Accretion geometry of the neutron star low mass X-ray binary Cyg X-2 from X-ray polarization measurements

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F23%3A00574444" target="_blank" >RIV/67985815:_____/23:00574444 - isvavai.cz</a>

Result on the web

<a href="https://hdl.handle.net/11104/0345186" target="_blank" >https://hdl.handle.net/11104/0345186</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1093/mnras/stac3726" target="_blank" >10.1093/mnras/stac3726</a>

Result language

angličtina

Original language name

Accretion geometry of the neutron star low mass X-ray binary Cyg X-2 from X-ray polarization measurements

Original language description

We report spectro-polarimetric results of an observational campaign of the bright neutron star low-mass X-ray binary Cyg X-2 simultaneously observed by IXPE, NICER, and INTEGRAL. Consistently with previous results, the broad-band spectrum is characterized by a lower-energy component, attributed to the accretion disc with kT(in) approximate to 1 keV, plus unsaturated Comptonization in thermal plasma with temperature kT(e) = 3 keV and optical depth tau approximate to 4, assuming a slab geometry. We measure the polarization degree in the 2-8 keV band P = 1.8 +/- 0.3 percent and polarization angle phi = 140 degrees +/- 4 degrees, consistent with the previous X-ray polarimetric measurements by OSO-8 as well as with the direction of the radio jet which was earlier observed from the source. While polarization of the disc spectral component is poorly constrained with the IXPE data, the Comptonized emission has a polarization degree P = 4.0 +/- 0.7 percent and a polarization angle aligned with the radio jet. Our results strongly favour a spreading layer at the neutron star surface as the main source of the polarization signal. However, we cannot exclude a significant contribution from reflection off the accretion disc, as indicated by the presence of the iron fluorescence line.

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

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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

Monthly Notices of the Royal Astronomical Society

ISSN

0035-8711

e-ISSN

1365-2966

Volume of the periodical

519

Issue of the periodical within the volume

3

Country of publishing house

US - UNITED STATES

Number of pages

10

Pages from-to

3681-3690

UT code for WoS article

001035850100014

EID of the result in the Scopus database

2-s2.0-85148270126