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Morphological Analysis of LAEs

Morphological Analysis of LAEs. Group Discussion Chair: Nicholas Bond. Possible Uses of this Discussion. Ascertain status of our current knowledge of LAE morphologies Guide the future direction of LAE morphology determination Critique methods already in use

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Morphological Analysis of LAEs

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  1. Morphological Analysis of LAEs Group Discussion Chair: Nicholas Bond

  2. Possible Uses of this Discussion Ascertain status of our current knowledge of LAE morphologies Guide the future direction of LAE morphology determination Critique methods already in use Advertise relevant papers, codes, techniques

  3. Morphologies of Star-Forming Galaxies at Low Redshift (Ostlin et al. 2005) highly varied: Ly, H, UV have distinct morphologies diffuse Ly often present, resonant scattering likely important kinematic properties may be most important factor in determining Ly brightness

  4. High-z LAEs Gronwall et al. Pirzkal et al. 2007 (4 < z < 5.7, 9 objects) - average size of 0.92 ± 0.50 kpc Venemans et al. 2005 (z=3.13 overdensity, 17 objects) ~ 25% unresolved with limits r < 0.6 - 1.3 kpc, ~ 55% resolved with r < 1.5 kpc Overzier et al. 2007 (z=4.1 overdensity, 12 objects) all < 3 kpc, mean of ~1 kpc Gronwall et al., in prep (z ~ 3.1, 28 objects) r ~ 0.4 - 2.3 kpc, majority are sub-kpc Bond et al., in prep.

  5. Substructure and Profile Shapes Bond et al. Pirzkal et al. 2007 (4 < z < 5.7, 9 objects) centrally concentrated ~45% show clumpy structure Venemans et al. 2005 (z=3.13 overdensity, 17 objects) ~ 20% show multiple clumps Gronwall et al., in prep (z ~ 3.1, 28 objects) wide range of Sersic indices most have C > 2.5 Venemans et al.

  6. What is the best morphological diagnostic for high-z LAEs? 2” Sersic index? Concentration/Asymmetry Parameters? Gini Coefficient? (Lotz et al. 2004) Other? How do these diagnostics depend upon depth for irregular/clumpy morphologies? Bond et al., in prep.

  7. What is the best morphological diagnostic for high-z LAEs?

  8. What software is available for morphology fitting of high-z galaxies? Which is optimal LAEs? Sextractor (Bertin & Arnouts 1996) GALFIT (Peng et al. 2002) GIM2D (Simard et al. 1999) Other?

  9. Which Rest-frame Wavebands Should We Target? • Ly imaging important to pinpoint line-emitting regions, but… • poor tracer of host morphology • subject to resonant scattering • requires long exposures from space-based observatories Pirzkal et al. 2006

  10. Distinguishing point sources from extended objects • important for determining LAE sizes, should be checked in both low-resolution (~1”) and high-resolution (~0.05”) images • F-test can be used -- 2 indicates relative improvement over PSF with multi-parameter fit (e.g. Sersic profile) • drizzling produces correlated noise, complicating 2 analysis Bond et al.

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