Placing LOFAR-detected quasars in C iv emission space: implications for winds, jets and star formation
Placing LOFAR-detected quasars in C iv emission space: implications for winds, jets and star formation
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将 LOFAR 探测到的类星体放置在 C iv 发射空间中：对风、喷流和恒星形成的影响
DOI：
10.1093/mnras/stab302
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发表时间：
2021
影响因子：
4.8
通讯作者：
Rankine A
中科院分区：
文献类型：
--
作者：
Rankine A
我们对斯隆数字巡天数据第14版中的一个样本的低频无线电和紫外特性进行了研究，该样本是低频阵列两米巡天第一次数据发布的一部分。类星体有红移1.5 <z< 3.5和光度。我们采用基于独立分量分析的紫外光谱重建来参数化用于推断吸积盘风强度的civλ 1549发射线和用于指示软x射线通量的Heiiλ1640发射线。我们发现无线电探测到的类星体与无线电未探测到的类星体在civ蓝移与等宽空间的同一区域被发现，但是最响、最亮和最大的射电源优先存在于低civ蓝移。此外，无线电探测分数随着蓝移的增加而增加，而无线电噪声分数则减少。在射电安静星群中，我们观察到一定范围的Heii等效宽度，以及具有热光度的Baldwin效应，而射电嘈杂星群大多具有较强的Heii，与较强的软x射线通量相一致。强氦的存在是探测射电声发射的必要条件，但不是充分条件，这表明射流形成中存在一定程度的随机性。利用能量论证和蒙特卡罗模拟，我们探索了风、紧凑型喷流和恒星形成作为射电安静发射源的可能性，排除了任何一种可能性。类星体的存在具有相似的紫外线特性，但不同的射电特性表明，也许射电和紫外线发射正在追踪发生在不同时间尺度上的活动。
We present an investigation of the low-frequency radio and ultraviolet properties of a sample of ≃10 500 quasars from the Sloan Digital Sky Survey Data Release 14, observed as part of the first data release of the Low-Frequency-Array Two-metre Sky Survey. The quasars have redshifts 1.5 <z< 3.5 and luminosities. We employ ultraviolet spectral reconstructions based on an independent component analysis to parametrize the Civλ1549-emission line that is used to infer the strength of accretion disc winds, and the Heiiλ1640 line, an indicator of the soft X-ray flux. We find that radio-detected quasars are found in the same region of Civblueshift versus equivalent-width space as radio-undetected quasars, but that the loudest, most luminous and largest radio sources exist preferentially at low Civblueshifts. Additionally, the radio-detection fraction increases with blueshift whereas the radio-loud fraction decreases. In the radio-quiet population, we observe a range of Heiiequivalent widths as well as a Baldwin effect with bolometric luminosity, whilst the radio-loud population has mostly strong Heii, consistent with a stronger soft X-ray flux. The presence of strong Heiiis a necessary but not sufficient condition to detect radio-loud emission suggesting some degree of stochasticity in jet formation. Using energetic arguments and Monte Carlo simulations, we explore the plausibility of winds, compact jets, and star formation as sources of the radio quiet emission, ruling out none. The existence of quasars with similar ultraviolet properties but differing radio properties suggests, perhaps, that the radio and ultraviolet emission is tracing activity occurring on different time-scales.