A1 Refereed original research article in a scientific journal

First spectropolarimetric observation of the neutron star low-mass X-ray binary GX 3+1




AuthorsGnarini, Andrea; Farinelli, Ruben; Ursini, Francesco; Bianchi, Stefano; Capitanio, Fiamma; Matt, Giorgio; Ng, Mason; Tarana, Antonella; Bobrikova, Anna; Cocchi, Massimo; Fabiani, Sergio; Kaaret, Philip; Poutanen, Juri; Ravi, Swati

PublisherEDP SCIENCES S A

Publishing placeLES ULIS CEDEX A

Publication year2024

JournalAstronomy and Astrophysics

Journal name in sourceASTRONOMY & ASTROPHYSICS

Journal acronymASTRON ASTROPHYS

Article number A123

Volume692

Number of pages7

ISSN0004-6361

eISSN1432-0746

DOIhttps://doi.org/10.1051/0004-6361/202452642(external)

Web address https://doi.org/10.1051/0004-6361/202452642(external)

Self-archived copy’s web addresshttps://research.utu.fi/converis/portal/detail/Publication/478066523(external)


Abstract

We report the first simultaneous X-ray spectropolarimetric observation of the bright atoll neutron star low-mass X-ray binary GX 3+1, performed by the Imaging X-ray Polarimetry Explorer (IXPE) joint with NICER and NuSTAR. The source does not exhibit significant polarization in the 2–8 keV energy band, with an upper limit of 1.3% at a 99% confidence level on the polarization degree. The observed spectra can be well described by a combination of thermal disk emission, the hard Comptonization component, and reflected photons off the accretion disk. In particular, from the broad Fe Kα line profile, we were able to determine the inclination of the system (i ≈ 36◦ ), which is crucial for comparing the observed polarization with theoretical models. Both the spectral and polarization properties of GX 3+1 are consistent with those of other atoll sources observed by IXPE. Therefore, we may expect a similar geometrical configuration for the accreting system and the hot Comptonizing region. The low polarization is also consistent with the low inclination of the system.


Downloadable publication

This is an electronic reprint of the original article.
This reprint may differ from the original in pagination and typographic detail. Please cite the original version.





Last updated on 2025-27-01 at 19:26