said, Astrophysics "seeks to ascertain the nature of the h ...

: How does ordinary matter assemble into the large-scale structures that we see today? And how do

black hole A black hole is a region of spacetime where gravitation, gravity is so strong that nothing, including light or other Electromagnetic radiation, electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts t ...

s grow and shape the

Universe The universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy. The Big Bang theory is the prevailing cosmological description of the development of the universe. Acc ...

? Both questions can only be answered using a sensitive X-ray space observatory. Its combination of scientific performance exceeds any existing or planned X-ray missions by over one order of magnitude on several parameter spaces: effective area, weak line sensitivity, survey speed, just to mention a few. ''Athena'' will perform very sensitive measurements on a wide range of celestial objects. It will investigate the chemical evolution of the hot plasma permeating the intergalactic space in cluster of galaxies, search for elusive observational features of the Warm-Hot Intergalactic Medium, investigate powerful outflows ejected from accreting black holes across their whole mass spectrum, and study their impact on the host galaxy, and identify sizeable samples of comparatively rare populations of Active Galactic Nuclei (AGN) that are key to understanding the concurrent cosmological evolution of accreting black holes and galaxies. Among them are highly obscured and high-redshift (z≥6) AGN. Furthermore, ''Athena'' will be an X-ray observatory open to the whole astronomical community, poised to provide wide-ranging discoveries in almost all fields of modern astrophysics, with a large discovery potential of still unknown and unexpected phenomena. It represents the X-ray contribution to the fleet of large-scale observational facilities to be operational in the 2030s (incl.

SKA Ska (; ) is a music genre that originated in Jamaica in the late 1950s and was the precursor to rocksteady and reggae. It combined elements of Caribbean mento and calypso with American jazz and rhythm and blues. Ska is characterized by a walki ...

, ELT,

ALMA Alma or ALMA may refer to: Arts and entertainment * ''Alma'' (film), a 2009 Spanish short animated film * ''Alma'' (Oswald de Andrade novel), 1922 * ''Alma'' (Le Clézio novel), 2017 * ''Alma'' (play), a 1996 drama by Joshua Sobol about Alma ...

LISA Lisa or LISA may refer to: People People with the mononym * Lisa Lisa (born 1967), American actress and lead singer of the Cult Jam * Lisa (Japanese musician, born 1974), stylized "LISA", Japanese singer and producer * Lisa Komine (born 1978), J ...

...).

The ''Athena'' Community Office

The ''Athena'' Science Study Team (ASST) established the ''Athena'' Community Office (ACO) to obtain support in performing its tasks assigned by ESA, and most especially in the ASST role as "a focal point for the interests of the broad scientific community". Currently, this community is formed by more tha
800 members spread around the world
The ACO is meant to become a focal point to facilitate the scientific exchange between the ''Athena'' activities and the scientific community at large, and to disseminate the ''Athena'' science objectives to the general public. The main tasks of the ACO can be divided into three categories: * Organisational aspects and optimisation of the community efforts assisting the ASST in several aspects, as for instance helping to the promotion of ''Athena'' science capabilities in the research world, through Conferences & Workshops or supporting the production of ASST documents, including the White Papers identifying the scientific synergies of ''Athena'' with other observational facilities in the early 2030s * Keep the ''Athena'' community informed on the status of the project with the regular release of th

brief news, weekly news on the ''Athena'' web portal and in the social channels. * Develop communication and outreach activities, of particular interest, are th

The ACO is led by th
Instituto de Física de Cantabria (CSIC-UC)
Further ACO contributors are the

Université de Genève The University of Geneva (French: ''Université de Genève'') is a public research university located in Geneva, Switzerland. It was founded in 1559 by John Calvin as a theological seminary. It remained focused on theology until the 17th centur ...

(MPE) and L'Institut de Recherche en Astrophysique et Planétologie (IRAP).

References

External links

The ''Athena'' X-ray observatory: ''Community Support Portal''

''Athena'' on ESA Cosmic Vision website

''Athena'' mission proposal video on YouTube

The ''Athena'' Wide Field Imager website

The ''Athena'' X-ray Integral Field Unit website

X-IFU, unveiling the secrets of the hot and energetic Universe video on YouTube

Silicon pore optics mirror video

Silicon pore optics mirror animation
{{Future spaceflights Space telescopes X-ray telescopes European Space Agency Future spaceflights Cosmic Vision 2035 in science