ARCCOSCentre of Excellence in Evolutionary Cosmology

University of Central Lancashire

Galaxies on a MeshGalaxies on a Mesh

Brad Gibson

Stephanie Courty, Chris Brook, Patricia Sanchez-Blazquez, Romain Teyssier

ARCCOSCentre of Excellence in Evolutionary Cosmology

What We Did…What We Did…

• parent cosmological dark matter simulation from Projet Horizon• select halo randomly• “zoom”-style re-simulation w/7 more levels w/baryonic physics (res = 400pc; 106 M)

• analyse• repeat (touch on just 2 here, 1 of which was simulated with and without a polytropic equation of state ISM formalism)

We may not be the first, but we’re the first with a gridcode (to z=0, anyways):

cf. Sommer-Larsen et al (2003); Abadi et al (2003); Governato et al (2004,2007); Robertson et al (2004); Okamoto et al (2005); Bailin et al (2005)

ARCCOSCentre of Excellence in Evolutionary Cosmology

What We Found (or are finding…)What We Found (or are finding…)

• Basic Characteristics • Disk Kinematics• Disk Chemistry• Disk Edges• Accretion History• Future Directions

Data looking for exploitation… please send suggestions.

ARCCOSCentre of Excellence in Evolutionary Cosmology

Basic CharacteristicsBasic Characteristics

B/D0.6; 0.02; fast rotating galaxy occupying a low-spin halo

ARCCOSCentre of Excellence in Evolutionary Cosmology

Comparing Star Formation HistoriesComparing Star Formation Histories

cf. Fenner, Murphy & Gibson (2005)semi-numerical MW model

cf. Bailin et al (2005) cosmological disk (GCD+ w/Abadi et al (2003) ICs) & Brook et al (2004) semi- cosmological disk (both SPH)

(Bailin)(Brook)

ARCCOSCentre of Excellence in Evolutionary Cosmology

MetallicitiesMetallicities

Gas

60 kpc

0.03 dex/kpc

Stars

ARCCOSCentre of Excellence in Evolutionary Cosmology

Disk Kinematics: Disk Heating & the Thick DiskDisk Kinematics: Disk Heating & the Thick Disk

Quillen & Garnett (2001)

Holmberg et al (2007)

cf. Bailin et al (2005) cosmological disk (GCD+ w/Abadi et al (2003) ICs) & Brook et al (2004) semi-cosmological disk (both SPH)

(Bailin)(Brook)

Thick disk?

Brook, Courty, BKG (2008)

ARCCOSCentre of Excellence in Evolutionary Cosmology

Disk KinematicsDisk Kinematics

The thick disk (in Bailin et al 2005 disk w/Abadi et al ICs) lagsmuch like the spirals in Yoachim & Dalcanton (2008), butobservations say….

• mass-dependent lag (YD08)• Rthick > Rthin (YD06)• Rthick : Rthin independent of environment (Santiago & Vale 2008)

Brook, Courty, BKG (2008)

ARCCOSCentre of Excellence in Evolutionary Cosmology

Disk Edges: GasDisk Edges: Gas

Lopsided HI gas disk with truncation nearR=19kpc and NHI=2x1019 cm-2

cf. THINGS (nice agreement)

Extended ionised disk cf. Bland-Hawthorn et al (1997)

N(HI)

N(HII)

BKG et al (2008), if I have to…

ARCCOSCentre of Excellence in Evolutionary Cosmology

Disk Edges: Stars / Radial MigrationDisk Edges: Stars / Radial Migration

Sanchez-Blazquez, Courty, BKG (2008); cf Roskar et al (2008ab)

Bandpass / HeightIndependent Breaks

.. but.. radial migration does occur

U-shaped age behaviourreflected in colour gradients;differential star formation ininner vs outer disk (cf. Roskar)

ARCCOSCentre of Excellence in Evolutionary Cosmology

Gas Accretion HistoryGas Accretion History

1 0.5 M/yr of gas flux at R=30 kpc

2 1 M/yr of vertical gas flux at z=6 kpc

cf. Fenner et al (2005)semi-numerical MW model

Courty, BKG (2008); cf Dekel et al (2008), Ocvirk et al (2008)

ARCCOSCentre of Excellence in Evolutionary Cosmology

Future DirectionsFuture Directions

• Higher resolution

ARCCOSCentre of Excellence in Evolutionary Cosmology

Higher Resolution - Fully CosmologicalHigher Resolution - Fully Cosmological

400pc (stars)

400pc (gas)

200pc (stars) 200pc (gas)

200pc (gas)

ARCCOSCentre of Excellence in Evolutionary Cosmology

Future DirectionsFuture Directions

• Higher resolution• Scaling relations (mass, environment)• ISM physics (polytropic index; blast wave parametrisation)• Warp/lopsidedness characterisation• “Lick” indices• Dusty radiative transfer• High-Velocity Clouds• Radial flows• SPH vs AMR comparisons w/identical initial conditions• GEtool/GCD+ chemistry to RAMSES [Chemical Tagging]

ARCCOSCentre of Excellence in Evolutionary Cosmology

SummarySummary

• the first fully cosmological hydro-mesh disks taken to z=0?• at 400pc resolution, the AMR simulations suffer from similar overmerging/overcooling/ovencentralisation as the SPH ones• RAMSES is extremely efficient (recent 200pc run completed in 1 week, wall time)• saturated disk heating in semi-cosmological SPH simulations not clearly replicated (yet) in cosmological simulations• neutral gas disk edges truncate at comparable column densities to observed edges; ionised disks extend beyond the neutral disk, as observed• radial stellar migration is observed, with surface brightness and colour profiles consistent with those observed• disk “size” also growing more or less in agreement with observations• gas accretion (cold and hot) is both “smooth” and “clumpy”, but growth remains more-or-less “inside-out”• disk-halo circulation “flux” is >> infalling “flux” (10-50x, but highly preliminary), as observed