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arXiv 1607.00848astro-ph.GA
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NGC 4303的核活动和环核恒星形成的SINFONI视图

A SINFONI view of the nuclear activity and circum-nuclear star formation in NGC 4303

Rogemar A. Riffel, L. Colina, T. Storchi-Bergmann, J. Piqueras Lopez, S. Arribas, R. Riffel, M. Pastoriza, Dinalva A. Sales, N. Z. Dametto, A. Labiano, R. I. Davies

摘要:

本文给出了星系NGC 4303内部0.7x0.7kpc ~ 2电离气体(由HI和[Fe Ⅱ]线追踪)和分子气体(H_2)的发射线通量分布和运动学的新图,空间分辨率为40- 80 pc,速度分辨率为90-150 km/s。最有希望的特征是一个200- 250秒差距的环核恒星形成区。来自电离气体和分子气体的辐射显示出不同的通量分布:最强的HI和[Fe II]辐射来自环西侧(年龄约为400万年),而H2辐射则在环的核心和东侧(年龄> 1000万年)最强。我们发现,增强热H2发射的区域与增强的[Fe II]和HI发射的区域是反相关的,这可以归因于星暴后的区域,这些区域不再具有电离光子,但仍然足够热(~ 2000 K)以激发H2分子。线的比例是一致的存在的活动星系核的核心。最年轻的区域的恒星质量在0.3-1.5E5 Msun之间,电离和热分子气体的质量分别约为0.25-1.2E4 Msun和2.5-5 Msun。恒星和气体的速度场显示出旋转模式,与气体呈现出更大的速度振幅比恒星,与观察到的偏差为H2沿核酒吧,在那里增加速度色散也观察到,可能与非圆形运动沿酒吧。环中的恒星比周围的恒星表现出更小的速度色散,这可以归因于它们最近由冷气体形成的较冷的动力学。

英文摘要:

We present new maps of emission-line flux distributions and kinematics in both ionized (traced by HI and [FeII] lines) and molecular (H2) gas of the inner 0.7x0.7kpc2 of the galaxy NGC4303, with a spatial resolution 40-80pc and velocity resolution 90-150 km/s obtained from near-IR integral field specroscopy using the VLT instrument SINFONI. The most promiment feature is a 200-250pc ring of circum-nuclear star-forming regions. The emission from ionized and molecular gas shows distinct flux distributions: while the strongest HI and [FeII] emission comes from regions in the west side of the ring (ages~4Myr), the H2 emission is strongest at the nucleus and in the east side of the ring (ages>10Myr). We find that regions of enhanced hot H2 emission are anti-correlated with those of enhanced [FeII] and HI emission, which can be attributed to post starburst regions that do not have ionizing photons anymore but still are hot enough (~2000K) to excite the H2 molecule. The line ratios are consistent with the presence of an AGN at the nucleus. The youngest regions have stellar masses in the range 0.3-1.5E5 MSun and ionized and hot molecular gas masses of ~0.25-1.2E4 Msun and 2.5-5 Msun, respectively. The stellar and gas velocity fields show a rotation pattern, with the gas presenting larger velocity amplitudes than the stars, with a deviation observed for the H2 along the nuclear bar, where increased velocity dispersion is also observed, possibly associated with non circular motions along the bar. The stars in the ring show smaller velocity dispersion than the surroundings, that can be attributed to a cooler dynamics due to their recent formation from cool gas.

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