27 papers
EXPO: a quantum leap in fast, wide-band X-ray polarimetry for astrophysics
Paolo Soffitta, Sebastien Guillot, Ian Hutchinson +137
The Enhanced X-ray Polarimetry Observatory (EXPO) is a mission concept proposed to ESA as an M8 candidate, with a prospective launch in 2041. Building on the scientific success of…
Energy-Resolved Limits on Orbital X-ray Polarization Modulation in Cygnus X-1
Sohee Chun, Bert Vander Meulen, Kun Hu +1
Reflection off the companion star and its focused stellar wind is predicted to modulate the X-ray polarization of black hole X-ray binaries at half the orbital period ($P_{\rm orb}…
Predictions for the X-ray polarisation modulation in Cygnus X-1 from reflection off the stellar companion and its wind
Bert Vander Meulen, Kun Hu, Victoria Grinberg +1
Context. Cyg X-1 is one of the brightest X-ray binaries and has been observed multiple times with the Imaging X-ray Polarimetry Explorer (IXPE). Recent studies report tentative evi…
X-ray Polarization Signatures from Comptonization by Magnetic Reconnection Plasmoids
John Groger, Kun Hu, Henric Krawczynski
Emission from X-ray binaries in the hard spectral state is dominated by high-energy radiation attributed to the Compton scattering of seed photons. The prevalent model of the Compt…
Design of a mission to measure the shape and substructure of the 511 keV gamma-ray line from the center of the Milky Way
Kun Hu, Matthew Fritts, Daniel Becker +23
The 511 keV electron-positron annihilation feature near the galactic center has been detected for more than half a century, yet its origin remains a mystery. In this paper, we desc…
Refined Constraints on the Hard X-ray Polarization of the Crab Pulsar and Nebula Derived from an Extended XL-Calibur Dataset
Matthew G. Baring, Jacob Casey, Sohee Chun +26
We present updated hard X-ray polarization measurements of the Crab pulsar and nebula obtained with the balloon-borne polarimeter XL-Calibur in the ~19-64 keV energy range. During…