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Galaxies on a Mesh

Galaxies on a Mesh. Brad Gibson. University of Central Lancashire. Stephanie Courty , Chris Brook, Patricia Sanchez-Blazquez, Romain Teyssier. What We Did…. parent cosmological dark matter simulation from Projet Horizon select halo randomly

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Galaxies on a Mesh

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  1. Galaxies on a Mesh Brad Gibson University of Central Lancashire Stephanie Courty, Chris Brook, Patricia Sanchez-Blazquez, Romain Teyssier

  2. 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)

  3. 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.

  4. Basic Characteristics B/D0.6; 0.02; fast rotating galaxy occupying a low-spin halo

  5. Comparing Star Formation Histories 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) cf. Fenner, Murphy & Gibson (2005)semi-numerical MW model

  6. Stars 0.03 dex/kpc Metallicities Gas 60 kpc

  7. Disk Kinematics: Disk Heating & the Thick Disk Brook, Courty, BKG (2008) 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) Holmberg et al (2007) Thick disk? Quillen & Garnett (2001)

  8. Disk Kinematics Brook, Courty, BKG (2008) • 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)

  9. Disk Edges: Gas BKG et al (2008), if I have to… Lopsided HI gas disk with truncation nearR=19kpc and NHI=2x1019 cm-2 cf. THINGS (nice agreement) N(HII) N(HI) Extended ionised disk cf. Bland-Hawthorn et al (1997)

  10. Disk Edges: Stars / Radial Migration Sanchez-Blazquez, Courty, BKG (2008); cf Roskar et al (2008ab) .. but.. radial migration does occur Bandpass / HeightIndependent Breaks U-shaped age behaviourreflected in colour gradients;differential star formation ininner vs outer disk (cf. Roskar)

  11. Gas Accretion History Courty, BKG (2008); cf Dekel et al (2008), Ocvirk et al (2008) 1  0.5 M/yr of gas flux at R=30 kpc cf. Fenner et al (2005)semi-numerical MW model 2  1 M/yr of vertical gas flux at z=6 kpc

  12. Future Directions • Higher resolution

  13. Higher Resolution - Fully Cosmological 400pc (stars) 200pc (stars) 200pc (gas) 200pc (gas) 400pc (gas)

  14. Future 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]

  15. Summary • 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

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