45 citations · 219 across the 24 of their papers we have counts for
25 papers
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…
Magnetar Fireballs and Short Bursts: Curved Spacetime Lensing, QED Effects, Spectra, Polarization, and Impulse Responses
Zorawar Wadiasingh, Hoa Dinh Thi, Constantinos Kalapotharakos +12
Magnetar short bursts (SBs) are hard X-ray transients of durations s peaking at keV, and are prime targets for new high-energy missions and polarimeters. The…
Resonant Inverse Compton Scattering and Hard X-ray Emission in Magnetar Magnetospheres
Kun Hu, Nicholas Rackers, Alexander Y. Chen
Magnetars are a subclass of neutron stars with ultra-strong surface magnetic fields. Some magnetars exhibit persistent hard X-ray emission, characterized by power-law tails with ph…
A New Approach for Testing Einstein's Theory of Gravity Close to Rapidly Spinning Black Holes
Shravan Vengalil Menon, Kun Hu, Henric Krawczynski
The Penrose process and the collisional Penrose process involve particles decaying or interacting very close to a spinning black hole, respectively, during which some particles are…
Pulsed, Polarized X-ray Emission from Neutron Star Surfaces: the Effects of Vacuum Birefringence in the Magnetosphere
Hoa Dinh Thi, Matthew G. Baring, Kun Hu +4
Intense magnetic fields in the atmospheres of neutron stars render non-trivial angular dependence of intensity and polarization of soft X-ray emission originating from their surfac…
Monte Carlo Simulations of Polarized Radiative Transfer in Neutron Star Atmospheres
Hoa Dinh Thi, Matthew G. Baring, Kun Hu +2
Soft X-ray emission from neutron stars affords powerful diagnostic tools for uncovering their surface and interior properties, as well as their geometric configurations. In the atm…
Magnetic Thomson Transport in High Opacity Domains
Matthew G. Baring, Kun Hu, Hoa Dinh Thi
X-ray radiation from neutron stars manifests itself in a variety of settings. Isolated pulsars, and magnetars both exhibit quasi-thermal persistent soft X-ray emission from their s…
Pulsed and Polarized X-ray Emission from Neutron Star Surfaces
Matthew G. Baring, Hoa Dinh Thi, George A. Younes +1
The intense magnetic fields of neutron stars naturally lead to strong anisotropy and polarization of radiation emanating from their surfaces, both being sensitive to the hot spot p…
Dramatic Drop in the X-Ray Polarization of Swift J1727.81613 in the Soft Spectral State
Jiří Svoboda, Michal Dovčiak, James F. Steiner +34
Black-hole X-ray binaries exhibit different spectral and timing properties in different accretion states. The X-ray outburst of a recently discovered and extraordinarily bright sou…
Systematic effects on a Compton polarimeter at the focus of an X-ray mirror
M. Aoyagi, R. G. Bose, S. Chun +23
XL-Calibur is a balloon-borne Compton polarimeter for X-rays in the 15-80 keV range. Using an X-ray mirror with a 12 m focal length for collecting photons onto a beryllium sc…
IXPE observation confirms a high spin in the accreting black hole 4U 1957+115
L. Marra, M. Brigitte, N. Rodriguez Cavero +113
We present the results of the first X-ray polarimetric observation of the low-mass X-ray binary 4U 1957+115, performed with the Imaging X-ray Polarimetry Explorer in May 2023. The…
First X-ray polarization measurement confirms the low black-hole spin in LMC X-3
Jiří Svoboda, Michal Dovčiak, James F. Steiner +109
X-ray polarization is a powerful tool to investigate the geometry of accreting material around black holes, allowing independent measurements of the black hole spin and orientation…
Tensor Perturbations from Bounce Inflation Scenario in f(Q) Gravity
Kun Hu, Tanmoy Paul, Taotao Qiu
In this paper, we construct a bounce inflation cosmological scenario in the framework of the modified symmetric teleparallel gravity, namely f(Q) theory, and investigate the tensor…
Evaluation of several explanations of the strong X-ray polarization of the black hole X-ray binary 4U 1630-47
Henric Krawczynski, Yajie Yuan, Alexander Y. Chen +6
The Imaging X-ray Polarimetry Explorer (IXPE) observations of the X-ray binary 4U 1630-47 in the high soft state revealed high linear polarization degrees (PDs) rising from 6% at 2…
The First X-ray Polarization Observation of the Black Hole X-ray Binary 4U 1630-47 in the Steep Power Law State
Nicole Rodriguez Cavero, Lorenzo Marra, Henric Krawczynski +107
The Imaging X-ray Polarimetry Explorer (IXPE) observed the black hole X-ray binary 4U 1630-47 in the steep power law (or very high) state. The observations reveal a linear polariza…
X-ray Polarization of the Black Hole X-ray Binary 4U 1630-47 Challenges Standard Thin Accretion Disk Scenario
Ajay Ratheesh, Michal Dovčiak, Henric Krawczynski +112
Large energy-dependent X-ray polarization degree is detected by the Imaging X-ray Polarimetry Explorer ({IXPE}) in the high-soft emission state of the black hole X-ray binary 4U 16…
The first X-ray polarimetric observation of the black hole binary LMC X-1
Jakub Podgorny, Lorenzo Marra, Fabio Muleri +108
We report on an X-ray polarimetric observation of the high-mass X-ray binary LMC X-1 in the high/soft state, obtained by the Imaging X-ray Polarimetry Explorer (IXPE) in October 20…
High-Energy Photon Opacity in the Twisted Magnetospheres of Magnetars
Kun Hu, Matthew G. Baring, Alice K. Harding +1
Magnetars are neutron stars characterized by strong surface magnetic fields generally exceeding the quantum critical value of 44.1 TeraGauss. High-energy photons propagating in the…
Polarized Radiation Signals from Highly Magnetized Neutron Star Surfaces
Kun Hu, Matthew G. Baring, Joseph A. Barchas +1
The surfaces of neutron stars are likely sources of strongly polarized soft X rays due to the presence of strong magnetic fields. Scattering transport in the surface layers is crit…
Intensity and Polarization Characteristics of Extended Neutron Star Surface Regions
Kun Hu, Matthew G. Baring, Joseph A. Barchas +1
The surfaces of neutron stars are sources of strongly polarized soft X rays due to the presence of strong magnetic fields. Radiative transfer mediated by electron scattering and fr…
The Mysterious Magnetospheres of Magnetars
Matthew G. Baring, Zorawar Wadiasingh, Peter L. Gonthier +2
Magnetars are the most luminous compact objects in the stellar mass range observed in the Milky Way, with giant flares of hard X-ray power ~10^45 erg/sec being detected from three…
Polarized Radiation Transfer in Neutron Star Surface Layers
Joseph A. Barchas, Kun Hu, Matthew G. Baring
The study of polarized radiation transfer in the highly-magnetized surface locales of neutron stars is of great interest to the understanding of accreting X-ray pulsars, rotation-p…
Opacities for Photon Splitting and Pair Creation in Neutron Star Magnetospheres
Kun Hu, Matthew G. Baring, Zorawar Wadiasingh +1
Over the last four decades, persistent and flaring emission of magnetars observed by various telescopes has provided us with a suite of light curves and spectra in soft and hard X-…