Year: 2026
Type: conference-abstract
Abstract: The Enhanced X-ray Polarimetry Observatory (EXPO) is a mission concept proposed to ESA as an M8 candidate, with a prospective launch around 2041. Building on the scientific success of the Imaging X-ray Polarimetry Explorer (IXPE), EXPO is designed not only to overcome its two main limitations, the narrow 2–8 keV energy band and the very slow repointing time, but also to unlock new scientific capabilities. A wide energy band and fast repointing are essential for addressing key questions in high-energy astrophysics, including the origin of the hard X-ray emission in magnetars and black-hole binaries, particle acceleration in supernova remnants and pulsar-wind nebulae, radiative transfer in highly magnetized plasmas, X-ray reflection in accretion flows and active galactic nuclei, and the prompt and afterglow emission of gamma-ray bursts and of magnetar flares. The payload combines broadband imaging X-ray polarimetry with rapid time-domain capability. Five focusing X-ray telescopes employ gas photoelectric polarimeters based on the Timepix ASIC family with InGrid amplification, enabling true three-dimensional track reconstruction and operation over the 2–35 keV band through optimized low- and medium-energy detector configurations. The mirror modules are based on proven electroformed nickel technology with Au/C coatings and an XMM-like focal length of 7.5 m. The polarimeters are complemented by three dedicated detection systems: (i) a coded-mask Wide Field Instrument (WFI), derived from SVOM /ECLAIRs, providing continuous monitoring of a ∼2 sr field of view and autonomous transient localization; (ii) a Spectral Imaging Camera (SIC), based on stacked CMOS and CdTe detectors, providing simultaneous broadband imaging spectroscopy for accurate spectro-polarimetric decomposition; and (iii) an Instrument Control Unit (ICU), responsible for payload management, onboard WFI image reconstruction, transient identification, and autonomous spacecraft repointing. Together, these capabilities will extend X-ray polarimetry into the hard X-ray domain and open a new observational window on fast transients, time-domain astrophysics, and multi-messenger astronomy. This paper presents the concept of the mission EXPO, its payload architecture, and the scientific opportunities provided by its unique combination of broadband polarimetry and rapid response.
DOI: 10.1117/12.3105324
Authors: Paolo Soffitta, Sebastien Guillot, Ian Hutchinson, Fabio Muleri, Mark Pearce, Andrea Santangelo, Daniele Spiga, Ivan Agudo, Gino Bruno Amata, Jarosław Bakala, Elisabetta Baracchini, Stefano Basso, Jörg Bayer, Benedikt Bergmann, Jaroslaw Borek, Enrico Bozzo, Søren Krinstian Brandt, Carl Budtz-Jørgensen, Vadim Burwitz, Stefano Cesare, Jerome Chenevez, Enrico Costa, Elisa Costantini, Vincenzo Cotroneo, Walter Cugno, Riccardo Ferrazzoli, Nicolas De Angelis, Desiree Della Monica Ferreira, Klaus Desch, Giorgio Dho, Giuseppe Di Persio, Sergio Fabiani, Davide Fiorina, Szymon Gburek, Markus Gruber, Allan Hornstrup, Jennifer Jones, Jochen Kaminski, Mózsi Kiss, Irfan Kuvvetli, Carlo Lefevre, Hannah Lerman, Hooghui Liu, Pasqualino Loffredo, Niels Lund, Hemanth Manikantan, Melissa McHugh, Paul O'Brien, Stephane Paltani, Giovanni Pareschi, Stefano Piacentini, Vladislavs Plesanovs, John Rankin, Ajay Ratheesh, Selina Ringsborg Howalt Owe, Alda Rubini, Miguel Andrés Sánchez Carrasco, Emanuele Scalise, Konrad R. Skup, Gianpiero Tagliaferri, Chris Tenzer, Berend Winter, Silvia Zane, Lorenzo Amati, Alessio Anitra, Maria Cristina Baglio, Thibault Barnouin, Stefano Bianchi, Fabrizio Bocchino, Markus Boettcher, Niccolò Bucciantini, Sara Capecchiacci, Fiamma Capitanio, Martina Cardillo, Eugene Churazov, Stefano Covino, Filippo D'Ammando, Laura Di Gesu, Alessandro Di Marco, Tiziana Di Salvo, Michal Dovciak, Lorenzo Ducci, Hua Feng, Giorgio Galanti, Giancarlo Ghirlanda, Vittoria Elvezia Gianolli, Andrea Gnarini, Emanuele Greco, Jeremy Heyl, Adam Ingram, Svetlana Jorstad, Philip Kaaret, Ildar Khabibullin, Fabian Kislat, Henric Krawczynski, Josefin Larsson, Ioannis Liodakis, Frédéric Marin, Andrea Marinucci, Lorenzo Marra, Alan Marscher, Herman Marshall, Giorgio Matt, Marco Miceli, Riccardo Middei, Romana Mikusincova, Alexander Mushtukov, Kirpal Nandra, Lara Nava, Giuseppe Maria Oppedisano, Salvatore Orlando, Simone Pagliarella, Alessandro Papitto, Pierre-Olivier Petrucci, Oleh Petruk, Jakub Podgorny, Juri Poutanen, Arne Rau, Agata Roszanska, Felix Ryde, Vincenzo Sapienza, Patrick Slane, James Steiner, Valery Suleimanov, Jiri Svoboda, Daniele Tagliacozzo, Antonella Tarana, Fabrizio Tavecchio, Roberto Taverna, Francesco Tombesi, Sergey Tsygankov, Youli Tuo, Roberto Turolla, Francesco Ursini, Alexandra Veledina, Jacco Vink, Martin C. Weisskopf, Fei Xie, Hoacheng Zhang, Menglei Zhou
Language: English
Subfield: Instrumentation
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: G1576260938, G3291346338, G4917691183
OpenAlex ID: W7203616074