CO Multi-line Imaging of Nearby Galaxies (COMING). III. Dynamical effect on molecular gas density and star formation in the barred spiral galaxy NGC 4303
CO Multi-line Imaging of Nearby Galaxies (COMING). III. Dynamical effect on molecular gas density and star formation in the barred spiral galaxy NGC 4303
复制标题
附近星系的 CO 多线成像（即将推出）。
DOI：
10.1093/pasj/psz022
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发表时间：
2019
影响因子：
2.3
通讯作者：
N.; Shibata
中科院分区：
文献类型：
--
作者：
Yajima;Y.; Sorai;K.; Kuno;N.; Muraoka;K.; Miyamoto;Y.; Kaneko;H.; Nakanishi;H.; Nakai;N.; Tanaka;T.; Sato;Y.; Salak;D.; Morokuma-Matsui;K.; Matsumoto;N.; Pan;H-A; Noma;Y.; Takeuchi;T. T.; Yoda;M.; Kuroda;M.; Yasuda;A.; Oi;N.; Shibata
作为近星系CO多线成像（COMING）项目的一部分，我们给出了对近棒旋星系NGC 4303的（J= 1-0）和（J= 1-0）同时映射的结果。棒旋星系在棒区的恒星形成效率（SFE）通常比旋臂低。本文结合历史资料和远紫外及24 μm观测资料，研究了银盘内八个不同区域分子气体（H2）的超临界流体效应与体密度的关系。我们证实，在酒吧区的SFE是低于39%，在旋臂。此外，在各个区域的光谱进行速度对齐堆叠分析。积分强度比（R12/13）范围为10至17是这种堆叠的结果。通过非局域热力学平衡（non-LTE）分析，由R12/13导出了分子气体的固定动力学温度。杆部的n（H2）比臂部低31%~ 37%，SFE与n（H2）有较强的正相关，相关系数为0.8。此外，我们还发现了分子云的速度色散（ΔV/sini）对的依赖关系。具体来说，当Δ V/sini< 100 km s−1时，n（H2）随Δ V/sini的增加而增加。另一方面，当ΔV/sini> 100 km s−1时，n（H2）随着Δ V/sini的增加而减小。这些关系表明，分子气体的体积密度是引起超临界流体能量变化的主要原因，而分子气体的体积密度则受云-云碰撞、切变和增强的云内湍流等动力学因素的影响。
We present the results of(J= 1–0) and(J= 1–0) simultaneous mappings toward the nearby barred spiral galaxy NGC 4303 as part of the CO Multi-line Imaging of Nearby Galaxies (COMING) project. Barred spiral galaxies often show lower star-formation efficiency (SFE) in their bar region compared to the spiral arms. In this paper, we examine the relation between the SFEs and the volume densities of molecular gasn(H2) in the eight different regions within the galactic disk withdata combined with archival far-ultraviolet and 24 μm data. We confirmed that SFE in the bar region is lower by 39% than that in the spiral arms. Moreover, velocity-alignment stacking analysis was performed for the spectra in the individual regions. Integrated intensity ratios ofto(R12/13) ranging from 10 to 17 were the results of this stacking. Fixing a kinetic temperature of molecular gas,was derived fromR12/13via non-local thermodynamic equilibrium (non-LTE) analysis. The densityn(H2) in the bar is lower by 31%–37% than that in the arms and there is a rather tight positive correlation between SFEs andn(H2), with a correlation coefficient of ∼0.8. Furthermore, we found a dependence ofon the velocity dispersion of inter-molecular clouds (ΔV/sini). Specifically,n(H2) increases as ΔV/siniincreases when ΔV/sini< 100 km s−1. On the other hand,n(H2) decreases as ΔV/siniincreases when ΔV/sini> 100 km s−1. These relations indicate that the variations of SFE could be caused by the volume densities of molecular gas, and the volume densities could be governed by the dynamical influence such as cloud–cloud collisions, shear, and enhanced inner-cloud turbulence.