Transcript A model for the joint formation and evolution of spheroidal galaxies and high redshift QSOs Gian Luigi Granato INAF and SISSA + L.

A model for the joint formation
and evolution of spheroidal
galaxies
and high redshift QSOs
Gian Luigi Granato
INAF and SISSA
+
L. Silva, A. Lapi, F. Shankar, L. Danese, G. De Zotti,
A. Bressan, J. Mao
Uncertainties in galaxy formation
models in cosmological context
• For many years uncertainties both in cosmology and
physical processes
• Now “precision cosmology era”, background model
rather well constrained (though mysterious in nature)
concordance CDM model:
(m,,b,h,ns,8)'(0.3,0.7,0.04,0.7,0.95,0.75¥0.9)
• Main physical processes driving luminous galaxy
formation are extremely complex and still hotly
debated
The problem with luminous matter
To compare scenarios of galaxy formation with
observations two very critical and uncertain steps:
1. Model the non linear evolution of baryonic matter:
most driving processes occur well below the resolution
of any simulation (sub-grid physics) and are also
poorly understood.
2. Model the interaction of photons produced by stars
and accretion processes with the dusty ISM.
Come to Laura Silva talk next Tuesday!
Di Matteo et al 05
Simulation of merging of spirals without treatment of
induced QSO activity…
..and WITH (crude and uncertain sub-grid) treatment
of induced QSO activity and ensuing feedback on ISM
Di Matteo et al 05
Fate of initial gas
Without AGN
With AGN
In stars
Cold SF gas
Hot halo gas
Expelled from halo
In SMBH
89%
1.2%
9.8%
0.05%
-
52%
0%
11.1%
38%
1.6%
The predicted star formation histories and final
morphologies are completely different. This result is
driven by processes not simulated from first principles.
Ab-initio models or toy models?
• First principles models do not exist: in any
computation sub-grid physics is dominant and
treated (if ever) through semi-analytic-like recipes
• Extensive comparisons between different scenarios
and data are done by means of fully semi-analytic
models (SAM) for baryons, possibly as postprocessing of gravity-only simulations for DM.
• “By definition” of SAM, many a-priori assumptions on
the general behaviour of the system.
• More proper naming could be toy models?.
Standard SAMs
Most SAMs assume a disk galaxy merger
driven sequence of processes leading to
present day galaxy populations
1. The outcome of gas cooling in DMH is
gaseous rotation supported disk, with
mild SF (Rees & Ostriker 1977, Silk 1977,
White & Rees 1978….);
2. Disk mergers are the only driver of
bursty SF and of the formation of
spheroids (White & Rees 1991, Cole 1991, …
omissis…Cole et al 2000).
Problems of standard SAMs
Calculations based on this general scheme show
severe mismatches with observations
– Difficult to reproduce the bright end of LLF.
Models predict too many (and too young-blue)
bright galaxies (e.g. Benson et al 2003)
– Beyond z'1-1.5 too few bright galaxies
– Cosmic downsizing
– Absence of cooling flows in real rich clusters
– Properties of local E galaxies
Likely all facets of the same problem. Some key
ingredient is missing or/and the scheme needs
revision
Promising solution: mutual link between
SF and AGN activity
Strong and increasing observational evidences and
theoretical suggestions of a link, e.g.:
– MBH-spheroid relations (Lsph, Msph, sph)
– Similarity of cosmic SFR(z) and LQSO(z)
– Simulated galaxy mergers drive gas to the centre
Despite this, only very recently began to be
incorporated into SAM.
Energy budget of AGN and SNae during spheroid
growth
Since Msph/MBH~1000, feed-back from a SMBH could
easily exceed the binding energy of the spheroid:
Accretion energy
0.1
200 2
Spheroid binding energy
 200
mostly released on a short timescale (a few e-folding)
To compare with
N1,0.01 esn,51
SNae energy
10
2
Spheroid binding energy
 200
released more “gently”
AGN feedback mechanism
However the mechanism for energy injection is
unclear
– Radiation pressure, mostly on dust (Voit et al
1993, Murray et al 2005)
– Radiative heating (e.g. Ostriker & Ciotti 2004)
– Kinetic outflow from AGN (likely generated by RP
on lines; e.g. Murray et al 1995)
– Complex interplay between SN and AGN FB
(Monaco 2004)
QSO mode vs Radio mode AGN
feedback in SAM
AGN feedback has been considered only very recently
in SAMs, and in two well distinct flavours, with different
aims:
– FB associated with the main phase of BH growth, related
to the bright high-z QSOs, to sterilize massive high-z
galaxies, little affected by SNae (Granato et al 2001,
2004, Monaco & Fontanot 2005; Menci et al 2006)
– FB associated with lower redshift, low accretion rate
phase of AGN, optically irrelevant , to halt cooling
flows and avoid overproduction of local bright
galaxies (Bower et al 2006, Croton et al 2006, see
also Cattaneo et al 2006)
ABC model (Granato et al 2001,2004; Silva
et al 2005; Lapi et al 2006)
Observations suggest an early and fast (»1 Gyr) assembly of
most baryons in Es with more massive objects forming faster.
To get downsizing within hierarchical assembly of DM we propose
a revision of SAMs (Anti-hierarchical Baryonic Collapse ABC):
1. Reduce role of gas disk formation at high z: cool collapsing
gas in big halos at high-z start vigorous SF without setting in a
quiescent disk.
2. Large SFR promotes the development of SMBH from a seed,
which after »0.5 Gyr powers an high-z QSO.
3. Keep into account the feed-back of this QSO on the host.
ABC evolutionary sequence
SMG – dusty ERO with growing SMBH
» 0.5 Gyr
High redshift QSO
» 0.05 Gyr
Red and dead massive high z galaxy
» many Gyr
Local Spheroid (E+bulges) with dormant SMBH
The model passes all tests against these
populations
Scheme of ABC (Granato et al 2004) at high z
Halos form, gas is 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…
..with SMBH growth promoted by SF
eventually powering high z QSO after » 0.5
Gyr, which cleans ISM and quenchs further
SF and then itself. QSO phase
(almost) passive evolution of stellar
population. Red and dead massive galaxies
at high z (ERO) with dormant SMBH
baryonic components and mass transfer processes
HOT GAS
RESERVOIR
(low J)
Viscous
accretion
SMBH-QSO
Radiative
cooling
COLD GAS
Radiation
drag
(SFR)
Collapse
STARS
Stellar
evolution
SNae feedback
&
QSO feedback
IGM
Arrows give a set of simple differential
equations for the masses in the various
components, solved numerically
SFR
Galaxy
Plugging this into statistic of dark matter halos as a
function of Mvir and zvir we get predictions for many
populations, connected by evolutionary
sequence
SMBH
Accretion rate
VERY Dusty and huge SF
) SMGs – dusty ERO
SMBH cleans the
ISM ) high z QSO
Little ISM, almost
passive evolution
) passive ERO
Local Ell
and
SMBH
SFR
Galaxy
Accretion rate
SMBH
Phase 1: VERY Dusty and huge SF and baby SMBH growth
lasting » 0.5-1 Gyr ) SMG with mild obscured AGN activity –
dusty ERO
ABC naturally reproduces SMGs (e.g. no ad-hoc IMF)
SCUBA 850 m
data
Silva et al 2005
model
MAMBO 1200 m
Silva et al 2005
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 PRE-QSO PHASE IN SMGs
The build up by accretion of the SMBH gives rise to a mild AGN
activity in sub-mm galaxies, detectable only in hard-X. This has
now been found (Alexander et al 03,04,05)
dM/dt(BH)>0.013 M¯/yr
) L(0.5-8)>1E43 erg/s
dM/dt(BH)>0.13 M¯/yr
) L(0.5-8)>1E44 erg/s
(Granato et al 2006)
By converse, the normal disk merging scenario for SMGs predicts
too high M and dM/dt for the SMBH in SMG, because of the »1
Gyr phase of disturbance and SMBG growth preceding the final
merge and huge SF.
Tdelay ' 0.3-1 Gyr, a key built-in feature
SFR
Galaxy
Accretion rate
SMBH
Phase 2: SMBH cleans the ISM ) high z QSO
('5£107-108 yrs)
General methodology of “QSO only models” (e.g. Whythe & Loeb
2003; Mahmood et al 2004):
LF ( L, z )
d 2 N DMH dM DMH dM SMBH
tQ
dtvir dM DMH dM SMBH dL
Ingredients and assumptions:
•Haloes formation rate (e.g. derivative of HMF (PS) )
•SMBH-DMH mass relationship (e.g. from self-regulation)
•SMBH mass-luminosity relation (e.g. Eddington)
•QSO appears immediately and shines for time tQ
But the required shine time tQ is too short (' galaxy dynamical
time-scale '107 ys at z=3 and a few 106 at z=6) to satisfy the
Soltan argument and the local SMBH mass function with plausible
accretion efficiency 10-15%.
In our view the problem is mainly due to neglecting the time
delay between virialization and detectable QSO activity
Lapi et al in 2006
Lapi et al 2006
HMF or formation rate has to be considered at z(tvir-tdelay) rather
than at z(tvir) ) less objects ) higher tQ
Our ABC model for QSO-spheroids co-evolution has this delay
and the intrinsic light curve built-in (but not the visibility time tQ).
The (high-z) QSO LFs are another fundamental test!
Optical QSO LF (tQ'4x107 yr)
z=1.5
Lapi et al 2006
z=3
data Croom et al 2004
z=4.5
data Pei et al 1995
z=6
data Fan et al 2004
X-ray QSO LF (tQ'108 yr)
 Ueda et al. (2003)
 La
Franca et
al. (2005)

Barger et al. (2005)
z=1.5
z=2
Lapi et al 2006
The ABC model well reproduces the evolution of high-z
optical and X-ray LF of QSO with the only addition of a
plausible visibility time ' (a few) 107 yr in optical and
'108 yr in X, as suggested by demography studies of
local SMBH (Shankar et al 2005, Marconi et al 2005).
The delay between halo formation and peak of SMBH
accretion is a crucial ingredient.
SFR
Galaxy
Accretion rate
SMBH
Phase 3: Little ISM ' passive evolution ) red and
(almost) dead massive high-z galaxies (many Gyrs)
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 galaxies, by a fraction
increasing with z
Massive galaxies at high redshift
Adapted from Drory et al 2005
Baugh et al 2005
(Durham SAM)
Granato et al 2004 ABC
SFR
Galaxy
Accretion rate
SMBH
Phase 4: Local Ellipticals and dormant SMBHs
Local K band Luminosity function of spheroids
Data:
Huang et al 2003
Kochanek et al 2001
Granato et al 2004
Sheroid-SMBH correlations
dispersion interpreted as
different virialization
epochs
 = 0.57 ± 0.05 Vvir
Tighter MBH-M*?
Mass function of local SMBHs
observations
model
K Band counts
Silva et al 2004, 2005
All Ellipticals
Late type
Passive Ellipticals
Onset of SF in early universe: (I) LFs of LBGs…
MODEL:
Dotted z=10
Dashed z=7.5
Solid z=5.5
Dot-dashed z=3.5
Adopting:
0.4
A1350
 M*   Z 
 0.35 


1 
 M yr   Z 
0.6
1e13
DATA:
Empty circles z=3
Empty squares z=4
Filled squares z=5
Filled circles z=6
(Mao et al submitted)
1e12
1e10
1e11
cfr shapley et al 2001
..and (II) LFs of Ly emitters
DATA:
Triangles upper and lower limits at z=6.4
circles z=5.7
MODEL:
Dotted z=8
Solid z=6.4
Dashed z=5.7
(Mao et al submitted)
Additional ingredient here is IGM transmission »0.5 at z>6.4 and 1 at z=5.7
Work in progress: Lick spectral indices and colours of
Ellipticals (Silva et al. in preparation).
Mg1
Red: data
Black: models
Sigma [km/s]
C-M relation
CONCLUSION
The mutual link between the formation of spheroids and the AGN
activity is a key ingredient that must be included into models of
galaxy formation.
Evolution
The prescriptions of the ABC scenario (Granato et al. 2001, 2004)
lead (in one shot) to predictions in general agreement with many
observations which are disturbing for traditional SAMs:
•statistic of sub-mm galaxies and their mild AGN activity
•cosmic evolution of QSO activity
•statistic of massive galaxies at high-z
•local mass function of SMBH
•local K band LF of spheroids
•abundances in ellipticals
Main papers: Granato et al. 2001, 2004; Silva et al 2005; Granato
et al 2006; Lapi et al 2006, Mao et al 2007, Silva et al in prep