IXPE Observations of the Quintessential Wind-accreting X-Ray Pulsar Vela X-1

0572125 - ASÚ 2024 RIV US eng J - Článek v odborném periodiku
Forsblom, S. - Poutanen, J. - Tsygankov, S. S. - Dovčiak, Michal - Karas, Vladimír … celkem 101 autorů
IXPE Observations of the Quintessential Wind-accreting X-Ray Pulsar Vela X-1.
Astrophysical Journal Letters. Roč. 947, č. 2 (2023), č. článku L20. ISSN 2041-8205. E-ISSN 2041-8213
Institucionální podpora: RVO:67985815
Klíčová slova: pulsars * starlight polarization * neutron stars
Obor OECD: Astronomy (including astrophysics,space science)
Impakt faktor: 7.9, rok: 2022
Způsob publikování: Open access

The radiation from accreting X-ray pulsars was expected to be highly polarized, with some estimates for the polarization degree of up to 80%. However, phase-resolved and energy-resolved polarimetry of X-ray pulsars is required in order to test different models and to shed light on the emission processes and the geometry of the emission region. Here we present the first results of the observations of the accreting X-ray pulsar Vela X-1 performed with the Imaging X-ray Polarimetry Explorer. Vela X-1 is considered to be the archetypal example of a wind-accreting, high-mass X-ray binary system, consisting of a highly magnetized neutron star accreting matter from its supergiant stellar companion. The spectropolarimetric analysis of the phase-averaged data for Vela X-1 reveals a polarization degree (PD) of 2.3% +/- 0.4% at the polarization angle (PA) of47.degrees 3 +/- 5.degrees 4. A low PD is consistent with the results obtained for other X-ray pulsars and is likely related to the inverse temperature structure of the neutron star atmosphere. The energy-resolved analysis shows the PD above 5 keV reaching 6%-10% and a similar to 90 degrees difference in the PA compared to the data in the 2-3 keV range. The phase-resolved spectropolarimetric analysis finds a PD in the range 0%-9% with the PA varying between80 degrees and 40 degrees.
Trvalý link: https://hdl.handle.net/11104/0342978