FORMATION AND FORMATION AND EVOLUTION OF EARLY TYPE EVOLUTION OF EARLY TYPE

GALAXIES:GALAXIES:Hierarchical or Monolithic?Hierarchical or Monolithic?

CCesare Chiosi

Department of Physics & Astronomy “Galileo Galilei”

University of Padova, Italy

Castiglione della Pescaia 16 -20 September, 2013

11

…….and collaborators.and collaborators

Umberto BuonomoUmberto Buonomo

Giovanni CarraroGiovanni Carraro

Letizia Cassara’ Letizia Cassara’

Tommaso GrassiTommaso Grassi

Emiliano MerlinEmiliano Merlin

Cesario LiaCesario Lia

Stefano PasettoStefano Pasetto

Lorenzo PiovanLorenzo Piovan

Rosaria Tantalo Rosaria Tantalo

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Setting the scene: Setting the scene: Cosmic Proportions Cosmic Proportions

Dark Energy 70%Dark Energy 70% Dark Matter 25%Dark Matter 25% Baryonic Matter + Neutrinos 5% Baryonic Matter + Neutrinos 5%

In this context: Galaxy Fomation and Evolution are hot topics of modern Astrophysics

33

Classical Paradigm of Classical Paradigm of Galaxy Formation (ETGs, in Galaxy Formation (ETGs, in

particular)particular) Cosmological Model of the UniverseCosmological Model of the Universe

Dark Energy + Dark Matter + Baryonic Matter (& Neutrinos)Dark Energy + Dark Matter + Baryonic Matter (& Neutrinos)

Hierarchical Clustering of Dark Matter Hierarchical Clustering of Dark Matter

Hierarchical mergers of DM+BM haloes to form “visible” Hierarchical mergers of DM+BM haloes to form “visible” galaxies all over the Hubble timegalaxies all over the Hubble time

Massive galaxies are the end product of repeated mergers and Massive galaxies are the end product of repeated mergers and are in place only at recent times.are in place only at recent times.

But data do not exactly tell this and …..But data do not exactly tell this and …..44

How did massive ellipticals How did massive ellipticals form? (Mergers vs. Collapse)form? (Mergers vs. Collapse)

Which mechanism(s) can Which mechanism(s) can explain the complex SFHs explain the complex SFHs

of dwarf galaxies?of dwarf galaxies?

In brief, the main questions In brief, the main questions are: are: Ellipticals & Dwarfs Ellipticals & Dwarfs

55

White 1996, “early” hierarchical modelWhite 1996, “early” hierarchical model: these : these galaxies form late (z < 1) by the merging of galaxies form late (z < 1) by the merging of already assembled discs. already assembled discs. Evidence from stellar Evidence from stellar populations (Matteucci 1996), the tightness of the populations (Matteucci 1996), the tightness of the fundamental plane (Renzini & Ciotti, 1993), the fundamental plane (Renzini & Ciotti, 1993), the evolution of the color-magnitude relation (Kodama et evolution of the color-magnitude relation (Kodama et al., 1998; Blakeslee et al., 2003; Ellis et al. 2006) and al., 1998; Blakeslee et al., 2003; Ellis et al. 2006) and the local Mg2-the local Mg2- relation (Bernardi et al. 2003) relation (Bernardi et al. 2003) suggested that they formed early (z > 2) in a short burst suggested that they formed early (z > 2) in a short burst of star formation. Chiosi & Carraro (2002) and Merlin & of star formation. Chiosi & Carraro (2002) and Merlin & Chiosi (2006) showed how this is indeed achievable in Chiosi (2006) showed how this is indeed achievable in numerical simulations, provided that mass, density and numerical simulations, provided that mass, density and energy budgets of protogalactic halos are correctly energy budgets of protogalactic halos are correctly taken into account. taken into account.

Bell 2004, De Lucia et al. 2006, “dry mergers” Bell 2004, De Lucia et al. 2006, “dry mergers” hierarchical modelhierarchical model: massive ellipticals could be : massive ellipticals could be assembled late by assembled late by dry mergersdry mergers of other ellipticals, of other ellipticals, to preserve the oldness of their stellar populations to preserve the oldness of their stellar populations while producing a low assembly redshift.while producing a low assembly redshift. This This possibility is severely constrained by the modest (if any) possibility is severely constrained by the modest (if any) evolution of the high end of the stellar mass function evolution of the high end of the stellar mass function since z = 1.5 (Bundy et al. 2006; Cimatti et al. 2006): since z = 1.5 (Bundy et al. 2006; Cimatti et al. 2006): while models predict a doubling of stellar masses (De while models predict a doubling of stellar masses (De Lucia & Blaizot, 2007), evidence excludes an evolution Lucia & Blaizot, 2007), evidence excludes an evolution larger than 0.2 dex (Monaco et al. 2006). larger than 0.2 dex (Monaco et al. 2006).

Massive ETGs are elusive GalaxiesMassive ETGs are elusive Galaxies

Downsizing scenario: at variance with the hierarchical trend of DM halos, more massive galaxies tend to form their stars earlier and in a shorter period than smaller galaxies, which experience more prolonged star formation histories (at odd with ‘naive’ hierarchical models). See e.g. Bundy et al. 2006, Clemens 2006. Recent observations of massive and red spheroids at very high redshift (e.g. Cimatti 2007, 2008) support this scenario.

Perez-Gonzalez et al. 2007

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Dwarf galaxies are elusive as well...• The star formation histories of LG Dwarfs are all different from one another.

• Many dIrrs contain significant old populations (RGBs, and/or RR Lyr stars).

• The most recent star-formation episodes are relatively short, ranging from 10-500 Myr in duration in both dIrrs and dSphs. Seemingly, long intermediate-age episodes of star formation may actually be made by many short, unresolved, bursts. • Chemical considerations suggest that the oldest populations in these galaxies are younger than the oldest Galactic globular clusters. Anyway, very few single galaxies contain only stars older than 10 Gyr. Some galaxies may contain very few or no stars older than 10 Gyr.

Mateo (1998)

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So…current scenarios are So…current scenarios are

HierarchicalHierarchical:: massive ETGs are the end product of massive ETGs are the end product of subsequent mergers of smaller sub-units over time scales subsequent mergers of smaller sub-units over time scales almost equal to the Hubble time.almost equal to the Hubble time.

Dry MergersDry Mergers: fusion of gas-free galaxies to avoid star : fusion of gas-free galaxies to avoid star formation. formation. Wet MergersWet Mergers: the same but with some stellar : the same but with some stellar activity.activity.

MonolithicMonolithic: ETGs form at high redshift by rapid collapse and : ETGs form at high redshift by rapid collapse and undergo a single, prominent star formation episode, ever undergo a single, prominent star formation episode, ever since followed by quiescence.since followed by quiescence.

Revised MonolithicRevised Monolithic: a great deal of the stars in massive : a great deal of the stars in massive ETGs are formed very early-on at high redshifts and the ETGs are formed very early-on at high redshifts and the remaining ones at lower redshifts. remaining ones at lower redshifts.

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Hierarchical or Monolithic ?Hierarchical or Monolithic ?

For long time the preference has gone to the hierarchical For long time the preference has gone to the hierarchical scheme that was considered the reference frame for any scheme that was considered the reference frame for any theory of ETGs formation (the massive ones in particular). theory of ETGs formation (the massive ones in particular).

The success of this theory is mainly due to the The success of this theory is mainly due to the achievements obtained in modelling the large scale achievements obtained in modelling the large scale gravitational structures of the Universe (filamentary gravitational structures of the Universe (filamentary structure, galaxy groups and clusters). However its structure, galaxy groups and clusters). However its extension to individual galaxies has never been validated extension to individual galaxies has never been validated by solid independent arguments.by solid independent arguments.

Because of it, the potential capability of the monolithic-like mode has not been fully explored.

We intend to show here that this latter scheme

works equally well, if not better.99

Aims of this Review…..Aims of this Review…..

We concentrate on the models obtained with the Revised Monolithic scheme.

First we highlight the role of the initial density and total mass of the system in determining the kind of star formation that takes place in ETGs.

Second, we shortly report how they are able to reproduce current observational data for ETGs.

Finally, we quickly present galaxy models with DUST in the ISM and the effect of this on SEDs and colors.

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Which kind of Star Which kind of Star Formation?Formation?

… from Observational Hints … from Observational Hints (1)(1)

Scale Relations:Scale Relations: Faber-Jackson Faber-Jackson Effective Radius- Surface Brightness Effective Radius- Surface Brightness Fundamental Plane & kappa space Fundamental Plane & kappa space

Diameter (m=20.75 mag/sec^2) - velocity Diameter (m=20.75 mag/sec^2) - velocity

dispersion – surface brigthnessdispersion – surface brigthness

SFR - Mass - Luminosity - RedshiftSFR - Mass - Luminosity - Redshift

40L

83.0 ee IR

85.036.1 ee IR

07.04.10 en ID

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Which kind of Star Formation?Which kind of Star Formation?…from Observational Hints …from Observational Hints

(2)(2) HR diagrams for nearby dwarf galaxies of the LG.

Integrated spectra, magnitudes, colors, line absortpion indices for galaxies of the local Universe

The same but as a function of the redshift for distant galaxies.

The chemical properties (abundances, abundance ratios, gradients).

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Which kind of Star Which kind of Star Formation?Formation?

…from Observational Hints …from Observational Hints (3)(3)

Colour-Magnitude RelationColour-Magnitude Relation

a-enhancement: [a/Fe] vs [Fe/H] a-enhancement: [a/Fe] vs [Fe/H] SFR SFR

The UV excessThe UV excess

Line strength indicesLine strength indices

Two indices diagnosticsTwo indices diagnostics

…… …… the list is very long !1313

It follows that …..It follows that …..

Over the years, all the topics mentioned above have been extensively investigated to conclude that:

In some way the kind of SF occurring in ETGs depends on their mass and density (which one?).

It is early, short and intense in massive (and high density) ETGs and long, less efficient, and perhaps in bursts, in the low-mass (and low-density) ones.

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We would like to address and We would like to address and answer the following answer the following

questions…questions… Under which physical conditions either a single prominent

episode or several episodes of star formations do occur?

Which model best explains the whole pattern of observational data for ETGs? The hierarchical or the monolithic ? Or a complex combination of the two?

Standard semi-analytical galaxy models are not suited to the aim, because they already contain the answer built in.

The numerical NB-TSPH simulations are the right tool provided they include accurate treatments of important physical processes such as SF, heating by energy deposit, cooling by radiative processes, and chemical enrichment, … suitable initial conditions..

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Simulating the formation of cosmic Simulating the formation of cosmic structuresstructures: Ingredients and recipes

Matter

• Dark Matter

• Gas

• Stars

Interactions

• Gravity

• Hydrodynamics

• “Specials”

Cosmological

View Temporal evolution

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• Matter

• Dark Matter

• Gas

• Stars• Interactions

• Gravity

• Hydrodynamics

• “Specials”

• Cosmological framework

• Temporal evolution

“Particles” (“bodies”) with different properties, moving in the phase space

Newton’s law 3j

i ijj ij

ma G r

r

Particle-particle (N²)

Simulating the formation of cosmic Simulating the formation of cosmic structures:structures: requirements of a NB-TSPH code (Dark Matter)

Tree structure (N logN)

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• Matter

• Dark Matter

• Gas

• Stars

• Interactions

• Gravity

• Hydrodynamics

• “Specials”

• Cosmological framework

• Temporal evolution

“Particles” (“bodies”) with different properties, moving in the phase space

Conservation laws

(Only for gas particles)

Smoothed Particle Hydrodynamics

Simulating the formation of cosmic Simulating the formation of cosmic structures:structures:Requirements of a NB-TSPH code (Gas)

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• Matter

• Dark Matter

• Gas

• Stars

• Interactions

• Gravity

• Hydrodynamics

• “Specials”

•Cosmological framework

• Temporal evolution

“Particles” (“bodies”) with different properties, freely moving in the phase space• Energy sinks and sources:

• Cooling (radiative cooling, inverse Compton effect)• Heating (Stellar feedback, UV cosmic background, “exotic” sources)

• Chemical composition and enrichment• Star formation• ...• Cosmological expansion of the

Universe• Appropriate boundary conditions

Simulating the formation of cosmic Simulating the formation of cosmic structures:structures:Requirements of a NB-TSPH code (Stars)

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Extremely large ranges in physical values- mass: 106 ---> 1014 Mo (8 orders of magnitudes)- temperature: 10 ---> 108 K (7 orders of magnitudes)- distances: 1 ---> 107 pc (7 orders of magnitudes)- times: 1 ---> 1010 years (10 orders of magnitudes)- density: 10-33 ---> 10-18 g/cm3 (25 orders of magnitudes)

Very large numbers of particles are (would be…) neededBaryonic mass of a typical galaxy: 1011 MoMass of a typical small structure: 106 MoParticles to resolve small structures: from 102---> 107 particles (without considering outskirts...) – feasible ? ---> often lower resolution

Extremely violent phenomenaSupernova explosionsSupersonic turbulence and shocksAGN feedbacks

Simulating the formation of cosmic Simulating the formation of cosmic structuresstructures

2020

Realistic Models of Galaxies Realistic Models of Galaxies require accurate Input Physics require accurate Input Physics

& & precise Numerical precise Numerical

AlgorithmsAlgorithms 1. Parallel code: Evol

2. Initial conditions: start at very early epochs

3. Cooling and Heating 4. Feed back by SN & SW, Chemical enrichment 5. Interstellar Medium (presence of dust) 6. Star Formation (prescriptions)

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7. Gravitational pot 8. Formation Histories (mass and densities)

9. Mass assembling and 3D structure

10. Stars after assembling

11. Surface and volume mass densities

12. Ages and metals of stars

13. Galactic winds

14. Dust in ISM and photometry

15. Scale Relationships2222

1. The Parallel NB-TSPH Code: 1. The Parallel NB-TSPH Code: EvoLEvoL

No details are given No details are given here………..here………..

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CDM CosmologyCDM Cosmology

HH00=70.1 km/s/Mpc =70.1 km/s/Mpc Flat GeometryFlat Geometry ΩΩ=0.721 =0.721 σσ88=0.817 =0.817 Baryonic Fraction Baryonic Fraction ≃ ≃ 00..16561656

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2525

2. Initial Conditions2. Initial Conditions from from Cosmological SimulationsCosmological Simulations

COSMIC returns the initial comoving positions and initial peculiar velocities of all particles at the time the highest density perturbation in the field exits the linear regime. Therefore, the kind of DM proto-haloes that are in place at each redshift are known.

Start from a simulation for a given simulation for a given model of the Universe (model of the Universe (SCDM SCDM oror CDM CDM ))

Fully cosmological initial conditions in CDM concordance cosmology Ho = 70.1 km/s/Mpc, =0.721, b=0.046, baryon ratio 0.1656, 8=0.817, n=0.96.

Large scale simulations calculated with COSMIC (Bertschinger 1995)

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Lukic et al. (2007) PlaneLukic et al. (2007) Plane Number density of haloes per Number density of haloes per

MpcMpc33 as a function of the as a function of the mass and redshift.mass and redshift.

The underlying IMF is from The underlying IMF is from Warren (2003), see also Warren (2003), see also Press & Schechter and others.Press & Schechter and others.

Scale factor is neededScale factor is needed to the to the volume coverd by typical volume coverd by typical surveys.surveys.

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We estimate that 5 × 106 is a reasonable choice. Take the numer of ETGs in SDSS (about 60,000) and compare it with the total number of galaxies (over one million). Since the total volume covered by SDSS is about 108 Mpc3, the above estimate for the number ETGs corresponds to about 5% of the total volume. Therefore the scale is C ≃ 0.05 × 108.

Therefore haloes as massive as 1011 to 1012 Mo (and somewhat larger) have some probability of being already in place at redshifts larger than 5 (before the GDFs startdecreasing by mergers).

Initial Conditions

Instead of searching inside a large scale simulation, the perturbation Instead of searching inside a large scale simulation, the perturbation (proto-halo) best suited to our proposes, we simply suppose that a (proto-halo) best suited to our proposes, we simply suppose that a perturbation of this type is there and derive with COSMIC the position perturbation of this type is there and derive with COSMIC the position and velocities of the DM+BM particles from a smaller area of the and velocities of the DM+BM particles from a smaller area of the large scale field around the perturbation we are interested in.large scale field around the perturbation we are interested in.

The box has a size of l=9.2 comoving Mpc, and is described by grid The box has a size of l=9.2 comoving Mpc, and is described by grid of 46of 4633 particles; impose a constrained density peak to induce a particles; impose a constrained density peak to induce a virialized structure at the center of box; impose a gaussian spherical virialized structure at the center of box; impose a gaussian spherical overdensity with average linear density contrastoverdensity with average linear density contrast = = (with(with =3, =3, 5, 10) 5, 10) smoothed over a region of 3.5 comoving Mpc; COSMICS smoothed over a region of 3.5 comoving Mpc; COSMICS returns the initial comoving positions and peculiar velocities at the returns the initial comoving positions and peculiar velocities at the moment in which the particle with the highest density is exiting the moment in which the particle with the highest density is exiting the linear regime.linear regime.

2727

Cut off a sphere of radius l/2 change the comoving coordinates to Cut off a sphere of radius l/2 change the comoving coordinates to physical values (by dividing the comoving value by the expansion physical values (by dividing the comoving value by the expansion parameter a=1/z-1 with z the initial redshift) and add a radial parameter a=1/z-1 with z the initial redshift) and add a radial outward velocity to each particle, proportional to the radial position outward velocity to each particle, proportional to the radial position and initial redshift thus mimicking the outward Hubble flowand initial redshift thus mimicking the outward Hubble flow

Where Where H(zH(z) is need cosmological model) is need cosmological model

Add a minimum value of solid-boy rotation with spin parameterAdd a minimum value of solid-boy rotation with spin parameter =0.02=0.02

Gas particles have mass mGas particles have mass mgasgas=01.656 m=01.656 moo, DM particles have mass , DM particles have mass MMDMDM = (1-0.1656) m = (1-0.1656) moo

Total number of MD and gas particles 2 x 58000.Total number of MD and gas particles 2 x 58000.

Initial conditionsInitial conditions

2/5

2/1||

GM

EJ

( )flow prv H z d pr start comovingd a r 3

0( ) (1 )mH z H z

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Set of Model Galaxies Set of Model Galaxies Initial parameters of model galaxies (Merlin et al. 2012)

These initial conditions are similar to those adopted by Merlin & Chiosi (2006, 2007) 2929

6. Stirring in the Gravitational 6. Stirring in the Gravitational Pot Pot

Duty cicle: …stars – energy generation - gas heating –

gas enriching – gas cooling – stars….

The pot: the gravitational potential well

Therefore: total galaxy mass & initial density are the key parameters

For all details see Chiosi & Carraro (2002), Merlin et al (2010, 2011, 2012)

It follows that…..

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7. Star Formation Histories: 7. Star Formation Histories: Same initial over-density but different Same initial over-density but different

massesmasses

Chiosi & Carraro (2002Chiosi & Carraro (2002MNRAS, 335, 335) MNRAS, 335, 335) predicted that SFR predicted that SFR changes from monolithic to bursting mode at decreasing masschanges from monolithic to bursting mode at decreasing massand anticipated downsizing and time delay.and anticipated downsizing and time delay. 5151

Key Result for the SFR:Key Result for the SFR:Same mass but different Same mass but different

initial over-densityinitial over-density

Chiosi & Carraro (2002,Chiosi & Carraro (2002,MNRAS, 335, 335) MNRAS, 335, 335) predicted that SFR predicted that SFR changes from monolithic to bursting mode at decreasing changes from monolithic to bursting mode at decreasing overdensity (environment) and fixed mass. overdensity (environment) and fixed mass.

This basic dependence of the SFR on the total galaxy mass and initial over-density (environment) has been amply confirmed over the years by many observational and theoretical studies.

It is worth noting here that this is possible It is worth noting here that this is possible only in the monolithic-like scenarios. only in the monolithic-like scenarios.

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The same from indicesThe same from indices

Later re-proposed by Thomas et al (2005) analysing the linestrength indices for a sampleof nearby galaxies.

Picture from Thomas et al. (2005) & Renzini (2006, ARAA)

5353

Predicting future Predicting future observational observational

confirmation: Goodsconfirmation: Goods

From Chiosi & Carraro (2002) see also Giavalisco et al (2006) 5454

SFH: old results fully SFH: old results fully confirmedconfirmed

High Mass HMHigh Mass HM

Medium Mass MMMedium Mass MM

Low Mass LMLow Mass LM

DensityDensity

High Medium Low Very LowHigh Medium Low Very Low

Merlin et al 2012

5858

8. Assembling the Stellar 8. Assembling the Stellar MassMass

Top Panel: percentage of assembled Top Panel: percentage of assembled mass at given redshift with respect to mass at given redshift with respect to the star mass at z=1.the star mass at z=1.

Color code: red z=10, blue z=5, Color code: red z=10, blue z=5, green z=2, black z=1.5 green z=2, black z=1.5

Bottom Panel: redshift at which a Bottom Panel: redshift at which a given percentage given percentage pp of the total stellar of the total stellar mass at z=1 is assembledmass at z=1 is assembled

Color code: red Color code: red pp=50%, black =50%, black pp=99%=99%

I, J: I for density, J for massI, J: I for density, J for mass

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9. Stellar Content after 9. Stellar Content after Assembly Assembly

Mass (MMass (MOO))

HMHM1.7x101.7x101313

MMMM2.7x102.7x101111

LMLM4.2x104.2x1099

Density HD MD LD VLDDensity HD MD LD VLD

RedshiftRedshift

HDHM 0.27HDHM 0.27MDHM 0.56MDHM 0.56LDHM 0.49LDHM 0.49VLDHM 1.0VLDHM 1.0

HDMM 1.0HDMM 1.0MDMM 0.88MDMM 0.88LDMM 0.6LDMM 0.6VLDMM 0.15VLDMM 0.15

HDLM 0.73HDLM 0.73MDLM 0.79MDLM 0.79LDLM 0.25LDLM 0.25VLDLM 0.51VLDLM 0.51

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10. Surface Mass Density 10. Surface Mass Density ProfilesProfiles

MassMass

HMHM

MMMM

LMLM

Density HD MD LD VLDDensity HD MD LD VLD

Log Log [g/cm [g/cm22]]

Log r Log r [kpc][kpc]

Z = 1Z = 1

Black Diamonds: Reff

1/(0.324 2 )[( ) 1]R

0( )m

eff

rm

S r e

6161

Where m=4 for HM-, m=1.5 for IM-, and m=2.5 for LM- galaxies in partial agreement with the empirical luminosity – index relationship by Caon et al (1993). In any case mHM > mIM + LM .

Mass Density ProfilesMass Density Profiles

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MassMass

HMHM

MMMM

LMLM

Density HD MD LD VLDDensity HD MD LD VLD

Log Log [g/cm [g/cm33]]

Log r Log r [kpc][kpc]

Z = 1Z = 1

6262

11. Ages of Stellar 11. Ages of Stellar PopulationsPopulations

MassMass

HMHM

MMMM

LMLM

Density HD MD LD Density HD MD LD VLDVLD

RedshiftRedshift

HDHM 0.27HDHM 0.27MDHM 0.56MDHM 0.56LDHM 0.49LDHM 0.49VLDHM 1.0VLDHM 1.0

HDMM 1.0HDMM 1.0MDMM 0.88MDMM 0.88LDMM 0.6LDMM 0.6VLDMM 0.15VLDMM 0.15

HDLM 0.73HDLM 0.73MDLM 0.79MDLM 0.79LDLM 0.25LDLM 0.25VLDLM 0.51VLDLM 0.51

Virial radius is equal to rmax in the abscsissa 6363

Metallicities of Stellar Metallicities of Stellar PopulationsPopulations

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MassMass

HMHM

MMMM

LMLM

Density HD MD LD VLDDensity HD MD LD VLD

RedshiftRedshift

HDHM 0.27HDHM 0.27MDHM 0.56MDHM 0.56LDHM 0.49LDHM 0.49VLDHM 1.0VLDHM 1.0

HDMM 1.0HDMM 1.0MDMM 0.88MDMM 0.88LDMM 0.6LDMM 0.6VLDMM 0.15VLDMM 0.15

HDLM 0.73HDLM 0.73MDLM 0.79MDLM 0.79LDLM 0.25LDLM 0.25VLDLM 0.51VLDLM 0.51

Virial radius is equal to rmax in the abscsissa 6464

Predicted vs observed mass-Predicted vs observed mass-metallicity relationshipmetallicity relationship

It flattens out !!!

SLOAN DATA

Tremonti et al (2004 ApJ 613, 898)

Chiosi & Carraro (2002)

From old NB-TSPH models

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10

5

50%

99%

Mean Metallicity vs Mean Metallicity vs MassMass

Merlin et al (2012)

SFR is implicit !

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Adding the SFR:Adding the SFR:Metallicity – Mass – SFR Metallicity – Mass – SFR

Mannucci, Cresci et al (2010), Cresci et al (2011)Mannucci, Cresci et al (2010), Cresci et al (2011)6767

Metallicity-SFR-outflow-infall Metallicity-SFR-outflow-infall RelationshipRelationship

Various physical causes at work.Various physical causes at work.

From the chemical point of view, From the chemical point of view, NB-TSPH models grossly obey the NB-TSPH models grossly obey the scheme :infall (early) + outflow scheme :infall (early) + outflow (late).(late).

With infall the metallicity tends to With infall the metallicity tends to the yield, with outflow the the yield, with outflow the metallicity tends to freeze out. metallicity tends to freeze out.

Mass-SFR relation: in massive Mass-SFR relation: in massive galaxies the SFR is early and galaxies the SFR is early and intense. This cuses early outflows intense. This cuses early outflows and freezing out of metallicity.and freezing out of metallicity.

All this in agreement with the All this in agreement with the alpha-enhancement problem. alpha-enhancement problem. 6868

Gradients in MetallicityGradients in Metallicity

Confirmed by the observational study of Forbes et al (2005)

Chiosi & Carraro (2002)

Confirmed by Merlin et al (2012, MNRAS, 427, 1530)

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Gradients in MetallicityGradients in Metallicity

Left to right, top to bottom: HDHM, LDHM, HDLM, LDLM at their last computed age

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Gradients in Mean Gradients in Mean Metallicity Metallicity

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Merlin et al (2012)

12. Galactic 12. Galactic WindsWinds

Galactic winds occur but not according to the Larson (1974) model, thus ruling out a point of severe contradiction 7272

More on Galactic WindsMore on Galactic Winds

Model LDLM

Z= 4.4

Z= 1.0

Z= 0.2

Model HDHM

Z= 2.2

Z= 1.0

Z= 0.05

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outward

outside

escapedHDHM LDHM

LDLMHDLM

IDIM

z=10

z=7

HD LD

Galactic WindsGalactic Winds

Phase Diagrams at z=2

Galactic winds are rich in metalsGalactic winds are rich in metals

HM

LM

Fractions of gas leaving the system

Dotted: gas outside Rext; Dashed: gas directed outwards (faster than Hubble Flow)Solid: gas radial velocity larger than vesc

HDHM LDHM

HDLM LDLM

7474

-enhancement-enhancement

Tantalo & Chiosi (2002, AA 388, 396)

Not in conflict with the galactic wind !

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MgMg22 – – Relationship Relationship

Confirmed by Mehelrt et al (2003) …… 7676

Colour-Magnitude Colour-Magnitude RelationshipRelationship

Galaxies get redder at increasing luminosity

SF activity tends to occur earlier and to be confined in time at increasing mass

The tightness of the CMR implies for a given Hubble time (and coordination mechanism) that EGs are old, around 13 Gyr (Bower et 1994) and nearly coeval.

But CMR for field EGs more dispersed, perhaps longer periods of star formation changing from galaxy to galaxy (Schweizer & Seitzer 1992). Mergers are compatible with this.

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General ConclusionsGeneral Conclusions All the models belong to the revised

monolithic scheme, because mergers of sub-structures occurr early on.

Star formation is driven by the total mass and mean initial density. It gradually changes with the density and mass as

schematically shown here.

Downsizing is a result !

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General ConclusionsGeneral Conclusions Galaxy formation is complete at redshifts larger than 2.Galaxy formation is complete at redshifts larger than 2.

Structural properties, of present day models agree with current Structural properties, of present day models agree with current data.data.

Some problems with the absolute value of the mean metallicity Some problems with the absolute value of the mean metallicity and the metallicity gradients (easy to solve).and the metallicity gradients (easy to solve).

Conspicuous galactic winds occur, which is important for ICM enrichment.

The mass in stars per unit mass of a galaxy is nearly constant thus implying a universal star forming mechanism.

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General ConclusionsGeneral Conclusions

Important scale relations are reproduced by the Important scale relations are reproduced by the models.models.

Photometric properties of galaxies are matched.Photometric properties of galaxies are matched.

The MThe M** - R - Ree relation is the result of a more subtle relation is the result of a more subtle game than the simple merging-wind mechanism.game than the simple merging-wind mechanism.

The revised monolithic promises to be the right trail to follow in the forest of galaxy formation and evolution, whereas the classical hierarchical scheme does not seem to be so promising in reproducing the large variety of observational properties of ETGs at the same time.

122122Οπερ έδει δείξαιΟπερ έδει δείξαι

To take away….To take away….

““Non eventus imputari debet cuiusque Non eventus imputari debet cuiusque rei, sed consilium”rei, sed consilium” Lucius Annaeus Seneca, Retor, Contr., 5, Lucius Annaeus Seneca, Retor, Contr., 5, 342342

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HORA ESTHORA EST Thank you for your Thank you for your attentionattention

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