X-ray Polarimetry as a Tool to Measure the Black Hole Spin in Microquasars: Simulations of IXPE Capabilities

Abstract

Measurements of the angular momentum (spin) of astrophysical black holes are extremely important, as they provide information on the black hole formation and evolution. We present simulated observations of a X-ray binary system with the Imaging X-ray Polarimetry Explorer (IXPE), with the aim to study the robustness of black hole spin and geometry measurements using X-ray polarimetry. As a representative example, we used the parameters of GRS 1915+105 in its former unobscured, soft state. In order to simulate the polarization properties, we modeled the source emission with a multicolor blackbody accounting for thermal radiation from the accretion disk, including returning radiation. Our analysis shows that the polarimetric observations in the X-ray waveband will be able to estimate both spin and inclination of the system with a good precision (without returning radiation we obtained for the lowest spin $\Delta a\le 0.4$ (0.4/0.998 $\sim$ 40%) for spin and $\Delta i\le 30^{\circ }$ (30${}^{\circ }$/70${}^{\circ }$ $\sim$ 43%) for inclination, while for the higher spin values we obtained $\Delta a\le 0.12$ ($\sim$ 12%) for spin and $\Delta i\le 20^{\circ }$ ($\sim$ 29%) for inclination, within 1$\sigma$ errors). When focusing on the case of returning radiation and treating inclination as a known parameter, we were able to successfully reconstruct spin and disk albedo in $\Delta a\le 0.15$ ($\sim$ 15%) interval and $\Delta$ albedo $\le 0.45$ (45%) intervals within 1$\sigma$ errors. We conclude that X-ray polarimetry will be a useful tool to constrain black hole spins, in addition to timing and spectral-fitting methods.

11 pages, 10 figures

References in corpus (8)

• X-ray Properties of Black-Hole Binaries
• A Parallax Distance to the Microquasar GRS 1915+105 and a Revised Estimate of its Black Hole Mass
• ixpeobssim: a Simulation and Analysis Framework for the Imaging X-ray Polarimetry Explorer
• Broad iron K-alpha emission lines as a diagnostic of black hole spin
• Three-Dimensional Simulations of Magnetized Thin Accretion Disks around Black Holes: Stress in the Plunging Region
• Thermal disc emission from a rotating black hole: X-ray polarization signatures
• Constraining the size of the corona with fully relativistic calculations of spectra of extended corona. I - the Monte Carlo radiative transfer code
• Spectral and polarization properties of black hole accretion disc emission: including absorption effects

Cited by in corpus (8)

• Dramatic Drop in the X-Ray Polarization of Swift J1727.8$-$1613 in the Soft Spectral State
• X-ray Polarization of the Black Hole X-ray Binary 4U 1630-47 Challenges Standard Thin Accretion Disk Scenario
• X-ray polarisation properties of thermal-radiative disc winds in binary systems
• First X-ray polarization measurement confirms the low black-hole spin in LMC X-3
• Accretion Disc Evolution in GRO J1655-40 and LMC X-3 with Relativistic and Non-Relativistic Disc Models
• Accretion Geometry of Black Hole X-ray Binaries: Insights from X-ray Observations
• The detection of high X-ray polarization from an accretion disc corona source and its modelling via Monte Carlo radiation transfer simulation
• Measuring black hole spin through gravitational lensing of pulsars