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arXiv 2308.03477astro-ph.GA
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ALMA 300 pc 分辨率下的 z=6.79 类星体成像:无证据表明超大质量黑洞影响 [C II] 动力学

ALMA 300 pc resolution imaging of a z=6.79 quasar: no evidence for supermassive black hole influence on the [C II] kinematics

Romain A. Meyer, Marcel Neeleman, Fabian Walter, Bram Venemans

AI总结:

本研究利用 ALMA 对 z=6.79 类星体进行高分辨率观测,发现 [C II] 动力学呈恒定速度弥散,表明质量分布平坦,中心区域无黑洞引力影响迹象,暗示黑洞质量可能低于先前估计或辐射峰值未指示黑洞位置。

摘要:

我们展示了 Atacama Large Millimeter/submillimeter Array (ALMA) 在 $0.\"045$ ($\sim$300 pc) 分辨率下对 $z=6.79$ 类星体 J0109--3047 的 [C II] 158 $\mu\rm{m}$ 和尘埃连续谱观测结果。尘埃和 [C II] 辐射被限制在 $\sim 500\\, \rm{pc}$ 半径内,中心光束 ($r<144\\ \rm{pc}$) 占总连续谱 ([C II]) 辐射的 $\sim$25% (8%)。远红外光度密度径向增加,从 $\sim$5 $\times 10^{11} L_\odot\\ \rm{kpc}^{-2}$ 增至中心值 $\sim$70 $\times 10^{11} L_\odot\\ \rm{kpc}^{-2}$ (SFRD $\sim$50-700 $M_\odot\\ \rm{yr}^{-1}\\ \rm{kpc}^{-2}$)。[C II] 动力学以弥散为主,具有恒定速度弥散 $137 \pm 6\\,\rm{km\\ s}^{-1}$。恒定弥散意味着其潜在质量分布非中心尖峰状,与平坦气体质量分布的预期一致。中心光束内速度弥散无上升趋势,与黑洞质量大于 $M_{\rm{BH}}<6.5\times 10^{8}\\ M_\odot$ ($2\sigma$ 置信水平) 不符,除非 ISM 性质发生高度微调变化,共同导致中心光束内气体质量减少量与黑洞质量相当。因此,我们的观测意味着:a) 黑洞质量小于先前测量值;或 b) 远红外和 [C II] 辐射中心峰值未指示黑洞位置,类星体近红外位置与 ALMA 连续谱辐射间的初步偏移支持了这一推测。

英文摘要:

We present Atacama Large Millimeter/submillimeter Array (ALMA) [C II] 158 $μ\rm{m}$ and dust continuum observations of the $z=6.79$ quasar J0109--3047 at a resolution of $0."045$ ($\sim$300 pc). The dust and [C II] emission are enclosed within a $\sim 500\, \rm{pc}$ radius, with the central beam ($r<144\ \rm{pc}$) accounting for $\sim$25\% (8\%) of the total continuum ([C II]) emission. The far--infrared luminosity density increases radially from $\sim$5 $\times 10^{11} L_\odot\ \rm{kpc}^{-2}$ to a central value of $\sim$70 $\times 10^{11} L_\odot\ \rm{kpc}^{-2}$ (SFRD $\sim$50-700 $M_\odot\ \rm{yr}^{-1}\ \rm{kpc}^{-2}$). The [C II] kinematics are dispersion-dominated with a constant velocity dispersion of $137 \pm 6 \,\rm{km\ s}^{-1}$. The constant dispersion implies that the underlying mass distribution is not centrally peaked, consistent with the expectations of a flat gas mass profile. The lack of an upturn in velocity dispersion within the central beam is inconsistent with a black hole mass greater than $M_{\rm{BH}}<6.5\times 10^{8}\ M_\odot\ (2σ$ level), unless highly fine-tuned changes in the ISM properties conspire to produce a decrease of the gas mass in the central beam comparable to the black hole mass. Our observations therefore imply either that a) the black hole is less massive than previously measured or b) the central peak of the far-infrared and [C II] emission are not tracing the location of the black hole, as suggested by the tentative offset between the near-infrared position of the quasar and the ALMA continuum emission.

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