Calibrating the role of TP-AGB stars in the cosmic matter cycle

Paola Marigo Department of Physics and Astronomy G. Galilei University of Padova, Italy

Why Galaxies Care about AGB Stars III. University of Vienna July 29, 2014

OUTLINE

1. The TP-AGB star conundrum in galaxy models up to high redshift.

2. The need for a physically sound calibration of the TP-AGB over the age-metallicity plane.

3. Magellanic Cloud clusters as classical calibrators and insidious problems. 4. Magellanic Cloud clusters as novel and more powerful calibration tools.

5. Moving beyond the MC clusters: excellent quality data for resolved AGB are available to be fully exploited! 6. A few steps along calibration cycle.

Adapted from M. Marengo (2000)

(O. Straniero’s talk ) (S. Höfner’s talk )

(I. Cherchneff’’s talk )

The TP-AGB evolution affects the spectrophotometric properties of galaxies up to high redshift.

Stellar spectra: visual and IR

Color-magnitude diagrams: Spitzer SAGE of the LMC

Spectral energy distributions: post star-burst galaxies at high z

Stellar atmospheres

Nearby resolved galaxies

Distant unresolved galaxies

22/10/2012

EVOLUTIONARY EFFECTS

POPULATION EFFECTS

Core He-burn + RGB +E-AGB O-rich TP-AGB stars C-stars Milky Way disk Milky Way Halo

AN EXAMPLE OF COMPLEX, WELL UNDERSTOOD, PHYSICS IN AGB STARS

MOLECULAR CHEMISTRY AESOPUS code (Marigo & Aringer 2009) on the fly in TP-AGB models

POPULATION EFFECTS

OPACITY

Marigo et al. 2013, MNRAS, 434, 488

Composite spectral energy distribution of 64 post-starburst galaxies with 0.7 ≲ 𝑧 ≲ 2.0 Kriek et al. 2010, ApJ, 722, L64

SED fitting with population synthesis models yields galaxies’ masses and ages.

The modelling of TP-AGB stars is critical!

An example of unsatisfactory treatment of the TP-AGB phase: EPS models for high redshift galaxies

Discrepancy by a factor ≳ 2-3 in galaxy mass and age among current EPS models

29/10/2012

MASS

AGE

Heavy TP-AGB Light TP-AGB

Based on the Millennium Cosmological Simulation Courtesy S. Charlot

TP-AGB uncertainties propagate further…

?

We need to calibrate the contribution of TP-AGB stars over the age-metallicity plane

No carbon stars at old ages and high metallicity What are the precise limits? How efficient is the third

dredge-up? What is the minimum mass

for the onset of hot-bottom burning ?

Nuclear fuel ∝ ∫𝐿(𝑡)𝑑𝑡 = integrated light

TP-AGB is maximum at ages ∼ 109 yr What is the exact peak amplitude ? How does it depend on metallicity? How long is the TP-AGB lifetime (Mi,Zi)? What is the rate of mass (gas and dust) injection from AGB stars?

Fuel Consumption Method AGB luminosities ⇒ nuclear fuel

Stellar Isochrone Method AGB star counts ⇒ lifetimes

Maraston 1998, 2005 Girardi & Marigo 2007

I. MAGELLANIC CLOUD CLUSTERS AS CLASSICAL TP-AGB CALIBRATORS: Pioneer work Frogel, Mould & Blanco 1990

Noel et al. 2013

Integrated colors

Nearby dwarf galaxies with HST : Marigo & Girardi 2007 TP-AGB models show an average excess: ∼ 40% in the AGB star counts ⇒ factor of ∼2 in the integrated near-IR flux RGB + AGB stars responsible for 21% + 17% of the integrated flux emitted by galaxies in the near IR (Melbourne et al. 2012, ApJ, 748, 47)

EPS model based on Maraston 2005 TP-AGB models overestimate the SEDs in the IR of high-z post star-burst galaxies (Kriek et al 2013, Zibetti et al. 2013)

… TP-AGB calibrations on MC clusters seem not to work well for other external galaxies …

The peak of TP-AGB contribution has been likely overestimated due to an AGB boosting effect at ages ∼ 1.6 Gyr (MTO ∼ 1.7 M)

Girardi et al. 2013, ApJ, 777, 142

Fuel Consumption Method AGB luminosities ⇒ nuclear fuel

Stellar Isochrone Method AGB star counts ⇒ lifetimes

Maraston 1998, 2005 Girardi & Marigo 2007 Noel, Greggio, Renzini, et al. 2013

Integrated colors

Reason: abrupt change in core He-burning lifetimes close to the critical mass MHeF (degenerate/non degenerate He cores)

The insidious TP-AGB boosting

Girardi et al. 2013, ApJ, 777, 142

Reason: abrupt change in core He-burning lifetimes close to the ciritical mass MHeF (degenerate/non degenerate He cores)

The insidious TP-AGB boosting

Girardi et al. 2013, ApJ, 777, 142

A triple TP-AGB develops at an age of 1.65 Gyr!

Reason: abrupt change in core He-burning lifetimes close to the ciritical mass MHeF (degenerate/non degenerate He cores)

SSP integrated luminosity

Girardi et al. 2013, ApJ, 777, 142

Age distribution of TP-AGB stars in MC clusters

boosting period

boosting period

The insidious TP-AGB boosting

Reason: abrupt change in core He-burning lifetimes close to the ciritical mass MHeF (degenerate/non degenerate He cores)

SSP integrated luminosity

Girardi et al. 2013, ApJ, 777, 142

Previous calibrations biased towards too heavy TP-AGB. Revision of MC clusters urgently needed!

Age distribution of TP-AGB stars in MC clusters

boosting period

boosting period

The insidious TP-AGB boosting

𝐿𝑆𝑆𝑆 𝑡 = �𝐿 𝑀𝑖 𝜑 𝑀𝑖 𝑑𝑀𝑖 𝑡=𝑐𝑐𝑐𝑐𝑡.

NGC 1978 NGC 419 NGC 1846

II. Beyond the classical calibration on MC clusters: H-R diagrams+abundances+variability+mass loss

𝑃0 𝑃1 𝑃2

𝑃0 𝑃1 𝑃2

Kamath et al. 2012, ApJ, 746, 20

Lebzelter et al. 2008, A&A, 486,511

Kamath et al. 2010, MNRAS 408,522

Lebzelter & Wood 2007

Lederer et al. 2009

AGB stars in MC clusters: constraints on nucleosynthesis and mixing (M,Z)

Envelope overshooting & Intershell composition

depth of the partially-mixed zone

Efficiency of the 3rd dredge-up

Minimum core mass for the 3rd dredge-up

Kamath et al. 2012, ApJ, 746, 20

III. BEYOND THE MC CLUSTERS: wide age-metallicity sampling and characterization

Fields and clusters 2MASS, VISTA, Spitzer, OGLE

The Magellanic Clouds

The Milky Way Bulge

62 dwarf galaxies d < 4 Mpc All metallicities down to very low

The ACS Nearby Galaxy Survey Treasury

2MASS,OGLE,WISE super-solar metallicity, old ages

Disk population Near solar metallicity

The Panchromatic Hubble Andromeda Treasury

Local Group dwarf

galaxies

Fields and clusters 2MASS, VISTA, Spitzer, OGLE

The Magellanic Clouds

The Milky Way Bulge

62 dwarf galaxies d < 4 Mpc All metallicities down to very low

The ACS Nearby Galaxy Survey Treasury

2MASS,OGLE,WISE super-solar metallicity, old ages

Disk population Near solar metallicity

The Panchromatic Hubble Andromeda Treasury

Local Group dwarf

galaxies

III. BEYOND THE MC CLUSTERS: wide age-metallicity sampling and characterization

Local Group dwarf

galaxies

Fields and clusters 2MASS, VISTA, Spitzer, OGLE

The Magellanic Clouds

The Milky Way Bulge

62 dwarf galaxies d < 4 Mpc All metallicities down to very low

The ACS Nearby Galaxy Survey Treasury

2MASS,OGLE, WISE super-solar metallicity, old ages

Disk population Near solar metallicity

TP-AGB OBSERVABLES

Optical, near-mid IR photometry

Spectral classification Long-period variability (OGLE) Mass-loss rates, wind

velocities, dust chemistry (Spitzer, ALMA) Chemical abundances Initial-final mass relation Stelllar parameters from

interferometry

The Panchromatic Hubble Andromeda Treasury

III. BEYOND THE MC CLUSTERS: wide age-metallicity sampling and characterization

I. TP-AGB lifetimes

from older TP-AGB models …

… to more recent ones …

Karakas et al. 2002

Marigo et al. 2013

Weiss & Ferguson 2009

Renzini & Voli 1981 Groenewegen & de Jong 1993 Mohucine & Lançon 2002 Marigo & Girardi 2007

Z=0.008

The ACS Nearby Galaxy Survey Treasury

62 dwarf galaxies d < 4 Mpc All metallicities down to very low

AGB star counts & luminosity functions Rosenfield et al. 2014, ApJ,

I.TP-AGB lifetimes: probing the low-metallicity low-mass regime

lifetimes

At low metallicities: Short TP-AGB lifetimes at older ages

𝜏 ≲ 1Myr for 𝑀𝑖 ≲ 1 𝑀⨀ Metallicity dependence: Z ↘ ⟹ 𝜏 ↘

more details in Rosenfield’s talk

TP-AGB TP-AGB

plot from Straniero et al. 2006

Before the onset of large-amplitude pulsation stellar winds in giants driven by other mechanisms, e.g. flux of Alfvén wave energy associated to cool chromospheres

pulsation-assisted dust-driven winds

Different stages of mass loss

(W. Vlemmings’ talk )

plot from Straniero et al. 2006

Before the onset of large-amplitude pulsation stellar winds in giants driven by other mechanisms, e.g. flux of Alfvén wave energy associated to cool chromospheres

pulsation-assisted dust-driven winds

Different stages of mass loss

Novel theoretical efforts: Cranmer & Saar 2011, ApJ, 741, 54 Magnetohydrodynamic turbolence in the convective subsurface zones dM/dt ∝ (FA* )12/7 , steep scaling with the magnetic energy flux⇒ efficient pre-dust mass loss in low-metallicity low-mass TP-AGB stars

compared to classical Reimers 1975 and Schröder & Cuntz 2005

(W. Vlemmings’ talk )

≳ 𝟔𝟔 white dwarfs, most in open clusters Extension to the low-mass end: CPMPs Catalan et al. 2008 old open clusters Kalirai et al. 2008 change of slope at 𝑀i ≈ 4 𝑀⨀ Large scatter hetereogeneous sources, various metallicities. Uncertainties due to WD models and stellar evolution 𝑀WD and 𝑡cooling: spectral fitting (Teff and g) + grid of WD models and theoretical M-R relation 𝑀i: 𝜏 𝑀i = τ cluster − 𝑡cooling(WD) Age and metallicity of clusters overshooting Thickness of the WD H/He layers Composition of the WD core (He, C-O, O-Ne)

II. The core mass growth: the initial-final mass relation

II. The core mass growth depends on: a) efficiency of mass loss

exponential increase

Superwind ⇒ PN ejection

Pulsation-assisted dust-driven wind

Figure adapted from Straniero et al. 2006

II. The core mass growth depends on: b) efficiency of the third dredge-up

The efficiency 𝜆 = Δ𝑚duΔ𝑚H

is poorly known from theory

Reduction of the core mass

General trend: the third dredge-up goes deeper at M ↑ and Z ↓

2 M, Z=0.02

O.Pols

Differences among different models, getting smaller in more recent calculations

Larger final masses at lower Z, (despite more efficient dredge- up) due to larger 𝑀c,1TP

Bressan et al. 2012

Accurate and homogeneous IFMR data can constrain mass loss and third dredge-up

NGC6819 NGC7789 Hyades Praesepe

Kalirai et al. 2014, ApJ, 782, 17

18 high S/N white dwarfs, homogeneous analysis, all clusters sharing Z =0.02 ([Fe/H]=+0.1)

𝑀c,1tp

Bracketing mass loss and third dredge-up

No dredge-up (λ=0)

deep dredge-up

The stronger the mass loss, the weaker the effect of the third dredge-up

Reimers 1975 Bedjin 1988 Vassiliadis & Wood 1993 Van Loon et al. 2005 Blöcker 1995

Calibrating mass loss, 3rddredge-up, lifetimes

Kalirai et al. 2014, ApJ, 782, 17

mass-loss

3rd dredge-up

TP-AGB lifetimes Inefficient C-star formation, see also poster S5-01 (Boyer et al.)

Z=0.02

ANGST calibration new IFMR data

CURRENT STATE OF THE CALIBRATION (ongoing)

ANGST calibration new IFMR data

CURRENT STATE OF THE CALIBRATION (ongoing)

ANGST data new IFMR data

The island of AGB stars: solar and MC metallicites and intermediate ages ≲ 𝟏𝟔𝟗 𝐲𝐲

CURRENT STATE OF THE CALIBRATION (ongoing)

Take away

Classical calibration on MC clusters: TP-AGB likely overestimated due to a boosting at ages aroung 1.7 Gyr. Complete revision needed.

Novel and extensive calibration on MC clusters: wealth of additional

information (long-period variability, chemical abundances, mass loss). Good constraints of the TP-AGB core mass growth and fuel: accurate and

homogeneous initial-final mass relation data. Calibration beyond the MC clusters: unprecedented high-quality data in

other nearby galaxies to probe unexplored regions of the age-metallicity plane (very low-and supersolar metallicities).

The «island» of TP-AGB stars: stronger TP-AGB contribution at

intermediate ages (∼1 Gyr) and MC – solar metallicities (ongoing calibration).

This research is supported under ERC Consolidator Grant

funding scheme (project STARKEY)

Why Galaxies Care about AGB Stars III. University of Vienna July 29, 2014

Emitted light by a TP-AGB star ∝ core mass growth + chemical yields

𝑬𝐓𝐓−𝐀𝐀𝐀 = � 𝒍 𝒕 𝒅𝒕 ∝ 𝑭𝐓𝐓−𝐀𝐀𝐀 ≃ 𝑿 + 𝟔.𝟏𝟏 𝑴𝐜𝐀𝐀𝐀𝐀 − 𝑴𝐜

𝟏𝐓𝐓 + 𝑭𝒀 𝐇𝐇 + 𝝉𝐀𝐀𝐀

𝑭𝒀 𝐂,𝐍,𝐎 Marigo & Girardi 2002

1st thermal pulse AGB-tip time

mass fraction

core mass growth

chemical yields

primary He, C, N, O

Emitted light by a TP-AGB star ∝ core mass growth + chemical yields

𝑬𝐓𝐓−𝐀𝐀𝐀 = � 𝒍 𝒕 𝒅𝒕 ∝ 𝑭𝐓𝐓−𝐀𝐀𝐀 ≃ 𝑿 + 𝟔.𝟏𝟏 𝑴𝐜𝐀𝐀𝐀𝐀 − 𝑴𝐜

𝟏𝐓𝐓 + 𝑭𝒀 𝐇𝐇 + 𝝉𝐀𝐀𝐀

𝑭𝒀 𝐂,𝐍,𝐎 Marigo & Girardi 2002

1st thermal pulse AGB-tip time

mass fraction

core mass growth

chemical yields

primary He, C, N, O

EMITTED LIGHT & CHEMICAL ENRICHMENT ARE COUPLED!

A hybrid approach: The COLIBRI code

It optimizes the ratio 𝐩𝐩𝐲𝐩𝐩𝐜𝐩𝐩 𝐩𝐜𝐜𝐚𝐲𝐩𝐜𝐲

𝐜𝐜𝐜𝐩𝐚𝐀𝐩𝐀𝐩𝐜𝐜𝐩𝐩 𝐩𝐩𝐩𝐚𝐇𝐩

• Initial conditions at the 1st TP from Parsec tracks (Bressan et al. 2012)

• Integrations of the 4 stucture

equations from the atmosphere down to the bottom of the H-burning shell.

• Sperically symmetric atmosphere • Hot-bottom burning : pp chains,

CNO cycle, NeNa, MgAl cycles, Cameron-Fowler Beryllium transport mechanism for 7Li production.

• Nuclear network coupled to a diffusive approximation of convection.

• PDCZ nucleosynthesis • Ausiliary analytic formalism from

Wagenhuber & Groenewegen 1998, Karakas et al. 2002, Bressan et al. 2012

Marigo et al. 2013, MNRAS, 434, 488

Convective envelope abundances

Photospheric molecular concentrations AESOPUS on-the-fly

TP-AGB nucleosynthesis and molecular chemistry lo

g

log

Mi=5 Msun Z=0.008

An efficient tool: ÆSOPUS Accurate Equation of State and OPacity Utility Software

Æsopi fabula: De sole et vento Illustra tion by Franc is Barlow, 1687

Marigo & Aringer 2009, A&A, 508, 1539

Rosseland mean opacites on demand for arbitrary chemical mixtures

Web-interface: http://stev.oapd.inaf.it/aesopus

Uncomparably fast performance: 1 opacity table computed in real time and ready in < 40 s Full freedom in setting the abundances of atoms from H to U

ÆSOPUS CHEMISTRY The EOS under instantaneous equilibrium assumption solved for the concentrations of 800 species: 300 atoms and ions + 500 molecules

Z=0.02 Z=0

22.07.2013

ÆSOPUS opacity H and He: continuum true absorption, scattering, line transitions,

collision-induced absorption heavier elements: atoms (Opacity Project database), molecules (line lists: HITRAN and other sources, optimized opacity sampling)

ÆSOPUS suitable for AGB star models

22/10/2012 Workshop del Dipartimento di Fisica e Astronomia G.Galilei

Marigo & Aringer 2009, A&A, 508, 1539 WEB interface http://stev.oapd.inaf.it/aesopus

C/O < 1

C/O > 1