DISCOVERY OF COHERENT PULSATIONS FROM THE ULTRALUMINOUS X-RAY SOURCE NGC 7793 P13
DISCOVERY OF COHERENT PULSATIONS FROM THE ULTRALUMINOUS X-RAY SOURCE NGC 7793 P13
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DOI：
10.3847/2041-8205/831/2/l14
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发表时间：
2016-09
期刊：
影响因子：
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通讯作者：
F. Fuerst;D. Walton;F. Harrison;D. Stern;D. Barret;M. Brightman;A. Fabian;B. Grefenstette;
中科院分区：
文献类型：
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作者：
F. Fuerst;D. Walton;F. Harrison;D. Stern;D. Barret;M. Brightman;A. Fabian;B. Grefenstette;
我们报告的相干脉动的检测超亮X射线源（ULX）NGC 7793 P13。0.42秒的近正弦脉动最初是在2016年使用XMM-牛顿和努斯塔进行的宽带X射线观测中发现的。随后，我们还在2013年和2014年拍摄的XMM-牛顿档案数据中发现了脉动。相干脉动的显著（105 σ）探测表明，P13中的致密天体是一颗中子星星，并且给出观测到的峰值光度为1040 erg s − 1（假设各向同性），它远高于1.4 M中微子吸积体的爱丁顿极限。这使得P13成为第二个已知由吸积中子星星提供动力的ULX。脉冲周期在不同时期之间变化，在2013-2016年期间缓慢但持续的旋转。这种上旋表明磁场为B ~ 1.5 × 1012 G，这是许多银河系吸积星的典型特征。对于极端亮度最可能的解释是高度的光束;然而，这很难与正弦脉冲轮廓相协调。
We report the detection of coherent pulsations from the ultraluminous X-ray source (ULX) NGC 7793 P13. The ≈0.42 s nearly sinusoidal pulsations were initially discovered in broadband X-ray observations using XMM-Newton and NuSTAR taken in 2016. We subsequently also found pulsations in archival XMM-Newton data taken in 2013 and 2014. The significant (≫5σ) detection of coherent pulsations demonstrates that the compact object in P13 is a neutron star, and given the observed peak luminosity of ≈1040 erg s − 1 (assuming isotropy), it is well above the Eddington limit for a 1.4 M ⊙ accretor. This makes P13 the second ULX known to be powered by an accreting neutron star. The pulse period varies between epochs, with a slow but persistent spin-up over the 2013–2016 period. This spin-up indicates a magnetic field of B ≈ 1.5 × 1012 G, typical of many Galactic accreting pulsars. The most likely explanation for the extreme luminosity is a high degree of beaming; however, this is difficult to reconcile with the sinusoidal pulse profile.