Super-Eddington accretion on to the neutron star NGC 7793 P13: Broad-band X-ray spectroscopy and ultraluminous X-ray sources
Super-Eddington accretion on to the neutron star NGC 7793 P13: Broad-band X-ray spectroscopy and ultraluminous X-ray sources
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中子星 NGC 7793 P13 上的超级爱丁顿吸积：宽带 X 射线光谱和超发光 X 射线源
DOI：
10.1093/mnras/stx2650
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发表时间：
2017
影响因子：
4.8
通讯作者：
L. Tao
中科院分区：
文献类型：
--
作者：
D. Walton;F. Fürst;F. Harrison;D. Stern;M. Bachetti;Didier Barret;M. Brightman;A. Fabian;M. Middleton;A. Ptak;L. Tao
我们利用来自xmm -牛顿、NuSTAR和钱德拉天文台的数据，对超发光x射线源（ULX）脉冲星NGC 7793 P13进行了详细的宽带x射线光谱分析，NGC 7793 P13是已知的超级爱丁顿源。P13的XMM-Newton +NuSTAR宽频带光谱在质量上与其他ULX样本的宽频带覆盖相似，这表明已知群体中额外的ULX可能含有中子星吸积体。通过时间平均、相位分辨和多历元研究，我们发现需要两个温度为~ 0.5和1.5 keV的非脉冲热黑体分量来拟合低于10 keV的数据，此外还需要第三个连续统分量，该连续统分量扩展到更高的能量，与吸积柱的脉冲发射有关。热成分的特征半径似乎是相似的，而且太大了，无法与中子星本身联系起来，因此需要两个成分可能表明磁层外的吸积流是复杂的。我们提出了一种情况，即超级爱丁顿吸积的厚内盘开始形成，但在它开始后不久就被中子星的磁场终止，这意味着中央中子星磁场的偶极分量的极限为B > 6 × 10^(12) G。在其他来源中类似的盘终止的证据可能提供进一步识别其他中子星ulx的方法。最后，我们研究了P13在其不寻常的“关闭”状态下所展示的光谱。这些数据需要一个硬幂律分量，表明中子星的残余吸积，以及热等离子体的发射，我们认为这可能与P13系统有关。
We present a detailed, broad-band X-ray spectral analysis of the ultraluminous X-ray source (ULX) pulsar NGC 7793 P13, a known super-Eddington source, utilizing data from the XMM–Newton, NuSTAR and Chandra observatories. The broad-band XMM–Newton+NuSTAR spectrum of P13 is qualitatively similar to the rest of the ULX sample with broad-band coverage, suggesting that additional ULXs in the known population may host neutron star accretors. Through time-averaged, phase-resolved and multi-epoch studies, we find that two non-pulsed thermal blackbody components with temperatures ∼0.5 and 1.5 keV are required to fit the data below 10 keV, in addition to a third continuum component which extends to higher energies and is associated with the pulsed emission from the accretion column. The characteristic radii of the thermal components appear to be comparable, and are too large to be associated with the neutron star itself, so the need for two components likely indicates the accretion flow outside the magnetosphere is complex. We suggest a scenario in which the thick inner disc expected for super-Eddington accretion begins to form, but is terminated by the neutron star's magnetic field soon after its onset, implying a limit of B ≲ 6 × 10^(12) G for the dipolar component of the central neutron star's magnetic field. Evidence of similar termination of the disc in other sources may offer a further means of identifying additional neutron star ULXs. Finally, we examine the spectrum exhibited by P13 during one of its unusual ‘off’ states. These data require both a hard power-law component, suggesting residual accretion on to the neutron star, and emission from a thermal plasma, which we argue is likely associated with the P13 system.
DOI：
10.3847/2041-8205/831/2/l14
发表时间：
2016-09
期刊：
The Astrophysical Journal Letters
影响因子：
--
作者：
F. Fuerst;D. Walton;F. Harrison;D. Stern;D. Barret;M. Brightman;A. Fabian;B. Grefenstette;
通讯作者：
F. Fuerst;D. Walton;F. Harrison;D. Stern;D. Barret;M. Brightman;A. Fabian;B. Grefenstette;
解析的原子线揭示了两个超发光 X 射线源的流出
DOI：
10.17863/cam.13121
发表时间：
2016
期刊：
--
影响因子：
--
作者：
Pinto C
通讯作者：
Pinto C