Gaia and ground based spectroscopic surveys: science synergies

Alejandra Recio-Blanco Observatoire de la Côte d’Azur (Nice, France)

Outline !

1. Stars as fossils !

2. Observation thresholds in Galactic archaeology (4 levels of information) ! - Data (Gaia and ground-based surveys) !

- Physical properties of the Galaxy

What we would like to know !

- Physical processes of Galaxy evolution

What we would like to understand !

3. Conclusions

1. Stars as fossils

Stars are fossils we can work with: - A star of 0.8Mo leaves more than 13Gyr ! - ages z ≥ 6.

1. Stars as fossils

Fossil information about Galactic (sub)populations: 1. Position and Kinematics:

1. Stars as fossils

Fossil information about Galactic (sub)populations: 2. Chemical composition

Chemical tagging Free parameters of an isolated system: star formation rate, initial mass function, galactic winds…

How to disentangle this fossil record to arrive to this ? !

How to disentangle this fossil record? !

Observational thresholds of Galactic Archaeology and what do they tell us?

First threshold: Positions & magnitudes

1. Data 2. Phy. properties 3. Phy. processes

On the Construction of the Heavens. By William Herschel, Esq. F. R. S. Philosophical Transactions of the Royal Society of London, Vol. 75. (1785), pp. 213-266.

First threshold: Positions & magnitudes

1. Data 2. Phy. properties 3. Phy. processes

VISTA

First threshold: Positions & magnitudes

1. Data 2. Phy. properties 3. Phy. processes

Gaia: Positions, Gmag

First threshold: Positions & magnitudes

1. Data 2. Phy. properties 3. Phy. processes

Gaia: BPRP data

First threshold: Positions & magnitudes

1. Data 2. Phy. properties 3. Phy. processes

- 2D spatial distributions !

- Photometric stellar atmospheric parameters

González et al. (2013) VVV Bulge metallicity distribution

Ivezic et al. (2008) SDSS

First threshold: Positions & magnitudes

1. Data 2. Phy. properties 3. Phy. processes

- 2D spatial distributions !

- Photometrical stellar atmospheric parameters

Bailer-Jones et al. (2013) Gaia BPRP based expected parameter accuracies !Down to G~19

First threshold: Positions & magnitudes

1. Data 2. Phy. properties 3. Phy. processes

- 2D spatial distributions !

- Photometrical stellar atmospheric parameters

Bailer-Jones et al. (2013) Gaia BPRP based expected parameter accuracies !Down to G~19

First threshold: Positions & magnitudes

1. Data 2. Phy. properties 3. Phy. processes

- Recent accretions (streams)Belokurov et al. (2006) Ivezic et al. (2008)

2nd threshold:Distances & propermotions

1. Data 2. Phy. properties 3. Phy. processes

- Parallaxes (distances) - Proper motions

Credits François Mignard

Gaia huge step forward

2nd threshold:Distances & propermotions

1. Data 2. Phy. properties 3. Phy. processes

HR diagrams

Baade, 1944

2nd threshold:Distances & propermotions

1. Data 2. Phy. properties 3. Phy. processes

3D distributions

Hyades in 3D Credits Anthony Brown

2nd threshold:Distances & propermotions

1. Data 2. Phy. properties 3. Phy. processes

- Stellar cluster’s studies (membership) !

- Disc evolution processes (photometric metallicity gradients): migration, disc heating by mergers,… !

- Stellar structure and evolution models

3nd threshold: Spectroscopy

1. Data 2. Phy. properties 3. Phy. processes

- Radial velocities - Spectroscopic stellar parameters - Individual element abundances

3nd threshold: Spectroscopy

1. Data 2. Phy. properties 3. Phy. processes

3nd threshold: Spectroscopy

1. Data 2. Phy. properties 3. Phy. processes

3nd threshold: Spectroscopy

1. Data 2. Phy. properties 3. Phy. processes

3nd threshold: Spectroscopy

1. Data 2. Phy. properties 3. Phy. processes

3nd threshold: Spectroscopy

1. Data 2. Phy. properties 3. Phy. processes

3nd threshold: Spectroscopy

1. Data 2. Phy. properties 3. Phy. processes

- Stellar parameters, chemical compositions - 3D kinematics - Dynamics (orbits) !

Chemo-dynamical constraints to models

3nd threshold: Spectroscopy

1. Data 2. Phy. properties 3. Phy. processes

Gaia: Apsis pipeline - GSPspec (Bailer-Jones et al. 2013) (Recio-Blanco et al. 2014b, sub.)

Credits O. Marchal & D. Katz

3nd threshold: Spectroscopy

1. Data 2. Phy. properties 3. Phy. processesGaia GSPspec performances (Recio-Blanco et al. 2014b, sub.)

3nd threshold: Spectroscopy

1. Data 2. Phy. properties 3. Phy. processesGaia GSPspec performances (Recio-Blanco et al. 2014b, sub.)

3nd threshold: Spectroscopy

1. Data 2. Phy. properties 3. Phy. processes

G-type dwarfs

early-type stars

3nd threshold: Spectroscopy

1. Data 2. Phy. properties 3. Phy. processes

Late-type stars - Errors in metallicity lower than ~0.1 dex for

G_RVS < 12-13 - Good recovery of the [alpha/Fe] - Performances degrade for fainter stars but still

good parametrization ! Early-type stars

- Very good results down to GRVS ~ 13 - Very good log g recovery thanks to Paschen lines

3nd threshold: Spectroscopy

1. Data 2. Phy. properties 3. Phy. processes - Stellar parameters, chemical compositions

Gaia: GSPspec (Recio-Blanco et al. 2014b, sub.)

- Important contribution for bright stars (added scientific value on Teff (->ages), metallicity and individual abundances

!

- Help to GSPphot parametrization on Teff-extiction degeneracy

3nd threshold: Spectroscopy

1. Data 2. Phy. properties 3. Phy. processes

GES: VLT/Giraffe spectra (performances) Recio-Blanco & GES consortium, in prep.

3nd threshold: Spectroscopy

1. Data 2. Phy. properties 3. Phy. processes

GES: Thin to thick disc transition Recio-Blanco et al. 2014

3nd threshold: Spectroscopy

GES: Thin to thick disc transition Recio-Blanco et al. 2014

1. Data 2. Phy. properties 3. Phy. processes

3nd threshold: Spectroscopy

GES: Thin to thick disc transition ESO FEROS+HARPS archive homogeneous analysis

AMBRE project (P.I. de Laverny)

8105 stars solar neighborhood

Mikolaitis+ in prep.

1. Data 2. Phy. properties 3. Phy. processes

3nd threshold: Spectroscopy

GES: Thin to thick disc transition Recio-Blanco et al. 2014

The thick disc seems to lie in thinner and thinner layers as metallicity increases.!

1. Data 2. Phy. properties 3. Phy. processes

3nd threshold: Spectroscopy

GES: Thin to thick disc transition Guiglion et al. 2014, in prep.

Detailed study of disc rotational velocity

1. Data 2. Phy. properties 3. Phy. processes

3nd threshold: Spectroscopy

GES: Thin to thick disc transition Guiglion et al. 2014, in prep.

1. Data 2. Phy. properties 3. Phy. processes

3nd threshold: Spectroscopy

GES: Thin to thick disc transition Guiglion et al. 2014, in prep.

1. Data 2. Phy. properties 3. Phy. processes

3nd threshold: Spectroscopy

GES: Thin to thick disc transition Guiglion et al. 2014, in prep.

Minchev+ 2014

1. Data 2. Phy. properties 3. Phy. processes

3nd threshold: Spectroscopy

GES: Thin to thick disc transition Recio-Blanco et al. 2014

The eccentricity distribution of the thick disc peaks at higher values than the thin disc one

1. Data 2. Phy. properties 3. Phy. processes

3nd threshold: Spectroscopy

GES: Thin to thick disc transition Recio-Blanco et al. 2014

Metallicity dependence of eccentricity : thick disc -> yes thin disc -> no !

1. Data 2. Phy. properties 3. Phy. processes

3nd threshold: Spectroscopy

GES: Thin to thick disc transition Recio-Blanco et al. 2014

Metallicity dependence of eccentricity : thick disc -> yes thin disc -> no !But need of more accurate distances for dynamics !!

Gaia accurate distances needed

1. Data 2. Phy. properties 3. Phy. processes

3nd threshold: Spectroscopy

GES: Metallicity gradients in the disc Mikolaitis et al. 2014

Mikolaitis et al. 2014

1. Data 2. Phy. properties 3. Phy. processes

3nd threshold: Spectroscopy

GES: Metallicity gradients in the disc Mikolaitis et al. 2014

Mikolaitis et al. 2014

1. Data 2. Phy. properties 3. Phy. processes

3nd threshold: Spectroscopy

GES: Metallicity gradients in the disc

Mikolaitis et al. 2014

1. Data 2. Phy. properties 3. Phy. processes

4th threshold: Ages

Gaia revolution with important synergies with ground-based data

Direct constraints on the time-evolving chemo-dynamical picture of the Milky Way

Conclusions

- Gaia will induce a strong quantitative and qualitative change:

* completeness * spatial distributions, kinematics * [Fe/H] and [alpha/Fe] (bright part) * dynamics ! * ages !! !

- Ground-based spectroscopic surveys : * complete chemical information in the Gaia sphere of accurate ages * Vrad and chemical information for fainter stars

Conclusions

- Future ground-based surveys (eg. 4MOST, WEAVE…) covering the halo will complete the present ones.

!

- IR surveys as APOGEE (I&II) important to cover the bulge.

Available positions at the Observatoire de la Côte d’Azur (Nice, France) !

1) Post-doc for 2 years 2) Phd grant !

Starting date ~ 1st October 2015 !Deadline: 1st February 2015