Transcript Document

The MBH-Mstar relation in obscured AGNs at high z:
New clues on the Black Holes-Galaxy co-evolution
Julian Enrique Sarria Chavez
Terza Università di Roma
With: R. Maiolino, F. La Franca, F. Pozzi,
S. Berta, F. Cocchia, G. Melini et al.
How did the local MBH - Mbul relation come into place?
Various theoretical models have been
proposed. Each of them predict a
different evolution of the
MBH-Mbul relation at high-z
(see e.g. Lamastra’s talk)
Locally:
MBH/Mbulge ~0.002
Marconi & Hunt 2003
Jian Hu 2009
Lamastra+10
Redshift evolution of (MBH/Mstar)(z)/(MBH/Mstar)(z=0)=G(z)
type 1 AGN:
G(z>1) > G(z=0)
but bias due to AGN
luminosity selection?
(“Lauer’s bias”)
models
type 2 AGN in SMGs:
G(z>1) < G(z=0)
but bias due to SF
selected host?
(SF~Mstar)
New near-IR (1-2.4mm) integral field spectroscopy
(SINFONI+VLT) of high-z obscured AGNs
Selection criteria 14 objects:
- X-ray selected (F2-10keV>10-14 erg cm-2 s-1)
- High X-ray/Optical ratio (X/O>10)
- Very red colors: R-K>5 (EROs)
- K~18 (dominated by the host galaxy)
Results:
-Spectroscopic identification of 7 objects
- 1.3 < z < 2.1
- 1044 < L2-10keV < 1045 erg s-1
type 2 QSOs
- 1022.3<NH<1023 cm-2
Example of spectra
H
maps
XMM172 nord, H z= 1,6679
XMM172, H z= 1,71
Weighing Black Holes with the broad line H
Although obscured, three of the targets show broad H
-> can be used to infer the black hole mass
through the virial estimators
(Greene et al. 2005)
Issue of broad H broad flux being suppressed by
dust extinction
-> we inferred the “intrinsic” AGN luminosity from X-rays
The inferred black hole masses are in the range 107<MBH<109 M
The inferred accretion rates are close to the Eddington limit

M BH

M Edd

Lbol
LEdd  1
The optical and near-IR light is
dominated by the host galaxy, hence
the optical/near-IR SED can be used
to constrain the stellar mass in the
host galaxy (Pozzi et al. 2010)
Resulting MBH-Mstar relation at z~2
unobscured
obscured
X-ray selected
obscured in SMGs
Resulting MBH-Mstar relation at z~2
unobscured
• z~2 X-ray selected obscured
QSOs have black hole
UNDERMASSIVE relative to
the local relation
• Their galaxies form faster
than their black hole;
obscured • The AGN selection bias
X-ray
(“Lauer’s bias”) would go in
selected
the opposite direction
 the effect is real
obscured in SMGs
• Obscured AGNs show the
opposite evolution of MBH/Mstar
w.r.t. unobscured AGNs
• Either most unobscured AGNs are affected by strong
selection effects (“Lauer’s bias”)
• Or obscured and unobscured AGNs follow different
evolutionary paths
Resulting MBH-Mstar relation at z~2
By measuring the SFR (from the
SED) and the BH accretion rate
(from LX) it is possible to define
the expected evolution on the
MBH-Mstar diagram
unobscured
108 yr
obscured
X-ray
selected
obscured in SMGs
They are rapidly moving
towards the local relation
Conclusions
- We have measured the redshift for 7 sources (1.3<z<2.1)
- We detected broad Hα in three of these targets, which allowed
us to estimate their black hole masses.
- The galaxy masses have been estimated from their SED
- z~2 obscured AGNs have MBH/Mstar lower than the local relation,
in contrast with unobscured AGNs
• Either most unobscured AGNs are affected by strong
selection effects
• Or obscured and unobscured AGNs follow different
evolutionary paths