Numerical simulations of galaxy formation in a lcdm universe
This presentation is the property of its rightful owner.
Sponsored Links
1 / 21

Numerical Simulations of Galaxy Formation in a LCDM Universe PowerPoint PPT Presentation


  • 89 Views
  • Uploaded on
  • Presentation posted in: General

Mario G. Abadi Observatorio Astronómico De La Universidad Nacional De Córdoba CONICET, Argentina Collaborators: Julio Navarro: University of Victoria, Canada Matthias Steinmetz: Astrophysikalisches Institute, Postdam, Germany Vincent Eke: University of Durham, United Kingdom

Download Presentation

Numerical Simulations of Galaxy Formation in a LCDM Universe

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Numerical simulations of galaxy formation in a lcdm universe

Mario G. Abadi

Observatorio Astronómico De La Universidad Nacional De Córdoba

CONICET, Argentina

Collaborators:

Julio Navarro: University of Victoria, Canada

Matthias Steinmetz: Astrophysikalisches Institute, Postdam, Germany

Vincent Eke: University of Durham, United Kingdom

Andres Meza: Universidad de Chile, Santiago, Chile

Amina Helmi: Kapteyn Astronomical Institute, Groningen, Netherlands

Numerical Simulations of Galaxy Formation in a LCDM Universe


Lcdm universe

LCDM Universe

  • WMAP and LSS results have established LCDM model as the new paradigm of hierarchical structure formation

  • Low mass density but flat scenario

  • Fully specified by the following cosmological parameters:

  • Constituents 70% dark energy, 26% dark matter and 4% baryons

  • Amplitude of mass fluctuation in spheres of 8 Mpc/h is given by RMS=0.9 and a Hubble´s constant h=0.7with no tilt in the initial power spectrum

  • Success in LS (>1mpc) closer to linear regime


Galaxy formation

Galaxy Formation

  • Observed disk at odds with ”natural” trends of hierarchical models

  • Difficult to reconcile the early collapse and eventful merging history with dynamical clues which point to a smooth assembly of disks

  • Fragility of disks to rapid fluctuations of the gravitational potential such as those stirred by mergers or satellite accretion events

  • Dominant, cold, thin, stellar disks points to a histoty of mass accretion where major mergers have player a minor role

  • Age of oldest disk stars used to estimate the epoch of the last major merger (14 gyrs in the solar neighborhood)

  • Milky Way’s thick disk has its origin in an early thin disk of velocity and size comparable to today’s but “thickened” by the accretion of a satellite


Numerical simulations

Numerical Simulations

  • Initial conditions given by the lambda CDM model

  • Astrophysics: gravitation, hydrodynamics, radiative cooling, star formation, feedback and metals

  • Initially only dark matter and gas particles

  • Gas particles transformed in star particles

  • 8 simulations finished with M~ 1-2x10^11 solar masses and N~0.6-1.8x10^5 star particles inside 20 kpc @ z=0


The formation and evolution of a disk galaxy

The Formation and Evolution of a Disk Galaxy


Luminous galaxy radius 20 kpc

Luminous GalaxyRadius ~ 20 kpc


Dark matter halo virial radius 300 kpc

Dark Matter HaloVirial Radius ~ 300 kpc


Luminous stellar halo virial radius 300 kpc

Luminous Stellar HaloVirial Radius ~ 300 kpc


Observational and theoretical approach

Observational and Theoretical Approach

  • Observational

  • Photometric (luminosity, isophotes, surface brightness profile decomposition, bulge to disk ratio, fundamental plane, colors, star formation)

  • Kinematics (gas and stars rotation curves, velocity maps, Tully fisher and Faber Jackson relation)

  • Theoretical

  • Dynamics (dark matter, gas and stars properties, evolution, mass distribution, velocity support, dynamical decomposition, in-situ vs accretion, origin of different components)


All stars

All Stars


Spheroid

Spheroid


Thick disk

Thick Disk


Thin disk

Thin Disk


Dynamical decomposition

Dynamical Decomposition


The formation and evolution of a disk galaxy1

The Formation and Evolution of a Disk Galaxy


Disk vs halo formation

Disk

Young (90%) + old (10%)

Rotational velocity supported

Outcome of a smooth dissipative deposition (and transformation into stars) of gas cooling more or less continuously off the intergalactic medium

Eggen Lynden-bell & Sandage (1962)

Correlations between metallicity and kinematics of 221 stars in the solar neighborhood

Halo

Old (predate the last major merger)

Velocity dispersion supported

Build up over an extended period of time through a number of early mergers

Searle & Zinn (1978)

Wide range of metal abundances independent of radius for 177 red gigants in 19 globular clusters

Disk vs Halo Formation


Halo evidence of accretion events

Halo Evidence of Accretion Events

  • Tidal streams of the Sagittarius dSph galaxy (Ibata el al. 1994)

  • Substructure in the galactic halo (Helmi et al. 1999)

  • Giant stream of metal-rich giants around Andromeda (Ibata el al. 2001)


Disk evidence of accretion events

Disk Evidence of Accretion Events

  • Monoceros ring in the outer Galaxy (Yanny et al. 2003)

  • Canis Major dwarf (Martin et al. 2004)

  • Arcturus stream (Navarro et al. 2004)

  • Debris from omega Cen parent galaxy in the solar neighborhood (Meza et al. 2005)

  • Substructure in the Galactic disk (Helmi et al. 2005)


Conclusions

Conclusions

  • Galaxy componets in cosmological context: spheroid, thin disk, thick disk, but also stellar halo, satellites and dark matter halo

  • Simulated galaxies resemble observed galaxies, surface brightness, colors, etc

  • Different implementation of astrophysical effects in order to avoid efficient star formation at early times and massive spheroid and stellar halos

  • Stellar halos form from mergers

  • Disk form from dissipative collapse

  • There is growing evidence that the hierarchical models are correct


The inner milky way

The Inner Milky Way

Inner bright components: spheroid (or bulge), thin disk and thick disk

  • Infrared Milky Way image (DRIBE COBE NASA)


The outer milky way

The Outer Milky Way

Inner bright components: spheroid (or bulge), thin disk and thick disk

Outer faint components: satellites and stellar halo both difficult to detect in other galaxies

Outer dark components: dark matter halo and substructure

  • Infrared Milky Way image (DRIBE COBE NASA)


  • Login