Transcript Joint formation of QSO and Ellipticals

A Physical Model for Co-evolution
of QSOs and of their Spheroidal
Hosts
Gianfranco De Zotti
with: Francesco Shankar, Andrea Lapi, Luigi
Danese, Gian Luigi Granato, Michele Cirasuolo,
Paolo Salucci, Laura Silva
Observational connections between
galaxy and BH properties
• BH are generally connected with the (generally
old) bulge stellar population not with the younger
disk population (Kormendy & Gebhardt 2001;
Kormendy & Ho 2000; Salucci et al. 2000)
• Tight relationship between BH mass and stellar
velocity dispersion (Tremaine et al. 2002):
• M_BH is also well correlated with the mass in stars (Häring
& Rix 2004):
• Further relationships can be derived comparing the Galactic
Halo Mass Function with the Stellar and BH mass functions
or with the velocity dispersion function (Shankar et al.
2005):
where the GHMF is derived from the halo mass function
(Sheth & Tormen 2002), adding the contribution of subhalos (Vale & Ostriker 2004) and subtracting that of groups
and clusters (Martinez et al. 2002)
Examples:
• Mass in stars vs halo mass
Different behaviour above and below Mh~2.5 1011 Msun !
The -Vvir relation and the Velocity Dispersion Function
(Loeb & Peebles 2003; Cirasuolo et al 2005)
The -Vvir relation is a key ingredient to connect theoretical
predictions with observations
Vvir is controlled by dynamics of halos, while  feels the effect of
dissipative baryon setting
From observational point of
view:
(L) + (L- relation)  ()
From theoretical point of view:
n(Mvir, zvir) + v2vir  (vvir)
PS+ST
GMvir/rvir
Loeb & Peebles (2003)
The -Vvir relation and the Velocity Dispersion Function
 = 0.57 ± 0.05 Vvir
Dynamical attractor (Gao et al. 2004)? Major mergers rarer in
sufficiently massive halos?
A simplified feedback model
(Shankar et al. 2005; Granato et al. 2004)
• The gas, heated at virial temperature, cools
down and falls towards the central starforming region at a rate
where
and
fcosm= b/DM0.19
Dezotti:
• The time derivative of the cold, star-forming
 is the effective
efficiency of cold
gas removal by
SN feedback
gas mass is
where R0.3 for a Salpeter IMF and
so that the efficiency of gas removal by SN
feedback is
Setting
The differential equation can be solved to give:
where  = 1– R +  and
At the present time
For
and 1-Rconst.
so that
consistent with the data
For small masses,
so that
with a much flatter slope than inferred from
the data (effect of reheating?)
BH growth
Radiation drag dissipates the angular
momentum of gas clouds allowing them to
infall toward the central BH at a rate
(Kawakatu & Umemura 2002):
The final BH mass is then:
After Granato et al. (2004):
since
and, for
,
Thus, for large masses,
and
For small masses ( « 1)
consistent with the steepening indicated by
the data:
whence
Dezotti:
f_c: covering
factor of AGNdriven winds
AGN energy transferred to the gas
• Kinetic luminosity (Granato et al. 2004), erg/s
N_22: gas column
densityi n 10^22
cm^-2
f_h: fraction of
AGN kinetic
power transferred
to the gas
• For Eddington limited accretion:
with
for  = 0.1, so that
for
e.g.:
and
Scheme of our semi analytical model at high z
Halos form, gas is shock heated to virial T
Gas cools, collapse and forms stars directly, in small
halos SNae quench SF, in big ones nothing prevents a
huge burst of SF ('1000 M¯/yr over 0.5 Gyr), SMGs
phase
SF promotes the growth of a SMBH, powering high z
QSO. QSO activity expels the ISM, terminating SF and
its own growth. QSO phase
(almost) passive evolution of stellar population follows.
ERO phase with dormant SMBH
INGREDIENTS of physical model (zvir>1.5, logM vir>11.5)
1. formation of dark matter halos, starting from primordial
density fluctuations. PS (ST) formalism is used
2. shock-heating & radiative cooling of gas in DM halos
3. collapse of cold gas & star formation from cold gas
4. chemical and energetic feedback from stars (SNae)
5. formation of low angular momentum reservoir with a rate 
SFR (radiation drag Umemura 2001)
6. Growth of SMBH, limited by Eddington, viscosity, fuel
availability
7. Feed-back on cold gas due to increasing QSO activity
8. luminosity evolution of stellar populations
9. absorption of starlight by dust & re-emission in IR+sub-mm
(our GRASIL, Silva et al 1998)
Example at zvir=4
Evolution of SMBH
accretion
rate
Evolution of galaxy
Mvir=2e12
Mvir=1e13
Evolution faster in more massive halos
Granato et al 2004
SFR
Chemical abundances (in stars) at z=0 as a function of
M(halo)
Granato et al 2004
K band local Luminosity function of spheroids
Data:
Huang et al 2003
Kochanek et al 2001
Granato et al 2004
Silva et al 2005
<—— Cimatti et al. (2002)
<—— Somerville et al. (2004)
Star forming
Passive
Fontana et al 2004: galaxy stellar mass function in K20 sample
z = 0.5
z =1.3
z = 0.9
z = 1.8
Standard SAMs
Granato et al 2004
Standard SAMs underproduce massive galaxy, by a fraction
increasing with z
ABC scenario naturally reproduces SMGs statistic
SCUBA 850 m
data
model
MAMBO 1200 m
5.7 mJy z dist
Chapman et al
2005 (73 sources)
Model
MEDIAN
2.2
QUARTILE
1.7-2.8
2.2
1.6-3.3
The central BH
dispersion interpreted as
different virialization
epochs
Steepening at low ?
(due to greater effectiveness
of SNae and lower )
 = 0.57 ± 0.05 Vvir
Tighter MBH-M*?
MBH vs Mh (1)
MBH vs Mh (2)
Mass function of local SMBH
observations
model
THE PRE-QSO PHASE
The build up by accretion of the SMBH, promoted by SF and
before the bright optical QSO phase, gives rise to a mild AGN
activity in sub-mm galaxies detectable in hard-X.
Indeed ~75% of >4 mJy SCUBA sources host an X-ray AGN with
intrinsic LX[0.5-8]1043-1044 erg s-1 (Alexander et al 03,04,05)
dM/dt(BH)>0.02 M¯/yr )
L(0.5-8)>1E43 erg/s
dM/dt(BH)>0.2 M¯/yr )
L(0.5-8)>1E44 erg/s
dM/dt(BH)>1 M¯/yr ) L(0.58)>5E44 erg/s
QSO luminosity functions
(work in progress)
+ slow decrease of Lbol/ LEdd with z, from 4 at >6 to 0.8 at <2
Optical LF (1)
z=1.5
tvis=3 107 yr
Optical LF (2)
z=3.1
tvis=4 107 yr
Optical LF (3)
z=4.5
tvis=4 107
yr
Optical LF (4)
z=6
tvis=4 107 yr
Evolution of the optical luminosity function
QSOs with L>3 1047 erg/s
Our model is not affected by this problem!
(and without tuning of parameters)
Models in which a fraction of the halo mass is accreted at each
major merger, when normalized to produce the density of QSO at
z»6, tend to overproduce the density at lower z (Bromley et al.
2004).
..the cosmic accretion rate is in agreement with results of
optical surveys (e.g. Fan et al. 2003)
Unabsorbed X-ray (0.5-8 keV) light curve of QSOs
zvir=4
Mh=2.5 1012 Msun
X-ray binaries
 AGN activity
Mh=2.5 1013 Msun
Hard X-ray luminosity function (1)
 Ueda et al. (2003)

Barger et al. (2005)
z=1.5
tvis= 108 yr
Hard X-ray luminosity function (2)
 La Franca et al. (2005)
 Ueda et al. (2003)

Barger et al. (2005)
z=1.5
tvis= 3 108 yr
Hard X-ray luminosity function (3)
 La Franca et al. (2005)
 Ueda et al. (2003)

Barger et al. (2005)
z=2.5
tvis= 108 yr
Clustering
SCUBA - QSO - EROs are subsequent stages inside large
DM halos 
highly and similarly clustered.
SCUBA galaxies
Z > 1.5
r0= 83 Mpc/h
(Smail et al. 2003)
QSOs
r0  6.4 Mpc/h
(Grazian et al. 2004)
EROs
Z  1.2
r0  5-12 Mpc/h
Bright
Ellipticals
(Daddi et al. 2003)
Z0
r0= 8-11 Mpc/h
(Norberg et al. 2003)
Conclusions (1)
• A simple physical recipe accounts for the observed
galaxy & AGN “downsizing” in the framework of the
standard hierarchical clustering scenario
• Key role played by SN and AGN feedback; the relative
importance varies with Mh
• Faster and earlier evolution for more massive objects
• Data consistent with basic galaxy and AGN properties
in large halos (Mh  2.5 1011 Msun) established at the
virialization epoch; subsequent merging and baryon
dissipation have apparently little effect
Conclusions (2)
• The model successfully reproduces:
o the observational relationships between Mh,
Mbulge, and MBH
o the the galaxy velocity dispersion function and the
fundamental plane relationships (Cirasuolo et al.
2005)
o the local BH mass function (Shankar et al. 2005a)
o the galaxy and QSO epoch-dependent luminosity
functions in different bands
Conclusions (3)
• The model yields:
o an extended dust-obscured phase of BH growth
o a fast increase of the MBH/Mstar ratio in the pre-optical
QSO phase (cf. Borys et al. 2005)
o mildly differential evolution of the LF
o optical visibility time 1 e-folding time
o hard X-ray visibility time  3–4 e-folding times
o higher luminosity sources are less absorbed (cf. La
Franca et al. 2005)
o high metallicity and -enhancement associated to highz quasars; metallicity increases with luminosity (cf.
Roberto Maiolino’s talk)
Conclusions (4)
o faster high-z decline of QSO luminosity density,
compared with SFR
o MBH – Mstar and MBH –  relations established at
high z in the optically bright QSO phase and
unchanged during the subsequent passive
evolution (ERO) phase
o a prolonged “starving” phase of massive BHs (low
radiative/accretion efficiency, ADAF, C-DAF,
ADIOS ...)
• Additional ingredients required for less massive
halos, which evolve more slowly, are mostly
associated with disk galaxies, and are found in
lower density environments