XMM-Newton discovery of transient X-ray pulsar in NGC 1313
XMM-Newton discovery of transient X-ray pulsar in NGC 1313
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DOI：
10.1111/j.1745-3933.2008.00478.x
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发表时间：
2008-02
影响因子：
--
通讯作者：
S. Trudolyubov
中科院分区：
文献类型：
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作者：
S. Trudolyubov
我们报告了在2004年11月23日对螺旋星系NGC 1313的XMM-牛顿观测中发现的瞬态X射线脉冲星XMMU J031747.5−663010的发现和分析。X射线源在0.3 - 7 keV的能量范围内表现出周期为P = 765.6 s的脉动和接近正弦的脉冲形状，脉冲分数为38%。XMMU J031747.5−663010的X射线光谱很硬，并且在0.3 - 7 keV能带中符合光子指数为1.5的吸收简单幂律。该源的X射线特性和没有比20等更亮的光学/紫外对应物使我们能够将XMMU J031747.5−663010确定为位于NGC 1313的吸积X射线脉冲星。源LX的0.3 - 7 keV吸收光度估计为1.6 × 10 39 erg s −1，使其成为已知最亮的X射线源之一。基于相对较长的脉冲周期和源的瞬态行为，我们将其归类为Be二元X射线脉冲星候选者。XMMU J031747.5−663010是在本星系群之外发现的第二颗X射线脉冲星，之前在附近的螺旋星系NGC 2403中发现了短暂的18秒脉冲源CXMMU J073709.1+653544。
We report on the discovery and analysis of the transient X-ray pulsar XMMU J031747.5−663010 detected in the 2004 November 23 XMM‐Newton observation of the spiral galaxy NGC 1313. The X-ray source exhibits pulsations with a period P ∼ 765.6 s and a nearly sinusoidal pulse shape and pulsed fraction ∼38 per cent in the 0.3‐7 keV energy range. The X-ray spectrum of XMMU J031747.5−663010 is hard and well fitted with an absorbed simple power law of photon index � ∼ 1.5 in the 0.3‐7 keV energy band. The X-ray properties of the source and the absence of an optical/ultraviolet counterpart brighter than 20 mag allow us to identify XMMU J031747.5−663010 as an accreting X-ray pulsar located in NGC 1313. The estimated absorbed 0.3‐7 keV luminosity of the source LX ∼ 1.6 × 10 39 erg s −1 , makes it one of the brightest X-ray pulsars known. Based on the relatively long pulse period and transient behaviour of the source, we classify it as a Be binary X-ray pulsar candidate. XMMU J031747.5−663010 is the second X-ray pulsar detected outside the local group, after transient 18 s pulsating source CXOU J073709.1+653544 discovered in the nearby spiral galaxy NGC 2403.