X-ray spectropolarimetric characterization of the Z-source GX 340+0 in the normal branch
arXiv:2508.13278 · doi:10.1051/0004-6361/202555134
Abstract
This study presents an X-ray spectropolarimetric characterisation of the Z-source GX 340+0 during the normal branch (NB) and compares it with that obtained for the horizontal branch (HB), using IXPE, NICER and NuSTAR observations. The analysis reveals significant polarisation, with polarisation degrees (PD) of \% in the NB and \% in the HB, indicating a notable decrease in polarisation when transitioning from the HB to the NB. The polarisation angles show a consistent trend across the states. Spectropolarimetric analysis favours a dependence of the polarisation on the energy. The Comptonised component shows similar polarisation in both the HB and NB and is higher than the theoretical expectation for a boundary or spreading layer. This suggests a contribution from the wind or the presence of an extended accretion disc corona (ADC) to enhance the polarisation. The results obtained here highlight the importance of using polarimetric data to better understand the accretion mechanisms and the geometry of this class of sources, providing insights into the nature of the accretion flow and the interplay between different spectral components. Overall, the findings advance our understanding of the physical processes governing accretion in low-mass X-ray binaries.
A&A 702, A101 (2025)
References in corpus (31)
- Modelling the behaviour of accretion flows in X-ray binaries
- Thermonuclear (type-I) X-ray bursts observed by the Rossi X-ray Timing Explorer
- The Masses and Spins of Neutron Stars and Stellar-Mass Black Holes
- Analyzing the Data from X-ray Polarimeters with Stokes Parameters
- ixpeobssim: a Simulation and Analysis Framework for the Imaging X-ray Polarimetry Explorer
- Relativistic iron emission lines in neutron star low-mass X-ray binaries as probes of neutron star radii
- Design, Construction, and Test of the Gas Pixel Detectors for the IXPE Mission
- Handling Background in IXPE polarimetric data
- A weighted analysis to improve the X-ray polarization sensitivity of IXPE
- Evidence of a Broad Relativistic Iron Line from the Neutron Star Low-Mass X-ray Binary Serpens X-1
- Science objectives of the Einstein Probe mission
- Relativistic X-ray Reflection Models for Accreting Neutron Stars
- Accretion geometry of the neutron star low mass X-ray binary Cyg X-2 from X-ray polarization measurements
- Disk reflection signatures in the spectrum of the bright Z-source GX 340+0
- An explanation of the Z-track sources
- Cygnus X-3 revealed as a Galactic ultraluminous X-ray source by IXPE
- Discovery of strongly variable X-ray polarization in the neutron star low-mass X-ray binary transient XTE J1701462
- Radius Constraints from Reflection Modeling of Cygnus X-2 with NuSTAR and NICER
- Analytical techniques for polarimetric imaging of accretion flows in Schwarzschild metric
- Highly Significant Detection of X-Ray Polarization from the Brightest Accreting Neutron Star Sco X-1
- First detection of X-ray polarization from the accreting neutron star 4U 1820-303
- X-ray polarisation properties of thermal-radiative disc winds in binary systems
- X-Ray Polarized View on the Accretion Geometry in the X-Ray Binary Circinus X-1
- A connection between accretion states and the formation of ultra-relativistic outflows in a neutron star X-ray binary
- X-ray polarization from accretion disk winds
- Discovery of a strong rotation of the X-ray polarization angle in the galactic burster GX 13+1
- New polarimetric study of the galactic X-ray burster GX 13+1
- Polarized radiation from the spreading layer of the weakly magnetized neutron stars
- X-ray spectro-polarimetric characterization of GX 340+0 in the horizontal branch: a highly inclined source?
- X-ray Dips and Polarization Angle Swings in GX 13+1
- IXPE view of the Sco-like source GX 349+2 in the normal branch