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Supermassive Black Holes in Radio-loud AGNs

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Presentation on theme: "Supermassive Black Holes in Radio-loud AGNs"— Presentation transcript:

1 Supermassive Black Holes in Radio-loud AGNs
Xue-Bing WU (Peking Univ.) Collaborators: PKU: FuKun Liu, Ran Wang NAOC: JinLin Han, MinZhi Kong

2 1. Introduction Supermassive black holes in nearby galaxies (mass determined by stellar, gas, & water maser dynamics) (Kormendy & Richstone 1995; Kormendy & Gebhardt 2001; Ho 1999) Supermassive black hole formation is closely related to galaxy formation MBH  4 Tremaine et al. (2002)

3 AGN Structure Supermassive black hole Accretion disk Broad line region
Dusty torus Narrow line region Jet

4 Black hole mass estimations of AGNs
Direct methods Stellar dynamics: not feasible, since the AGN is too bright. Gas kinematics: only in a few cases, if the gas is seen in Keplerian rotation. In M87, r=75 pc disk yields Msun Megamasers: only in several edge-on Sy2s. In NGC4258, 0.02 pc resolution gives perfect Keplerian rotation.  Msun

5 Indirect Methods Accretion disk fitting of the big blue bump in the UV/optical spectra of AGN Standard thin disk model (Shakura & Sunyaev 1973):

6 Broad gravitational-redshifted Iron K line of Seyfert 1 galaxies--accretion disk modeling
Tanaka et al. (1995); Nandra et al. (1997) Fabian et al. (1989)

7 Reverberation mapping from optical variability
Peterson (1997) Broad emission line region: pc; The AGN's photoionizing continuum radiation is reprocessed into emission lines RBLR estimated by the time delay that corresponds to the light travel time between the continuum source and the line-emitting gas: RBLR =c  t V estimated by the FWHM of broad emission line MrK 335: t=15.6 days

8 BLR Scaling with Luminosity
Photoionization model prediction r  L0.6±0.1 Kaspi et al. (2000) Same ionization parameter Same density r  L1/2 With the empirical R-L relation, we can estimate the BLR size from the optical continuum luminosity

9 SMBH and Galactic Bulge
Relations of black hole mass with bulge luminosity and central velocity dispersion (for both normal galaxies & AGNs) AGN Ferrarese et al. (2001) With the MBH -σ relation, we can estimate the BH mass of AGNs from the measured stellar velocity dispersion

10 2. AGN BH Mass estimation with the R-LH relation
(Wu, Wang, Kong, Liu & Han 2004, A&A, 424, 793) BLR sizes are usually derived previously from the empirical relation R L5100A0.7(Kaspi et al. 2000). Can it apply to RL AGN? Optical jets of some AGNs have been observed by the HST (Scarpa et al. 1999; Jester 2003; Parma et al. 2003). Optical Synchrotron radiations have been found in some RL AGNs (Whiting et al. 2001; Chiaberge et al. 2002; Cheung et al. 2003)

11 For radio-loud AGNs, optical continuum luminosity may be significantly contributed from jets, thus may not be a good indicator of ionizing luminosity It may be better to use the relation between the emission line luminosity and the BLR size 3C 273

12 An empirical relation between the BLR size and emission line luminosity (Spearman’s rank r=0.91)
Comparison of the results obtained with two R-L relations : Using the R-L5100A relation may overestimate MBH for radio-loud quasars!

13 Recently we also extended such a study to UV broad emission lines (Kong, Wu, Wang, & Han 2005, A&A )

14 3. SMBH Mass of AGNs with elliptical host
(Wu, Liu & Zhang, 2002, A&A, 389, 742) Reverberation mapping can not apply to BL Lacs, a subclass of radio-loud AGNs without/with weak emission lines Only a dozen of BL Lacs have measured  values and the estimated SMBH masses: 5E7 to 1E9 solar masses (Falomo et al. 2002; Barth et al. 2002) Host galaxies of BL Lacs are ellipticals (Urry et al. 2000)  values can be derived based on the fundamental plane of ellipticals; then SMBH masses could be estimated for BL Lacs with high-quality images

15 Fundamental plane of elliptical galaxies
(Djorgovski & Davis 1987; Dressler et al. 1987; Faber et al. 1989; Jorgensen et al. 1996) (Bettoni et al. 2001)

16 SMBH Masses of AGNs with E host
Sample 1: 63 BL Lacs (51 HBLs; 12 LBLs) with known redshift from HST snapshot survey (Urry et al. 2001). No significant difference in SMBH masses between HBLs & LBLs Sample 2: HST imaging sample of 10 RGs, 10 RLQs & 9 RQQs with elliptical hosts (McLure et al. 1999; Dunlop et al. 2002). SMBH masses of RQQs are slightly less than those of RLQs; different from previous claims

17 Comparison of Eddington ratios of AGNs
Quasars Radio galaxy The Eddington ratios (dimensionless accretion rates) of radio galaxies are about two orders lower than those of quasars.

18 4. Discussion & Summary Knowing the BH mass is important and helpful to other AGN studies Accretion disk structure is strongly dependent on the accretion rate SD: Slim disk (Abramowicz et al. 1988) RTD, GTD: Radiation pressure and gas pressure dominated thin disk (Shakura-Sunyaev 1973) SLE: Hot, two-temperature disk (Shapiro, Lightman & Eardley 1976) ADAF: Advection dominated accretion flow (Narayan & Yi 1994) Abramowicz et al. (1995)

19 “A fundamental plane of black hole activity”
(Merloni et al. MNRAS, 2003)

20 SMBH in highest redshift quasar (z=6.4)
Supermassive black hole formed in the early universe! Willott et al. (2003) (UKIRT/UIST) Barth et al. (2003) (Keck II/NIRSPEC) FWHM(MgII)=5500km/s MBH=2E9 Msun FWHM(CIV)=9000km/s MBH=6E9 Msun FWHM(MgII)=6000km/s MBH=3E9 Msun

21 Summary Supermassive black holes with mass of 106 to 109 solar masses exist in the center of both normal and active galaxies Dynamic methods of estimating the BH mass can only be applied to several nearby AGNs. Reliable BH mass of AGNs (including RL AGNs) can be obtained by reverberation mapping, MBH -  relation and two empirical R-L relations BH mass study is important and helpful to other AGN studies (accretion rate; BH spin; jet…)

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