X-ray polarized view of the accretion geometry in the X-ray binary Circinus X-1

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F24%3A00582092" target="_blank" >RIV/67985815:_____/24:00582092 - isvavai.cz</a>

Výsledek na webu

<a href="https://hdl.handle.net/11104/0353541" target="_blank" >https://hdl.handle.net/11104/0353541</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.3847/2041-8213/ad1832" target="_blank" >10.3847/2041-8213/ad1832</a>

Jazyk výsledku

angličtina

Název v původním jazyce

X-ray polarized view of the accretion geometry in the X-ray binary Circinus X-1

Popis výsledku v původním jazyce

Cir X-1 is a neutron star X-ray binary characterized by strong variations in flux during its eccentric similar to 16.6 day orbit. There are also strong variations in the spectral state, and it has historically shown both atoll and Z state properties. We observed the source with the Imaging X-ray Polarimetry Explorer during two orbital segments, 6 days apart, for a total of 263 ks. We find an X-ray polarization degree in these segments of 1.6% +/- 0.3% and 1.4% +/- 0.3% at polarization angles of 37 degrees +/- 5 degrees and12 degrees +/- 7 degrees, respectively. Thus, we observed a rotation of the polarization angle by 49 degrees +/- 8 degrees along the orbit. Because variations of accretion flow, and then of the hardness ratio, are expected during the orbit, we also studied the polarization binned in hardness ratio and found the polarization angle differing by 67 degrees +/- 11 degrees between the lowest and highest values of the hardness ratio. We discuss possible interpretations of this result that could indicate a possible misalignment between the symmetry axes of the accretion disk and the Comptonizing region caused by the misalignment of the neutron star's angular momentum with respect to the orbital one.

Název v anglickém jazyce

X-ray polarized view of the accretion geometry in the X-ray binary Circinus X-1

Popis výsledku anglicky

Cir X-1 is a neutron star X-ray binary characterized by strong variations in flux during its eccentric similar to 16.6 day orbit. There are also strong variations in the spectral state, and it has historically shown both atoll and Z state properties. We observed the source with the Imaging X-ray Polarimetry Explorer during two orbital segments, 6 days apart, for a total of 263 ks. We find an X-ray polarization degree in these segments of 1.6% +/- 0.3% and 1.4% +/- 0.3% at polarization angles of 37 degrees +/- 5 degrees and12 degrees +/- 7 degrees, respectively. Thus, we observed a rotation of the polarization angle by 49 degrees +/- 8 degrees along the orbit. Because variations of accretion flow, and then of the hardness ratio, are expected during the orbit, we also studied the polarization binned in hardness ratio and found the polarization angle differing by 67 degrees +/- 11 degrees between the lowest and highest values of the hardness ratio. We discuss possible interpretations of this result that could indicate a possible misalignment between the symmetry axes of the accretion disk and the Comptonizing region caused by the misalignment of the neutron star's angular momentum with respect to the orbital one.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10308 - Astronomy (including astrophysics,space science)

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2024

Kód důvěrnosti údajů

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

Název periodika

Astrophysical Journal Letters

ISSN

2041-8205

e-ISSN

2041-8213

Svazek periodika

961

Číslo periodika v rámci svazku

1

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

12

Strana od-do

L8

Kód UT WoS článku

001140261500001

EID výsledku v databázi Scopus

2-s2.0-85182584553