Transcript HMM词性标注
Lecture 3 (1)黑洞的基本物理 (2)解释AGN的连续谱辐射的产生机制 • UV－optical • IR 2015/4/13 2 黑洞的形成 Rees图 Rees（1984） 2015/4/13 3 黑洞的定义 牛顿力学： 广义相对论： （1）球对称（Schwarzschild）,无角动量 c=G=1 进入视界的粒子在有限的时间内不可避免地落到中心。因此，视界包围的部分不 是恒星那样的实体，而更像一个“洞”。视界包围的部分称为黑洞，更准确地说， 史瓦西黑洞。 2015/4/13 4 黑洞的定义 （2）轴对称（Kerr-Newman），有电荷，有角动量。 Q＝0 Kerr解 c=G=1 2015/4/13 5 2015/4/13 6 Fuelling Rate As in stars, the rate at which energy is emitted by the nucleus gives us the rate at which energy must be supplied to the nuclear source by accretion: 能量平衡 dE L M c2 dt To power a typical AGN requires an accretion rate L 3 L44 1 M 2 1.8 10 M yr e c Accretion: conversion of gravitational potential energy to radiation. dU GM dm GM m L dt r dt r η的计算， Soltan假设 Most important ! 有效势能取极小的位置即最内稳定 圆轨道（Last stable circular orbit） If we ignore relativistic effects, set r=5Rs (which is about where most of the optical/UV continuum radiation is expected to originate): GMm GMm 2 U 0.1mc 5Rs 10GM / c 2 0.1, which is an order of magnitude more efficient than fusion of hydrogen to helium (=0.007). 取0.1， LQSO1046erg s-1 M L 3 L44 1 1.8 10 M yr e c 2 2M e yr 1 If we ignore relativistic effects, set r=5Rs (which is about where most of the optical/UV continuum radiation is expected to originate): GMm GMm 2 U 0.1mc 5Rs 10GM / c 2 ASCA (Tanakathan et al. 1995) of 0.1, which is an order of magnitude more efficient fusion hydrogen to helium (=0.007). 取0.1， LQSO1046erg s-1 M L 3 L44 1 1.8 10 M yr e c 2 2M e yr 1 Problem of Angular Momentum The mass accretion rate necessary to sustain the Eddington luminosity. LE 1 M Edd c 2 2.2M 8 M e yr In the simple spherical accretion model, Eddington accretion rate is a maximum possible accretion rate for mass M. This critical rate can easily be exceeded with the models that are not spherically symmetric, such as mass accretion occurs in a disk. （accrete ionized hydrogen gas） The major problem with fuelling a quasar by gravitational accretion is not the energy requirement, but angular momentum, since the accretion disk is so small. Infalling gas must lose most of its AM before reaching the AD, where further AM transfer can occur through viscosity. Problem of Angular Momentum The AM per unit mass is L/m=(GMr)1/2, where M is the mass interior to r, i.e., M=1011Msun and r=10kpc.If this unit mass is moved to within 0.01 pc of a 107 Msun central BH, where the viscosity might become important, its AM per unit mass must decrease to (107 x 0.01pc/1011x104pc)~10-5 of its initial value. Gravitational interactions with other galaxies are sometimes suspected of playing a major role in fuelling AGNs. Tidally-disrupted Star near BH Fuel also could be tidally disrupted stars, which place an upper limit on the central BH mass. A star of mass density near a massive body of density BH and radius R can approach no closer than the familiar Roche limit BH Roche Radius: rR 2.4 1/ 3 R Without being tidally disrupted. To ensure that a star is tidally disrupted before it crosses the event horizon requires rR > RS 3M rR 2.4 RS 4 RS3 3 1/ 3 1 c M 0.64 3 G 6 1/2 5 10 8 1/2 M Tidally-disrupted Star near BH ULMER 1999 Gezari et al. 2006 Tidally-disrupted Star near BH ULMER 1999 Disrupt Giant Stars? AGN的连续谱 归一化 平均谱 2015/4/13 21 AGN的连续谱 SED弥散很大 2015/4/13 22 AGN的连续谱 2015/4/13 23 小篮包 2015/4/13 24 2015/4/13 25 AGN的连续谱 2015/4/13 26 UV-Optical Continuum 2015/4/13 27 UV-Optical Continuum A More correct derivation takes into account how the energy is dissipated in the disk through viscosity which is a consequence of work done by viscous torques. If r >> Ri then 2015/4/13 28 UV-Optical Continuum 2015/4/13 29 UV-Optical Continuum 2015/4/13 30 UV-Optical Continuum 2015/4/13 32 UV-Optical Continuum 2015/4/13 33 UV-Optical Continuum 2015/4/13 34 UV-Optical Continuum(SS) 2015/4/13 35 UV-Optical Continuum(ADAF) 2015/4/13 36 UV-Optical Continuum 2015/4/13 37 2015/4/13 38 2015/4/13 39 UV-Optical Continuum 2015/4/13 40 2015/4/13 41 Free－free 发射拟合大蓝包 2015/4/13 42 Free－free 发射拟合大蓝包 2015/4/13 43 小篮包 2015/4/13 44 2015/4/13 45