Galactic Astronomy銀河物理学特論 I

Lecture 2-1: Active galaxies and super massive black holes in the local universe

Seminar: Gultekin et al. 2009, ApJ, 698, 198

Lecture:

2011/11/21

UV and optical spectra of Active Galactic Nuclei: Seyfert galaxies

Permitted emission lines (Ha,Hb,MgII,CIII],CIV,NV,Lya etc) of Seyfert 1 galaxies show broad component with FWHM of 2000-10000km/s (broad-lines). Forbidden transition lines ( 禁制線 ) does not have broad component, because the gas density of the broad-line region is higher than the critical density of the forbidden transitions. Forbidden emission lines as well as permitted ones show narrow emission with FWHM~100-1000km/s (narrow-lines).

Seyfert 1

Permitted lines: broad+narrow-line

Forbidden lines: narrow-line

Seyfert 2

Permitted lines: only narrow-line

Forbidden lines: narrow-line

Structure of active galactic nuclei:

Unified model of Seyfert 1 and 2 galaxies is proposed by Antonucci and Miller (1985, ApJ, 297, 621) based on the data obtained by spectro-polarimetric observation. Dust torus structure around the nuclei hide the broad-line region of Seyfert 2 galaxies. Emission from the broad-line can be observed through scattered light (though electron or dust scattering).

Miller et al. 1980, PASP, 92, 702Miller and Antonucci 1983, ApJL, 271, 7

Structure of active galactic nuclei:

Antonucci and Miller, 1985, ApJ, 297, 621

NGC5252 Morse et al. 1998, ApJ 505, 159

Unified model of AGNs:

From www.cv.nrao.edu/course/astr534/ExtraGalactic.html

Luminous AGN: QSOs,

Less-luminous AGN: Seyfert

Radio-loud: Radio-loud QSOs, radio galaxies

Radio-quiet:Radio-quiet QSOs, Seyferts

Structure of active galactic nuclei: X-ray data

Unified model with the dust torus structure is also supported by the X-ray spectra of Seyfert 2 galaxies. Their X-ray spectra show strong soft X-ray absorption.

Awaki et al. 1991,PASJ, 43, 195

Tran 2003, ApJ, 583, 632

Structure of active galactic nuclei: FIR view

Seyfert 2 galaxies with Hidden-broad-line region (HBLR) show “hot” MIR-FIR spectra similar to Seyfert 1 galaxies. (Non-HBLR Seyfert 2 galaxies show similar F25/F60 to HII-region, LINER, Starbursts (HLS). Non-HBLRs have lower intrinsic luminosity).

Selecting Seyfert 2 galaxies with optical emission line ratios:

Kauffmann et al. 2003, MNRAS, 346, 1055

AGNs tend to have stronger highly ionized emission lines, like [OIII]Solid line ： selection line by Kewly et al. (2001) model calculation, Dashed line : empirical line.

UV and optical spectra of AGNi: QSOs

QSOs show similar line properties to Seyfert 1 galaxies, but they are more luminous and their continuum is dominated by nuclear component (not by host galaxy).

Richards et al. 2003, ApJ, 126, 1131

Broad-band continuum of AGNs: QSOs

Kawaguchi et al. 2001, ApJ, 546, 966

Standard accretion disk (UV)

Inverse Compton emission (X-ray) from coronal component of surface of the disk.

AGN and super massive black holes:

Black hole massesof AGNs are determined with “reverberation” mapping method. The method measures the time-lag between the time-variation of the fluxes of the nuclear continuum and broad emission lines. The time lag corresponds to the typical distance between the black hole and the line emitting region. The black hole masses can be estimated with the distance and the line width. The lag-velocity diagram suggests the virialized condition of the broad-line region.

Peterson et al. 2004, ApJ, 613, 682

Measuring the black hole mass with stellar motions at the center.

VLT/SINFONI observation of velocity field of the central region of Centaurus A . It’s black hole mass is estimated to be 5.5x10^7 Msolar

Cappellari et al. 2009, MNRAS, 394, 660

Which is the primary relation ?:

Ferrarese and Merritt 2000, ApJ, 539, L9

Which is the primary relation ?:

MBH-LK relation has rms~0.3 dex in logMBH, MBH-Mbulge(=Re*Sigma^2, bulge virial mass) has 0.25 dex in logMBH.

Marconi and Hunt 2003, ApJ, 589, L21

Extending the MBH-Mspheroid relation to the smaller systems:

Search for dwarf Seyfert 1 galaxies with SDSS spectro-scopic data.

Barth et al. 2005, ApJ, 619, L151

Greene & Ho 2004, ApJ, 610, 722

Extending the MBH-Mspheroid relation to the smaller systems:

HST/STIS observation of a globular cluster G1 in M31. Its central velocity dispersion is 30km/s and the estimated black hole mass is MBH=18000Msolar 。

Gebhardt et al. 2005, ApJ, 634, 1093

Gebhardt et al. 2002, ApJ, 578, L41

Extending the MBH-Mspheroid relation to the smaller systems:

A search for SMBH at the center of the globular cluster M15 with HST STIS. If the excess velocity dispersion is explained with existence of SMBH, its mass is edimated to be MBH=3900Msolar. See next slide.

Gerssen et al. 2002, AJ, 124, 3270

Extending the MBH-Mspheroid relation to the smaller systems:

Proper motion survey of the globular cluster M15 with HST WFPC2. Comparison with N-body simulation (Baumgardt & Makino 2003, MNRAS, 340, 227) suggest that no black hole is necessary for the cluster. The upper limit is 500Msolar.

McNamara et al. 2003, ApJ, 595, 187