Black holes in barred galaxies: the Rosetta Stones of secular galaxy evolution

棒状星系中的黑洞：世俗星系演化的罗塞塔石碑

• 批准号: 1515001
• 负责人: Monica Valluri
• 金额: $ 39.95万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2020-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1515001&HistoricalAwards=false
• 关键词: Black; holes; barred; galaxies; Rosetta

Studies have been showing for some years that the size of a supermassive black hole in a galaxy is correlated with the size of the galaxy itself, perhaps unsurprisingly, but also with the appearance (the 'type') of the galaxy. However, the black hole mass is normally calculated by studying the motions of stars in the galaxy, and recent work suggests that the presence of a bar in the galaxy causes a significant perturbation in the stellar speeds, which has not been taken into account. This leads to a bias that over-estimates the mass and can hide the effect of galaxy type. This award supports development of a new numerical method that does not suffer from this problem. Comparison with other methods and careful checks throughout the work will lay the foundations for future better understanding of the co-evolution of galaxies and their central black holes.This project will work to correct this confounding factor in understanding how the co-evolution of black holes (BH) and galaxies depends upon the host galaxy's morphological type. Recent studies show that the unique orbital structure of a bar makes significant changes in line-of-sight velocity profiles, but although nearly 60% of spiral galaxies with existing dynamical BH mass measurements contain bars, all of those estimates were derived using axisymmetric models that do not account for the bar. The resultant systematic over-estimation bias can mask dependencies on host galaxy morphology. This study will (a) develop the first stellar dynamical orbit superposition code capable of accurately determining BH masses in barred disk galaxies; (b) run high resolution self-consistent N-body simulations of bars and generate mock kinematic datasets for validating the new code; (c) improve the BH mass measurements in several barred galaxies; and (d) obtain the first stellar dynamical BH mass measurements for two nearby galaxies with independent reverberation mapping (RM) estimates. Building a new code is crucial because: (1) the predicted over-estimate is comparable to the scatter and thus can mask genuine differences in BH growth mechanisms; (2) using stellar dynamics to confirm RM BH estimates is important for future high redshift estimates where only RM is possible; and (3) accurate BH masses for specific galaxies are critical for modeling the accretion physics of X-ray emitting gas.This multi-faceted project, involving N-body simulations, code development, and the modeling of real data, will give the graduate student involved the broad and strong technical skills necessary for a successful career. Other activities will provide future elementary school teachers with strong STEM (Science, Technology, Engineering, Mathematics) foundations through the university's school of education, involve non-science major undergraduates through a newly-developed course, and use a summer camp to inspire high school students to pursue STEM disciplines in college.

多年来的研究表明，星系中超大质量黑洞的大小与星系本身的大小有关，这也许并不奇怪，但也与星系的外观（“类型”）有关。然而，黑洞的质量通常是通过研究星系中恒星的运动来计算的，最近的工作表明，星系中存在的棒子会导致恒星速度的显著扰动，这一点没有被考虑在内。这导致了一种偏差，即过高估计质量，并可能隐藏星系类型的影响。这个奖项支持开发一种新的数值方法，它不会受到这个问题的困扰。与其他方法的比较以及在整个工作过程中的仔细检查将为未来更好地理解星系及其中心黑洞的共同演化奠定基础。这个项目将致力于纠正这个混淆因素，以理解黑洞（BH）和星系的共同演化如何取决于宿主星系的形态类型。最近的研究表明，棒子独特的轨道结构使视线速度轮廓发生了重大变化，但是尽管现有的动态黑洞质量测量中有近60%的螺旋星系包含棒子，但所有这些估计都是使用轴对称模型推导出来的，没有考虑棒子。由此产生的系统性高估偏差可以掩盖对宿主星系形态的依赖。这项研究将(a)开发第一个能够精确确定棒盘星系黑洞质量的恒星动态轨道叠加代码；(b)运行高分辨率自一致的棒材n体模拟，并生成模拟运动学数据集，用于验证新代码；(c)改进了几个棒星系的黑洞质量测量；(d)通过独立混响映射（RM）估计首次获得两个邻近星系的恒星动力学黑洞质量测量。建立一个新的代码是至关重要的，因为：(1)预测的高估与散射相当，因此可以掩盖黑洞生长机制的真正差异；(2)使用恒星动力学来确认RM BH估计对于未来只有RM可能的高红移估计是重要的；(3)精确的特定星系黑洞质量对于模拟x射线发射气体的吸积物理至关重要。这个多方面的项目，包括n体模拟、代码开发和真实数据建模，将为研究生的成功职业生涯提供广泛而强大的技术技能。其他活动将通过该大学的教育学院为未来的小学教师提供强大的STEM（科学、技术、工程、数学）基础，通过新开发的课程让非科学专业的本科生参与其中，并利用夏令营激励高中生在大学学习STEM学科。