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arXiv · 2210.03194

Observations of 4U 1626-67 with the Imaging X-ray Polarimetry Explorer

Herman L. Marshall·Mason Ng·Daniele Rogantini·Jeremy Heyl·Sergey S. Tsygankov·Juri Poutanen·Enrico Costa·Silvia Zane·Christian Malacaria·Ivan Agudo·Lucio A. Antonelli·Matteo Bachetti·Luca Baldini·Wayne H. Baumgartner·Ronaldo Bellazzini·Stefano Bianchi·Stephen D. Bongiorno·Raffaella Bonino·Alessandro Brez·Niccolo Bucciantini·Fiamma Capitanio·Simone Castellano·Elisabetta Cavazzuti·Stefano Ciprini·Alessandra De Rosa·Ettore Del Monte·Laura Di Gesu·Niccolo Di Lalla·Alessandro Di Marco·Immacolata Donnarumma·Victor Doroshenko·Michal Dovvciak·Steven R. Ehlert·Teruaki Enoto·Yuri Evangelista·Sergio Fabiani·Riccardo Ferrazzoli·Javier A. Garcia·Shuichi Gunji·Kiyoshi Hayashida·Wataru Iwakiri·Svetlana G. Jorstad·Vladimir Karas·Takao Kitaguchi·Jeffery J. Kolodziejczak·Henric Krawczynski·Fabio La Monaca·Luca Latronico·Ioannis Liodakis·Simone Maldera·Alberto Manfreda·Frederic Marin·Andrea Marinucci·Alan P. Marscher·Giorgio Matt·Ikuyuki Mitsuishi·Tsunefumi Mizuno·Fabio Muleri·C. -Y. Ng·Stephen L. ODell·Nicola Omodei·Chiara Oppedisano·Alessandro Papitto·George G. Pavlov·Abel L. Peirson·Matteo Perri·Melissa Pesce-Rollins·Pierre-Olivier Petrucci·Maura Pilia·Andrea Possenti·Simonetta Puccetti·Brian D. Ramsey·John Rankin·Ajay Ratheesh·Roger W. Romani·Carmelo Sgro·Patrick Slane·Paolo Soffitta·Gloria Spandre·Toru Tamagawa·Fabrizio Tavecchio·Roberto Taverna·Yuzuru Tawara·Allyn F. Tennant·Nicholas E. Thomas·Francesco Tombesi·Alessio Trois·Roberto Turolla·Jacco Vink·Martin C. Weisskopf·Kinwah Wu·Fei Xie·Norbert S. Schulz·Deepto Chakrabarty

Abstract

We present measurements of the polarization of X-rays in the 2-8 keV band from the pulsar in the ultracompact low mass X-ray binary 4U1626-67 using data from the Imaging X-ray Polarimetry Explorer (IXPE). The 7.66 s pulsations were clearly detected throughout the IXPE observations as well as in the NICER soft X-ray observations, which we use as the basis for our timing analysis and to constrain the spectral shape over 0.4-10 keV energy band. Chandra HETGS high-resolution X-ray spectra were also obtained near the times of the IXPE observations for firm spectral modeling. We find an upper limit on the pulse-averaged linear polarization of <4% (at 95% confidence). Similarly, there was no significant detection of polarized flux in pulse phase intervals when subdividing the bandpass by energy. However, spectropolarimetric modeling over the full bandpass in pulse phase intervals provide a marginal detection of polarization of the power-law spectral component at the 4.8 +/- 2.3% level (90% confidence). We discuss the implications concerning the accretion geometry onto the pulsar, favoring two-component models of the pulsed emission.

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Herman L. Marshall, Mason Ng, Daniele Rogantini, Jeremy Heyl, Sergey S. Tsygankov, Juri Poutanen, Enrico Costa, Silvia Zane, Christian Malacaria, Ivan Agudo, Lucio A. Antonelli, Matteo Bachetti, Luca Baldini, Wayne H. Baumgartner, Ronaldo Bellazzini, Stefano Bianchi, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Niccolo Bucciantini, Fiamma Capitanio, Simone Castellano, Elisabetta Cavazzuti, Stefano Ciprini, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Niccolo Di Lalla, Alessandro Di Marco, Immacolata Donnarumma, Victor Doroshenko, Michal Dovvciak, Steven R. Ehlert, Teruaki Enoto, Yuri Evangelista, Sergio Fabiani, Riccardo Ferrazzoli, Javier A. Garcia, Shuichi Gunji, Kiyoshi Hayashida, Wataru Iwakiri, Svetlana G. Jorstad, Vladimir Karas, Takao Kitaguchi, Jeffery J. Kolodziejczak, Henric Krawczynski, Fabio La Monaca, Luca Latronico, Ioannis Liodakis, Simone Maldera, Alberto Manfreda, Frederic Marin, Andrea Marinucci, Alan P. Marscher, Giorgio Matt, Ikuyuki Mitsuishi, Tsunefumi Mizuno, Fabio Muleri, C. -Y. Ng, Stephen L. ODell, Nicola Omodei, Chiara Oppedisano, Alessandro Papitto, George G. Pavlov, Abel L. Peirson, Matteo Perri, Melissa Pesce-Rollins, Pierre-Olivier Petrucci, Maura Pilia, Andrea Possenti, Simonetta Puccetti, Brian D. Ramsey, John Rankin, Ajay Ratheesh, Roger W. Romani, Carmelo Sgro, Patrick Slane, Paolo Soffitta, Gloria Spandre, Toru Tamagawa, Fabrizio Tavecchio, Roberto Taverna, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, Alessio Trois, Roberto Turolla, Jacco Vink, Martin C. Weisskopf, Kinwah Wu, Fei Xie, Norbert S. Schulz, Deepto Chakrabarty. 2022-10-06. Observations of 4U 1626-67 with the Imaging X-ray Polarimetry Explorer. https://doi.org/10.3847/1538-4357%2Fac98c2

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