Unveiling kinematic structure in the starburst heart of NGC 253
Unveiling kinematic structure in the starburst heart of NGC 253
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DOI：
10.1093/mnras/staa292
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发表时间：
2020-01
影响因子：
4.8
通讯作者：
D. Cohen;J. Turner;S. Consiglio
中科院分区：
文献类型：
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作者：
D. Cohen;J. Turner;S. Consiglio
作者：Cohen，丹尼尔P; Turner，Jean L; Consiglio，S Michelle|摘要：我们观测了NGC 253核爆发中的Brackett α发射线（4.05 μm），测量了电离气体的运动学，区分了由星星形成反馈驱动的运动和由中心质量结构引起的引力运动。在Keck II上使用NIRSPEC，我们通过$0^{\prime \prime }_{.} 5$狭缝跨过中心105 arcsec × 25 arcsec（85 × 425 pc）区域产生光谱立方体。Br α辐射可分解为四个核源：位于红外核心（IRC）的S1，位于射电核心的N1，以及位于东北部的较暗的N2和N3。谱线轮廓的特征是在宽的蓝色2翼顶部有一个主分量，其Δvprimary为90-130 $\rm km\，s^{-1}$（半峰全宽），其Δvbroad为300-350 $\rm km\，s^{-1}$，在西边还有一个红移的窄分量。从我们的立方体产生的速度场揭示了几种不同的模式。沿长轴的平均NE-SW速度梯度为+10 $\rm km\，s^{-1}$ arcsec−1沿着跟踪核盘的固体旋转曲线。在射电核心，等速度线变成S形，表明存在总长度为90秒差距（90秒差距）的次级核棒。棒的对称性将银河系中心和潜在的超大质量黑洞放在射电峰值附近，而不是IRC附近。第三个运动子结构是由IRC附近的蓝移气体形成的。这一特征很可能追踪到一个100-250 $\rm km\，s^{-1}$的恒星暴驱动的外流，可能将IRC与kpc尺度上观测到的银河风联系起来。
Author(s): Cohen, Daniel P; Turner, Jean L; Consiglio, S Michelle | Abstract: ABSTRACT We observed the Brackett α emission line (4.05 μm) within the nuclear starburst of NGC 253 to measure the kinematics of ionized gas, and distinguish motions driven by star formation feedback from gravitational motions induced by the central mass structure. Using NIRSPEC on Keck II, we obtained 30 spectra through a $0^{\prime \prime }_{.}5$ slit stepped across the central ∼5 arcsec × 25 arcsec (85 × 425 pc) region to produce a spectral cube. The Br α emission resolves into four nuclear sources: S1 at the infrared core (IRC), N1 at the radio core, and the fainter sources N2 and N3 in the northeast. The line profile is characterized by a primary component with Δvprimary ∼90–130 $\rm km\, s^{-1}$ (full width at half-maximum) on top of a broad blue 2wing with Δvbroad ∼300–350 $\rm km\, s^{-1}$, and an additional redshifted narrow component in the west. The velocity field generated from our cube reveals several distinct patterns. A mean NE–SW velocity gradient of +10 $\rm km\, s^{-1}$ arcsec−1 along the major axis traces the solid-body rotation curve of the nuclear disc. At the radio core, isovelocity contours become S-shaped, indicating the presence of secondary nuclear bar of total extent ∼5 arcsec (90 pc). The symmetry of the bar places the galactic centre, and potential supermassive black hole, near the radio peak rather than the IRC. A third kinematic substructure is formed by blueshifted gas near the IRC. This feature likely traces a ∼100–250 $\rm km\, s^{-1}$ starburst-driven outflow, potentially linking the IRC to the galactic wind observed on kpc scales.