Transcript Diapositiva 1

The joint formation of spheroids
and Super Massive Black Holes
Gian Luigi Granato
(INAF-Padova & SISSA)
with:
Michele Cirasuolo
Luigi Danese
Gianfranco De Zotti
Andrea Lapi
Francesco Shankar
Laura Silva
To compare scenarios of galaxy formation with
observations two very critical and uncertain steps:
1. Model the non linear evolution of ordinary matter:
most driving processes occur well below the
resolution of any simulation (sub-grid physics) and
are poorly understood ) a lot of uncertainty;
2. Model the interaction of photons produced by stars
and accretion processes with the dusty ISM.
Since long (Silva et al 1998, Granato et al 2001, 2004)
we have devoted efforts to these aspects
• Ab-initio or first principles models do not
really exist
• Most extensive comparison between
possible scenarios and data are done by
means of the semi-analytic models (SAM),
which by definition have many a-priori
assumptions, and you get what you put in
Almost all SAMs assume a galaxy merger driven
sequence of processes leading to present day galaxy
populations (Rees & Ostriker 1977, Silk 1977, White & Rees 1978…)
1.The first result of gas cooling is gaseous, disk
formation, supported by rotation and with mild SF;
2. Disk mergers are the only driver of bursty SF and of
the formation of spheroids.
1-2 are not necessarily true and for sure do not break
“naturally” the hierarchy: baryons tend to follow the
bottom-up hierarchy of CDM (i.e. gravity leads);
Problems of standard simulations: room for quasar?
Calculations based on this general scheme shows
mismatches indicating holes in our understanding of
galaxy formation.
In particular the evidence is growing that the coevolution of SMBHs and galaxies could play a role in at
least some of the following problems:
•Overcooling
•Cooling flow conundrum
•Scaling relations of clusters (L-T)
•Sub-mm and near IR selected high z-populations, and
properties of Ellipticals
Observations suggest an assembly of baryons in Es
mimicking to some extent the monolithic scenario with
more massive objects forming faster.
To get this within hierarchical assembly of DMH we
proposed a revision of SAM (Granato et al. 2001, 2004;
Anti-hierarchical Baryonic Collapse ABC):
1. Reduced 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, and promoting the
development of SMBH.
2. Keep into account the mutual feed-back between
formation of high-z QSO and their host galaxies largely
ignored by simulation (before us).
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
) Sub-mm – 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
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 PRE-QSO PHASE IN SMGs
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 only in hard-X
Indeed »50% of 5 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)>0.013 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 point
SFR
Galaxy
Accretion rate
SMBH
Phase 2: SMBH cleans the ISM ) high z QSO
(»5£107-108 yrs)
Optical QSO LF (tQ'4x107 yr)
z=1.5
Lapi et al submitted
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 submitted
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 galaxy, by a fraction
increasing with z
Silva et al 2005
Star forming
Passive
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
The central BH
dispersion interpreted as
different virialization
epochs
 = 0.57 ± 0.05 Vvir
Tighter MBH-M*?
Mass function of local SMBH
observations
model
Work in progress: comparison of Lick spectral indices
computed from models with available data (Silva et al.
in preparation).
Mg1
Sigma [km/s]
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 to look: Granato et al. 2001, 2004; Silva et al 2005;
Granato et al 2006; Lapi et al submitted, Silva et al in prep