Svitlana Zhukovska Max Planck Institute for Astrophysics

Transcription

1 Unveiling dust properties across galactic environments with dust evolution models Svitlana Zhukovska Max Planck Institute for Astrophysics Clare Dobbs (Uni Exeter), Ed Jenkins (Princeton Uni) Ralf Klessen (Uni Heidelberg) Thomas Peters, Thorsten Naab (MPA) Physics of ISM - 6 years of ISM-SPP 1573

2 Dust as diagnostics - extinction, emission, polarization, spectroscopy Molecular gas, star formation Magnetic fields Temperature Chemistry, optical depth Dust as active player Reprocessing of stellar light Surfaces for molecule formation Cooling agent Formation of planets and stars Grain properties Gas-to-dust ratio Chemical composition Optical properties Grain size distribution

3 Dust growth by accretion Young stars SN II AGB stars New grains Dust shattering, disruption by SNe COLD CLOUDS SN Ia DIFFUSE MEDIUM Dust growth by accretion Young stars SN II AGB stars New grains Dust shattering, disruption by SNe COLD CLOUDS SN Ia DIFFUSE MEDIUM

4 Why do we care about dust sources? Type II Supernovae Short timescales <40Myr Low dust masses per SN (<10-3 M sun ), GDR in ejecta: ~ Msun of dust per SN (Zhukovska+2008) Discovery of larger dust mass in SN1987A (talk by Phil Cigan) Cassiopeia A Low-mass stars at AGB (0.8 M sun <M<8M sun ) Long timescales 40 Myr - few Gyr Observations Gas-to-dust ratio ~ Theory: Ferrarotti&Gail 2006, Zhukovska+2008, Nanni+2013, 2014, Di Criscienzo+2013, many others oxygen, carbon-rich dust mass on fine M *, Z * grid

5 Why do we care about dust sources? Dust growth in ISM Timescale depends on local conditions, ZISM Critical metallicity Different dust properties? (Cornelia s talk) Sticking coefficient τ gr ~ Z α a 3 υ th n H a 3 = a3 a 2 Metallicity Mean grain size Zhukovska 2008 One zone chemical models of dust evolution Dwek 1998, Zhukovska+2008, Calura+2008,

6 LMC - local dust laboratory SAGE+HERITAGE Predictions for accumulated stardust Msun without destruction Msun with destruction Observed dust mass in ISM Msun log Production Rate Zhukovska&Henning 2013 first comparison of dust production rates by stars from theory and observations Evolution time [Gyr] now Zhukovska&Henning 2013

7 Constraints for SN dust from dwarf galaxies BCDs & dirr: young, small, gas-rich systems Spread in metallicities 7.2<12 + log (O/H)~ 8.6 Lots of dust, spread in dust-to-gas ratios I Zw 18 NASA/ESA/Y Izotov/T Thuan) GDR steepens at low Z Remy-Ruyer, Zhukovska+2014

8 Dust-to-gas ratio in dwarf galaxies Model 1: t burst =500 Myr, τ SF = 0.2 Gyr Model 2: t burst =500 Myr, τ SF = 2 Gyr Model 3: t burst =50 Myr, τ SF = 2 Gyr Models: Enhanced dust formation in SNII NO dust growth in ISM Zhukovska 2014

9 Dust-to-gas ratio in dwarf galaxies Low efficiencies of dust condensation in SNe Model 1: t burst =500 Myr, τ SF = 0.2 Gyr Model 2: t burst =500 Myr, τ SF = 2 Gyr Model 3: t burst =50 Myr, τ SF = 2 Gyr No single critical metallicity for transition: higher SFR higher Z crit, but shorter t crit Higher SFR Dust growth operates after a SF burst (opposite to SNII dust) Evolved galaxies are dominated by dust growth in ISM Models: Modest dust formation in SN II WITH dust growth in ISM Zhukovska 2014

10 Turbulent life of grains in multi-phase ISM with SILCC Smaller simulation box 500x500pc 10 6 tracer particles max resolution 4pc Cycle of matter between phases Mass exchange between phase Residence times Peters, Zhukovska+SILCC 2017

11 Turbulent life of grains in multi-phase ISM Residence time in ISM phase defined by temperature defined by chemistry Peters, Zhukovska+SILCC 2017

12 Dust evolution model Gas-to-dust ratio Roman-Duval+2014 First works to include dust in simulations Bekki 2013, 2015a,b, Yozin&Bekki 2014, Aoyama+2016 SPH simulations McKinnon+2016 AREPO AMR simulations New Dust Lifecycle Model Zhukovska, Dobbs, Jenkins, Klessen 2016 Dust evolution via post-processing of numerical simulations Improved dust model Growth by accretion in ISM Dust destruction Temperature-dependent sticking coefficient Effect of ion-grain collisions on growth timescales SNe in molecular clouds destruction in the diffuse phase

13 3D dust evolution models Stellar gravitational potential with 2-4 armed spiral component Heating and cooling Self gravity Stellar feedback instantaneous Evolution of spiral Milky Way-like disk thermal+kinetic energy added as Sedov solution 8 million SPH particles log column density [g/cm 2 ] m shp =312 M sun Evolution time 300 Myr Dobbs&Pringle 2013

14 Dust destruction/production balance Rate [M Gyr -1 pc -2 ] ECMRN3nm SN destruction, 3D model ISM growth, 3D model ISM growth, 1D model Stardust, 1D model Production Rate, % to total log n gas [cm -3 ] 10-3 Dust grows in CNM Time [Myr] Balance between destruction and production after ~130 Myr ISM growth rate 5-30 times larger than stardust production rate Zhukovska et al 2016

15 Timescales of growth and destruction Production, ECMRN3nm Production, CMRN3nm Destruction, CMRN3nm Lifetime in steady state is similar to classical lifetime of grains τ d ~0.5 Gyr Jones+1996, Bocchio+2015 Timescales [Gyr] τ destr = M ISM f SN R SN m cleared Time [Myr]

16 3D dust evolution models Clues from Si gas phase abundances log Si gas abundance relatively to solar [Si/H] gas N H, cm -2 Zhukovska et al, in prep

17 Gas evolution 3D dust evolution with 3D hydrodynamics models Clues from Si gas phase abundances WNM Depletion data from Jenkins 2009 CNM Local densities from C I fine structure lines from Jenkins&Trip 2011

18 3D dust evolution models Clues from Si gas phase abundances Double slope synthetic relation steeper slope of -0.5 determined by growth 1 dex dispersion similar to the observed data

19 3D dust evolution models Gas-to-dust mass ratio 600 mean 600 mean GDR GDR Σ gas, M pc A V Zhukovska et al, in prep

20 Take away messages Observations of local galaxies provide constraints for dust sources in dust evolution models: Dust re-formation in ISM dominates production in evolved galaxies Timescales of dust destruction/re-formation ~0.5 Gyr < timescale of dust input by stars Dust-to-gas ratio in the ISM is not the same: at least a factor of 2 Double slope of the [Si/H] gas -ngas relation: steeper slope of -0.5 in CNM explained by models with dust mass growth Sticking coefficient must decrease with T gas in hydrodynamic galactic simulations