活动星系核统一模型和.ppt

1、活动星系核统一模型和超大质量黑洞的形成与增长,张双南 清华大学物理系和天体物理中心 科学院高能所粒子天体物理重点实验室,2,Emission Line Spectra from Seyfert AGNs,Broad emission lines from Type-I Seyfert AGN,Narrow emission lines from Type-II Seyfert AGN,3,Unification scheme for type-I and type-II AGNs,4,Investigation of the obscuring circumnuclear torus in t

2、he active galaxy Mrk231: Kloeckner et al., Nature, 2003,The inferred model of the nuclear torus. The molecular material moves from top right to bottom left (northwest to southeast). Virial estimates of the central mass concentration give (7.23.8) x107 solar masses.,5,Sky deep surveys of Chandra and

3、HST show that the fraction of type II AGN is decreasing with the hard X-ray luminosity.,This indicates a breakdown of the strong unification model where the covering factor H/Ri is independent of luminosity and redshift. This has been taken as the evidence of evolution of torus geometry,Hasinger et

4、al 2003 Similar correlation has been found by Steffen et al. (2003). Sazonov Smak 1984),0.0250.1,25,The accreted matter (Mbh)acc is about 10-3 of the total outflowing mass Mout.,Based on model parameters for the accretion rates in different branches: a seed BH with mass 2106 M, can grow up to BH wit

5、h mass 2108 M within 10 Gyr.,Radiation efficiency in the lower branch: 0.0250.1,26,The massive seed BH problem in the early Universe,One common problem for any kind of BH growth model: how was the massive seed BH ( 106 M) produced in the early Universe? Some extremely massive BHs (109 M) are found a

6、t very high redshift.,27,SMBH formation in the early Universe: Shen, Hu, Lou most BH binaries are transients (the same S-curve). Coincident?,30,Summary,Unification model of Active Galactic Nuclei BH + Accretion Disk + Dusty Torus; Disk and Torus are coplanar Most EM-radiation from disk and the torus

7、 covers part of the disk Observed disk flux is inclination angle dependent: Type I AGNs are normally brighter than Type II AGNs Two models coeval growth of supermassive BH with bulge Mergers of smaller systems Accretion of material from the disk (BH growth) and outflows from the disk (bulge growth)

8、Formation of seed supermassive BHs Bondi (spherical) accretion of self-interacting dark matter halo Growth of some supermassive BHs (in a small percentage of quasars) in the early Universe Eddington accretion of baryonic matter onto seed supermassive BHs.,31,Further work and open questions,Is X-ray

9、emission from AGNs really from accretion disk? Previously the X-ray emission is usually believed from optically thin corona. If the X-ray emission is really from the disk, then relativistic effects on its continuum spectra should be revealed. Maybe for individual AGN we can find a way to estimate its inclination angle accurately and then study the spectral correlation with the inclination angle? For our two phase BH growth model, one important question to ask is: can this model reproduce the observed luminosity function of AGNs? Which kind