XL-Calibur -- a second-generation balloon-borne hard X-ray polarimetry mission

Abstract

XL-Calibur is a hard X-ray (15-80 keV) polarimetry mission operating from a stabilised balloon-borne platform in the stratosphere. It builds on heritage from the X-Calibur mission, which observed the accreting neutron star GX 301-2 from Antarctica, between December 29th 2018 and January 1st 2019. The XL-Calibur design incorporates an X-ray mirror, which focusses X-rays onto a polarimeter comprising a beryllium rod surrounded by Cadmium Zinc Telluride (CZT) detectors. The polarimeter is housed in an anticoincidence shield to mitigate background from particles present in the stratosphere. The mirror and polarimeter-shield assembly are mounted at opposite ends of a 12 m long lightweight truss, which is pointed with arcsecond precision by WASP - the Wallops Arc Second Pointer. The XL-Calibur mission will achieve a substantially improved sensitivity over X-Calibur by using a larger effective area X-ray mirror, reducing background through thinner CZT detectors, and improved anticoincidence shielding. When observing a 1 Crab source for $t_{\mathrm{day}}$ days, the Minimum Detectable Polarisation (at 99% confidence level) is $\sim$2$\%\cdot t_{\mathrm{day}}^{-1/2}$. The energy resolution at 40 keV is $\sim$5.9 keV. The aim of this paper is to describe the design and performance of the XL-Calibur mission, as well as the foreseen science programme.

arXiv comment19 pages, 17 figures. Accepted for publication in Astroparticle Physics

References in corpus (32)

• Physics of Strongly Magnetized Neutron Stars
• A relativistic jet from Cygnus X-1 in the low/hard X-ray state
• The enhanced X-ray Timing and Polarimetry mission - eXTP
• Cyclotron lines in highly magnetized neutron stars
• Cosmic X-ray background and Earth albedo Spectra with Swift/BAT
• Analyzing the Data from X-ray Polarimeters with Stokes Parameters
• The Trigonometric Parallax of Cygnus X-1
• X-ray Polarization from Accreting Black Holes: Coronal Emission
• Polarization of the Crab pulsar and nebula as observed by the Integral/IBIS telescope
• High-Altitude Emission from Pulsar Slot Gaps: The Crab Pulsar
• A model for cyclotron resonance scattering features
• XIPE: the X-ray Imaging Polarimetry Explorer
• 3D Kinetic Pulsar Magnetosphere Models: Connecting to Gamma-Ray Observations
• Thermal disc emission from a rotating black hole: X-ray polarization signatures
• Crab: the standard X-ray candle with all (modern) X-ray satellites
• Scientific Prospects for Hard X-ray Polarimetry
• Pulse Profiles, Spectra and Polarization Characteristics of Non-Thermal Emissions from the Crab-Like Pulsars
• X-Ray Polarimetry with the Polarization Spectroscopic Telescope Array (PolSTAR)
• Accretion geometry of the black-hole binary Cygnus X-1 from X-ray polarimetry
• Polarimetry in the hard X-ray domain with INTEGRAL SPI
• The Compton Spectrometer and Imager
• Polarized synchrotron emission from the equatorial current sheet in gamma-ray pulsars
• Optimization of the Design of the Hard X-ray Polarimeter X-Calibur
• Multiple cyclotron line-forming regions in GX 301-2
• Multiwavelength Polarization of Rotation-Powered Pulsars
• Observations of a GX 301-2 Apastron Flare with the X-Calibur Hard X-Ray Polarimeter Supported by NICER, the Swift XRT and BAT, and Fermi GBM
• The PoGO+ Balloon-Borne Hard X-ray Polarimetry Mission
• Performance of the PRAXyS X-ray Polarimeter
• Optimising a balloon-borne polarimeter in the hard X-ray domain: from the PoGOLite Pathfinder to PoGO+
• The Halo Occupation Distribution of Obscured Quasars: Revisiting the Unification Model
• Preflight performance studies of the PoGOLite hard X-ray polarimeter
• Inorbit Performance of the Hard X-ray Telescope (HXT) on board the Hitomi (ASTRO-H) satellite

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• ALP induced polarization effects on photons from galaxy clusters
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• Spectral and polarization properties of reflected X-ray emission from black-hole accretion discs for a distant observer: the lamp-post model
• The design and performance of the XL-Calibur anticoincidence shield
• Axion-like Particle Effects on Photon Polarization in High-Energy Astrophysics
• The 511-CAM Mission: A Pointed 511 keV Gamma-Ray Telescope with a Focal Plane Detector Made of Stacked Transition Edge Sensor Microcalorimeter Arrays
• DarpanX: A Python Package for Modeling X-ray Reflectivity of Multilayer Mirrors
• Gamma-Ray Polarimetry
• XL-Calibur measurements of polarised hard X-ray emission from the Crab
• The Relative Importance of Faraday Rotation and QED Birefringence for the Linear Polarization of X-rays from Mass Accreting Black Holes
• Systematic effects on a Compton polarimeter at the focus of an X-ray mirror
• Cyclotron lines in subcritical X-ray pulsars: Monte Carlo simulations reveal the origin of the observed variability
• Optimal Summary Statistics for X-ray Polarization
• Sidelobe Modeling and Mitigation for a Three Mirror Anastigmat Cosmic Microwave Background Telescope
• In search of the third dimension in Compton X-ray polarimeters
• Development of the cadmium zinc TElluride Radiation Imager (TERI)
• General History of X-Ray Polarimetry in Astrophysics
• Performance of the X-Calibur Hard X-Ray Polarimetry Mission during its 2018/19 Long-Duration Balloon Flight