Galaxies on a Mesh
description
Transcript of Galaxies on a Mesh
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