On the role of radial migration on

the chemical evolution of the Milky Way

N. Prantzos

Institut d’Astrophysique de Paris

Age - Metallicity Metallicity

distribution

O/Fe vs Fe/H

OLD Models

Solar

Neighborhood

Constraints:

Local

column densities

Of gas, stars, SFR

as well as

O/Fe vs Fe/H

(requires SNIa

for late Fe)

Age – Metallicity

(uncertain)

Metallicity distribution

(requires

slow infall)

Casagrande et al. 2011

CG Survey

-Little metallicity evolution

in the past 10 Gyr

- Sizeable dispersion

0.2 dex (~60% at 1 )

at all ages

Age-metallicity relation in the solar neighborhood

Casagrande et al. 2011Bensby et al. 2014

Cartledge et al. 2006 : local ISM appears well mixed

Nieva and Simon-Diàz (2011)

11 OB-stars in Orion

Young stars have

~solar abundances,

after 4.5 Gy

of chemical evolution

Either

1. Chemical evolution was

locally inefficient

in the past 4.5 Gy

Or

2. Metal production was

Diluted by infall

Or

3. The Sun was formed

in the inner disk

which had metallicity Z⊙4.5 Gy ago

Nieva and Przybilla(2012)

Similar conclusions from a high resolution NLTE analysis

of 29 nearby B-stars in the field

( within a few hundred pc from the Sun)

Fluctuations of less than 10% (0.04 dex) from the mean

Old AND young stars of both high and low metallicities

Inadequacy of the simple models for the solar neighborhood

Casagrande et al. 2011

CG Survey

<0.5 Gy

>5 Gy

the most metallic stars (2-3 Z☉) - CANNOT be LOCAL (their Z > Z(local ISM)

- they are NOT the youngest

The issue of the thick disk

Data: Reddy et al. 2006

Old (>8-9 Gyr) stars,

have larger scaleheight,

velocity dispersion

and higher O/Fe ratio

than young (thin disk) stars

of the same metallicity

Thick

Thin

Thick

Thin

Summary of features of the solar neighborhood

impossible to reproduce with simple models of chemical evolution

- Little metallicity evolution in the past 10 Gyr, on average

- Sizeable dispersion 0.2 dex (~60% at 1 ) at all ages

- Old AND young stars of both high and low metallicities

- The most metallic stars (2-3 Z☉)are more metal rich

than the local ISM and young stars ; they are NOT the

youngest

- The two-branch behavior of O/FE vs Fe/H in the local

thick and thin disks

Sellwood and Binney 2002Casagrande et al. 2011

It can « naturally » explain

(assuming a disk metallicity gradient)

the observed dispersion in

local age-metallicity relation

EFFECT OF TRANSIENT SPIRALS

(Sellwood and Binney 2002)

Stars just inside corotation with spirals

swap places with those just outside it;

Radial migration (churning)without heating radially the disk

Radial inflow of gas

Radial mixing of stars

Kubryk, NP, Athanassoula AA 2013, 2015a,b

1D semi-analytical model with parametrized infall in a DM halo,

SFR from H2, observed DTD for SNIa rate, detailed chemical evolution

(H to Zn, with Z-dependent yields from massive and LIM stars)

radial motions of gas (parameterised radial inflow)

radial migration of stars (inspired from N-body simulations)

DISK: NOT independently evolving rings 1-zone models INADEQUATE

Sellwood & Binney 2002

Schoenrich & Binney 2009

Minchev et al. 2013a,b

Loebman et al. 2010

Grant and Kawata 2013

4 Gyr8

12 Gyr

Comparison to present-day profiles of MW disk

Solar Neighborhood

Radial Migration

1. Increases the

average stellar age

by ~1 Gyr

At all radii

2. … and brings locally

stars from

~1.5 kpc inwards

(on average)

3. The most metal-rich

local stars come

from several kpc inwards

and are ~4 Gyr old

In situ

In situ +

epicycles

In situ +

Epicycles

+ RadMigr

Solar Neighborhood

Radial Migration

1. Modifies the

apparent local SFR(Röskar et al. 2008)

2. Creates dispersion

in the age-metallicity

relation…

(Sellwood and Binney 2002)

3. …more than

the epicyclic motion

(~0.08 dex)

and comparable with

observations (~0.2 dex)

Obs; Casagrande et al. 2011

Obs: Bensby et al. 2014

Dispersion

Epicycles

Total

Casagrande et al. 2011

Bensby et al. 2014

Age-Metallicity

Model: local gas

Model: all local stars

Solar Neighborhood : stars with different ages and from different regions at all metallicities

Obs (CGS )

Casagrande et al. 2011

The most metallic stars (2-3 Z☉)

- are not the youngest

<0.5 Gy>5 Gy

Solar Neighborhood : stars with different ages and from different regions at all metallicities

Obs (CGS )

Casagrande et al. 2011

The most metallic stars (2-3 Z☉)

- are not the youngest

- are not local

Assuming that

the thick disk is

the old disk (>9 Gyr)

we recover the

[a/Fe] vs Fe/H behavior

(Schoenrich and Binney 2009)

because O and Fe sources

have different timescales

and the

metallicity distributions

of both

the thick and thin disks

Data: Adibekyan et al. 2011

Stars in the thick local disk

mostly from

the inner disk

(3-4 kpc)

with more rapid

star formation

Evolution of thin (<9 Gyr) and thick (>9 Gyr) disks

with yields NORMALISED to solar for AVERAGE LOCAL (8 kpc) STAR 4.5 Gyr old

Data: Bensby et al. 2014Data: Adibekyan et al. 2011

Chieffi & Limongi 2017

13-120 M⊙

Full range of stellar masses and

metallicities

Role of rotation: 3 sets of models

Yields of massive stars

Rotation enhances the yields

of several elements

(in particular s-elements)

and produces primary N and F

A distribution function favouringmore rotating stars at lowest metallicities

Produces quasi-primary N at [Z]~-3 andcorrect amounts of s-nuclei at [Z]~-1

Isotopic abundances

Up to Zn:

Better than a factor of 2

Mg Al Cl K Sc Ti V

Poorly or

underproduced

Above Zn:

s- nuclei: Better than ~20%

(r-yields fixed to reproduce

solar r- component)

NP, Abia, Chieffi, Limongi,

Cristallo

AA submitted

Goswami & NP 2000 with yields from Woosley & Weaver 1995

William Alfred FowlerPhysics Nobel 1983

Fred Hoyle

Alpha/Fe evolution OK

Primary N ~OK

Mn, Ni, Cu: OK

Mg, Al: ~underproduced

Ti: obs. : like alphathe. : like Fe

K, Sc, V, Zn: not OK

Chemical evolutionwith new Roma yields

Rot vs Non Rot

Chemical evolutionwith new Roma yields

Rot vs Non Rot

S-procces from LIMSIs secondary andappears only at

[Fe/H] > -1

S-process from rotatingMassive stars isquasi-primary,

but at lowmetallicities it is

overwhelmedby r-component

Thin Thick

Adibekyan

Bensby

Mishenina

Calculations with new yields (Roma) for massive and LIM stars for all isotopes up to Pb (including s-nuclei)

The evolution of Li in the thin and thick disks

(NP de Laverny, Guiglion, Recio-Blanco, Worley 2017 AA in press)At least three sources of Li:

Big Bang

Cosmic rays

Stellar (>60% of solar Li)

Delayed ([Fe/H]>-1)

Timescale > 1 Gy

2 important problems

1. What is the primordial Li ?

SBBN vs Spite plateau ?

2. Which stellar source ?

Novae , Red giants or AGBs ?

What timescale ?

AMBER data (Guiglion et al. 2016) suggest different sequences of evolution

for the thick and thin disks

Double sequence explained

by radial migration, for

Thin disk <9 Gy

Thick disk >9 Gy

1. long lived Li source

(M<1.6 M⊙, >2 Gy)

FOR LOW LiP

no Li depletion in stellar

atmospheres is required

to explain the upper envelope

of observations

FOR HIGH LiP

Metallicity-dependent

Li depletion in stellar atmospheres i

is required

2. Short lived Li source

(M~2-4 M⊙, ~0.15-1 Gy)

Independently of LiPLi depletion in stellar atmospheres

is required

to explain the upper envelope

of observations

Is Li destroyed by stars

at higher than solar

metallicities ???

(AMBRE, GES, HARPS)

Radial migration in MW disk may explain

1. Dispersion in local age-metallicity

2. Presence of metal-rich stars locally

3. Presence of old metal-rich and

young metal-poor stars locally

4. Double sequence of O/Fe in local thin and thick disks

5. Double sequence of Li/H in thin and thick disks (new)

Also : different evolution of X/Fe in thin and thick disks will help

constraining stellar nucleosynthesis for -1< [Fe/H]<1

Preliminary: s/Fe not expected to behave (very) differently

because of similarity in evolutionary timescales of their sites