On the geometry of broad emission region in quasars

Roberto Decarli

Turin - May, 20th, 2008

Università degli Studi dell’InsubriaDipartimento di Fisica e Matematica

Dottorato in Astronomia e Astrofisica

M. LabitaA. TrevesR. Falomo

Bettoni et al., 2003

Supermassive Black Holesand their host galaxies

• Massive BHs are found in all massive spheroids (Kormendy & Richstone, 1995)

• MBH depends on the luminosity, mass, stellar velocity dispersion of the host spheroid.

• Rinf ≈ GMBH/*2 ~0.002 Rspheroid

• A joint evolution of the BH and the spheroid took place.

• Independent measures of MBH and the host galaxy properties are needed.

Virial determination of MBH

• In Type-1 AGNs, the emission lines from gas at R~0.01-0.5 pc are observed (« Rinf!!).

• Gas emission lines are Doppler broadened (> 1000 km/s).• Reverberation mapping proved that the gas motion is mainly

gravitational

• RBLR = A (L)0.7 (Kaspi et al., 2000)

• vBLR = f · FWHM

• From the host galaxy luminosity: log MBH=-0.50 MR - 2.60 (Bettoni et al., 2003)

G

vRM BLRBLR

BH

2

VPfG

FWHMfLA 227.0 )()(

The geometrical factor f• f is a function of the adopted BLR dynamical model:

– Isotropic model: f =√3 /2 (fixed).Broad line shape: gaussian.

– Thin disk model: f =1/(2 sin ).Broad line shape: depend on the (unknown) radial mass distribution.

– Thick disk model: f =1/(2 c1 sin + 2 c2 / √3). c1 and c2 depend on and disk H/R.Broad line shape: unconstrained at high values of ; gaussian at small .

Line of sight

Line of sight

Line of sight

The sample

• Low redshift (z<0.6) quasars with:– images in the HST-WFPC2 archive and published values of the

luminosity of the host galaxies– at least 1 spectrum from the HST-FOS archive, from the SDSS or

from on-purpose observations at the Asiago 1.82m Telescope.

• 49 targets. 16 of them have both optical and UV spectra.

Asiago

SDSS

HST-FOS

1613

20

Optical spectra: 36 objects

UV spectra: 29 objects

Tot.: 49

The FUV-to-V spectrum of low-z QSOs

Decarli et al (2008)

Labita et al (2006)

H and CIV broad lines

From RBLR - L relations:

RBLR(H) ≈ 1.5 RBLR(CIV)Comparing the FWHMs:

FWHM (H) is NOT correlated with FWHM (CIV)

From the FWHM/line ratio:

H and CIV fill different regions of the FWHM/line plane, H being closer to the Gaussian case

Decarli et al (2008)

Virial Products and MBH

• We compare the VPs with the MBH as estimated from the host galaxy luminosity.

• The CIV-based VPs are well correlated with MBH. H data show a significantly worse spread.

f and the line width

• Pieces of evidence supporting a flat BLR in radio loud quasars: the FWHM-Rc-l dependence

• f is found to depend on the line width!

• The isotropic model predict f = const, while the dependence on the line width is consistent with a disk-like scenario.

• The f -FWHM dependence is observed both for radio loud and radio quiet quasars.

A sketch of the BLR geometry

• We suggest that:– an isotropic model of the BLR cannot account for the observed f values

and f-FWHM relation, nor for the shape of (at least) CIV line– a thin disk model can explain most of the observables related to the CIV

broad line, but is inconsistent with H data– a thicker disk may represent a valid model for H– since RBLR(H)>RBLR(CIV), we suggest that a disk the thickness of which

increases with R may explain the differences in the behaviour of the two lines

– radio loudness do not affect directly the BLR geometry.

Dusttorus

Dusttorus

Accretion disk

H emitting clouds

CIV emitting clouds

FeII template subtraction and Gauss-Hermite polynomials

Direct measures on data or fit?

The host galaxy of quasars• In quasars, the nuclear light overwhelms

the galaxy luminosity; the surface brightness is ∝ (1+z)-4

• The observed image is:

(galaxy + nucleus) ⊗ PSF

• We use our Astronomical Image Decomposition and Analysis (AIDA) software in order to:

– Model the PSF on the field stars;

– Superimpose a nuclear point-like source to a galaxy model;

– Convolve them with the PSF model and fit it to the observed quasar light profile.

• The host galaxy luminosity and morphology (according to the best-fitting galaxy model) are thus found.

QSO

PSF

AIDA Widget

Bibliography

• A pdf presentation of AIDA is available at:http://www.math.unipa.it/~daa_erice07/contributors/uslenghi.pdf

• Bettoni D., Falomo R., Fasano G., Govoni F., 2003, A&A, 399, 869• Collin S., Kawaguci T., Peterson B.M., Vestergaard M., 2006, A&A, 456, 75• Decarli R., Labita M., Treves A., Falomo R., 2007, accepted for publication

in MNRAS• Kaspi S., et al., 2000, ApJ, 533, 631• Kaspi S., et al., 2005, ApJ, 629, 61• Kaspi S., et al., 2007, ApJ, 659, 997• Kormendy J., Richstone D., 1995, ARA&A, 33, 581• Labita M., Treves A., Falomo R., Uslenghi M., 2006, MNRAS, 373, 551