Mass entrainment and turbulence-driven acceleration of ultra-high energy cosmic rays in Centaurus A
Mass entrainment and turbulence-driven acceleration of ultra-high energy cosmic rays in Centaurus A
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半人马座 A 超高能宇宙射线的质量夹带和湍流驱动加速
DOI：
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
O. Bromberg
中科院分区：
文献类型：
--
作者：
S. Wykes;J. Croston;M. Hardcastle;J. Eilek;P. Biermann;A. Achterberg;J. Bray;A. Lazarian;M. Haverkorn;R. Protheroe;O. Bromberg
对FR I射电星系半人马座A在射电、X射线和伽马射线波段的观测提供了轻子加速到几TeV的证据，以及强子加速到几十EeV的线索。综合现有的观测约束的物理条件和粒子含量的喷流，内叶和巨大的半人马座A的瓣，我们的目标是评估其作为一个超高能宇宙射线源的可行性。我们应用了几种确定喷流功率的方法，并验证了各种功率估计值的一致性，即101 × 10 43 erg s-1。采用标度关系的基础上以前的结果为3C 31，我们估计粒子数密度的射流，包括可用的无线电波x射线观测。我们的模型是兼容的喷流通过外部卷吸的热气体的物质为1.3 × 10 21 g s-1和1.7 × 10 22 g s-1通过内部卷吸的喷流包含的恒星。这导致了辐射粒子和磁场产生的内部波瓣压力与我们导出的外部压力之间的不平衡。基于对其他FR I源外部环境的了解，我们估计巨瓣内的热压力为1.5× 10 −12 dyn cm −2，由此我们推导出温度下限为1.6× 10 8 K。利用动力学和浮力参数，我们分别推断出4.4亿− 6.45亿年和5.6亿年为巨裂片的声波交叉年龄和浮力年龄，这与它们的光谱年龄不一致。我们重新调查粒子加速的可行性，通过随机过程中的叶片，把新的约束的能量和湍流输入的叶片。相同的“非常热”的温度s，允许夹带计算和丢失的压力之间的自洽性，也允许随机UHECR加速度模型的工作。
Observations of the FR I radio galaxy Centaurus A in radio, X-ray and gamma-ray bands provide evidence for lepton acceleration up to several TeV and clues about hadron acceleration to tens of EeV. Synthesising the available observational constraints on the physical conditions and particle content in the jets, inner lobes and giant lobes of Centaurus A, we aim to evaluate its feasibility as an ultra-high-energy cosmic-ray source. We apply several methods of determining jet power and affi rm the consistency of various power estimates of∼ 1× 10 43 erg s −1 . Employing scaling relations based on previous results for 3C 31, we estimate particle number densities in the jets, encompassing available radio throug h X-ray observations. Our model is compatible with the jets ingesting ∼ 3× 10 21 g s −1 of matter via external entrainment from hot gas and∼ 7× 10 22 g s −1 via internal entrainment from jet-contained stars. This leads to an imbalance between the internal lobe pressure available from radiating particles and magnetic fie ld, and our derived external pressure. Based on knowledge of the external environments of other FR I sources, we estimate the thermal pressure in the giant lobes as 1.5× 10 −12 dyn cm −2 , from which we deduce a lower limit to the temperature of∼ 1.6× 10 8 K. Using dynamical and buoyancy arguments, we infer∼ 440− 645 Myr and∼ 560 Myr as the sound-crossing and buoyancy ages of the giant lobes respectively, inconsistent with their spectral ages. We re -investigate the feasibility of particle acceleration via stochastic processes in the lobes, placing new constraints on the energetics and on turbulent input to the lobes. The same ‘very hot’ temperature s that allow self-consistency between the entrainment calculations and the missing pressure also allow stochastic UHECR acceleration models to work.
半人马座 A 黑洞的质量，来自 SINFONI AO 辅助的恒星运动学积分场观测
DOI：
10.1111/j.1365-2966.2008.14377.x
发表时间：
2009
影响因子：
4.8
作者：
Cappellari M
通讯作者：
Cappellari M
DOI：
10.1111/j.1365-2966.2008.13162.x
发表时间：
2008-02
影响因子：
4.8
作者：
J. Croston;M. Hardcastle;M. Birkinshaw;D. Worrall;R. Laing
通讯作者：
J. Croston;M. Hardcastle;M. Birkinshaw;D. Worrall;R. Laing
半人马座北部中射电瓣中的喷射加热 X 射线细丝
DOI：
10.1088/0004-637x/698/2/2036
发表时间：
2009
期刊：
The Astrophysical Journal
影响因子：
--
作者：
Kraft R
通讯作者：
Kraft R