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arXiv 1912.04431astro-ph.HE
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快速监测M51:脉冲星ULX7的38天超轨道周期和新的瞬变ULX

Swift monitoring of M51: A 38-day super-orbital period for the pulsar ULX7 and a new transient ULX

Murray Brightman, Hannah Earnshaw, Felix Fürst, Fiona A. Harrison, Marianne Heida, Gianluca Israel, Sean Pike, Daniel Stern, Dominic J. Walton

摘要:

我们提出的结果,从监测活动与尼尔Gehrels斯威夫特天文台的M51星系,其中包含几个变量的超亮X射线源(ULXs)。持续的运动始于2018年5月,我们在这里报告$\sim1.5$多年的观察结果。该活动包括105次观测,典型的周期为3- 6天,目标是确定ULX的长期X射线可变性。其中两个变化最大的源是ULX 7和ULX 8,这两个源都是由中子星提供动力的,这些中子星的亮度超过其各向同性爱丁顿光度高达100倍。这进一步证明了中子星驱动的ULX是最易变的。我们的两个主要结果是,第一,ULX 7表现出一个周期性的流量调制与一个38天的周期变化超过一个半量级的流量从峰到谷。由于该系统的轨道周期已知为2天,因此调制是超轨道的,这是ULX双星几乎无处不在的特性。其次,我们确定了一个新的瞬态ULX,M51 XT-1,它的发病发生在我们的活动,达到峰值亮度的$\sim10^{40}$ erg s $^{-1}$,然后逐渐衰落,在未来的$\sim200$天,直到它滑到我们的观测检测限以下。结合瞬态的高质量Swift/XRT光变曲线,Chandra和XMM-Newton的偶然观测提供了对可能的超级爱丁顿事件的发生和演变的见解。

英文摘要:

We present the results from a monitoring campaign made with the Neil Gehrels Swift Observatory of the M51 galaxies, which contain several variable ultraluminous X-ray sources (ULXs). The ongoing campaign started in May 2018, and we report here on $\sim1.5$ years of observations. The campaign, which consists of 105 observations, has a typical cadence of 3--6 days, and has the goal of determining the long-term X-ray variability of the ULXs. Two of the most variable sources were ULX7 and ULX8, both of which are known to be powered by neutron stars that are exceeding their isotropic Eddington luminosities by factors of up to 100. This is further evidence that neutron star powered ULXs are the most variable. Our two main results are, first, that ULX7 exhibits a periodic flux modulation with a period of 38 days varying over a magnitude and a half in flux from peak to trough. Since the orbital period of the system is known to be 2 days, the modulation is super-orbital, which is a near-ubiquitous property of ULX pulsars. Secondly we identify a new transient ULX, M51 XT-1, the onset of which occurred during our campaign, reaching a peak luminosity of $\sim10^{40}$ erg s$^{-1}$, before gradually fading over the next $\sim200$ days until it slipped below the detection limit of our observations. Combined with the high-quality Swift/XRT lightcurve of the transient, serendipitous observations made with Chandra and XMM-Newton provide insights into the onset and evolution of a likely super-Eddington event.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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