Evolution of the - PowerPoint Presentation

Slide1

Evolution of the metallicity gradients in disk galaxies from integrated stellar populations

Patricia Sánchez-Blázquez And the CALIFA collaborationSlide2

Evolution of the metallicity gradients in cosmological simulations

Gibson et al. (2013

)

(see also Pilkington et al. 2012)

Enhanced feedback

Normal feedback

Stellar populations with CALIFA P. Sanchez-

Blazquez

Cozumel 2016Slide3

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 redshiftsDifficult 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 2016Slide4

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 redshiftsDifficult 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 2016Slide5

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.

Stellar populations with CALIFA P. Sanchez-

Blazquez

Cozumel 2016

http://astro.u-strasbg.fr/~ocvirk/STECKMAP

galaxy

fitPeak to peak variations of the inverse model matrixStellar Population models: MILES (Vazdekis et al. 2010; PSB et al. 2006: http://miles.iac.es)Slide6

Age-Z relation

Stellar age distribution

Steckmap

outputs

i

nput data

recovered

Stellar populations with CALIFA P. Sanchez-

Blazquez

Cozumel 2016Slide7

Ruiz-Lara et al (2015)Comparison between CMD and

integrated stellar populations

Stellar populations with CALIFA P. Sanchez-

Blazquez

Cozumel 2016Slide8

S/N~40 per

Å

(@ 5800Å)

Mean values

PSB

et al. (2014)

Stellar populations with CALIFA P. Sanchez-

Blazquez

Cozumel 2016Slide9

S/N~40 per

Å

(@ 5800Å)

Mean values

PSB et al. (2014)

Stellar populations with CALIFA P. Sanchez-

Blazquez

Cozumel 2016Slide10

Metallicity gradients for populations with different ages

Stellar populations with CALIFA P. Sanchez-

Blazquez

Cozumel 2016

HII regions

Age< 4

Gyr

Age> 4

Gyr

< 9

Gyr

Age> 9Slide11

Comparison of young

and old stellar

metallicity

gradients

g

rad

[Z/H] (old) – grad

[Z/H] (young)

Stellar populations with CALIFA P. Sanchez-

Blazquez

Cozumel 2016Slide12

Differences in the

metallicity gradients

for

different

stellar populations

Stellar populations with CALIFA P. Sanchez-

Blazquez

Cozumel 2016Slide13

Evolution of the metallicity gradient

Stellar populations with CALIFA P. Sanchez-

Blazquez

Cozumel 2016

Gradients were steeper in the past, but the evolution is mildSlide14

Evolution of the metallicity gradients with time

Stellar populations with CALIFA P. Sanchez-

Blazquez

Cozumel 2016

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)Slide15

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.SummaryEvolution of the metallicity gradient P. Sanchez-Blazquez Cozumel 2016