Transcript Gas and dust evolution in distant AGN

COSMIC DOWNSIZING
and
AGN METALLICITY
at HIGH REDSHIFT
Roberto Maiolino
INAF - Oss. Arcetri & Oss. Roma
Tohru Nagao
INAF - Oss. Arcetri & NAOJ
Alessandro Marconi
INAF - Oss. Arcetri
Mass-Metallicity relation
in galaxies at z=0
Tremonti et al. 2004
Chemical version of the
cosmic downsizing (anti-hierarchical growth)
Evolution of the Mass-Metallicity relation:
massive galaxies chemically evolve rapidly at high-z
QSOs
QSOs
12
11
z=0
1
10
3
5
9
lg M* = 8
(Kobulnicky et al. 2003, Shapley et al. 2005, Savaglio et al. 2005, Maiolino et al. 2006)
The metallicity of the
Broad Line Region at 2<z<4.5
~ 5000 QSO optical spectra (UV-rest) from SDSS DR2
Sample large enough to disentagle the
dependence on redshift and on luminosity
22 high quality composite spectra
in bins of redshift and luminosity
Lya
NV
SiII
OI+SiII
CIV
SiIV OIV]
NIV]
CII
HeII
OIII]
AlII
SiIII]
AlIII
CIII]
“1600A bump”
NIV+AlII+NIII+Fe
fit residuals
Nagao, Marconi & Maiolino 2006
Photoionization models:
Accurate fluxes for
15 emission lines
- Cloudy
- Integration over different
distributions (in r and n)
of gas clouds
- Spanning various gas
metallicities (abundances
prop. to solar, except for N)
matching flux ratios
(+ constraints from EW)
“best” metallicity
for each [z,L] bin
Hagai (!)
Nagao et al. 2006
Metallicity of
the BLR at 2<z<4.5
Average trends
- Significant dependence
on Luminosity
Consequence of the mass-metallicity relation
Z  M*  MBH  LQSO
...but also dependence on accretion rate
(Shemmer et al. 2004)
- No evolution with redshift
No metallicity evolution even
in the most distant QSOs at 4.5<z<6.4
(close to re-ionization)
From near-IR spectra
(=UV rest-frame) of 20 QSO
J1148+52
z=6.4
QSOs probe the most extreme cases of
anti-hierarchical growth:
their host galaxies are fully evolved, from
the chemicalpoint of view, already at very
high redshift
QSOs
QSOs
12
11
z=0
1
10
3
5
9
lg M* = 8
Selection effects
associated with
QSO-galaxy coevolution
Passive evolution +
Unobscured QSO
Star formation +
Obscured AGN






wind




Large number of emission
lines: possible to contrain
abundances patterns
Best matches
with abundances
at/after the wind
Pipino & Matteucci 2004
Granato et al. 2004
QSOs
best fit
The Broad Lines sample only a tiny, nuclear region
... not representative of the host galaxy?
Use Narrow Lines in obscured AGNs
NLR evolution at 1.2<z<3.8
- 51 optical spectra (UV-rest) of high redshift
narrow line radio galaxies (HzRG)
- 10 optical spectra (UV-rest) of high redshfit X-ray
selected QSO2 in the Chandra Deep Field South
CIV/HeII vs. CIII]/CIV diagram:
- sensitive to metallicity
- removes degeneracy from U
- possible to control effects of shocks and dust
Nagao, Maiolino & Marconi 2006
NLR evolution
at 1.2<z<3.8
CIV / HeII
No evolution with redshift
among HzRG at 1.2<z<3.8
3
1
(local)
0.5
Dependence on Luminosity
CIV / HeII
3
1
(local)
0.5
0.3
CIII] / CIV
1
At z>4 little information on NLR metallicity
...but information on gas in host galaxy for some QSOs
J1148+52
z=6.4
same [CII]/CO as loc. ULIRGs
same [CII]/FIR as loc. ULIRGs
 strong enrichment of carbon in the
host already at z=6.4
CONCLUSIONS
Luminosity-Metallicity relation:
consequence of Mass-Metallicity relation
BLR in galaxies
&
NLR No metallicity evolution with redshift:
QSO are extreme cases of the cosmic
downsizing (in its chemical version)
Abundance patterns matching expectations of
AGN-galaxy joint evolutionary models