Dynamic and Spatial Properties of Satellites in Isolated Galactic Systems Abel B. Diaz

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Dynamic and Spatial Properties of Satellitesin
Isolated Galactic SystemsAbel B. Diaz
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Presentation Outline

• Rotation Curves Probing the mass distribution
• The Problem
• Rotation Curves of Isolated Galaxy Systems
• Stellar properties of Satellites
• The Holmberg effect
• 2D Rotation Curve

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Rotation CurvesProbing the mass distribution

• Within Galaxy
• Well known
• External to Galaxy
• Not well known

Fritz Zwicky (1933) Babcock (1939)Vera Rubin
(1970)
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The Problem

• How does the mass distribution of galaxies change
  with distance beyond the disk of the galaxy?

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What would this tell us?

• Learning more about the mass distribution of
  isolated galaxies may provide insight into galaxy
• formation
• evolution
• LSS

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So how can this be done?

• Rotation Curves of Isolated Galaxy Systems
• Dominate source of gravitation
• The center-of-mass of the system is located at
  center of primary galaxy
• Satellites relatively small compared to primary
• Maintains center-of-mass located at the center of
  primary

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Limits on Isolated Galaxies

• Small number of detectable satellites
• Line-of-sight velocity
• Projected distance

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Isolated Galaxy Ensembles
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Interlopers

• Observed redshift cosmological redshift
  Doppler redshift
• The peculiar velocities of the satellites can be
  on the order of 400km/s
• Uncertainty of distance along the line-of-sight

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Velocity Dispersions
McKay (2002), Prada et al (2003), and Brainerd
(2004)
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The Data Sample

• New York University Value-Added Galaxy Catalog
  (NYU-VAGC)
• Lowz (Sub Sample of 50,000 galaxies)

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Ensembles
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Robust Analysis
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Velocity Dispersion Curve
Prada et al (2003), and Brainerd (2004)
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Galaxies Types
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Early vs. Late

• Early type galaxies have larger halos than late
  type galaxies
• Conroy et al. (2007)

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What These Results Tell Us

• Rotation curve (consistent with NFW)
• Supports hierarchical scenario
• Halo sizes
• Larger primordial dark matter halos for early
  type galaxies than for late type galaxies

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Stellar Properties

• How does the satellite stellar properties change
  as a function of distance from the primary?
• Star formation from self gravity or tidal effects
  from primary

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Stellar properties of Satellites
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What Does This Mean

• Primaries cause "tidal" effects on their
  satellites
• Kosh and Grebal (2006)
• More pronounced in satellites with primaries that
  have a larger mass (halo)
• Different distribution in Systems at larger z
  (longer ago)

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The Holmberg Effect
Holmberg (1969)
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Modeling

• Check for Isotropy
• polar fraction 0.70
• Mean f 45 degrees
• Interloper check
• P/T 0.5

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Results for Primary tilt No Holmberg found in my data
Kolmogorov-Smirnov (KS) test
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Results for Varying tilts angle
No Holmberg found in my data
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Binned Results for Primary tilt Brainerd (2005)
Sales Lambas (2004), Koch Grebel
(2006) Zaritsky et al. (1997)
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Binned Results for Primary tilt 60o
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What does this tell us?

• Dark Matter halo
• Spherical
• Puts constraints on models
• Infall through fillaments

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2D Velocity Dispersions

• Velocity Distribution
• Isotropic about primary
• DM halo
• Spherical

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Conclusion

• The Dynamic Properties
• Dark Matter Halos
• Different sizes for different type of galaxies
• Consistent with NFW (hierarchical scenario)
• The Spatial Properties
• Satellites are isotropically distributed, and
  have isotropic velocity distribution
• Spherical Dark Matter Halo
• Star formation depends on distance from their
  primary
• Primaries effect their satellites