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arXiv 2408.09708astro-ph.HEhep-ph
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AXPs/SGRs:带壳的奇异星?

AXPs/SGRs: strange stars with crusts?

Guojun Qiao, Lunhua Shang, Renxin Xu, Kejia Lee, Yongquan Xue, Qijun Zhi, Jiguang Lu, Juntao Bai

AI总结:

针对磁星模型解释AXPs/SGRs辐射存在的争议与观测矛盾,研究提出带壳奇异星模型作为替代,可解释更多相关观测事实。

摘要:

反常X射线脉冲星(Anomalous X-ray Pulsars,AXPs)和软γ射线重复暴源(Soft Gamma-Ray Repeaters,SGRs)的辐射被认为由其强磁场的耗散提供能量,这也是“磁星(magnetar)”这一名称的由来。结合计时和能量观测结果,磁星模型很容易得到认可。从计时角度看,假设偶极辐射计算得到的AXPs和SGRs的磁场强度极强。从能量角度看,AXPs和SGRs的X射线/软γ射线光度大于其自转能损失率(即$ L_{\rm X}>\dot E_{\rm rot}$)。因此有理由认为高能辐射来自磁能衰减,磁星模型也已被广泛讨论(或接受)。但我们认为:(1)假设自转能损失由偶极辐射主导(即$\frac{E}_{\rm rot}\simeq\frac{E}_μ$)来计算磁场可能存在争议,我们提出还应考虑外流粒子携带的能量;(2)X射线光度大于自转能损失率这一事实并不一定意味着辐射能量来自磁场衰减,这需要进一步的观测检验。此外,一些观测事实与“磁星”模型相冲突,例如反磁星、高磁场脉冲星的观测,以及AXPs/SGRs的射电和X射线观测。因此,我们提出带壳奇异星模型作为替代方案,它可以解释更多AXPs/SGRs的观测事实。

英文摘要:

The emission of Anomalous X-ray Pulsars (AXPs) and Soft Gamma-Ray Repeaters (SGRs) is believed to be powered by the dissipation of their strong magnetic fields, which coined the name `magnetar'. By combining timing and energy observational results, the magnetar model can be easily appreciated. From a timing perspective, the magnetic field strengths of AXPs and SGRs, calculated assuming dipole radiation, are extremely strong. From an energy perspective, the X-ray/soft gamma-ray luminosities of AXPs and SGRs are larger than their rotational energy loss rates (i.e., $ L_{\rm X}>\dot E_{\rm rot}$). It is thus reasonable to assume that the high-energy radiation comes from magnetic energy decay, and the magnetar model has been extensively discussed (or accepted). However, we argue that: (1) calculating magnetic fields by assuming that rotational energy loss is dominated by dipole radiation (i.e., $\dot{E}_{\rm rot}\simeq\dot{E}_μ$)) may be controversial, and we suggest that the energies carried by outflowing particles should also be considered; and (2) the fact that X-ray luminosity is greater than the rotational energy loss rate does not necessarily mean that the emission energy comes from the magnetic field decaying, which requires further observational testing. Furthermore, some observational facts conflict with the `magnetar' model, such as observations of anti-magnetars, high magnetic field pulsars, and radio and X-ray observations of AXPs/SGRs. Therefore, we propose a crusted strange star model as an alternative, which can explain many more observational facts of AXPs/SGRs.

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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