Signatures of Type Ia Supernovae Explosions and their Cosmological Implications

研究宇宙的膨胀需要精确地测定到遥远星系的距离。天文学家这样做的方法之一是使用星系中某种类型的超新星（SN）或爆炸的恒星作为测量标尺。Ia型超新星是由一颗古老的小白矮星（WD）爆炸产生的，由于WD恒星的大小相当相似，Ia型SNe的可观测特征也很相似，这意味着不同星系中两颗Ia型SNe的相对亮度差异主要是由于距离的差异。为了使这种方法能够正确地推进宇宙学，天文学家必须更好地了解Ia型超新星的细节以及它们之间的差异。佛罗里达州立大学（FSU）的一个研究小组将通过详细研究各种Ia型爆炸场景、WD恒星的结构、爆炸的热力学以及磁场在超新星中的作用来进一步了解这一点。他们将通过复杂的计算机模型来模拟SNe，并与观测结果进行比较。研究团队将包括研究生和本科生，首席研究员和他的团队将开发并在FSU天文馆展示有关SNe，宇宙学和相关天文学主题的节目。超新星Ia白矮星的热核爆炸是宇宙学的关键，因为它们的亮度和光曲线的明显均匀性。然而，爆炸场景的多样性和WD祖星可能的红移演化给高精度宇宙学带来了问题。爆炸场景可能包括靠近钱德拉塞卡质量（M_Ch）的WD爆炸，次M_Ch WD爆炸，以及两个WD的动态合并。对于所有场景，该团队将使用现有的和新的爆炸模型来计算非局部热力学平衡光曲线，颜色-亮度关系以及近红外和中红外光谱。他们将使用辐射水电代码HYDRA，包括流体动力学和正电子输运。将开发和使用工具，以现有观察结果为基准进行数据分析。

Studying the cosmological expansion of the Universe requires precise determination of distances to faraway galaxies. One of the ways that astronomers do this is by using a certain type of supernova (SN), or exploding star, in a galaxy as a measuring stick. A Type Ia SN results from the detonation of an old, small white dwarf (WD) star, and because WD stars are fairly similar in size, the observable features of Type Ia SNe are similar, meaning that the relative difference in brightness between two Type Ia SNe in different galaxies is primarily due to a difference in distance. For this method to work properly to advance cosmology, it is essential that astronomers have a better understanding of the details of Type Ia SNe and the differences among them. A research group at Florida State University (FSU) will further this understanding by studying in detail the various Type Ia explosion scenarios, the structure of WD stars, the thermodynamics of the explosions, and the role of magnetic fields in supernovae. They will do this through sophisticated computer models that produce simulated SNe to compare to observations. The research team will include both graduate and undergraduate students, and the principal investigator and his team will develop and present shows at the FSU planetarium about SNe, cosmology, and related astronomy topics.Thermonuclear explosions of white dwarfs, SNe Ia, are key in cosmology due to their brightness and the apparent homogeneity of their light curves. However, the diversity of explosion scenarios and possible WD progenitor evolution with redshift pose a problem for high precision cosmology. Explosion scenarios may include a WD explosion close to the Chandrasekhar mass (M_Ch), a sub-M_Ch WD, and the dynamical merger of two WDs. For all scenarios, the team will use existing and new explosion models to calculate non-local thermodynamic equilibrium light curves, color-brightness relations, and near and mid-infrared spectra. They will use the radiation-hydro code HYDRA and include hydrodynamics and positron transport. Tools will be developed and employed for data analysis using existing observations as a benchmark.