合并中 harboring 低光度双类星体的富气星系(z = 6.05):最亮类星体的有希望前身星系
Merging gas-rich galaxies that harbor low-luminosity twin quasars at z = 6.05: a promising progenitor of the most luminous quasars
AI总结:
本研究利用 ALMA 观测了 z = 6.05 处的一个低光度类星体对系统,发现其具有极高的气体质量、恒星形成率、潮汐相互作用及快速外流特征,模拟表明其并合后将演化为早期宇宙中最明亮、最极端的星暴类星体之一。
摘要:
我们报告了对最近在 z = 6.05 发现的一个类星体-类星体对系统(Matsuoka et al. 2024)进行的 ALMA [CII] 158 μm 谱线及其下方的远红外(FIR)连续谱发射观测(分辨率为 0''.57 × 0''.46)。这两个类星体核(C1 和 C2)较暗(M_1450 ≳ -23 mag),但我们探测到了非常明亮的 [CII] 发射,它桥接了两体之间 12 kpc 的区域并向外延伸(总光度 L_[CII] ≃ 6 × 10^9 L_⊙)。基于 [CII] 估算的系统总恒星形成率约为 550 M_⊙ yr^{-1}(基于红外估算的尘埃遮蔽 SFR 约为 100 M_⊙ yr^{-1}),基于 [CII] 估算的总气体质量约为 10^{11} M_⊙。这两个星系的动力学质量很大(C1 约为 9 × 10^{10} M_⊙,C2 约为 5 × 10^{10} M_⊙)。[CII] 中存在平滑的速度梯度,表明这些类星体是一个潮汐相互作用系统。我们在 C1 周围识别出一个动力学上截然不同的快速 [CII] 成分:对该处谱线的详细检查揭示了一个宽翼成分的存在,我们将其解释为速度约为 600 km s^{-1} 的快速外流的标志。在考虑多相气体后,这些外流的预期质量负载因子 ≳ 2-3,介于 AGN 驱动和星暴驱动的外流之间。文献中的流体动力学模拟预测,该类星体对在并合后将演化为一个光度极高(M_1450 ≲ -26 mag)、星暴剧烈(≳ 1000 M_⊙ yr^{-1})的类星体,这是早期宇宙中最极端的族群之一。
英文摘要:
We present ALMA [CII] 158 $μ$m line and underlying far-infrared (FIR) continuum emission observations ($0''.57 \times 0''.46$ resolution) toward a quasar-quasar pair system recently discovered at $z = 6.05$ (Matsuoka et al. 2024). The quasar nuclei (C1 and C2) are faint ($M_{\rm 1450} \gtrsim -23$ mag), but we detect very bright [CII] emission bridging the 12 kpc between the two objects and extending beyond them (total luminosity $L_{\rm [CII]} \simeq 6 \times 10^9~L_\odot$). The [CII]-based total star formation rate of the system is $\sim 550~M_\odot$ yr$^{-1}$ (IR-based dust-obscured SFR is $\sim 100~M_\odot$ yr$^{-1}$), with a [CII]-based total gas mass of $\sim 10^{11}~M_\odot$. The dynamical masses of the two galaxies are large ($\sim 9 \times 10^{10}~M_\odot$ for C1 and $\sim 5 \times 10^{10}~M_\odot$ for C2). There is a smooth velocity gradient in [CII], indicating that these quasars are a tidally interacting system. We identified a dynamically distinct, fast [CII] component around C1: detailed inspection of the line spectrum there reveals the presence of a broad wing component, which we interpret as the indication of fast outflows with a velocity of $\sim 600$ km s$^{-1}$. The expected mass loading factor of the outflows, after accounting for multiphase gas, is $\gtrsim 2-3$, which is intermediate between AGN-driven and starburst-driven outflows. Hydrodynamic simulations in the literature predicted that this pair will evolve to a luminous ($M_{\rm 1450} \lesssim -26$ mag), starbursting ($\gtrsim 1000~M_\odot$ yr$^{-1}$) quasar after coalescence, one of the most extreme populations in the early universe.
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