Optimization of the design of the hard X-ray polarimeter X-Calibur

Guo, Q.; Beilicke, M.; Garson, A.; Kislat, Fabian; Fleming, David E.B.; Krawczynski, H.

doi:10.1016/j.astropartphys.2012.11.006

Cited by 42 publications

(38 citation statements)

References 31 publications

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“…With the advance of modern polarimeters, either based on the photoelectric effect (e.g., Costa et al 2001), gas-filled time-projection chambers (e.g., Black et al 2007), or Compton scattering (e.g., Guo et al 2013), it will soon be possible to measure the X-ray polarization from nearby and bright AGN. The expected AGN polarization in the soft energy band (2-10 keV) should be of similar levels than in the optical band (Marin et al 2016a), but due to Compton and inverse-Compton scattering, the hard X-ray band might show a distinctive polarization.…”

Section: Discussionmentioning

confidence: 99%

Polarized radiative transfer modeling of warped and clumpy dusty tori

Marin

Schartmann

2017

A&A

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Context. Active galactic nuclei (AGN) are anisotropic objects surrounded by an optically thick equatorial medium whose true geometry still defies observers. Aims. We aim to explore the optical scattering-induced polarization that emerges from clumpy and warped dusty tori to check whether they can fit the unified model predictions. Methods. We ran polarized radiative transfer simulations in a set of warped and non-warped clumpy tori to explore the differences induced by distorted dust distributions. We then included warped tori in a more complex model representative of an AGN to check, using polarimetry and imaging methods, whether warps can reproduce the expected polarization dichotomy between Seyfert-I and Seyfert-II AGN. Results. The main results from our simulations highlight that isolated warped structures imprint the polarization degree and angle with distinctive signatures at Seyfert-I orientations. Included in an AGN model, the signatures of warps are easily (but not always) washed out by multiple scattering in a clumpy environment. Imaging polarimetry may help to detect warped tori, but we prove that warps can exist in AGN circumnuclear regions without contradicting observations. Conclusions. Two warped tori with a non-significant difference in geometry in terms of photometry or spectroscopy can have entirely different signatures in polarimetry. Testing the geometry of any alternative model to the usual dusty torus using polarized radiative transfer is a necessary approach to verify or reject a hypothesis.

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Section: Discussionmentioning

confidence: 99%

Polarized radiative transfer modeling of warped and clumpy dusty tori

Marin

Schartmann

2017

A&A

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“…The azimuthal distribution is resolved by 4 × 8 = 32 pixels for each of the 64 depth bins along the optical axis. Detailed information on the simulations to optimize the X-Calibur design (as presented in this paper) can be found in Krawczynski et al [2011] and Guo et al [2013].…”

Section: Designmentioning

confidence: 99%

“…2 in a one-day balloon flight. The energy-dependent detection efficiency of the polarimeter depends on (i) the effective area and point-spread function of the X-ray mirror, (ii) the fraction of scatterings compared to competing interactions such as photo-absorption, and (iii) the geometrical detector coverage to record a high fraction of scattered X-rays (minimization of possible escape paths) [Guo et al, 2010]. This section describes the overall design of the polarimeter, as well as the characteristics of its individual components.…”

Section: Scientific Potentialmentioning

confidence: 99%

“…The proposed polarimeters use focusing mirrors to collect photons from the source. Photoelectric effect polarimeters, like the Gravity and Extreme Magnetism SMEX (GEMS) mission [Hill et al, 2012] and XIPE , track the direction of photo electrons ejected in photoelectric effect interactions of the X-rays. The ASTRO-H mission (to be launched in 2015) will carry the Soft Gamma-Ray Imager.…”

Section: Introductionmentioning

confidence: 99%

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Design and Performance of the X-ray Polarimeter X-Calibur

Beilicke

Kislat

Zajczyk

et al. 2014

J. Astron. Instrum.

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Received (to be inserted by publisher); Revised (to be inserted by publisher); Accepted (to be inserted by publisher); X-ray polarimetry promises to give qualitatively new information about high-energy astrophysical sources, such as binary black hole systems, micro-quasars, active galactic nuclei, neutron stars, and gamma-ray bursts. We designed, built and tested a X-ray polarimeter, X-Calibur, to be used in the focal plane of the balloon-borne InFOCµS grazing incidence X-ray telescope. X-Calibur combines a low-Z scatterer with a CZT detector assembly to measure the polarization of 20 − 80 keV X-rays making use of the fact that polarized photons scatter preferentially perpendicular to the electric field orientation. X-Calibur achieves a high detection efficiency of 80%. The X-Calibur detector assembly is completed, tested, and fully calibrated. The response to a polarized X-ray beam was measured successfully at the Cornell High Energy Synchrotron Source. This paper describes the design, calibration and performance of the X-Calibur polarimeter. In principle, a similar space-borne scattering polarimeter could operate over the broader 2 − 100 keV energy band.

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“…Could a next-generation space-borne X-ray polarimeter like PolSTAR (a space-borne version of the balloon-borne XCalibur experiment (Beilicke et al 2012(Beilicke et al , 2014Guo et al 2013) with excellent sensitivity in the 3-50 keV energy band), PRAXyS (Polarimetry of Relativistic X-ray Sources, Jahoda et al 2015), IXPE (Imaging X-ray Polarimetry Explorer, Weisskopf et al 2014), or XIPE (X-ray Imaging Polarimetry Explorer, Soffitta et al 2013) detect the variation in polarization predicted by the HS model? We considered two methods to search for the variations in polarization: (i) the analysis of the Fourier-transformed Stokes parameters and derived quantities, and (ii) the analysis of the polarization fraction and angle as functions of QPO phase.…”

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confidence: 99%

Studies of the Origin of High-Frequency Quasi-Periodic Oscillations of Mass-Accreting Black Holes in X-Ray Binaries With Next-Generation X-Ray Telescopes

Beheshtipour

Hoormann

Krawczynski

2016

ApJ

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Observations with RXTE (Rossi X-ray Timing Explorer) revealed the presence of high-frequency quasi-periodic oscillations (HFQPOs) of the X-ray flux from several accreting stellar-mass black holes. HFQPOs (and their counterparts at lower frequencies) may allow us to study general relativity in the regime of strong gravity. However, the observational evidence today does not yet allow us to distinguish between different HFQPO models. In this paper we use a general-relativistic ray-tracing code to investigate X-ray timing spectroscopy and polarization properties of HFQPOs in the orbiting Hotspot model. We study observational signatures for the particular case of the 166 Hz quasi-periodic oscillation (QPO) in the galactic binary GRS1915+105. We conclude with a discussion of the observability of spectral signatures with a timing-spectroscopy experiment such as the LOFT (Large Observatory for X-ray Timing) and polarization signatures with space-borne X-ray polarimeters such as IXPE (Imaging X-ray Polarimetry Explorer), PolSTAR (Polarization Spectroscopic Telescope Array), PRAXyS (Polarimetry of Relativistic X-ray Sources), or XIPE (X-ray Imaging Polarimetry Explorer). A mission with high count rate such as LOFT would make it possible to get a QPO phase for each photon, enabling the study of the QPO-phase-resolved spectral shape and the correlation between this and the flux level. Owing to the short periods of the HFQPOs, first-generation X-ray polarimeters would not be able to assign a QPO phase to each photon. The study of QPO-phase-resolved polarization energy spectra would thus require simultaneous observations with a first-generation X-ray polarimeter and a LOFT-type mission.

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Optimization of the design of the hard X-ray polarimeter X-Calibur

Cited by 42 publications

References 31 publications

Polarized radiative transfer modeling of warped and clumpy dusty tori

Polarized radiative transfer modeling of warped and clumpy dusty tori

Design and Performance of the X-ray Polarimeter X-Calibur

Studies of the Origin of High-Frequency Quasi-Periodic Oscillations of Mass-Accreting Black Holes in X-Ray Binaries With Next-Generation X-Ray Telescopes

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