Ensenada 08 The Formation of Disk Galaxies. Improvements, Challenges, Artificial Images F.Governato,AlysonBrooks,G.Stinson(MacMaster) B.Willman(CfA), L.Mayer (Zurich), T.Quinn, C.Brook, L. MacArthur (Caltech), J.Wadsley (McMaster) & the UW N-Body Shop + Patrik Jonsson (UCSC)
• Physical and Numerical Processes affecting the Mass Distribution in L* Galaxies•Artificial Images: Comparing Simulations with Observations•The Assembly of Galaxy Disks: Shocks or Cold Flows?
Cosmological hydro simulations of MW formation.(Ngas, Ndm > 106 within Rvir + BlastWave feedback model ) (Governato, Willman, Mayer et al. 2006, 2007) Frame = 200 kpc Green= Gas Blue & Red = Stars zLMM: z = 1. Spin = 0.036 Rd (I band) = 7.3 kpc B/D (I band) = 0.37 U-R = 1.55 WMAP cosmology Run carried to z=0 ~ 100k CPU hrs.
cosmological galaxy formation: 10 GalaxiesVolume renormalization technique: ~ 100 - 300 pc spatial resolution in a50Mpc box (DM + GAS) 300 MpcLarge scale tidal torques preserved,crucial for angular momentum of halosHalos masses: 1010- 3 x 1012 MoRange of Last major merger: ~ 5 - 1Range of halo spins: 0.01 - 0.05Within Virial Radius: 1e6 DM, 3 Mpc 1e6 Gas , 2-3e6 star particles.
Star Formation/Feedback Gas Stars Dynamical time Kroupa IMF SF efficiency Padova lifetimes SF Threshold Winds Metals < 8 Msun Blast SN Ia Wave > 8 Msun No Cooling SN II Stinson et al 20062 free parameters: C*, eSN
MW Satellites: UV field + SN feedback onBAR Cosmic AbundanceYONSTOD 30-50 Km/secMRATIO
But Feedback crucial to regulate star formationEffect of blastwave feedback on SFH of galaxy with halo of 1011 Mo If blastwave feedback is on, star formation peaks at Last Major Merger z< 1 AFTER Feedback OFF Last Major Merger. Feedback ON Progenitors forms stars inefficiently due to feedback SF in bulges suppressed. SFH includes all progenitors at any given time
How have Simulations of Galaxy Formation improved over the past few years?Algorithms + CPU Power (N: 10k to 3-5 million)Description of Physical Processes
I - Physical and Numerical Processes affecting the DM&baryon distribution In the central regions of Galaxies Catinella et al 06 Governato et al 07 100.000 DMVrot 1.000.000 DM Vrot converges at 2-3 Rd R/Rd R kpc
GADGET-2, No Feedback Naab et al Apj 07 Peak Vel decreases 30% as mass resolution Increases 125 fold.
Effects of Feedback. Zavala et al 08No FB FB on.
L. Mayer, 08The effects of limited resolution in gaseous disks Embedded in a DM + hot gas halo. Isolated disk galaxy + hot haloN=1.000.000 100.000 30.000 Eps 0.5kpc 0.5kpc 2kpc
Mass Distribution of GalaxiesResolution & Feedback Effects in a Milky Way sized galaxy No Star Formation Star Formation Star Formation+SN Feedback does not Change the mass distribution unless Coupling ~ 100%
Mass Distribution of GalaxiesResolution & Feedback Effects in a Milky Way sized galaxy Resolution + Star Formation + SN.
Baryon Distribution Gas Fraction Small Galaxies: FeedbackL* : Star Form. +Feedback +Resolution Galaxies>L* : SF+ ResolutionVc
Angular Momentum Loss in Galaxies • Dynamical friction on cold gas Navarro & White 96 • Angular Mom. Transfer in Gas Spiral waves: Linden-Bell & Kalnajs 1971• Torques from “grainy” DM halos (T.Kaufmann 07)• Artificial Viscosity @Hot/Cold gas Interface (Okamoto 06)
Rotation Curves RevisitedHigh-res galaxies - > 106 dm and gas/stars particles within Rvir Galaxies contain the right AmountKm/sec 320 of baryon and DM Within a few Rds 205 Km/sec 118 Km/sec
Using Sunrise… Monte-Carlo method “Photons” are emitted and scattered/absorbed stochastically (courtesy Patrik Jonsson) http://www.ucolick.org/~patrik/sunrise/ Stars Gas & MetalsDust follows the metal distribution of the gas component See also codes by Narayanan and Chakrabarti
A Multi Color, Dust reddened Milky Way like Galaxy formed in a cosmological simulation.
The Velocity- Size Relation Courteau 07 Sa High Res V: W20 Mag: Sunrise
The Assembly of Galaxy Components: The DiskBaugh et al 06
The New Model of Gas accretion: Cold Flows “Cold mode” (Keres et al. 04) hot accretion of galactic gas accretion: gas creeps along the equilibrium line between heating and Cooling. It never Shocks to Tvir. cold accretionCourtesy of Hoeft & Yepes
Gas Accretion I: disk stars @ z=0 clumpy cold flows shocked Halo Mass: 4e10 2e11 1e12 3e12 Brooks et al in prep.
Accretion of different components in L* Galaxies Stars accreted as stars form part of the bulge. (thick disk faint) Late accretion forms disks