Dust Extinction toward Type Ia Supernovae

Ia型超新星（SNe Ia）是强大的宇宙学“标准化蜡烛”，是遥远星系距离的最精确指示器。这使得它们对于测量宇宙的膨胀率至关重要。然而，在精确宇宙学中使用它们的一个限制因素在于我们校正因尘埃干扰而导致的新天星光变暗的能力，这种现象被称为“尘埃消光”。密苏里-哥伦比亚大学的天文学家将通过对大约60颗超新星Ia的系统探测来研究超新星Ia的尘埃消失，这些超新星Ia是由星载和地面望远镜在从紫外到光学到近红外的宽波长范围内观测到的。通过将观测到的每个Ia SN的光度（光谱和光强）与未消光的原始模板Ia SN的光度（光谱和光强）进行比较，研究人员将确定消光量及其波长依赖性（即消光曲线）。导出的消光曲线将与理论模型进行比较，使科学家能够探索每个SN Ia的尘埃大小和组成。最后，研究人员将探索尘埃和消光特性是否以及如何随着Ia超新星的固有特性及其宿主星系的相关特性而系统地变化。这项研究将对培养研究生和发展密苏里大学的本科天文学课程产生积极影响，并通过积极的社区推广计划教育非科学专业和普通公众。在分析Ia型超新星的光曲线时，一个长期存在的难题是它们的表观颜色和亮度变化的性质。宇宙学分析中广泛使用的“红-暗”色-光度关系掩盖了这样一个事实，即它有两个独立的物理起源：(i)由爆炸的白矮星物理学产生的内在相关性；（ii）由于宿主星系中的星际尘埃而产生的明显的变暗和变红。研究人员将探索尘埃和消光特性是否以及如何随着Ia超新星的固有特性（例如，固有颜色、光度、光曲线形状、衰减率、光谱特性和膨胀速度）以及宿主星系的特性（例如，形态类型、金属丰度）而系统地变化。这项工作将帮助天文学家了解主要的系统效应，以确定SNe Ia的宇宙学参数，了解SNe的固有颜色以及由于宿主星系的消光而变暗。因此，它可能会影响超新星宇宙学和星系外灭绝的知识。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Type Ia supernovae (SNe Ia) are powerful cosmological "standardizable candles" and the most precise indicators of the distance to faraway galaxies. This makes them critical for measuring the expansion rate of the universe. However, a limiting factor in their use for precision cosmology rests on our ability to correct for the dimming of SNe light due to intervening dust, a phenomenon known as "dust extinction." Astronomers at the University of Missouri - Columbia will study the dust extinction toward SNe Ia through a systematic exploration of about 60 SNe Ia observed by space-borne and ground-based telescopes over a broad wavelength range spanning from the ultraviolet through the optical to the near infrared. By comparing the observed photometry (spectrum and intensity of light) of each SN Ia with that of a pristine template SN Ia without extinction, the researchers will determine the extinction quantity and its wavelength dependence (i.e., extinction curve). The derived extinction curve will be compared to theoretical models, enabling the scientists to explore the dust size and composition for each SN Ia. Finally, the researchers will explore whether and how the dust and extinction properties vary systematically with the intrinsic properties of SNe Ia as well as with relevant properties of their host galaxies. This research will have a positive impact on training graduate students and on developing an undergraduate astronomy program at the University of Missouri, as well as educating non-science majors and the general public, through a vigorous program of community outreach.A longstanding puzzle in the analysis of SN Ia light curves is the nature of their apparent color and brightness variations. The "redder-dimmer'' color-luminosity relation widely used in cosmological SN Ia analyses masks the fact that it has two separate physical origins: (i) an intrinsic correlation, which arises from the physics of exploding white dwarfs and (ii) an apparent dimming and reddening due to interstellar dust in the host galaxy. The researchers will explore whether and how the dust and extinction properties vary systematically with the intrinsic properties of SNe Ia (e.g., intrinsic color, luminosity, light-curve shape, decline rate, spectroscopic properties, and expansion velocity) as well as the properties of their host galaxies (e.g., morphological type, metallicity). The work will help astronomers to understand the dominant systematic effects for the determination of cosmological parameters from SNe Ia, knowledge of SNe intrinsic colors and dimming due to extinction by host galaxy. It could thus impact both supernova cosmology and the knowledge of extragalactic extinction.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.