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arXiv 2102.01087astro-ph.HE
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作为超高能Cosmic Ray候选源的FR 0射电星系的研究

Scrutinizing FR 0 Radio Galaxies as Ultra-High-Energy Cosmic Ray Source Candidates

Lukas Merten, Margot Boughelilba, Anita Reimer, Paolo Da Vela, Serguei Vorobiov, Fabrizio Tavecchio, Giacomo Bonnoli, Jon Paul Lundquist, Chiara Righi

摘要:

Fanaroff-Riley(FR)0射电星系是一类新的射电星系,通常比公认的FR 1和FR 2星系更弱,但数量更多。后一类被认为是能量高达${\sim}10^{20}$ eV的超高能宇宙射线(UHECR)源。基于这一猜想,UHECR加速和生存在FR 0源环境中的可能性进行了研究。在这样做时,基于来自FR 0目录(FR 0 CAT)的数据编译平均光谱能量分布(SED)。由此产生的光子场被用作UHECR的目标,UHECR遭受电磁对产生、光衰变、光介子产生损失和同步辐射。多种机制进行了讨论,以评估UHECR的加速概率,包括费米-I级和逐渐剪切加速,和粒子从源区逃逸。这项工作表明,在一个混合的情况下,结合费米和剪切加速度,FR 0星系可以有助于观察到的UHECR流量,只要$Γ_\mathrm{j}\gtrsim 1.6$,剪切加速度开始占主导地位的逃逸。即使在不太乐观的情况下,FR 0也会对膝盖和脚踝之间的宇宙射线通量做出贡献。我们的结果是相对强大的实现磁湍流模型和加速冲击的速度。

英文摘要:

Fanaroff-Riley (FR) 0 radio galaxies compose a new class of radio galaxies, which are usually weaker but much more numerous than the well-established class of FR 1 and FR 2 galaxies. The latter classes have been proposed as sources of the ultra-high-energy cosmic rays (UHECRs) with energies reaching up to ${\sim}10^{20}$ eV. Based on this conjecture, the possibility of UHECR acceleration and survival in an FR 0 source environment is examined in this work. In doing so, an average spectral energy distribution (SED) based on data from the FR 0 catalog (FR0CAT) is compiled. The resulting photon fields are used as targets for UHECRs, which suffer from electromagnetic pair production, photo-disintegration, photo-meson production losses, and synchrotron radiation. Multiple mechanisms are discussed to assess the UHECR acceleration probability, including Fermi-I order and gradual shear accelerations, and particle escape from the source region. This work shows that in a hybrid scenario, combining Fermi and shear accelerations, FR 0 galaxies can contribute to the observed UHECR flux, as long as $Γ_\mathrm{j}\gtrsim 1.6$, where shear acceleration starts to dominate over escape. Even in less optimistic scenarios, FR 0s can be expected to contribute to the cosmic-ray flux between the knee and the ankle. Our results are relatively robust with respect to the realized magnetic turbulence model and the speed of the accelerating shocks.

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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