Obscured AGN in the (z)COSMOS survey

AGN9, Ferrara, May 25 2010

Angela BongiornoMax-Planck-Institut für extraterrestrische Physik, Garching, GERMANY

AND

Andrea Merloni

Marco Mignoli

Gianni Zamorani

Marcella Brusa

And

The COSMOS/zCOSMOS teams

Complete census of AGN (in particular obscured population)

How obscured AGN evolve

Fraction of obscured AGN (as a function of e.g. L and z)

Hie

rarc

hica

l gr

owth

Grow

th of SM

BH

Gas inflow

AGN feedback Active

Quasar

Starburst &buried Quasar

Normal galaxies

Galaxy mergers

(adapted from Hopkins et al., 2008)

THE COSMIC EVOLUTION SURVEY

• 2 deg2 equatorial • HST treasury project• Deep: ACS iAB < 27• Multi-wavelength observations• Similar volume as SDSS, but fainter and higher z• 19-band photo-z

RA = 10:00:28.6

Dec = +02:12:21

Multi-wavelength Data:XMM HST

Spitzer

SubaruVLA

VLA 1.4 GHz – 7 μJy

Spitzer-IRAC 3-8 μm – 10 μJy

Spitzer-MIPS 24 µm – 15 mJy

HST-ACS – iAB~27

Subaru Bvriz – mAB~27

GALEX N/F UV – mAB~26

XMM 0.5-10 keV – 10-15 cgs

Chandra 0.5-2 keV -- 2x10-16cgs

Chandra

SPECTRA: the z-COSMOS project

600 hrs of observation with VIMOS on VLT started April 2005

Spectra will be obtained for:

• ~20,000 galaxies at 0.3 < z < 1.0 selected to have IAB<22.5

(BRIGHT SAMPLE)

• ~10,000 galaxies at 1.4 < z <2.5 with BAB<25 and chosen by color-

selection criteria (DEEP SAMPLE)• Extra targets from XMM, GALEX and radio catalogue

VIMOS @VLT

P.I. S. Lilly

zCOSMOS Institutes ETH Zurich

LAM Marseille

LAOMP Toulouse

INAF Milano

INAF Bologna

MPE Garching

VIMOS @VLT

[OIII] Line Luminosity Function I Comparison with other surveys

SDSS type2 (Reyes+08)

local LF SDSS (Hao+05)

XLF XMM-HBS (DellaCeca+08)

COSMOS X-ray LF

(Bongiorno, Mignoli, Zamorani et al., 2010 A&A 510, 56B)

Luminosity-dependent density evolution (LDDE)

1=2.13 2=0.5 L*=1.1 1041 *=2.55 10-5

Fraction of type-2 AGN

0.15< z <0.3 from ∼65% to ∼50% from L[O III]=106.2 -108.2 L to 108.2-109.2L

• at L[OIII] > Lc, decreasing fraction of type–2 AGN with luminosity

• What happen at L[OIII] < Lc?

0.3< z <0.45 and 0.5< z <0.92 from ∼80% to ∼25% from L[O III =106.2-108.5L ⊙ to L[O III]=109.0-109.6L ⊙

(Bongiorno, Mignoli, Zamorani et al., 2010 A&A 510, 56B)

SDSS (Reyes08)zCOSMOS

SDSS type-2 AGN sample @z<0.3 (Kauffmann & Heckman 2008)

BH accretion as a function of galaxy properties…

Feast: Galaxies rich in cold gas ; BH growth is regulated by small-scale feedback.

Famine: Galaxies poor in cold gas. BH accretes ~0.3% - 1% of the mass lost by evolved bulge stars.

~2% Edd

Eddington Log(L[OIII]/MBH) =1.7

BH accretion and star formation…at higher redshift

using the 20k zCOSMOS type-2 AGN sample 392 sources @ z~1

(close to the peak of the cosmic AGN and star formation density)➤ AGN hosts masses through SED fitting

• AGN templates: - Elvis et al. (1994) - E(b-v)=0 - 0.3 in 0.01 steps• Galaxy templates: - 14 phenomenological from Polletta (2007) - Libr. of synthetic sp. (Bruzual & Charlot) a) 10 declining SFH SFR e-t/ =[0.1-30] Gyr tage=[50Myr-5 Gyr] tage<tuniv(z) 0 < E(B-V) <0.5 b) 1 constant SF

Separate the Spectral Energy Distribution of AGN into nuclear+host components and derive the host properties

(Merloni, Bongiorno et al. 2010 ApJ 708, 137M)

Red/Purple: Galaxy templateBlue: AGN template

Used Bands6 SUBARU bands

K band (CFHT)4 Spitzer/IRAC

24m Spitzer/MIPS

SED fitting M* (scaling relation) BH masses

(150)

~1.5%Edd~0.2%Edd

( Bongiorno, Merloni et al. in prep)

BH accretion and star formation…at higher redshift

➤ Computation of the BH Masses

( Bongiorno, Merloni et al. in prep)

~0.6%Edd~0.02%Edd

Using the sSFR to distinguish “old” and “young” galaxies

(391)

( Bongiorno, Merloni et al. in prep)

Using the sSFR to distinguish “old” and “young” galaxies

Dotted lines: [OIII] completeness limit

Gradual trend towards lower Eddington ratios with older stellar population content.

However … selection effect still to be fully accounted for…