1. Patricia Sánchez-Blázquez And the CALIFA collaboration
Evolution of the metallicity gradients in disk galaxies from integrated stellar populations
Patricia Sánchez-Blázquez
And the CALIFA collaboration

2. Evolution of the metallicity gradients in cosmological simulations
Enhanced feedback
Normal feedback
Gibson et al. (2013)
(see also Pilkington et al. 2012)
Stellar populations with CALIFA P. Sanchez-Blazquez Cozumel 2016

3. Evolution of the metallicity gradient (Observations)
Metallicity gradient using tracers of different ages (OB stars, PN, RGB stars, clusters)
Difficult to age date populations older than ~2 Gyr.
Possible flattening with time (e.g., Maciel et al. 2003)
Steepening with time (e.g., Sanghellini et al. 2010)
(1a) In external galaxies (M33, M81, NGC300, M31)
 flattening, steepening and invariant
(2) Measuring gradients at different redshifts
Difficult due to resolution related problems
 Very steep metallicity gradients at high redshift (Yuan+ 2011; Jones+2001,2013,2015)
Mild or even positive metallicity gradients (Cresci+2010; Queyrel+2012, Troncoso+2014, etc)
A variety but mostly flat at high redshift (Leethochawalit+2016)
(3) Astroarchaeology (Tracing the metallicity gradient of stars at different ages)
Stellar populations with CALIFA P. Sanchez-Blazquez Cozumel 2016

4. Evolution of the metallicity gradient (Observations)
Metallicity gradient using tracers of different ages (OB stars, PN, RGB stars, clusters)
Difficult to age date populations older than ~2 Gyr.
Possible flattening with time (e.g., Maciel et al. 2003)
Steepening with time (e.g., Sanghellini et al. 2010)
(1a) In external galaxies (M33, M81, NGC300, M31)
 flattening, steepening and invariant
(2) Measuring gradients at different redshifts
Difficult due to resolution related problems
 Very steep metallicity gradients at high redshift (Yuan+ 2011; Jones+2001,2013,2015)
Mild or even positive metallicity gradients (Cresci+2010; Queyrel+2012, Troncoso+2014, etc)
A variety but mostly flat at high redshift (Leethochawalit+2016)
(3) Astroarchaeology (Tracing the metallicity gradient of stars at different ages)
Stellar populations with CALIFA P. Sanchez-Blazquez Cozumel 2016

5. 82 face-on disk galaxies galaxies from the CALIFA survey
STECKMAP (STEllar Content via Maximum A Posteriori, Ocvirk et al. 2006ab)
It is non parametric, and thus provides properties such as the stellar age distribution with minimal constraints on their shape
The ill-conditioning of the problem is taken into account through explicit regularization.
galaxy
fit
Peak to peak variations of the inverse model matrix
74x65
Stellar Population models: MILES (Vazdekis et al. 2010; PSB et al. 2006:
Stellar populations with CALIFA P. Sanchez-Blazquez Cozumel 2016

6. Steckmap outputs Stellar age distribution Age-Z relation input data
recovered
Stellar populations with CALIFA P. Sanchez-Blazquez Cozumel 2016

7. Comparison between CMD and integrated stellar populations
Ruiz-Lara et al (2015)
Stellar populations with CALIFA P. Sanchez-Blazquez Cozumel 2016

8. S/N~40 per Å (@ 5800Å) Mean values PSB et al. (2014)
Stellar populations with CALIFA P. Sanchez-Blazquez Cozumel 2016

9. S/N~40 per Å (@ 5800Å) Mean values PSB et al. (2014)
Stellar populations with CALIFA P. Sanchez-Blazquez Cozumel 2016

10. Metallicity gradients for populations with different ages
HII regions
Age< 4 Gyr
Age> 4 Gyr < 9 Gyr
Age> 9
Stellar populations with CALIFA P. Sanchez-Blazquez Cozumel 2016

11. Comparison of young and old stellar metallicity gradients
grad[Z/H] (old) – grad[Z/H] (young)
Stellar populations with CALIFA P. Sanchez-Blazquez Cozumel 2016

12. Differences in the metallicity gradients for different stellar populations
Stellar populations with CALIFA P. Sanchez-Blazquez Cozumel 2016

13. Evolution of the metallicity gradient
Gradients were steeper in the past, but the evolution is mild
Stellar populations with CALIFA P. Sanchez-Blazquez Cozumel 2016

14. Evolution of the metallicity gradients with time
We find little evolution in the metallicity gradient compatible with cosmological simulations with enhanced feedback
See also Magrini et al. (2016)
Leethochawalit et al. (2016)
Stellar populations with CALIFA P. Sanchez-Blazquez Cozumel 2016

15. Summary
We are studying the stellar populations in a sample of face-on disk galaxies from the CALIFA survey to study the evolution of the metallicity gradient.
We find very little evolution of the metallicity gradient with time but the trend is that gradient become flatter (less negative) with time.
The gradients may have been steeper in the past and flatten due to dynamical processes (but comparing the results using integrated spectra with those of direct metallicity measurements we can constrain the importance of radial migration.
Evolution of the metallicity gradient P. Sanchez-Blazquez Cozumel 2016