EVOLUCION QUIMICA DEL UNIVERSO - Argentina.gob.ar · The study of the Formation and Evolution of Galaxies requires to be able to follow the evolution of the structure in large scale,

Patricia B. Tissera

EVOLUCION QUIMICA DEL UNIVERSO

Patricia B. TisseraInstituto de Astronomía y Física del Espacio

Patricia B. TisseraPatricia B. Tissera

In the last years, studies of chemical elements obtained in the Local Universeand at high redshifts have improved dramatically.

Chemical patterns are the result of different mechanisms which contribute togalaxy formation

growth of the structure:collapse, mergers, infall, etc

gas cooling and condensation

star formation and stellar evolution

supernova feedback:chemical + energy release

environmental effects: starvationstrangulation, etc


Supernova feedback is one of the process that contribute to structure the Insterstellar Medium (ISM).

CHEMICAL ENRICHMENT HYDRODYNAMICAL HEATING

•SN: Main source of heavy elements

•Change the cooling time

•evaporates cold-dense gas •galactic winds which can results

in outflows or galactic fountains

•Regulates the star formation activity and enriches the ISM and IGM•Affects the gas dynamics


WHY DO WE CARE ABOUT METALLICITY ?

Chemical abundances and dynamical properties provide more stringentconstrains for galaxy formation models.

Eggen, Lynden-Bell & Sandage (1962): “galactic archaeology “ proposingthe so-called monolithic collapse model from studies of halo stars.

The MCM was first challenged by Searle (1977) : Galactic globular clustersshow a wide range of metals abundances essentially independent of radius from the Galactic Center.

The importance of fossil signatures in the chemical/dynamical patterns whichcan be related to the history of formation.

Patricia B. Tissera

THE MILKY WAY

BULGEDM HALO

THIN DISCTHICK DISC

STELLAR HALO

Patricia B. Tissera

Patricia B. Tissera

Freeman & Bland-Hawthorn 2002

Patricia B. Tissera


The Local Group


GalaxiesLuminosity-metallicity and mass-metallicity relations:

There are well-known LMR and MMR in the local Universe.Observations suggest evolution in the zero point and slope of both relations.

SDSS: Tremonti et al .2004

Erb et al 2006: z~2.5


Damped Lymanα Systems


Damped Lymanα Systems


The study of the Formation and Evolution of Galaxies requires to be able tofollow the evolution of the structure in large scale, which is mainly determined

by gravitation,gravitation, and to describe the action of other processes such asgas cooling, star formation, stellar evolutiongas cooling, star formation, stellar evolution, etc.

Smooth Particle Hydrodynamics simulations are one of the mostpopular techniques to study galaxy formation.

However, the complex interaction of the non-linear gravitationalevolution and dissipative gas dynamics plus the action ofseveral physical process which introduce their own lengthand time-scales make the modelling of galaxy formation a severechallenge.


Simple one-zone model was discussed by Van den Bergh (1962) , Schmidt (1963)Four hypothesis:

The system is isolated: no inflows or outflows.The systems is well mixed at all timesThe systems starts from primordial abundances: Z(0)=0IMF and nucleosynthesis yields are unchanged

Instantaneous recycling

CHEMICAL FEEDBACK

There are numerous chemodynamical models for galaxy formation which have sofisticated the Simple Model (e.g. Larson 1976; Tinsley & Laron 1979; Burkert & Hensler 1988; Ferrini et al. 1992; Chiappini, Matteucci & Gratton1997):

sophisticated stellar evolutionpoor initial conditions for galaxy formation

Patricia B. Tissera

Patricia B Tissera

CHEMICAL FEEDBACK

Including chemical enrichment by individual elements provides a powerful tool to study galaxy formation in cosmological scenarios:

First attempts to introduce chemical feedback in SPH simulationsof MilkyWay type galaxies:

There are implementations that follow the metallicity (Springel & Hernquist2003 and references therein)

Steinmetz & Muller (1994) SNII; global metallicityRaiteri et al. (1996; also Berczik 1999) SNII & SNIa; Fe & HCarraro et al. (1998)

Mosconi, Tissera, Lambas & Cora. (2001): SNII & SNIa, 13 ele.Lia, Portinari & Carraro (2002):detailed SE; difusionKawata & Gibson (2003):SNII, SNIa,IS; Eth +EkinKobashashi (2004):detail SE; Eth +EkinScannapieco, Tissera, White, Springel (2005): SNII & SNIa, 13 +

Multiphase+SNE

Patricia B. Tissera

Gravity

Patricia B. Tissera

Patricia B. Tissera

Smooth Particle Hydrodynamics


FEEDBACK

Numerical space Physical space NeedStar particles � Stellar populations

↔

IMF:SNe

long-lived stars

M* > 10 Mo; typical life-times: ~ 106 yrType II Sne

Main source of iron (Fe)Typical life-times: ~ GyrType Ia Sne

Produce most O, Si, Ca, etc

YIELDS

Patricia B. Tissera

When SN explosions take place, they distribute metals according to the SPH technique. For a given chemical element x at a particle i,

Exploding star particle

Gaseous neighbours

CHEMICAL FEEDBACK

Mxi = ∑j mj/ρj Mxi W(rij,hij)

Mxj =mj/ρj Mxi W(rij,hij)

Each neigbhour will receive

i j

Patricia B. Tissera

Sutherland & Dopita (1993).

At T= 10000 and ρ= ρ*:τcool for primordial gas is 50 largerthan that of [Fe/H]=0.5 gas.

CHEMICAL FEEDBACK

τcool ∝ T /ρ Λ(T)

Patricia B. Tissera

ENERGY FEEDBACK: Problems that we want to solve

Formation of spiral galaxies: angular momentum content,dynamical and chemical properties.

Galactic outflows: transportation of enriched material intothe intergalactic and the intercluster media.

Formation of dwarf galaxies.

Regulation of the star formation process.


OUR MODEL:

We develop a new model to eject the SN energy and a modification to the SPH formalism so that different phases in the gas component can coexist.

Patricia B. Tissera

SN energy (1051 ergs each SN) released by a star particle is distributedwithin its gaseous neighbours.

The Cold/DiffuseCold/Diffuse neighbours of a star particle:T < 8 × 104 K and ρ > 0.1 ρ*

εrad radiated away

εcold cold and densecold and dense neighboursεhot =1- εhot - εcold diffusediffuse neighbours

Patricia B. Tissera

ENERGY FEEDBACK


Cold gas particles accumulates it ina ReservoirReservoir until it is highenough to ensure that the gasparticle will join “its own hot phaseits own hot phase”according to the decoupling scheme.

Diffuse gas particles thermalize the energy “instantaneously”.

ENERGY FEEDBACK

Patricia B. Tissera

Milky Way Type galaxy: Multiphase ISM

Patricia B. Tissera

Milky Way Type galaxy: Multiphase ISM

25kpc/h




10^12Mo/h

10^9Mo/h

NO FEEDBACK FEEDBACK

Star formation is regulated without introducing anymass scale parameter.



100 kpc/h

Patricia B. Tissera

Chemical properties of baryons together with dynamical andkinematical information can provide clues for unveiling the historyof formation of the structure.

Patricia B. Tissera

Supernova feedback is a key process in the formation of the structure.

Modelling SN feedback is tricky but it is possible if a multiphaseISM is also modelled.

Numerical simulations provide a tool to interpret observational data within a cosmological model.

Patricia B. TisseraPatricia B. Tissera11th Latin-American Regional IAU Meeting

December 12 – 16 2005

Patricia B. Tissera

MILKY WAY:THIN DISC

Rotationally supported: σ/V <<1.Scale-length ~ 2-2.5 kpc (Siegel et al. 2001), hz ~ 280 pcStellar age distribution ~ [2,14]Gyr and [Fe/H] peaks at ~ -0.2

(Nordstrom et al. 2004)

IAG-Lenac Advanced School

Patricia B. Tissera

scale-lenght ~ 3 kpc , hz ~ 1 kpc (assuming a double exponential) .t_medio ~ 12.5 +- 1.4 Gyr (Liu &Chaboyer 2000)-2.2 < [Fe/H] <0.5 with <[Fe/H]> ~ -0.6 (Chiba & Beers 2000) higher [O/Fe] than the stars in the thin disc.

MILKY WAY:THICK DISC


thick

thin

Patricia B. Tissera

MILKY WAY: BULGE

hz ~ 2 kpc; averged age ~ 10 Gyr for stars with hz > 400 pcmetallicity peak: [Fe/H] ~ -0.3 dex ( Zoccali et al. 2003).lower [O/Fe] with respect to halo starsthere are young stars and on-going star formation

( Van Loon et al. 2003)


Patricia B. Tissera

MILKY WAY: STELLAR HALO

J/M ~ 0 (Freeman 1987); sopported by dispersion<[Fe/H] > ~ -1.5 dex (Ryan & Nories 1991;Chiba & Beers (2000)

(σr, σphi, σz ) ~ (141, 106, 94) km/s


halo

Patricia B. Tissera

with decoupling

without decouplin

Pearce et al. (1999, 2001)

Patricia B. Tissera

with decoupling

without decouplin

Pearce et al. (1999, 2001)

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EVOLUCION QUIMICA DEL UNIVERSO - Argentina.gob.ar · The study of the Formation and Evolution of Galaxies requires to be able to follow the evolution of the structure in large scale,