Ultrasoft state of microquasar Cygnus X-3: X-ray polarimetry reveals the geometry of the astronomical puzzle

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F24%3A00597858" target="_blank" >RIV/67985815:_____/24:00597858 - isvavai.cz</a>

Result on the web

<a href="https://hdl.handle.net/11104/0355687" target="_blank" >https://hdl.handle.net/11104/0355687</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1051/0004-6361/202451356" target="_blank" >10.1051/0004-6361/202451356</a>

Result language

angličtina

Original language name

Ultrasoft state of microquasar Cygnus X-3: X-ray polarimetry reveals the geometry of the astronomical puzzle

Original language description

Cygnus X-3 is an enigmatic X-ray binary that is both an exceptional accreting system and a cornerstone for population synthesis studies. Prominent X-ray and radio properties follow a well-defined pattern, and yet the physical reasons for the state changes observed in this system are not known. Recently, the presence of an optically thick envelope around the central source in the hard state was revealed using the X-ray polarization data obtained with the Imaging X-ray Polarimetry Explorer (IXPE). In this work we analyse IXPE data obtained in the ultrasoft (radio quenched) state of the source. The average polarization degree (PD) of 11.9 +/- 0.5% at a polarization angle (PA) of 94 degrees +/- 1 degrees is inconsistent with the simple geometry of the accretion disc viewed at an intermediate inclination. The high PD, the blackbody-like spectrum, and the weakness of fluorescent iron line imply that the central source is hidden behind the optically thick outflow, similar to the hard-state geometry, and its beamed radiation is scattered, by the matter located along the funnel axis, towards our line of sight. In this picture the observed PD is directly related to the source inclination, which we conservatively determine to lie in the range 26 degrees < i < 28 degrees. Using the new polarimetric properties, we propose a scenario that can be responsible for the cyclic behaviour of the state changes in the binary.

Czech name

—

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

<a href="/en/project/GX21-06825X" target="_blank" >GX21-06825X: Accreting Black Holes in the new era of X-ray polarimetry missions</a><br>

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

688

Issue of the periodical within the volume

Aug.

Country of publishing house

FR - FRANCE

Number of pages

8

Pages from-to

L27

UT code for WoS article

001291438500008

EID of the result in the Scopus database

2-s2.0-85201696202