The joint formation of spheroids and Super Massive Black Holes

Gian Luigi Granato(INAF-Padova & SISSA)

with:Michele Cirasuolo

Luigi DaneseGianfranco De Zotti

Andrea LapiFrancesco 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 co-evolution 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).

HOT GASCOLD GAS

RESERVOIR(low J)

STARS IGM

SMBH-QSO

SNae feedback&QSO feedback

Radiative cooling

Radiation drag(SFR)

Viscous accretion

Collapse

baryonic components and mass transfer processes

Stellarevolution

Arrows give a set of simple differential equations for the masses in the various components, solved numerically

Galaxy

SMBHAccretion rate

SFR

VERY Dusty and huge SF ) Sub-mm – dusty ERO

SMBH cleans the ISM ) high z QSO

Little ISM, almost passive evolution ) passive ERO

Local Elland SMBH

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

Galaxy

SMBH

SFR

Accretion rate

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)

5.7 mJy z dist MEDIAN QUARTILEChapman et al 2005 (73 sources)

2.2 1.7-2.8

Model 2.2 1.6-3.3

SCUBA 850 m

MAMBO 1200 m

model

data

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.

Phase 2: SMBH cleans the ISM ) high z QSO (»5£107-108 yrs)

Galaxy

SMBHAccretion rate

SFR

Tdelay ' 0.3-1 Gyr, a key built-in point

Optical QSO LF (tQ'4x107 yr)

z=1.5data Croom et al 2004

z=3 data Pei et al 1995

z=4.5 z=6data Fan et al 2004

Lapi et al submitted

X-ray QSO LF (tQ'108 yr)

z=1.5 z=2

Barger et al. (2005)

Ueda et al. (2003) La Franca et al. (2005)

Lapi et al submitted

Galaxy

SMBHAccretion rate

SFR

Phase 3: Little ISM ' passive evolution ) red and (almost) dead massive high-z galaxies (many Gyrs)

Z ' 0.5

Z ' 0.9

Z ' 1.3

Z ' 1.8

Fontana et al 2004: galaxy stellar mass function in K20 sample

Standard SAMsGranato et al 2004

Standard SAMs underproduce massive galaxy, by a fraction increasing with z

Silva et al 2005

Star formingPassive

Adapted from Drory et al 2005

Massive galaxies at high redshift

Baugh et al 2005 (Durham SAM)

Granato et al 2004 ABC

Galaxy

SMBHAccretion rate

SFR

Phase 4: Local Ellipticals and dormant SMBHs

Local K band Luminosity function of spheroids

Data:Huang et al 2003Kochanek et al 2001

Granato et al 2004

The central BH

= 0.57 ± 0.05 V= 0.57 ± 0.05 Vvirvir

dispersion interpreted as different virialization epochs

Tighter MBH-M*?

Mass function of local SMBH

observationsmodel

Work in progress: comparison of Lick spectral indices computed from models with available data (Silva et al. in preparation).

Sigma [km/s]

Mg1

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.

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

Evolution