Complex variations in X-ray polarization in the X-ray pulsar LS V +44 17/RX J0440.9+4431

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F23%3A00582492" target="_blank" >RIV/67985815:_____/23:00582492 - isvavai.cz</a>

Result on the web

<a href="https://hdl.handle.net/11104/0350554" target="_blank" >https://hdl.handle.net/11104/0350554</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1051/0004-6361/202347088" target="_blank" >10.1051/0004-6361/202347088</a>

Result language

angličtina

Original language name

Complex variations in X-ray polarization in the X-ray pulsar LS V +44 17/RX J0440.9+4431

Original language description

We report on Imaging X-ray polarimetry explorer (IXPE) observations of the Be-transient X-ray pulsar LS V +44 17/RX J0440.9+4431 made at two luminosity levels during the giant outburst in January-February 2023. Considering the observed spectral variability and changes in the pulse profiles, the source was likely caught in supercritical and subcritical states with significantly different emission-region geometry, associated with the presence of accretion columns and hot spots, respectively. We focus here on the pulse-phase-resolved polarimetric analysis and find that the observed dependencies of the polarization degree and polarization angle (PA) on the pulse phase are indeed drastically different for the two observations. The observed differences, if interpreted within the framework of the rotating vector model (RVM), imply dramatic variations in the spin axis inclination, the position angle, and the magnetic colatitude by tens of degrees within the space of just a few days. We suggest that the apparent changes in the observed PA phase dependence are predominantly related to the presence of an unpulsed polarized component in addition to the polarized radiation associated with the pulsar itself. We then show that the observed PA phase dependence in both observations can be explained with a single set of RVM parameters defining the pulsar's geometry. We also suggest that the additional polarized component is likely produced by scattering of the pulsar radiation in the equatorial disk wind.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

10308 - Astronomy (including astrophysics,space science)

Project

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Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2023

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Astronomy & Astrophysics

ISSN

0004-6361

e-ISSN

1432-0746

Volume of the periodical

677

Issue of the periodical within the volume

September

Country of publishing house

FR - FRANCE

Number of pages

10

Pages from-to

A57

UT code for WoS article

001162839200001

EID of the result in the Scopus database

2-s2.0-85170824456