| Title: |
IXPE Observations of the Quintessential Wind-accreting X-Ray Pulsar Vela X-1 |
| Authors: |
Forsblom, Sofia V; Poutanen, Juri; Tsygankov, Sergey S; Bachetti, Matteo; Marco, Alessandro Di; Doroshenko, Victor; Heyl, Jeremy; Monaca, Fabio La; Malacaria, Christian; Marshall, Herman L; Muleri, Fabio; Mushtukov, Alexander A; Pilia, Maura; Rogantini, Daniele; Suleimanov, Valery F; Taverna, Roberto; Xie, Fei; Agudo, Iván; Antonelli, Lucio A; Baldini, Luca; Baumgartner, Wayne H; Bellazzini, Ronaldo; Bianchi, Stefano; Bongiorno, Stephen D; Bonino, Raffaella; Brez, Alessandro; Bucciantini, Niccolò; Capitanio, Fiamma; Castellano, Simone; Cavazzuti, Elisabetta; Chen, Chien-Ting; Ciprini, Stefano; Costa, Enrico; Rosa, Alessandra De; Monte, Ettore Del; Gesu, Laura Di; Lalla, Niccolò Di; Donnarumma, Immacolata; Dovčiak, Michal; Ehlert, Steven R; Enoto, Teruaki; Evangelista, Yuri; Fabiani, Sergio; Ferrazzoli, Riccardo; Garcia, Javier A; Gunji, Shuichi; Hayashida, Kiyoshi; Iwakiri, Wataru; Jorstad, Svetlana G; Kaaret, Philip; Karas, Vladimir; Kitaguchi, Takao; Kolodziejczak, Jeffery J; Krawczynski, Henric; Latronico, Luca; Liodakis, Ioannis; Maldera, Simone; Manfreda, Alberto; Marin, Frédéric; Marinucci, Andrea; Marscher, Alan P; Matt, Giorgio; Mitsuishi, Ikuyuki; Mizuno, Tsunefumi; Negro, Michela; Ng, Chi-Yung; O’Dell, Stephen L; Omodei, Nicola; Oppedisano, Chiara; Papitto, Alessandro; Pavlov, George G; Peirson, Abel L; Perri, Matteo; Pesce-Rollins, Melissa; Petrucci, Pierre-Olivier; Possenti, Andrea; Puccetti, Simonetta; Ramsey, Brian D; Rankin, John; Ratheesh, Ajay; Roberts, Oliver J; Romani, Roger W; Sgrò, Carmelo; Slane, Patrick; Soffitta, Paolo; Spandre, Gloria; Sunyaev, Rashid A; Swartz, Douglas A; Tamagawa, Toru; Tavecchio, Fabrizio; Tawara, Yuzuru; Tennant, Allyn F; Thomas, Nicholas E; Tombesi, Francesco; Trois, Alessio; Turolla, Roberto; Vink, Jacco; Weisskopf, Martin C; Wu, Kinwah; Zane, Silvia; IXPE Collaboration |
| Source: |
The Astrophysical Journal Letters , 947 (2) , Article L20. (2023) |
| Publisher Information: |
The American Astronomical Society |
| Publication Year: |
2023 |
| Collection: |
University College London: UCL Discovery |
| Subject Terms: |
Pulsars; Starlight polarization; Neutron stars; High mass x-ray binary stars; Magnetic fields; Accretion |
| Description: |
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) of −47.°3 ± 5.°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 ∼90° 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 between −80° and 40°. |
| Document Type: |
article in journal/newspaper |
| File Description: |
text |
| Language: |
English |
| Relation: |
https://discovery.ucl.ac.uk/id/eprint/10168684/1/Zane_Forsblom_2023_ApJL_947_L20.pdf; https://discovery.ucl.ac.uk/id/eprint/10168684/ |
| Availability: |
https://discovery.ucl.ac.uk/id/eprint/10168684/1/Zane_Forsblom_2023_ApJL_947_L20.pdf; https://discovery.ucl.ac.uk/id/eprint/10168684/ |
| Rights: |
open |
| Accession Number: |
edsbas.144C8BE2 |
| Database: |
BASE |