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arXiv 2209.10554astro-ph.GAastro-ph.HE
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超新星遗迹中的奇射电圈

On Odd Radio Circles as Supernova Remnants

Sumit K. Sarbadhicary, Todd A. Thompson, Laura A. Lopez, Smita Mathur

摘要:

在现代全天空无线电巡天中发现的弧大小的奇射电圈(ORC)的起源仍然不确定,解释范围从星暴/活动星系核驱动的冲击到低密度环境介质中的超新星遗迹(SNR)。使用校准良好的无线电光变曲线模型,我们评估的可能性,ORC无线电信噪比在低环境密度的演变。我们的模型意味着ORC 1-5和J 0624 -6948(靠近LMC)作为SNR必须分别在200 kpc和100 kpc的距离太阳,考虑到它们观测到的通量密度和角尺寸。为了在银河系的环星系介质中演化,我们的模型要求ORC 1-5在50 kpc内是以喷射物为主的SNR,在$(0.2-1.2) \times 10^{-3}$ cm $^{-3}$的环境密度中演化。然而,这在统计学上是不可能的,因为ORC 1-5的年龄为$<640$年,比它们在这些密度下的预期寿命$\gtrsim$ 10 $^5$年要小得多,而且因为低SN率和恒星晕的陡峭轮廓意味着在50 kpc范围内可以忽略不计的类ORC SNRs数量。J 0624 -6948的环银河中等信噪比场景更有可能(尽管概率仍然很低),因为我们的模型允许J 0624 -6948为$\lesssim$ 3000年。另一方面,J 0624 -6948解释为50千秒差距(LMC)距离处的Sedov-Taylor信噪比,对于大范围的环境密度是可能的($6 \times 10^{-4} - 0.5$ cm $^{-3}$)和年龄$\sim$ $(0.2-2.6) \times 10^4$ yr,同时也与当地HI环境一致。

英文摘要:

The origin of arcmin-sized Odd Radio Circles (ORCs) found in modern all-sky radio surveys remain uncertain, with explanations ranging from starburst/AGN-driven shocks to supernova remnants (SNRs) in the low-density ambient medium. Using well-calibrated radio light curve models, we assess the possibility that ORCs are radio SNRs evolving in low ambient densities. Our models imply that ORCs 1-5 and J0624-6948 (near the LMC) as SNRs must be within 200 kpc and 100 kpc from the Sun respectively, given their observed flux densities and angular sizes. To be evolving in the circumgalactic medium of the Milky Way, our models require ORCs 1-5 to be ejecta-dominated SNRs within 50 kpc, evolving in ambient densities of $(0.2-1.2) \times 10^{-3}$ cm$^{-3}$. However, this is statistically unlikely because ORCs 1-5 would have ages $<640$ yrs, much smaller than their expected lifetimes of $\gtrsim$10$^5$ yrs at these densities, and because the low SN rate and steep profile of the stellar halo imply a negligible number of ORC-like SNRs within 50 kpc. The circumgalactic medium SNR scenario for J0624-6948 is more likely (though still low probability) compared to ORCs 1-5, as our models allow J0624-6948 to be $\lesssim$3000 yrs. On the other hand, the interpretation of J0624-6948 as a Sedov-Taylor SNR at 50 kpc (LMC) distance is possible for a wide range of ambient densities ($6 \times 10^{-4} - 0.5$ cm$^{-3}$) and ages $\sim$$(0.2-2.6) \times 10^4$ yr, while also being consistent with the local HI environment.

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