Spectroscopic Indicators of Galaxy Evolution:

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Spectroscopic Indicators of Galaxy Evolution

• Early-type Galaxies in Cl002416 at z0.4

Sean Moran Ge/Ay 132
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Large Scale Surveys of Cl002417 (z0.39) and
MS0451-03 (Z0.54)

• Cl0024
• 39 sparsely sampled WFPC2 images, to 5 Mpc
• Spectra of over 200 members
• MS0451
• Full coverage with 40 ACS pointings in progress
• Complimentary cluster 8x LX of Cl0024

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Morphology-Densityand Environmental Processes

• Mix of galaxy types depends on where you look
• More Ellipticals in cluster centers
• Clusters laboratories to study galaxies over a
  large range of S
• Chicken or Egg
• initial conditions (E/S0 form in initially denser
  regions)
• environmental processes (galaxies are transformed
  by environment as they fall into denser regions.)

Treu et al. (2003)
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Environmental Processes

• Spectral Properties as fn of radius to
  disentangle these processes
• First results on Cl0024 look at Early type
  galaxies OII, OIII, H?, Hd
• Are there abrupt and/or gradual changes in galaxy
  properties?

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OII
(Osterbrock 1989)

• Emission from OII 3726, 3729Å can indicate
  ongoing star formation (HII regions near O, B
  stars)
• Transitions from
• 2D3/2-4S3/2
• 2D5/2-4S3/2
• Also prominent in AGN

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OIII
(Osterbrock 1989)

• Emission from OIII 4959Å , 5007Å can also
  indicate star formation
• Transitions from
• 1D2-3P2
• 1D2-3P1
• Additional transition at 4363A too weak at these
  distances (1S0-1D2)
• Also in AGN

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H?, Hd

• Hydrogen Balmer absorption may indicate recent
  star formation
• A and F stars relatively short-lived, but exhibit
  strong Balmer lines
• Balmer emission may indicate either AGN activity
  or more HII regions from O, B stars.
• Line ratios help distinguish

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• AGN show emission in H?, sometimes in Hd
• For non-AGN, EW of lines increases w/ radius
• Population of early types shows some star
  formation at edge of cluster

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Conclusions

• Via OII, OIII, we identify AGN within a
  narrow range in cluster radius
• OII, H?, Hd EWs increase outward some early
  types undergo gentle interaction with cluster
  environment
• Will want to see if the trends in spectral
  features of spiral galaxies are as abrupt as we
  see for early types.