Max-Planck Institut für Astronomie

Seeing the invisibleQuasar host galaxies from SDSS stacked imagesRoberto Decarli, Stefano Zibetti

AGN10 - September 11th, 2012

Black holes and host galaxies

• How do galaxies and BHs coevolve?

Gultekin et al. (2009)M

BH

MB

HLHost

s*Rinf

Blackholes

BLR

Host galaxies

• How do galaxies and BHs coevolve?

• What are the properties of a galaxy which hosts a QSO?(feedback, AGN triggering, ...)

Fabian et al. (2003)

Black holes and host galaxies

l Ll

RB

LR

MBH = G-1 RBLR vBLR2

RBLR ~ l Lla

vBLR = f FWHM

Virial estimates of MBH

CIV – MgII – Hb

QSO host galaxies

0.3 0.8Redshift

Gain depth through stacking!

340 SDSS images ≈ 1/2 hr 8m class telescope

“Population” properties vs. individual objects

0.3

0.8

Redsh if

tMBH5 107 2 109

Decarli & Zibetti (in prep)

15,018QSOs

446

Decarli & Zibetti (in prep)

Quasari-

bandmask

Decarli & Zibetti (in prep)

Quasar

Reference star

Decarli & Zibetti (in prep)

Stack of the quasars

Stack of the ref.stars

DifferenceMax PSF subtraction

Max PSF + fit galfit

galfit (residuals) galfit (residuals,different scale)

Residuals: ~ 1% signal

Decarli & Zibetti (in prep)

MBH~5 107 Mo MBH~2 109 Mo

0.3

0.8

Redsh if

tMBH5 107 2 109

Decarli & Zibetti (in prep)

Decarli & Zibetti (in prep)0.3<z<0.4

r-z

z

0.3

<z<

0.4

Color-mag of QSO hosts

r-z

z

0.4

<z<

0.5

Color-mag of QSO hosts

r-z

z

0.5

<z<

0.6

Color-mag of QSO hosts

r-z

z

0.6

<z<

0.7

Color-mag of QSO hosts

r-z

z

0.7

<z<

0.8

Color-mag of QSO hosts

Structural parameters

nse

rsic

R

eff [

kpc]

MBH – Mhost at z>0

ConclusionsOur stacking analysis on SDSS images allowed us to:

• directly measure the SED of QSO host galaxies with unprecedented accuracy in 4 bands

• locate QSO hosts in the color-mag plane up to z=0.8=> QSO host galaxies are the bluest

galaxies at given luminosity & redshift

• derive structural parameters (nsersic, Reff) for QSO host galaxies in multiple bands

• infer reliable stellar masses => first MBH – Mhost relation at z>0

Decarli & Zibetti (in prep)

Stack of the quasars

Stack of the ref.stars

Difference

Decarli & Zibetti (in prep)

Stack of the quasars

Stack of the ref.stars

Difference

Decarli & Zibetti (in prep)

Objects rejected in the jackknife analysis

Stack of the quasars

Stack of the ref.stars

Difference

QSO

PSF

QSO host galaxies

QSO host galaxies

QSO

PSF

QSO host galaxies

SFH

G ≡ MBH/Mhost increases of a factor ~7 from z=0 to z=3

Evolution ofMBH/Mhost

CIV – MgII – Hb

Decarli et al. (2010 a,b)