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Wide Field Camera 3:
The SOC Science Program Proposal


Text

An extraordinary panchromatic survey efficiency covering a critical decade of frequency space combined


Theme I: Star Formation at Half the Hubble Ti


Star Formation at Half the Hubble Tim
The Big Questions

What determined the properties that galaxies have today?

What set the balance between star formation and galaxy as How did feedback shape the galaxy mass function?


Star Formation at Half the Hubble Tim
Objective: To probe downsizing and merging in th critical 1 < z < 2 range by the:

Measurement of the star formation and stellar mass assemb rates from H-alpha grism spectroscopy and the rest-frame UV

Determination of the evolution of the faint end slope of the luminosity and mass functions.


Downsizing in Star Formation
Measure star-formation rates from H and UV continuum as a function of total stellar mass and environment for 0.7 < z < 2.5 Probe the LF down to M ~ 0.01M* Probe high, average and low density environments at z ~ 1.5. Understand SFR f(mass, z, ) and bridge from the present to z ~ 3.

from Juneau et al.


The LF as a Probe of Feedbac
Lambda-CDM predicts an LF much steeper than observed at the faint end AGN & SNe feedback and tidal stripping shape the bright & faint ends, respectively. The faint-end slope should evolve with redshift and environment. With WFC3 we can probe the faint-end slope at 0.7 < z < 2 with high precision

WFC3 Range


WFC3 IR & UV Survey at Intermediate Redshifts
UVIS imaging in F225W, F275W & F336W UV G280 prism slitless spectra 2000-4000A NIR imaging in F125W & F160W NIR G141 grism slitless spectra 1.1 - 1.7m Build on existing ACS & spectroscopic survey fields
Existing ACS WF3 IR

WF3 UV


Preliminary Orbit Requirement

Three Fields are to be selected from GOODS or COSMO @ high, average and low densities. Overlap with GRAPES/PEARS sought, if possible.


Theme II: Star Formation in Nearby Galaxies


Star Formation in Nearby Galaxi The Big Questions
How does star formation, and its history, vary amongs galaxies of different types?

What triggers & regulates star formation?

How universal is the Initial Mass Function?


Wide-Field Panchromatic Imaging
UV (200 - 400 nm; critical for star cluster age dating)

IR (to penetrate dust cocoons around the youngest reg of star formation)

Narrow band (to determine physical parameters such shock parameters, gas pressure, ionization parameters, s formation rates, etc.)


Overall Approach

To observe star formation in a wide range of environments in the local universe to determine how star formation is triggered, how it is regulated through feedback, and the degree to which it is universal.


Subaru

Cha

Spitzer


Strategy:
Broad band panchromatic filter set to distinguish age, metallicity, and extinction: F225W, F330W, F435W, F550M, F814W, F110W, F160W

Narrow band filters for ISM shocks, pressure, abundance, extinction & excitation: F373N [O II], F487N H-beta, F502N [O III], F656N H-alpha F673N [S II], F128N P-beta, F164N [Fe II]

Build on existing data sets, both HST (primarily ACS, WFCP2, STIS) and others (SPITZER/SINGS, CHANDRA, ANGST, GALEX, radio, etc.)


NGC 5253
UV+ V + IR

Panchromatic continuum images, plus extinction from Balmer Line Imaging gives the detailed star formation rate, star formation history and extinction distribution


NGC 5253
UV+V+I
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NGC 52

H-alpha, H-B [OIII] & [S

Panchromatic continuum images, plus extinction from Balmer Line Imaging gives the detailed star formation rate, star formation history and extinction distribution

Balmer Line and Forbidde Line ratios form Diagnosti Plots which separate the shock-excited gas from th photoionized gas (Dopita, Calzetti).


Examples of Diagnostic Plots
Observations: Calzetti et al. 2007 Models: Kewley & Dopita ShockExcited Regime

High Velocity Shock Mod Allen, Dopita & Kewley 2

Photoionized Regime

These tools quantify the energetics and the stellar energy feedb into the ISM of the galaxy observed. They identify outflows and


xample: Cluster Age dating & Triggering

Clusters in a HII super-bubble in the Antennae Galaxy

Cluster Ages

Ionized Hydrogen

The Age gradient implies there has been triggered star forma

The HII super-bubble is centered on the old cluster, the you clusters are located in the dusty shell of the super-bubble.

The young clusters have a total mass of 4 E6 Msun, some fiv more than the cluster which triggered their formation.


Measurement of star cluster formation histories back to ~10 Gyr to use fossil record of the assembly history of galaxies (e.g., to compare with results from the intermediate-Z proposal).

Exploration of the role of feedback. Obtain a full census of shock ioniz in a variety of galactic physical and metallicity environments, and deriv efiiciency parameter for feedback.

Determination of whether the star formation laws (e.g., Schmidt law, cl mass and size functions, fractions of star formation in clusters/field, ...) the same in different environments.

Measurement of the IMF down to ~0.1 Msolar in R136/30 Dor and NG 3603 to determine if it is top-heavy in starbursts (will these clusters sur become globular clusters ?).


Nearby Galaxies covering a wide range of typ


Grand Design Starburst NGC4214 - Dwarf Gas-Rich


or - Massive LMC Star Cluster


Preliminary Orbit Requirements