Data di Pubblicazione:
2022
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 4U 1626-67 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 used as the basis for our timing analysis and to constrain the spectral shape over the 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 found 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 provided 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.
Tipologia CRIS:
03A-Articolo su Rivista
Elenco autori:
Marshall H.L.; Ng M.; Rogantini D.; Heyl J.; Tsygankov S.S.; Poutanen J.; Costa E.; Zane S.; Malacaria C.; Agudo I.; Antonelli L.A.; Bachetti M.; Baldini L.; Baumgartner W.H.; Bellazzini R.; Bianchi S.; Bongiorno S.D.; Bonino R.; Brez A.; Bucciantini N.; Capitanio F.; Castellano S.; Cavazzuti E.; Ciprini S.; De Rosa A.; Monte E.D.; Gesu L.D.; Lalla N.D.; Marco A.D.; Donnarumma I.; Doroshenko V.; Dovciak M.; Ehlert S.R.; Enoto T.; Evangelista Y.; Fabiani S.; Ferrazzoli R.; Garcia J.A.; Gunji S.; Hayashida K.; Iwakiri W.; Jorstad S.G.; Karas V.; Kitaguchi T.; Kolodziejczak J.J.; Krawczynski H.; Monaca F.L.; Latronico L.; Liodakis I.; Maldera S.; Manfreda A.; Marin F.; Marinucci A.; Marscher A.P.; Matt G.; Mitsuishi I.; Mizuno T.; Muleri F.; Ng C.-Y.; O'Dell S.L.; Omodei N.; Oppedisano C.; Papitto A.; Pavlov G.G.; Peirson A.L.; Perri M.; Pesce-Rollins M.; Petrucci P.-O.; Pilia M.; Possenti A.; Puccetti S.; Ramsey B.D.; Rankin J.; Ratheesh A.; Romani R.W.; Sgro C.; Slane P.; Soffitta P.; Spandre G.; Tamagawa T.; Tavecchio F.; Taverna R.; Tawara Y.; Tennant A.F.; Thomas N.E.; Tombesi F.; Trois A.; Turolla R.; Vink J.; Weisskopf M.C.; Wu K.; Xie F.; Chakrabarty D.; Schulz N.S.
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