(Cold) dust and gas in high-z AGNs: a prelude to Herschel and
ALMA Roberto Maiolino Osservatorio Astronomico di Roma
Slide 2
The cold side of AGNs Molecular transitions (gas mass,
dynamics...) Far-IR fine structure lines (PDR, HII, star formation,
dynamics...) Thermal dust emission (star formation, dust mass,...)
Cleaner view of the host galaxy (unaffected/little affected by AGN
light) than at other wavelengths...
Slide 3
Two modes of star formation starburst high efficiency
merger-interaction driven secular low efficiency disk instabilities
(smooth gas inflow) Daddi+10 Genzel+10 In what mode does black hole
accretion occur? Higher gas fraction at high-z Does this play a
role into BH accretion and obscuration at high-z? Tacconi+10 gas
fraction local QSOs high-z slope=1.3
Slide 4
Shao+10 Herschel: a tight connection between BH accretion and
galaxy formation only seen in the luminous QSO regime (merging?)
Low luminosity AGN hosts mostly undergoing secular evolution
Walter+09 1.5 kpc z=6.4 L AGN ~L Edd SFR ~ 1000 M o yr -1 kpc -2
(Eddington limited SF) gas ~ 10 10 M o kpc -2 (~GMC cores) M BH /M
bul L(SF) [erg/s] L(AGN) [erg/s]
Slide 5
CO velocity fields: AGN host galaxy dynamics at high z High z
QSO hosts Low z galaxies M BH -M * Relation out to z>6 M * ~ M
dyn -M gas CO Velocity (deprojected) Riechers+09 Wang+10
Lamastra+10 CO map (Einstein ring z~4.8) from CO rotation curve...
yes, the molecular gas rotates... and traces the dynamical mass...
really true?
Slide 6
If molecular gas in QSO hosts rotates and is dynamically
settled... wheres the feedback?!... the bulk of the gas
(~molecular) in the host galaxy seems unaffected by the presence of
a QSO. Mrk231 the closest QSO However past CO observations plagued
by narrow bandwidth -200 +200 0 Mrk231 re-observed with IRAM broad
bandwidth Feruglio+10 Velocity (km/s) Downes & Solomon 1998
Broad wings
Slide 7
Massive molecular outflow in Mrk231 extended over ~1 kpc
Inferred outflow rate ~ 2000 M /yr ! Will expel the available
molecular gas (hence stop star formation) in less than 10 7 yrs
Same outflow component observed by Herschel through OH and H 2 O
absorption Fisher+10
Slide 8
Herschel+ALMA powerful tools to probe dynamics and feedback in
high-z AGN hosts! But are molecular tracers really the best ones in
typical galaxies at high-z? Low metallicity (Z~0.3 Zsun) galaxy
observed by Herschel [CII]/CO ~ 50000 !!! Far-IR fine structure
lines (especially PDR tracers) more promising Cormier+10 [CII]
CO
Slide 9
star forming galaxies ULIRGs Far-IR fine structure lines in
high-z AGN hosts. Not only kinematics, but also galaxy physics.
Iono+06 Walter+09 Maiolino+05,09 Ivison+10 z>4 QSOs AGN in z~2
SMG AGN in z~2 SMG local ULIRGs local SB and SF galaxies n=10 6
n=10 4 n=10 2 G 0 =10 2 G 0 =10 4 L CO(1-0) /L bol L [CII] /L bol
[CII] @ z=4.4
Slide 10
Also NLR far-IR tracers at high-z, but not clear-cut in
identifying AGNs Sturm+10 Ferkinhoff+10 However, the mm/submm
spectral range host other powerful tracers of (obscured)
AGNs...
Slide 11
X-ray Dominated Regions (XDRs) Photo Dissociated Regions (PDRs)
UV X-ray X-rays penetrate deep into the molecular cloud and keep
the temperature high Maloney+96, Lepp & Dalgarno 96,
Meijerink+05,07
Slide 12
Van den Werf+10 Herschel-SPIRE XDR Powerful tool to identify
totally obscured and embedded AGNs
Slide 13
Weiss etal 2005/7 non - linear (slope 1.7) QSOs SMGs The high
CO excitation observed in high-z QSOs is probably associated with
XDR
Slide 14
X-ray Dominated Regions (XDRs) Photo Dissociated Regions (PDRs)
UV X-ray X-rays penetrate deep into the molecular cloud and keep
the temperature high high-T favors chemical reactions ( e.g.
formation of HCN) Maloney+96, Lepp & Dalgarno 96,
Meijerink+05,07
Slide 15
XDR-enhanced species can identify the presence of
hidden/elusive AGNs HCO+(1-0) Starbursts and Composite Sys Pure Sys
HCN / HCO+ HCN / CO Khono+08 Krips+09
Slide 16
With ALMA the identification of XDR will be feasible not only
in all local (obscured) AGNs, but also at high redshift HCN HCO+ CO
CCH Example of QSO at z=6.4 Not only ~ S/N on CO line ( detailed
dynamical studies, see discussion later on), but also several other
molecular lines -> astrochemistry -> XDR tracers IRAM 14
hours Bertoldi+03
