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Black hole accretion and host galaxies of obscured quasars
Vincenzo Mainieri
with
Angela Bongiorno, Andrea Merloni & COSMOS
Vincenzo Mainieri (ESO) QSO-2 and their host galaxies The X-ray Universe 2011
Introduction
AGN-galaxies co-evolutionM- relation: AGN and galaxies co-evolve (Magorrian et al. 1998; Gebhardt et al. 2000; Ferrarese & Merrit 2000; Tremaine et al. 2002)
Hickox+09Hopkins+08
Vincenzo Mainieri (ESO) QSO-2 and their host galaxies The X-ray Universe 2011
Introduction
AGN-galaxies co-evolution
Where the “food” is coming from?
Secular processes Major mergers
Vincenzo Mainieri (ESO) QSO-2 and their host galaxies The X-ray Universe 2011
QSO-2 sample Sample selection
Sample selection
Selection criteria:
LX>1044 erg s-1
NH>1022 cm-2
142 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..
Vincenzo Mainieri (ESO) QSO-2 and their host galaxies The X-ray Universe 2011
X-ray properties Stacking
Stacked X-ray spectrum
NH=(5.68.33.3)1022 cm-2
EW(FeK)~104 eV
• For the 34 QSO-2 with spectroscopic redshifts, only the rest-frame 2-10 keV band was used for each spectrum.
• Spectral binning was designed to match a fixed rest-frame 200eV intervals.
• The total accumulated counts are 4763
See Poster G41 (Salvato+11)
Vincenzo Mainieri (ESO) QSO-2 and their host galaxies The X-ray Universe 2011
QSO-2 sample Redshifts
Optical spectroscopyDn(4000) = 1.19±0.02 (Balogh+99)HδA = 4.7±0.4 (Worthey&Ottaviani97)
Vincenzo Mainieri (ESO) QSO-2 and their host galaxies The X-ray Universe 2011
SED
SED fitting : galaxy + AGN14 Bands Used
6 SUBARU bands (U-z)I + K band (CFHT)
4 Spitzer/IRAC24μm Spitzer/MIPS
Galaxy templates: - 14 phenomenological: Polletta (2007) - Libr. of synthetic sp. (B&C) a) 10 declining SFH SFR µe-t/t t=[0.1-30] Gyr tage=[50Myr-5 Gyr] tage<tuniv(z) 0 < E(B-V) <0.5 b) 1 constant SF
AGN template: -Richards et al. (2006): mean QSO SED from 259 IR-selected QSOs from the SDSS with Spitzer photometry
1<E(B-V)<9: <NH>~5x1022cm-2 (assuming 1/3 of Galactic dust-to-gas) -> E(B-V)~3
Vincenzo Mainieri (ESO) QSO-2 and their host galaxies The X-ray Universe 2011
SED
SED fitting : MIR/X-ray correlation
Gandhi+09
VISIR/VLT high resolution imaging of a sample of local Seyferts: the least contaminated core fluxes
• ~70 pc at z=0.01
• <40% contaminating star-formation in the unresolved flux
log L12.3m=(-4.37±3.08)+(1.106±0.071) log L2-10 keV
A strong MIR (12.3 m) / X-ray (2-10 keV) correlation :
Vincenzo Mainieri (ESO) QSO-2 and their host galaxies The X-ray Universe 2011
SED
SED fitting : galaxy + AGN
Chabrier IMF
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
• The AGN SED should fit the 12.3 m flux predicted using the Gandhi+09 correlation
Vincenzo Mainieri (ESO) QSO-2 and their host galaxies The X-ray Universe 2011
Host galaxy properties Stellar Mass
Stellar Mass
• Chabrier IMF
• Ilbert+10: parent sample of ~70,000 galaxies selected in the redshift range 0.8-1.5, where there is a good completeness for M*> 5x109 Msun
• We folded the parent sample with the X-ray sensitivity map
• 80% of the hosts have M*>1010 Msun
• the fraction increases with M*
• 80% of the hosts have M*>1010 Msun
• the fraction increases with M*
Vincenzo Mainieri (ESO) QSO-2 and their host galaxies The X-ray Universe 2011
Host galaxy properties Rest frame colors
Host galaxies classification
Photometric classification
Separating red and blue galaxies (Wilmer+06):
“Blue” QSO-2 : 42%
“Red” QSO-2 : 58%
Star formation activity classification
Active: log(sSFR/Gyr-1) > -1 (62%)
Quiescent: log(sSFR/Gyr-1) < -1 (38%)
~20% “red” hosts are dusty star-forming galaxies
(see also Cardamone+10, Lusso+11)
~20% “red” hosts are dusty star-forming galaxies
(see also Cardamone+10, Lusso+11)
Vincenzo Mainieri (ESO) QSO-2 and their host galaxies The X-ray Universe 2011
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).
• @ z~1 : 62% of the hosts are star-forming and their rates are comparable to the main-sequence “Noeske” relation
• @ z~1 : 62% of the hosts are star-forming and their rates are comparable to the main-sequence “Noeske” relation
• Similar evolution of the <SSFR>• Similar evolution of the <SSFR>
Vincenzo Mainieri (ESO) QSO-2 and their host galaxies The X-ray Universe 2011
Host galaxy properties Star formation
SFR-M* correlation
Lutz,VM+10
Mullaney+11
Daddi+10
Daddi+10
• @ z~1 : 62% of the hosts are star-forming and their rates are comparable to the main-sequence “Noeske” relation
• @ z~1 : 62% of the hosts are star-forming and their rates are comparable to the main-sequence “Noeske” relation
• Similar evolution of the <SSFR>• Similar evolution of the <SSFR>
Vincenzo Mainieri (ESO) QSO-2 and their host galaxies The X-ray Universe 2011
Host galaxy properties Morphology
Merging?
• Greene et al. 2009 (SDSS QSO-2): nearly one-quarter have highly disturbed morphologies
• Liu et al. 2009 (SDSS QSO-2): high fraction of double cores and physically associated companions from long-slit spectroscopy.
Cisternas+11: a) no difference in the distortion fractions between inactive and active galaxies; b) ~65% of the AGN hosts are disk dominated.
Vincenzo Mainieri (ESO) QSO-2 and their host galaxies The X-ray Universe 2011
Host galaxy properties Morphology
Morphology35 QSO-2 with z<1.2 & IAB<24
ZEST+ (Scarlata+07; Carollo+11): Five non-parametric diagnostics (asymmetry A, concentration C, Gini coefficient G, 2nd order moment of the brightest 20% of galaxy pixels M20, ellipticity e) + Sersic index n
Bulge-dominatedDisks Mergers
Lack of evidence is not necessarily evidence of lack: e.g. quasar phase at the end of the merging process (Di Matteo +05; Conselice03)?
23%
20%
57%
F7
75W
(i)
F1
60W
(H
)
Credits to the CANDELS team
Vincenzo Mainieri (ESO) QSO-2 and their host galaxies The X-ray Universe 2011
QSO-2 sample
Morphology and accretion rate
• bulge dominated galaxies tend to host low Edd ratios BHs • disks and mergers host high Edd ratios BHs
• bulge dominated galaxies tend to host low Edd ratios BHs • disks and mergers host high Edd ratios BHs
• lowest mass BHs are the fastest accretors (e.g McLure & Dunlop 2002; Netzer & Trakhtenbrot 2007)
• lowest mass BHs are the fastest accretors (e.g McLure & Dunlop 2002; Netzer & Trakhtenbrot 2007)
<MBH>~1x108 Msun
<MBH>~4x108 Msun
Vincenzo Mainieri (ESO) QSO-2 and their host galaxies The X-ray Universe 2011
Conclusions
• Type-2 QSOs reside almost exclusively in massive galaxies, 80% have M*>1010 MSUN and the fraction of galaxies hosting them monotonically increases with M*
• The majority of the hosts (>60%) are actively forming stars
• The SSFR of QSO-2 hosts is similar to what observed for star-forming (“Noeske”) galaxies at z~1.
• The evolution of SSFR of QSO-2 hosts is similar to the one of SFGs.
• Morphological analysis suggests that the majority of the hosts are bulge dominated.
• We do not find clear signature of merger activity for the majority of the hosts but it could be a time issue: QSO phase at the end of a major merger event.Difficult to test the quasar fueling models by studying the morphology.