Tracking the X-ray polarization of the black hole transient Swift J1727.8-1613 during a state transition

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F24%3A00598921" target="_blank" >RIV/67985815:_____/24:00598921 - isvavai.cz</a>

Result on the web

<a href="https://hdl.handle.net/11104/0356491" target="_blank" >https://hdl.handle.net/11104/0356491</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.3847/1538-4357/ad3faf" target="_blank" >10.3847/1538-4357/ad3faf</a>

Result language

angličtina

Original language name

Tracking the X-ray polarization of the black hole transient Swift J1727.8-1613 during a state transition

Original language description

We report on an observational campaign on the bright black hole (BH) X-ray binary Swift J1727.8-1613 centered around five observations by the Imaging X-ray Polarimetry Explorer. These observations track for the first time the evolution of the X-ray polarization of a BH X-ray binary across a hard to soft state transition. The 2-8 keV polarization degree decreased from ∼4% to ∼3% across the five observations, but the polarization angle remained oriented in the north-south direction throughout. Based on observations with the Australia Telescope Compact Array, we find that the intrinsic 7.25 GHz radio polarization aligns with the X-ray polarization. Assuming the radio polarization aligns with the jet direction (which can be tested in the future with higher-spatial-resolution images of the jet), our results imply that the X-ray corona is extended in the disk plane, rather than along the jet axis, for the entire hard intermediate state. This in turn implies that the long (≳10 ms) soft lags that we measure with the Neutron star Interior Composition ExploreR are dominated by processes other than pure light-crossing delays. Moreover, we find that the evolution of the soft lag amplitude with spectral state does not follow the trend seen for other sources, implying that Swift J1727.8-1613 is a member of a hitherto undersampled subpopulation.

Czech name

—

Czech description

—

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

Astrophysical Journal

ISSN

0004-637X

e-ISSN

1538-4357

Volume of the periodical

968

Issue of the periodical within the volume

2

Country of publishing house

GB - UNITED KINGDOM

Number of pages

16

Pages from-to

76

UT code for WoS article

001420978600001

EID of the result in the Scopus database

2-s2.0-85196085873