3-D-Spectroscopy of a sample of nearby Blue Compact Galaxies: Understanding the star-forming galaxy population in the local Universe and beyond

本提案旨在扩展和结束“附近蓝色致密星系样本的三维光谱：了解本地宇宙及其他地区的恒星形成星系群”项目，致力于用积分场光谱（IFS）方法研究蓝色致密星系（BCG）样本。BCGs是当代星系外研究的关键对象：由于体积小，它们提供了与早期宇宙的无与伦比的联系——在冷暗物质宇宙的框架下，由较小星系的分层合并形成的高质量系统——它们缺乏密度波和强大的剪切力，允许在简单的环境中探测恒星形成（SF）。为了研究这些有趣的天体，我们对36个星系的样本进行了IFS观测。数据已经减少，大部分分析已经完成：我们已经建立了整个样品的排放在线图、连续图、诊断线和速度图，并使用这些图确定了主要的HII区域，并推导了它们的物理参数和化学丰度。我们现在正在对这些结果进行解释，其中包括：1)解开样本星系中不同的恒星群；Ii)探索它们的演化状态，设计它们的恒星形成历史；Iii)寻找丰度非均质性；iv)研究星云电离机制，寻找agn和/或激波区；v)通过宇宙学模拟来约束矮星系的形成和演化过程。此外，最近在大型望远镜上出现的宽视场，高空间分辨率的IFS仪器，如VLT的多单位光谱探测器（MUSE），为我们在银河系尺度上理解SF开辟了新的可能性。现在，我们建议利用在IFS数据处理和分析中获得的丰富经验，利用MUSE的独特功能来研究BCGs中的SF过程以及大质量恒星与星际介质之间的相互作用。众所周知，恒星风和多个超新星爆炸的共同作用强烈地影响着它们周围的环境；当它们发生在低质量星系的浅引力势内时，效果尤其显著。恒星反馈可以触发（正反馈或星致SF）或抑制（负反馈）SF，并且可以将星际气体加速到大于星系逃逸速度的速度，污染星系间介质。但是，这究竟如何以及在多大程度上影响低质量星系的演化和化学富集，仍然是未知的。MUSE的观测提供了高空间分辨率和高灵敏度的数据，可以达到kpc的星系中心距离，这对解决这些问题至关重要。

This proposal aims to extend and conclude the project “3-D-Spectroscopy of a sample of nearby blue compact galaxies: understanding the star-forming galaxy population in the local Universe and beyond”, devoted to the study of a sample of Blue Compact Galaxies (BCG) by means of Integral Field Spectroscopy (IFS). BCGs are key objects in contemporary extragalactic research: being small, they offer an unparalleled link to the early Universe --- in the framework of a Cold Dark Matter Universe, high mass systems form by hierarchical mergers of smaller ones ---, and their lack of density waves and strong shear forces permits to probe the star formation (SF) in a simple environment. To investigate these intriguing objects, we have performed IFS observations for a sample of 36 galaxies. The data have been already reduced and the bulk of the analysis done: we have built emission-line, continuum, diagnostic-line and velocity maps of the whole sample and, using these maps, identified the major HII regions and derived their physical parameters and chemical abundances. We are working now in the interpretation of these results, which comprises i) to disentangle the distinct stellar populations of the sample galaxies; ii) to probe their evolutionary status and devise their star formation history; iii) to search for abundance inhomogeneities; iv) to look into the nebula ionization mechanism and search for AGNs and/or shocked regions and, v) to constraint, by means of cosmological simulations, the formation process and evolution of dwarf galaxies. In addition, the recent advent of wide field, high spatial resolution IFS instruments at large telescopes, as the Multi Unit Spectroscopic Explorer (MUSE) at the VLT, opens new possibilities in our understanding of the SF at galactic scales. We propose now, taking advantage of the large experience acquired in the IFS data processing and analysis, to exploit the unique capabilities of MUSE to investigate the SF process and the interplay between massive stars and the interstellar medium in BCGs. It is well known that the combined action of stellar winds and multiple supernova explosions strongly impacts their surroundings; the effects being particularly dramatic when they take place within the shallow gravitational potential of a low mass galaxy. Stellar feedback can trigger (positive feedback or star induced SF) or suppress (negative feedback) SF, and can accelerate the interstellar gas to velocities larger than the galaxy escape velocity, polluting the intergalactic medium. But how exactly, and to what extend, this affects the evolution and chemical enrichment of a low mass galaxy is still unknown. MUSE observations, providing high spatial resolution and high sensitivity data up to galactocentric distances of kpc, are essential and will contribute in this project to tackle these questions.