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  • 1. Bouchet, L.
    et al.
    Chauvin, Maxime
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Amestoy, P. R.
    Rouet, F. -H
    Buttari, A.
    Tools for analyzing large data-set and handling intensity variations of sources with INTEGRAL/SPI2014Ingår i: Proceedings of Science, Sissa Medialab Srl , 2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    The INTEGRAL/SPI X/gamma-ray spectrometer (20 keV-8 MeV) is an instrument for which it is essential to process many exposures at the same time to increase the low signal-to-noise ratio of the weakest sources and/or low-surface brightness extended emission. The processing of several years of data simultaneously (10 years actually) with traditional methods of data reduction is ineffective and sometimes not possible at all. Thanks to the newly developed tools, processing large data-sets from SPI is possible with both a reasonable turnaround time and low memory usage. We present also techniques that we have developed to overcome difficulties related to the intensity variation of sources/background between sources between consecutive exposures.

  • 2.
    Chauvin, Maxime
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, SE-10691 Stockholm, Sweden.
    Floren, H. -G
    Stockholm Univ, Dept Astron, SE-10691 Stockholm, Sweden.
    Friis, Mette
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, SE-10691 Stockholm, Sweden..
    Jackson, Miranda
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Kamae, T.
    Univ Tokyo, Dept Phys, Tokyo 1130033, Japan..
    Kataoka, J.
    Waseda Univ, Res Inst Sci & Engn, Tokyo 1698555, Japan..
    Kawano, T.
    Hiroshima Univ, Dept Phys Sci, Hiroshima 7398526, Japan..
    Kiss, Mózsi
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, SE-10691 Stockholm, Sweden..
    Mikhalev, Victor
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, SE-10691 Stockholm, Sweden..
    Mizuno, T.
    Hiroshima Univ, Dept Phys Sci, Hiroshima 7398526, Japan..
    Tajima, H.
    Nagoya Univ, Inst Space Earth Environm Res, Nagoya, Aichi 4648601, Japan..
    Takahashi, H.
    Hiroshima Univ, Dept Phys Sci, Hiroshima 7398526, Japan..
    Uchida, N.
    Hiroshima Univ, Dept Phys Sci, Hiroshima 7398526, Japan..
    Pearce, Mark
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, SE-10691 Stockholm, Sweden..
    The PoGO plus view on Crab off-pulse hard X-ray polarization2018Ingår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 477, nr 1, s. L45-L49Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The linear polarization fraction (PF) and angle of the hard X-ray emission from the Crab provide unique insight into high-energy radiation mechanisms, complementing the usual imaging, timing, and spectroscopic approaches. Results have recently been presented by two missions operating in partially overlapping energy bands, PoGO+ (18-160 keV) and AstroSat CZTI (100-380 keV). We previously reported PoGO+ results on the polarization parameters integrated across the light curve and for the entire nebula-dominated off-pulse region. We now introduce finer phase binning, in light of the AstroSat CZTI claim that the PF varies across the off-pulse region. Since both missions are operating in a regime where errors on the reconstructed polarization parameters are non-Gaussian, we adopt a Bayesian approach to compare results from each mission. We find no statistically significant variation in off-pulse polarization parameters, neither when considering the mission data separately nor when they are combined. This supports expectations from standard high-energy emission models.

  • 3.
    Chauvin, Maxime
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Floren, H. -G
    Jackson, Miranda
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Kamae, T.
    Kawano, T.
    Kiss, Mózsi
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Kole, Merlin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Mikhalev, Victor
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Moretti, Elena
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Max Planck Institute for Astrophysics, Germany.
    Olofsson, G.
    Rydström, Stefan
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Takahashi, H.
    Iyudin, A.
    Arimoto, M.
    Fukazawa, Y.
    Kataoka, J.
    Kawai, N.
    Mizuno, T.
    Ryde, Felix
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Tajima, H.
    Takahashi, T.
    Pearce, Mark
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Observation of polarized hard X-ray emission from the Crab by the PoGOLite Pathfinder2016Ingår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 456, nr 1, s. L84-L88Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have measured the linear polarization of hard X-ray emission from the Crab in a previously unexplored energy interval, 20-120 keV. The introduction of two new observational parameters, the polarization fraction and angle stands to disentangle geometrical and physical effects, thereby providing information on the pulsar wind geometry and magnetic field environment. Measurements are conducted using the PoGOLite Pathfinder - a balloon-borne polarimeter. Polarization is determined by measuring the azimuthal Compton scattering angle of incident X-rays in an array of plastic scintillators housed in an anticoincidence well. The polarimetric response has been characterized prior to flight using both polarized and unpolarized calibration sources. We address possible systematic effects through observations of a background field. The measured polarization fraction for the integrated Crab light curve is 18.4(-10.6)(+9.8) per cent, corresponding to an upper limit (99 per cent credibility) of 42.4 per cent, for a polarization angle of (149.2 +/- 16.0)degrees.

  • 4.
    Chauvin, Maxime
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik. The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, 106 91, Stockholm, Sweden.
    Florén, H. -G
    Friis, M.
    KTH, Skolan för teknikvetenskap (SCI), Fysik. The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, 106 91, Stockholm, Sweden.
    Jackson, M.
    KTH, Skolan för teknikvetenskap (SCI), Fysik. Present address: School of Physics and Astronomy, Cardiff University, Cardiff, CF24 3AA, UK.
    Kamae, T.
    Kataoka, J.
    Kawano, T.
    Kiss, M.
    KTH, Skolan för teknikvetenskap (SCI), Fysik. The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, 106 91, Stockholm, Sweden.
    Mikhalev, V.
    KTH, Skolan för teknikvetenskap (SCI), Fysik. The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, 106 91, Stockholm, Sweden.
    Mizuno, T.
    Ohashi, N.
    Stana, T.
    KTH, Skolan för teknikvetenskap (SCI), Fysik. The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, 106 91, Stockholm, Sweden.
    Tajima, H.
    Takahashi, H.
    Uchida, N.
    Pearce, Mark
    KTH, Skolan för teknikvetenskap (SCI), Fysik. The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, 106 91, Stockholm, Sweden.
    Correction: Shedding new light on the crab with polarized X-rays (Scientific Reports DOI: 10.1038/s41598-017-07390-7)2018Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, nr 1, artikel-id 7975Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This Article contains a typographical error in the legend of Figure 2. "Gaussian 1, 2 and 3& #x1D70E;" should read: "Gaussian 1, 2 and 3σ". 

  • 5.
    Chauvin, Maxime
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Florén, H. -G
    Jackson, Miranda
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Kamae, T.
    Kataoka, J.
    Kiss, Mózsi
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Mikhalev, Victor
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Mizuno, T.
    Takahashi, H.
    Uchida, N.
    Pearce, Mark
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    PoGO + polarimetric constraint on the synchrotron jet emission of Cygnus X-12019Ingår i: Monthly Notices of the Royal Astronomical Society: Letters, ISSN 1745-3925, Vol. 483, nr 1, s. L138-L143Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report a polarimetric constraint on the hard X-ray synchrotron jet emission from the Cygnus X-1 black hole binary system. The observational data were obtained using the PoGO+ hard X-ray polarimeter in 2016 July, when Cygnus X-1 was in the hard state. We have previously reported that emission from an extended corona with a low polarization fraction is dominating, and that the polarization angle is perpendicular to the disc surface. In the soft gamma-ray regime, a highly polarized synchrotron jet is reported with INTEGRAL observations. To constrain the polarization fraction and flux of such a jet component in the hard X-ray regime, we now extend analyses through vector calculations in the Stokes QU plane, where the dominant corona emission and the jet component are considered simultaneously. The presence of another emission component with different polarization angle could partly cancel out the net polarization. The 90 per cent upper limit of the polarization fraction for the additional synchrotron jet component is estimated as <10 per cent, <5 per cent, and <5 per cent for polarization angle perpendicular to the disc surface, parallel to the surface, and aligned with the emission reported by INTEGRAL data, respectively. From the 20-180 keV total flux of 2.6 × 10 -8 erg s -1 cm -2, the upper limit of the polarized flux is estimated as < 3 × 10 -9 erg s -1 cm -2.

  • 6.
    Chauvin, Maxime
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Florén, H. -G
    Jackson, Miranda
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Kamae, T.
    Kawano, T.
    Kiss, Mózsi
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Kole, Merlin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Univ Geneva, Switzerland.
    Mikhalev, Victor
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Moretti, Elena
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Olofsson, G.
    Rydström, Stefan
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Takahashi, H.
    Lind, J.
    Strömberg, J. -E
    Welin, O.
    Iyudin, A.
    Shifrin, D.
    Pearce, Mark
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    The design and flight performance of the PoGOLite Pathfinder balloon-borne hard X-ray polarimeter2016Ingår i: Experimental astronomy (Print), ISSN 0922-6435, E-ISSN 1572-9508, Vol. 41, nr 1, s. 17-41Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the 50 years since the advent of X-ray astronomy there have been many scientific advances due to the development of new experimental techniques for detecting and characterising X-rays. Observations of X-ray polarisation have, however, not undergone a similar development. This is a shortcoming since a plethora of open questions related to the nature of X-ray sources could be resolved through measurements of the linear polarisation of emitted X-rays. The PoGOLite Pathfinder is a balloon-borne hard X-ray polarimeter operating in the 25-240 keV energy band from a stabilised observation platform. Polarisation is determined using coincident energy deposits in a segmented array of plastic scintillators surrounded by a BGO anticoincidence system and a polyethylene neutron shield. The PoGOLite Pathfinder was launched from the SSC Esrange Space Centre in July 2013. A near-circumpolar flight was achieved with a duration of approximately two weeks. The flight performance of the Pathfinder design is discussed for the three Crab observations conducted. The signal-to-background ratio for the observations is shown to be 0.25 ±0.03 and the Minimum Detectable Polarisation (99 % C.L.) is (28.4 ±2.2) %. A strategy for the continuation of the PoGOLite programme is outlined based on experience gained during the 2013 maiden flight.

  • 7.
    Chauvin, Maxime
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, Stockholm, Sweden.
    Florén, Hans-Gustav
    Friis, Mette
    KTH, Skolan för teknikvetenskap (SCI), Fysik. The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, Stockholm, SwedenThe Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, Stockholm, Sweden.
    Jackson, Miranda
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Kamae, Tuneyoshi
    Kataoka, Jun
    Kawano, Takafumi
    Kiss, Mózsi
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Mikhalev, Victor
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Mizuno, Tsunefumi
    Ohashi, Norie
    Stana, Theodor
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Tajima, Hiro
    Takahashi, Hiromitsu
    Uchida, Nagomi
    Pearce, Mark
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Accretion geometry of the black-hole binary Cygnus X-1 from X-ray polarimetry2018Ingår i: Nature Astronomy, ISSN 2397-3366, Vol. 2, nr 8, s. 652-655Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Black hole binary (BHB) systems comprise a stellar-mass black hole and a closely orbiting companion star. Matter is transferred from the companion to the black hole, forming an accretion disk, corona and jet structures. The resulting release of gravitational energy leads to the emission of X-rays1. The radiation is affected by special/general relativistic effects, and can serve as a probe for the properties of the black hole and surrounding environment, if the accretion geometry is properly identified. Two competing models describe the disk–corona geometry for the hard spectral state of BHBs, based on spectral and timing measurements2,3. Measuring the polarization of hard X-rays reflected from the disk allows the geometry to be determined. The extent of the corona differs between the two models, affecting the strength of the relativistic effects (such as enhancement of the polarization fraction and rotation of the polarization angle). Here, we report observational results on the linear polarization of hard X-ray emission (19–181 keV) from a BHB, Cygnus X-14, in the hard state. The low polarization fraction, <8.6% (upper limit at a 90% confidence level), and the alignment of the polarization angle with the jet axis show that the dominant emission is not influenced by strong gravity. When considered together with existing spectral and timing data, our result reveals that the accretion corona is either an extended structure, or is located far from the black hole in the hard state of Cygnus X-1.

  • 8.
    Chauvin, Maxime
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Friis, Mette
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Jackson, Miranda
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Kawano, T.
    Kiss, Mózsi
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Mikhalev, Victor
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ohashi, N.
    Stana, Theodor-Adrian
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Takahashi, H.
    Pearce, Mark
    KTH, Skolan för teknikvetenskap (SCI), Fysik. The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, 106 91 Stockholm, Sweden.
    Calibration and performance studies of the balloon-borne hard X-ray polarimeter PoGO2017Ingår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 859, s. 125-133Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Polarimetric observations of celestial sources in the hard X-ray band stand to provide new information on emission mechanisms and source geometries. PoGO+ is a Compton scattering polarimeter (20-150 keV) optimised for the observation of the Crab (pulsar and wind nebula) and Cygnus X-1 (black hole binary), from a stratospheric balloon-borne platform launched from the Esrange Space Centre in summer 2016. Prior to flight, the response of the polarimeter has been studied with polarised and unpolarised X-rays allowing a Geant4-based simulation model to be validated. The expected modulation factor for Crab observations is found to be M-Crab = (41.75 +/- 0.85)%, resulting in an expected Minimum Detectable Polarisation (MDP) of 7.3% for a 7 day flight. This will allow a measurement of the Crab polarisation parameters with at least 5 sigma statistical significance assuming a polarisation fraction similar to 20% - a significant improvement over the PoGOLite Pathfinder mission which flew in 2013 and from which the PoGO+ design is developed.

  • 9.
    Chauvin, Maxime
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. AlbaNova University Centre, Sweden.
    Jackson, Miranda
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. AlbaNova University Centre, Sweden.
    Kawano, T.
    Kiss, Mózsi
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. AlbaNova University Centre, Sweden.
    Kole, Merlin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. AlbaNova University Centre, Sweden.
    Mikhalev, Victor
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. AlbaNova University Centre, Sweden.
    Moretti, Elena
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. AlbaNova University Centre, Sweden.
    Takahashi, H.
    Pearce, Mark
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. AlbaNova University Centre, Sweden.
    Optimising a balloon-borne polarimeter in the hard X-ray domain: From the PoGOLite Pathfinder to PoGO2016Ingår i: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 82, s. 99-107Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    PoGOLite is a balloon-borne hard X-ray polarimeter dedicated to the study of point sources. Compton scattered events are registered using an array of plastic scintillator units to determine the polarisation of incident X-rays in the energy range 20-240 keV. In 2013, a near circumpolar balloon flight of 14 days duration was completed after launch from Esrange, Sweden, resulting in a measurement of the linear polarisation of the Crab emission. Building on the experience gained from this Pathfinder flight, the polarimeter is being modified to improve performance for a second flight in 2016. Such optimisations, based on Geant4 Monte Carlo simulations, take into account the source characteristics, the instrument response and the background environment which is dominated by atmospheric neutrons. This paper describes the optimisation of the polarimeter and details the associated increase in performance. The resulting design, PoGO+, is expected to improve the Minimum Detectable Polarisation (MDP) for the Crab from 19.8% to 11.1% for a 5 day flight. Assuming the same Crab polarisation fraction as measured during the 2013 flight, this improvement in MDP will allow a 5 sigma constrained result. It will also allow the study of the nebula emission only (Crab off-pulse) and Cygnus X-1 if in the hard state.

  • 10.
    Chauvin, Maxime
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Oskar Klein Centre for Cosmoparticle Physics, Sweden.
    Jackson, Miranda
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Kawano, T.
    Kiss, Mózsi
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Oskar Klein Centre for Cosmoparticle Physics, Sweden.
    Kole, Merlin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Oskar Klein Centre for Cosmoparticle Physics, Sweden.
    Mikhalev, Victor
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Oskar Klein Centre for Cosmoparticle Physics, Sweden.
    Moretti, Elena
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Oskar Klein Centre for Cosmoparticle Physics, Sweden.
    Takahashi, H.
    Pearce, Mark
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Oskar Klein Centre for Cosmoparticle Physics, Sweden.
    Preflight performance studies of the PoGOLite hard X-ray polarimeter2016Ingår i: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 72, s. 1-10Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Polarimetric studies of astrophysical sources can make important contributions to resolve the geometry of the emitting region and determine the photon emission mechanism. PoGOLite is a balloon-borne polarimeter operating in the hard X-ray band (25-240 key), with a Pathfinder mission focussing on Crab observations. Within the polarimeter, the distribution of Compton scattering angles is used to determine the polarisation fraction and angle of incident photons. To assure an unbiased measurement of the polarisation during a balloon flight it is crucial to characterise the performance of the instrument before the launch. This paper presents the results of the PoGOLite calibration tests and simulations performed before the 2013 balloon flight. The tests performed confirm that the polarimeter does not have any intrinsic asymmetries and therefore does not induce bias into the measurements. Generally, good agreement is found between results from test data and simulations which allows the polarimeter performance to be estimated for Crab observations.

  • 11. Jourdain, E.
    et al.
    Roques, J. P.
    Chauvin, Maxime
    Université de Toulouse, France.
    Integral SPI* observations of cygnus x-1 in the soft state: What about the jet contribution in hard x-rays?2014Ingår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 789, nr 1, artikel-id 26Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    During the first 7 yr of the INTEGRAL mission (2003-2009), Cyg X-1 has essentially been detected in its hard state (HS), with some incursions in intermediate HSs. This long, spectrally stable period allowed in particular the measurement of the polarization of the high-energy component that has long been observed above 200 keV in this peculiar object. This result strongly suggests that here we see the contribution of the jet, known to emit a strong synchrotron radio emission. In 2010 June, Cyg X-1 underwent a completed transition toward a soft state (SS). It gave us the unique opportunity to study in detail the corona emission in this spectral state, and to investigate in particular the behavior of the jet contribution. Indeed, during the SS, the hard X-ray emission decreases drastically, with its maximum energy shifted toward lower energy and its flux divided by a factor of 5-10. Interestingly, the radio emission follows a similar drop, supporting the correlation between the jet emission and the hard component, even though the flux is too low to quantify the polarization characteristics.

  • 12.
    Kole, Merlin
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Chauvin, Maxime
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Fukazawa, Yasushi
    Fukuda, Kentaro
    Ishizu, Sumito
    Jackson, Miranda
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Kamae, Tune
    Kawaguchi, Noriaki
    Kawano, Takafumi
    Kiss, Mózsi
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Moretti, Elena
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Pearce, Mark
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Rydström, Stefan
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Takahashi, Hiromitsu
    Yanagida, Takayuki
    PoGOLino: A scintillator-based balloon-borne neutron detector2015Ingår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 770, s. 68-75Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    PoGOLino is a balloon borne scintillator-based experiment developed to study the largely unexplored high altitude neutron environment at high geomagnetic latitudes. The instrument comprises two detectors LhaL make use of LiCAF, a novel neutron sensitive scintillator, sandwiched by [GO crystals for background reduction. The experiment was launched on March 20th 2013 from the [orange Space Centre, Northern Sweden (geomagnetic latitude of 65 degrees), for a three hour flight during which the instrument Look data up loan altitude of 30.9 km. The detector design and ground calibration results are presented together with the measurement results from the balloon flight.

  • 13. Sofitta, P
    et al.
    Pearce, Mark
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Axelsson, M.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Chauvin, Maxime
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Burgess, Michael
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Kiss, Moszi
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Larsson, Josefin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ryde, Felix
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Xie, F
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zoghbi, A.
    et al.,
    XIPE the X-ray Imaging Polarimetry Explorer2016Ingår i: Proceedings of SPIE, SPIE - International Society for Optical Engineering, 2016, Vol. 9905, artikel-id UNSP 990515Konferensbidrag (Refereegranskat)
    Abstract [en]

    XIPE, the X-ray Imaging Polarimetry Explorer, is a mission dedicated to X-ray Astronomy. At the time of writing XIPE is in a competitive phase A as fourth medium size mission of ESA (M4). It promises to reopen the polarimetry window in high energy Astrophysics after more than 4 decades thanks to a detector that efficiently exploits the photoelectric effect and to X-ray optics with large effective area. XIPE uniqueness is time-spectrally-spatially- resolved X-ray polarimetry as a breakthrough in high energy astrophysics and fundamental physics. Indeed the payload consists of three Gas Pixel Detectors at the focus of three X-ray optics with a total effective area larger than one XMM mirror but with a low weight. The payload is compatible with the fairing of the Vega launcher. XIPE is designed as an observatory for X- ray astronomers with 75% of the time dedicated to a Guest Observer competitive program and it is organized as a consortium across Europe with main contributions from Italy, Germany, Spain, United Kingdom, Poland, Sweden.

  • 14. Takahashi, Hiromitsu
    et al.
    Chauvin, Maxime
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Fukazawa, Yasushi
    Jackson, Miranda
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Kamae, Tuneyoshi
    Kawano, Takafumi
    Kiss, Mozsi
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Kole, Merlin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Mikhalev, Victor
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Mizuno, Tsunefumi
    Moretti, Elena
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Pearce, Mark
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Rydström, Stefan
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Data acquisition system and ground calibration of polarized gamma-ray observer (PoGOLite)2014Ingår i: Proceedings of SPIE - The International Society for Optical Engineering, SPIE - International Society for Optical Engineering, 2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    The Polarized Gamma-ray Observer, PoGOLite, is a balloon experiment with the capability of detecting 10% polarization from a 200 mCrab celestial object between the energy-range 25-80 keV in one 6 hour flight. Polarization measurements in soft gamma-rays are expected to provide a powerful probe into high-energy emission mechanisms in/around neutron stars, black holes, supernova remnants, active-galactic nuclei etc. The pathfinder flight was performed in July 2013 for 14 days from Sweden to Russia. The polarization is measured using Compton scattering and photoelectric absorption in an array of 61 well-type phoswich detector cells (PDCs) for the pathfinder instrument. The PDCs are surrounded by 30 BGO crystals which form a side anti-coincidence shield (SAS) and passive polyethylene neutron shield. There is a neutron detector consisting of LiCaAlF6 (LiCAF) scintillator covered with BGOs to measure the background contribution of atmospheric neutrons. The data acquisition system treats 92 PMT signals from 61 PDCs + 30 SASs + 1 neutron detector, and it is developed based on SpaceWire spacecraft communication network. Most of the signal processing is done by digital circuits in Field Programmable Gate Arrays (FPGAs). This enables the reduction of the mass, the space and the power consumption. The performance was calibrated before the launch.

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