XIPE: The X-ray imaging polarimetry explorer

Paolo Soffitta, Xavier Barcons, Ronaldo Bellazzini, João Braga, Enrico Costa, George W. Fraser, Szymon Gburek, Juhani Huovelin, Giorgio Matt, Mark Pearce, Juri Poutanen, Victor Reglero, Andrea Santangelo, Rashid A. Sunyaev, Gianpiero Tagliaferri, Martin Weisskopf, Roberto Aloisio, Elena Amato, Primo Attiná, Magnus AxelssonLuca Baldini, Stefano Basso, Stefano Bianchi, Pasquale Blasi, Johan Bregeon, Alessandro Brez, Niccoló Bucciantini, Luciano Burderi, Vadim Burwitz, Piergiorgio Casella, Eugene Churazov, Marta Civitani, Stefano Covino, Rui Miguel Curado da Silva, Giancarlo Cusumano, Mauro Dadina, Flavio D'Amico, Alessandra De Rosa, Sergio Di Cosimo, Giuseppe Di Persio, Tiziana Di Salvo, Michal Dovciak, Ronald Elsner, Chris J. Eyles, Andrew C. Fabian, Sergio Fabiani, Hua Feng, Salvatore Giarrusso, René W. Goosmann, Paola Grandi, Nicolas Grosso, Gianluca Israel, Miranda Jackson, Philip Kaaret, Vladimir Karas, Michael Kuss, Dong Lai, Giovanni La Rosa, Josefin Larsson, Stefan Larsson, Luca Latronico, Antonio Maggio, Jorge Maia, Frédéric Marin, Marco Maria Massai, Teresa Mineo, Massimo Minuti, Elena Moretti, Fabio Muleri, Stephen L. O'Dell, Giovanni Pareschi, Giovanni Peres, Melissa Pesce, Pierre Olivier Petrucci, Michele Pinchera, Delphine Porquet, Brian Ramsey, Nanda Rea, Fabio Reale, Juana Maria Rodrigo, Agata Rózańska, Alda Rubini, Pawel Rudawy, Felix Ryde, Marco Salvati, Valdivino Alexandre de Santiago, Sergey Sazonov, Carmelo Sgró, Eric Silver, Gloria Spandre, Daniele Spiga, Luigi Stella, Toru Tamagawa, Francesco Tamborra, Fabrizio Tavecchio, Teresa Teixeira Dias, Matthew van Adelsberg, Kinwah Wu, Silvia Zane

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    Abstract X-ray polarimetry, sometimes alone, and sometimes coupled to spectral and temporal variability measurements and to imaging, allows a wealth of physical phenomena in astrophysics to be studied. X-ray polarimetry investigates the acceleration process, for example, including those typical of magnetic reconnection in solar flares, but also emission in the strong magnetic fields of neutron stars and white dwarfs. It detects scattering in asymmetric structures such as accretion disks and columns, and in the so-called molecular torus and ionization cones. In addition, it allows fundamental physics in regimes of gravity and of magnetic field intensity not accessible to experiments on the Earth to be probed. Finally, models that describe fundamental interactions (e.g. quantum gravity and the extension of the Standard Model) can be tested. We describe in this paper the X-ray Imaging Polarimetry Explorer (XIPE), proposed in June 2012 to the first ESA call for a small mission with a launch in 2017. The proposal was, unfortunately, not selected. To be compliant with this schedule, we designed the payload mostly with existing items. The XIPE proposal takes advantage of the completed phase A of POLARIX for an ASI small mission program that was cancelled, but is different in many aspects: the detectors, the presence of a solar flare polarimeter and photometer and the use of a light platform derived by a mass production for a cluster of satellites. XIPE is composed of two out of the three existing JET-X telescopes with two Gas Pixel Detectors (GPD) filled with a He-DME mixture at their focus. Two additional GPDs filled with a 3-bar Ar-DME mixture always face the Sun to detect polarization from solar flares. The Minimum Detectable Polarization of a 1 mCrab source reaches 14 % in the 2-10 keV band in 105 s for pointed observations, and 0.6 % for an X10 class solar flare in the 15-35 keV energy band. The imaging capability is 24 arcsec Half Energy Width (HEW) in a Field of View of 14.7 arcmin × 14.7 arcmin. The spectral resolution is 20 % at 6 keV and the time resolution is 8 μs. The imaging capabilities of the JET-X optics and of the GPD have been demonstrated by a recent calibration campaign at PANTER X-ray test facility of the Max-Planck-Institut für extraterrestrische Physik (MPE, Germany). XIPE takes advantage of a low-earth equatorial orbit with Malindi as down-link station and of a Mission Operation Center (MOC) at INPE (Brazil). The data policy is organized with a Core Program that comprises three months of Science Verification Phase and 25 % of net observing time in the following 2 years. A competitive Guest Observer program covers the remaining 75 % of the net observing time. © 2013 Springer Science+Business Media Dordrecht.
    Original languageEnglish
    Pages (from-to)523-567
    JournalExperimental Astronomy
    Issue number3
    Publication statusPublished - 1 Dec 2013


    • Astronomy
    • Polarimetry
    • X-ray


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