The x-ray polarization of compact objects in x-ray binaries allows us to understand the complex spacetimes surrounding these sources. XL-Calibur is a state-of-the-art, balloon-borne telescope that measures the linear polarization of stellar-mass black holes, neutron stars, and nebulae in the 15-80 keV energy band. The selected energy range allows for observing coronal emission from black holes while also enabling us to narrow down on emission models from neutron stars, pulsars, and magnetars. Early in 2024, XL-Calibur will be launched from Kiruna, Sweden for approximately 10 days to observe Cyg X-1 and Cyg X-3, or other sources chosen based on flux levels at the time of flight. Observations might be coordinated with the recently launched Imaging x-ray Polarimetry Explorer mission which measures polarization in the complimentary 2-8 keV band. Combined XL-Calibur and IXPE observations will yield information on both soft and hard x-rays allowing us to decompose the total emission from black holes into thermal disk and coronal. We discuss the characterization of the XL-Calibur CdZnTe detectors, the telescope mirror and truss setup, and preliminary results from our most recent flight.
XL-Calibur is a balloon-borne mission for hard x-ray polarimetry. The first launch is currently scheduled from Sweden in summer 2022. Japanese collaborators provide a hard x-ray telescope to the mission. The telescope’s design is identical to the Hard X-ray Telescope (HXT, conically-approximated Wolter-I optics) on board ASTROH with the same focal length of 12 m and the aperture of 45 cm, which can focus x-rays up to 80 keV. The telescope is divided into three segments in the circumferential direction, and confocal 213 grazing-incidence mirrors are precisely placed in the primary and secondary sections of each segment. The surfaces of the mirrors are coated with Pt/C depth-graded multilayer to reflect hard x-rays efficiently by the Bragg reflection. To achieve the best focus, optical adjustment of all of the segments was performed at the SPring-8/BL20B2 synchrotron radiation facility during 2020. A final performance evaluation was conducted in June 2021 and the experiment yields the effective area of 175 cm2 and 73 cm2 at 30 keV and 50 keV, respectively, with its half-power diameter of the point spread function as 2.1 arcmin. The field of view, defined as the full width of the half-maximum of the vignetting curve, is 5.9 arcmin.
In recent years, the number of CubeSats (U-class spacecrafts) launched into space has increased exponentially marking the dawn of the nanosatellite technology. In general, these satellites have a much smaller mass budget compared to conventional scientific satellites, which limits shielding of scientific instruments against direct and indirect radiation in space. We present a simulation framework to quantify the signal in large field-of-view gamma-ray scintillation detectors of satellites induced by x-ray/gamma-ray transients, by taking into account the response of the detector. Furthermore, we quantify the signal induced by x-ray and particle background sources at a Low-Earth Orbit outside South Atlantic Anomaly and polar regions. Finally, we calculate the signal-to-noise ratio (SNR) taking into account different energy threshold levels. Our simulation can be used to optimize material composition and predict detectability of various astrophysical sources by CubeSats. We apply the developed simulation to a satellite belonging to a planned CAMELOT CubeSat constellation. This project mainly aims to detect short and long gamma-ray bursts (GRBs) and as a secondary science objective, to detect soft gamma-ray repeaters (SGRs) and terrestrial gamma-ray flashes (TGFs). The simulation includes a detailed computer-aided design model of the satellite to take into account the interaction of particles with the material of the satellite as accurately as possible. Results of our simulations predict that CubeSats can complement the large space observatories in high-energy astrophysics for observations of GRBs, SGRs, and TGFs. For the detectors planned to be on board the CAMELOT CubeSats, the simulations show that detections with SNR of at least 9 for median GRB and SGR fluxes are achievable.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.