1. QSO2 and their host galaxies
BH accretion and on-going SF in obscured quasars
Vincenzo Mainieri
with
A. Bongiorno, A. Merloni, M. Bolzonella, M. Brusa, M. Carollo, G. Hasinger, K. Iwasawa, L. Pozzetti, M. Salvato, J. Silverman, G. Zamorani, E. Zucca & COSMOS
Vincenzo Mainieri IAU 1009

2. QSO2 and their host galaxies
QSO-2 sample
QSO2 and their host galaxies
Introduction
AGN-galaxies co-evolution
M-  relation: AGN and galaxies co-evolve (Magorrian et al. 1988; Gebhardt et al. 2000; Ferrarese & Merrit 2000; Tremaine et al. 2002)
Hopkins+08
Hickox+09
Vincenzo Mainieri (ESO)
QSO-2 and their host galaxies
COSMOS-Hawaii, 9/6/2010
Vincenzo Mainieri IAU 1009

3. QSO2 and their host galaxies
QSO-2 sample
QSO2 and their host galaxies
Sample selection
Sample selection
Selection criteria:
LX>1044 erg s-1
NH>1022cm-2
146 QSO-2
The galaxy to AGN contrast ratio is maximized: “easier” to study the morphology of the host as well as its stellar mass and SFR.
Caveat: UV light can be contaminated from scattered AGN light, SFR diagnostics (e.g. H, [OII]) excited by accretion power rather than young stars, etc..
Select a sample of AGN that is best suted to study the properties of their host galaxies.
Bright quasars but obscured.
Vincenzo Mainieri (ESO)
QSO-2 and their host galaxies
COSMOS-Hawaii, 9/6/2010
Vincenzo Mainieri IAU 1009

4. QSO2 and their host galaxies
QSO-2 sample
Redshifts
Redshift distribution
34 spectroscopic redshifts from zCOSMOS (Lilly+09) and IMACS (Trump+08)
112 photometric redshifts using gal+AGN templates (z=0.015, Salvato+09)
Vincenzo Mainieri (ESO)
QSO-2 and their host galaxies
COSMOS-Hawaii, 9/6/2010
Vincenzo Mainieri IAU 1009

5. QSO2 and their host galaxies
QSO-2 sample
BH masses and Eddington ratios
Marconi & Hunt (2003):
Log(MBH)= (M*-10.9)
Lbol=f(L[2-10 keV) from Hopkins+07
Vincenzo Mainieri (ESO)
QSO-2 and their host galaxies
COSMOS-Hawaii, 9/6/2010
Vincenzo Mainieri IAU 1009

6. QSO2 and their host galaxies
SED
SED fitting : galaxy + AGN
Multi-band photometry: U, B, V, g, r, I, z, J, H, K, IRAC, MIPS-24 micron
Galaxies SED templates: Bruzual & Charlot (2003) + SFHs + Calzetti’s law
AGN SED template : Richards et al. (2006)
0<E(B-V)<3: <NH>~5x1022cm-2 (assuming 1/3 of Galactic dust-to-gas) -> E(B-V)~3
Chabrier IMF
Vincenzo Mainieri (ESO)
QSO-2 and their host galaxies
COSMOS-Hawaii, 9/6/2010
Vincenzo Mainieri IAU 1009

7. QSO2 and their host galaxies
SED
SED fitting : galaxy + AGN
2 minimization comparing observed and template fluxes at the redshift of the QSO-2
PRIORS
The maximum allowed age is the age of the Universe at the redshift of the source
Vincenzo Mainieri (ESO)
QSO-2 and their host galaxies
COSMOS-Hawaii, 9/6/2010
Vincenzo Mainieri IAU 1009

8. QSO2 and their host galaxies
Host galaxy properties
QSO2 and their host galaxies
Stellar Mass
Stellar Mass
Chabrier IMF
Parent sample of ~7000 galaxies selected in the same redshift range and X-ray flux limits of the QSO-2 sample.
The fraction of galaxies hosting a QSO-2 increases with the stellar mass, consistently with what observed for the overall AGN population (e.g. Kauffmann et al. 03, Silverman et al. 2009)
Effect of the Gal+AGN sed in the mstar estimates.
Massive galaxies
Consistent with the SDSS results, see Kauffmann reference
Vincenzo Mainieri (ESO)
QSO-2 and their host galaxies
COSMOS-Hawaii, 9/6/2010
Vincenzo Mainieri IAU 1009

9. QSO2 and their host galaxies
Host galaxy properties
Rest frame colors
Host galaxies classification
Photometric classification
Separating red and blue galaxies (DEEP2, Cooper+07):
U-B=-0.032(MB+21.52)
“Blue” QSO-2 : 50%
“Red” QSO-2 : 50%
Star formation activity classification
Active: log(SSFR/Gyr-1) > -1 (75%)
Quiescent: log(SSFR/Gyr-1) < -1 (25%)
Color-magnitude plot.
Vincenzo Mainieri (ESO)
QSO-2 and their host galaxies
COSMOS-Hawaii, 9/6/2010
Vincenzo Mainieri IAU 1009

10. QSO2 and their host galaxies
Host galaxy properties
Star formation
SFR-M* correlation
Goal: compare the star formation in the QSO2 hosts with the tight correlation between SFR and M* of blue star-forming galaxies (e.g. Noeske+07; Daddi+07; Elbaz+07; Pannella+09; Rodighiero+10).
Vincenzo Mainieri (ESO)
QSO-2 and their host galaxies
COSMOS-Hawaii, 9/6/2010
Vincenzo Mainieri IAU 1009

11. QSO2 and their host galaxies
Host galaxy properties
QSO2 and their host galaxies
Star formation
SFR-M* correlation
Goal: compare the star formation in the QSO2 hosts with the tight correlation between SFR and M* of blue star-forming galaxies (e.g. Noeske+07; Daddi+07; Elbaz+07; Pannella+09; Rodighiero+10).
The star formation is not linked to a specific state of the AGNs.
The hosts are mostly evolving secularly: 2/3 are large rotating disks and 1/3 major mergers from dynamical studies of rest-frame optical/ UV selected high-redshift galaxies (e.g., Förster Schreiber et al. 2006; Genzel et al. 2008; Shapiro et al. 2008)
Major mergers does not seem the driver neither for sf nor agn accretion in this obscured quasars.
Strong trends of host SFR with AGN obscuration are lacking because such SFRs are pervasive in galaxies of similar
mass and redshift. The hosts are evolving secularly and star formation is not linked to a specific state of the AGNs.
The tightness of this relation suggests a high duty cycle of star formation. For massive z ∼ 2 galaxies, a strong role of
secular evolutionary processes compared to individual brief merger events is independently suggested by dynamical
studies of rest-frame optical/ UV selected high-redshift galaxies (e.g., F orster Schreiber et al. 2006; Genzel et al. 2008; Shapiro et al. 2008).
Vincenzo Mainieri (ESO)
QSO-2 and their host galaxies
COSMOS-Hawaii, 9/6/2010
Vincenzo Mainieri IAU 1009

12. QSO2 and their host galaxies
Host galaxy properties
QSO2 and their host galaxies
Co-evolution
Co-evolution of QSO-2 and their hosts
( e.g Netzer 2007 & 2009; Rowan-Robinson 1995)
Compare with the Herschel results (Fig. 6 of Shao+10).
Also Lutz+10.
Put my QSO-2 in this plane divided in different redshift bins.
We should look at SFR vs NH.
L(FIR) from the SFR using the Kennicutt+98 relation:
SFR(Msun yr-1)=L(FIR)/(5.8x1043 erg s-1)
Vincenzo Mainieri (ESO)
QSO-2 and their host galaxies
COSMOS-Hawaii, 9/6/2010
Vincenzo Mainieri IAU 1009

13. QSO2 and their host galaxies
Host galaxy properties
Co-evolution
Co-evolution of QSO-2 and their hosts
Shao+10
Compared to the Spitzer 70micron-based study of Mullaney et al. (2010), we are probing the rest frame far-infrared out
to z~1 where 70 micron data already enter the rest frame mid-IR with less favourable contrast between host emission
and AGN heated dust.
We should look at SFR vs NH.
Vincenzo Mainieri (ESO)
QSO-2 and their host galaxies
COSMOS-Hawaii, 9/6/2010
Vincenzo Mainieri IAU 1009

14. QSO2 and their host galaxies
Radiation pressure and absorption
Effective Eddington limit: the dust component of the gas surrounding the AGN greatly enhances the effect of radiation pressure above that for Thomson scattering so that an AGN which is sub-Eddington for ionized gas can appear super-Eddington for cold dusty gas (e.g. Laor & Draine 1993; Scoville & Norman 1995).
Long-lived stable clouds are not expected to survive in a regime where the effective Eddington limit is exceeded (Fabian+08,+09).
OUTFLOWS ?
MBH= (MK+24) Graham+07
Lbol from L2-10keV using Marconi+04 (or Hopkins+07)
z<1
Vincenzo Mainieri (ESO)
QSO-2 and their host galaxies
COSMOS-Hawaii, 9/6/2010
Vincenzo Mainieri IAU 1009