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EARLY TYPE GALAXIES: proposal summary for WFC3 SOC J. Silk + SOC (+ Kaviraj, Ferreras, Kay, Yi). Low redshift (z<0.1) early-type galaxies show widespread (>30%) recent star formation, 1-5% mass fraction, 300-500 Myrs old
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EARLY TYPE GALAXIES: proposal summary for WFC3 SOC J. Silk + SOC (+ Kaviraj, Ferreras, Kay, Yi) • Low redshift (z<0.1) early-type galaxies show widespread (>30%) recent star formation, 1-5% mass fraction, 300-500 Myrs old • Complex dynamic history revealed by age-correlated core kinematics • Merger histories with extended SFH are needed to fit multi-wavelength photometry • Did gas-rich major mergers of intermediate mass E’s form more massive E’s? Or dry mergers? • Or many minor mergers? • Do cores trace SMBH feedback? e.g. via dynamical scouring and/or via feedback from SMBH-induced outflows during core formation • Recent population synthesis modelling with AGB prefers young and dusty SED: • gas is shed by AGB stars should be dusty, whereas IGM infall should be dust-poor • Need WFC3 angular resolution + NUV +NIR photometry to • Compute the mass fraction of young stars (<1 Gyr old) to quantify past merger ‘dryness’ • Accurately measure structural parameters to study the presence of substructure, e.g. embedded disks, to explore the mass ratios and morphologies of their progenitors • Compare the distribution of dust, young stars and age-dated substructure to simulated 2D maps to constrain characteristics of the last merger event and the gas history SNR ~10 per pixel 5-100pc resolution F225W, F336W(U), F438W(B), F555W(V) F814W(I), F 487N(H),F125W(J),F160W(H) 30-50 orbits
The GALEX NUV colour magnitude relation • Expected tight relation in optical (g-r) CMR • Monolithic scenario (dustless) should give similar CMR in the UV • But NUV CMR shows a spread of 6 mags - strong UV sources present in nearby early-type galaxies
THE POWER OF NIR Maraston 2006
ETGs have complex star formation historiesas viewed in their predecessors (ERGs) at z=1.5-3 old passively evolving young starburst Papovich et al. 2006
Pixel-by-pixel analysis: NGC 2974 (E3 type) Far-UV Near-UV Optical (F555W) GALEX UV detects star-forming ring at r=6.2kpc Pixel-by-pixel young+old 2-comp. analysis Age of young comp Mass of young comp
Stellar ‘age-maps’ in early-type galaxies Unambiguous presence of young stars in galaxy centre coincident with KDC! Kinematically decoupled core McDermid R. M., et al., astro-ph/06022318
Kinematically decoupled cores (McDermid et al. 06) SAURON-OASIS Data: Compact KDCs: • Small: 100 pc's(≤ 0.1 Re) • Lightweight • Young: distinct, increasingly young toward center • Rotators Classic KDCs: Large: kpc's(0.3-0.4 Re) Massive Coeval: homogeneous old Non-rotators
CO: central disks (Young & Bureau, in prep) BIMA-SAURON Data: NGC4459 • CO cospatial with young stars and central stellar/gas disk • CO and stars/gas co-rotating SAURON CO
Observing list F225W F336W(U) F438W(B) F555W(V) F814W(I) F487N(H) F125W(J) F160W(H) SNR ~10 per pixel 5-100pc resolution
DO MASSIVE ELLIPTICALS FORM BY MERGERS? Conselice 2005
Build-up of luminosity and star formation rate Bouwens, Illingworth et al 2006
DO MASSIVE ELLIPTICALS FORM BY MINOR MERGERS? Movie by T. Naab