Large-scale stellar age-velocity spiral pattern in NGC 4030,Astronomy & Astrophysics

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Large-scale stellar age-velocity spiral pattern in NGC 4030
Astronomy & Astrophysics ( IF 5.4 ) Pub Date : 2024-12-17 , DOI: 10.1051/0004-6361/202452595
Iris Breda, Glenn van de Ven, Sabine Thater, Jesus Falcón-Barroso, Prashin Jethwa, Dimitri A. Gadotti, Masato Onodera, Ismael Pessa, Joop Schaye, Gerhard Hensler, Jarle Brinchmann, Anja Feldmeier-Krause, Davor Krajnović, Bodo Ziegler

The processes driving the formation and evolution of late-type galaxies continue to be a debated subject in extragalactic astronomy. Investigating stellar kinematics, especially when combined with age estimates, provides crucial insights into the formation and subsequent development of galactic discs. Post-processing of exceptionally high-quality integral field spectroscopy data of NGC 4030 acquired with the Multi Unit Spectroscopic Explorer (MUSE) has revealed a striking grand design spiral pattern in the velocity dispersion map, that has not been detected in other galaxies. This pattern spatially correlates with HII regions, suggesting that stars currently being born exhibit lower velocity dispersion as compared to surrounding areas where star-formation is less active. We examined the age-velocity relation (AVR) and propose that its configuration might be shaped by a combination of heating mechanisms, seemingly consistent with findings from recent high-resolution cosmological zoom-in simulations. The complex structure of the uncovered AVR of NGC 4030 supports the hypothesis that stellar populations initially inherit the velocity dispersion σ of the progenitor cold molecular gas, which depends on formation time and galactocentric distance, subsequently experiencing kinematic heating due to cumulative gravitational interactions during their lifetime. While advancing our understanding of the AVR, these findings also offer a new framework for investigating disc heating mechanisms and their role in the evolution of galactic discs.

中文翻译：

NGC 4030 中的大尺度恒星年龄-速度螺旋模式

驱动晚期星系形成和演化的过程仍然是银河系外天文学中一个有争议的话题。研究恒星运动学，特别是与年龄估计相结合时，为银河系盘的形成和后续发展提供了重要的见解。使用多单元光谱探测器（MUSE）对 NGC 4030 的超高质量积分场光谱数据进行后处理，揭示了速度色散图中引人注目的宏伟设计螺旋图案，这是在其他星系中未检测到的。这种模式在空间上与 HII 区域相关，这表明与恒星形成不太活跃的周围区域相比，当前诞生的恒星表现出较低的速度色散。我们研究了年龄-速度关系（AVR），并提出其构型可能由加热机制的组合塑造，这似乎与最近的高分辨率宇宙学放大模拟的结果一致。NGC 4030 发现的 AVR 的复杂结构支持了这样一个假设，即恒星种群最初继承了祖先冷分子气体的速度色散σ，这取决于形成时间和银河系中心距离，随后在其生命周期中由于累积的引力相互作用而经历运动学加热。在推进我们对 AVR 的理解的同时，这些发现还为研究盘加热机制及其在星系盘演化中的作用提供了一个新的框架。