Assigned ID: 1014 ----- Attempting Submission 1 (Sat Feb 26 23:33:22 GMT 2011) ----- HST Phase I Proposal 1014 (SED_cyc19.apt) successfully submitted. ----- Attempting Submission 2 (Sat Feb 26 23:50:28 GMT 2011) ----- Gravitational lensing does not just brighten galaxies, it stretches them into long arcs providing a great opportunity to analyze star formation and stellar populations in z=1-2 galaxies at unprecedented resolution- especially with HST. (1) We will study the distribution of Star Formation Intensity (i.e. star-formation rate per unit area, hereafter SFI) in well resolved arcs. Lensing conserves the surface brightness of lensed galaxies, even as it magnifies the objects in size and luminosity, allowing us to study the SFI distribution independent of lensing models. Starburst galaxies at redshifts z=0-6.7 show a definite upper limit to the intrinsic SFI independent of redshift. We will test whether this limit also holds at smaller spatial scales. (2) Our next analysis, pixel-to-pixel modelling of Spectral Energy Distributions (SEDs), will yield stellar populations and Star-formation-histories(SFH) of redshift 1-3 galaxies at an unprecedented spatial resolution. Stellar population modelling of z > 1 galaxies reaches 1 Kpc resolution at best, even with HST. Mixing populations at this scale can result in young stars dominating the light. WIth our pixel-to-pixel analysis, we will measure variations of stellar population across the galaxy at resolutions of up to 100 parsecs. In particular, we will quantify old stellar populations better by resolving out and separating young star-forming regions. We will then do SED fitting of the whole arc to calibrate how the analysis of the average light differs from a spatially well resolved analysis.

UNRESOLVED STELLAR POPULATIONS AND GALAXY STRUCTURE 12 Small false 0.0 0.0 false false false false SUPPORTED