Probing the polarized emission from SMC X-1: The brightest X-ray pulsar observed by IXPE

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F24%3A00617158" target="_blank" >RIV/67985815:_____/24:00617158 - isvavai.cz</a>

Result on the web

<a href="https://hdl.handle.net/11104/0364115" target="_blank" >https://hdl.handle.net/11104/0364115</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1051/0004-6361/202450937" target="_blank" >10.1051/0004-6361/202450937</a>

Result language

angličtina

Original language name

Probing the polarized emission from SMC X-1: The brightest X-ray pulsar observed by IXPE

Original language description

Recent observations of X-ray pulsars (XRPs) performed by the Imaging X-ray Polarimetry Explorer (IXPE) have made it possible to investigate the intricate details of these objects in a new way, thanks to the added value of X-ray polarimetry. Here we present the results of the IXPE observations of SMC X-1, a member of the small group of XRPs displaying super-orbital variability. SMC X-1 was observed by IXPE three separate times during the high state of its super-orbital period. The observed luminosity in the 2-8 keV energy band of L similar to 2x10(38) erg s(-1) makes SMC X-1 the brightest XRP ever observed by IXPE. We detect significant polarization in all three observations, with values of the phase-averaged polarization degree (PD) and polarization angle (PA) of 3.2 +/- 0.8% and 97 degrees +/- 8 degrees for Observation 1, 3.0 +/- 0.9% and 90 degrees +/- 8 degrees for Observation 2, and 5.5 +/- 1.1% and 80 degrees +/- 6 degrees for Observation 3, for the spectro-polarimetric analysis. The observed PD shows an increase over time with decreasing luminosity, while the PA decreases in decrements of similar to 10 degrees. The phase-resolved spectro-polarimetric analysis reveals significant detection of polarization in three out of seven phase bins, with the PD ranging between similar to 2% and similar to 10%, and a corresponding range in the PA from similar to 70 degrees to similar to 100 degrees. The pulse-phase resolved PD displays an apparent anti-correlation with the flux. Using the rotating vector model, we obtain constraints on the pulsar's geometrical properties for the individual observations. The position angle of the pulsar displays an evolution over time supporting the idea that we observe changes related to different super-orbital phases. Scattering in the wind of the precessing accretion disk may be responsible for the behavior of the polarimetric properties observed during the high-state of SMC X-1's super-orbital period.

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

—

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2024

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

691

Issue of the periodical within the volume

Nov.

Country of publishing house

FR - FRANCE

Number of pages

11

Pages from-to

A216

UT code for WoS article

001376706700001

EID of the result in the Scopus database

2-s2.0-85208674514