Measuring Black Hole Spin: Physics of the Inner Region of an Accretion Disk

黑洞是自然界中最简单的物体之一，只用质量和自转来描述。虽然已经估计了许多黑洞的质量，但自旋测量直到最近才变得可行。自旋估计中最大的系统误差来自于圆盘模型中的不确定性，特别是假设在最里面稳定的圆形轨道上的扭矩为零。该项目将对吸积盘内部区域进行二维和三维广义相对论磁流体力学数值模拟。它将通过拟合X射线双星的连续谱和拟合相对加宽的铁线，为可靠的自旋估计提供明确的指导方针。公众对黑洞研究的兴趣仍然很高，这项工作将以一种容易被公众和积极参与这项研究的初级研究人员理解的方式展示科学的智力兴奋。该项目是由美国国家科学基金会天文科学部和美国宇航局S天体物理理论项目共同资助的。

AST-0805832NarayanA black hole is one of the simplest objects in Nature, described only by mass and spin. While many black hole masses have been estimated, spin measurements have only recently become feasible. The largest systematic error in the spin estimates arises from uncertainties in the disk model, particularly the assumption of a vanishing torque at the innermost stable circular orbit. This project will carry out two- and three-dimensional numerical general relativistic magneto-hydrodynamical simulations of the inner regions of accretion disks. It will provide clear guidelines for reliable spin estimation, both by fitting the continuum spectra of X-ray binaries and by fitting relativistically broadened iron lines.Public interest in black hole research continues high, and this work will showcase the intellectual excitement of science in a way easily appreciated by the public, and by the junior researchers actively involved in the study. The PI has a strong record in such mentoring activities.This project is co-funded by the NSF Division of Astronomical Sciences and NASA?s Astrophysics Theory Program.