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arXiv 2103.02612astro-ph.HE
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超新星1987 A宽带X射线谱中没有脉冲星的热辐射和放射线

Thermal Emission and Radioactive Lines, but No Pulsar, in the Broadband X-Ray Spectrum of Supernova 1987A

Dennis Alp, Josefin Larsson, Claes Fransson

摘要:

超新星1987 A提供了一个独特的机会,可以在几十年内以前所未有的细节研究一颗不断演变的超新星。X射线发射主要是由喷出物和星周介质(主要是赤道环(ER))之间的相互作用决定的。我们分析了2012年至2020年期间获得的3.3 M NuSTAR数据和二十年的XMM-牛顿数据。自${\sim}$ 2013年以来,2 keV以下的通量有所下降,3-8 keV的通量有所增加,但已开始趋于平缓,10 keV以上的发射几乎保持不变。光谱很好地描述了由三个热冲击分量的模型。在0.3和0.9千电子伏的两个组件与ER中的致密团块,和一个4千电子伏的组件可能是从扩散气体在ER和周围的低密度H II区域的发射的组合。我们不赞成模型,涉及非热X射线发射和非热组件的限制,但不能坚决排除一个潜在的幂律。放射性谱线显示$^{44}$ Ti红移为$670^{+520}_{-380}$ km s $^{-1}$,$^{44}$ Ti质量为$1.73_{-0.29}^{+0.27}\times{}10^{-4}$太阳质量,$^{55}$ Fe质量为$<4.2\times{}10^{-4}$太阳质量。紧凑型物体的35-65 keV亮度极限是$2\times{}10^{34}$ erg s $^{-1}$,并且10-20 keV通量的$<15$ %是脉冲的。考虑到以前的限制,我们得出结论,目前没有迹象表明一个紧凑的对象,除了一个可能的暗示尘埃加热的中子星在最近的ALMA图像。

英文摘要:

Supernova 1987A offers a unique opportunity to study an evolving supernova in unprecedented detail over several decades. The X-ray emission is dominated by interactions between the ejecta and the circumstellar medium, primarily the equatorial ring (ER). We analyze 3.3 Ms of NuSTAR data obtained between 2012 and 2020, and two decades of XMM-Newton data. Since ${\sim}$2013, the flux below 2 keV has declined, the 3-8 keV flux has increased, but has started to flatten, and the emission above 10 keV has remained nearly constant. The spectra are well described by a model with three thermal shock components. Two components at 0.3 and 0.9 keV are associated with dense clumps in the ER, and a 4 keV component may be a combination of emission from diffuse gas in the ER and the surrounding low-density H II region. We disfavor models that involve non-thermal X-ray emission and place constraints on non-thermal components, but cannot firmly exclude an underlying power law. Radioactive lines show a $^{44}$Ti redshift of $670^{+520}_{-380}$ km s$^{-1}$, $^{44}$Ti mass of $1.73_{-0.29}^{+0.27}\times{}10^{-4}$ solar masses, and $^{55}$Fe mass of $<4.2\times{}10^{-4}$ solar masses. The 35-65 keV luminosity limit on the compact object is $2\times{}10^{34}$ erg s$^{-1}$, and $<15$% of the 10-20 keV flux is pulsed. Considering previous limits, we conclude that there are currently no indications of a compact object, aside from a possible hint of dust heated by a neutron star in recent ALMA images.

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