David R. Law Hubble Fellow, UCLA The Physical Structure of Galaxies at z ~ John McDonald, CFHT Galaxies in the Distant Universe: Ringberg Castle May 17, 2010

Summary Star-forming galaxies have globally high  Galaxies with M * < M  have little velocity shear Galaxies with M * > M  show more pronounced shear Rest UV/optical morphologies similar for low M *, differ over M * Strong mass-radius relation What are the spatially resolved properties of z~2-3 galaxies?

Redshift distribution of the galaxy sample (Steidel et al. 2004) Introduction: The Optical Galaxy Sample Optically-selected by color, confirmed by rest-UV spectra (e.g. Steidel et al. 2004) ~1500 spec. redshifts in ~ 10 fields Extensive photometric/spectroscopic data, NIR H  survey (120+ galaxies; Erb et al. 2006) Broad Physical Properties: Rapidly starforming: SFR ~ 30 M  /year, energetic outflows High gas fraction: M gas /M * = 2.1/3.6 x M  Clustering statistics  halo mass M  Color selection method (Steidel et al. 2004)

OSIRIS Survey: Observing Log NameRedshiftTime Q0449-BX h 30m Q1217-BX h 45m HDF-BX h Q1623-BX h 30m Q1623-BX h 30m Q1623-BX h 45m Q1623-BX h 15m Q1700-BX h 15m Q1700-BX h 30m Q1700-BX h 30m DSF2237a-C h 30m Q2343-BX h 45m Q2343-BX h 30m Q2343-BX h 30m Q2343-BX h 18 nights total, ~ 7 nights good conditions Results published in Law et al. (2007, 2009), see also Wright et al. (2007, 2009) 24 galaxies observed, 15 detected, 13 high-quality. Varied selection criteria (H  bright, high/low M *, NIRSPEC kinematics, etc.)

Results: Low v/  sources 7/13: No significant resolved velocity structure v/  ~ 0.5 3/13: Measurable resolved velocity shear v/  ~ 1 3/13: Multiple components, some with shear, some without

Results: Low v/  sources Star forming regions compact (r < 2 kpc) High velocity dispersion in all galaxies  ~ km/s Genuine dispersion, not unresolved gradients Coherent shear in 4 sources V/  ~ 1 Often inconsistent with simple rotation models Generally don’t look like smooth rotating disks 1-d velocity curves along kinematic major axis for 13 OSIRIS galaxies. Black points represent velocities, red velocity dispersion (Law et al. 2009).

Stellar mass vs. velocity shear (Law et al. 2009) Galaxies with velocity shear have significantly greater stellar mass Low-mass galaxies more likely to be dynamically dominated by gas. High-mass galaxies more likely to show rotation. See, e.g., N. Forster-Schreiber Kinematics are tied to mass/gas fraction Stellar mass vs. H  radius (Förster-Schreiber et al. 2009)

Testing sensitivity threshold with NIFS Difference in sensitivity: OSIRIS observations optimized for angular resolution, comparatively shallow Look for low surface brightness emission around OSIRIS sample using deep Gemini/NIFS observations (2010a: Glazebrook/Abraham/Law/McDermid). 45 hours total, 8-10 hours on each object from the OSIRIS sample. Program ~ 66% complete, results coming soon. OSIRIS/NIFS Ha detections for GDDS Integration time 3 hours.

Rest-optical HST imaging program 42 orbit Cycle 17 HST WFC3/IR (F160W) imaging program. GO-11694: D. Law (PI), C. Steidel, Sarah Nagy, A. Shapley FWHM ~ 0.19’’, limiting magnitude ~ 26.8 AB/arcsec 2 50 galaxies in 2 fields to date Full program >300 spec. confirmed z ~ 2-3 galaxies in 10 fields Many with rest-optical long-slit or IFU (OSIRIS/SINFONI) spectroscopy HST WFC3/IR image of Q field.

HST imaging: morphologies Morphologies generally similar to previous rest-UV studies Multiple nuclei, clumps, chains, non-nucleated features Compare Q1700 field to previous ACS imaging (Cycle 15, PI: Shapley) Postage stamps of galaxies at z= (3’’ squares)

ACSWFC3 ACSWFC3 ACSWFC3 M*M* M*M* M*M* HST imaging: mass-size relation ACS/F814W: Rest-frame 2700/2000 Å at z=2/3 WFC3/F160W: Rest-frame 5100/3900 Å at z=2/3 5.0e9 9.0e10 2.4e10 1.4e9

HST imaging: mass-size relation Strong relation between GALFIT effective radius R e and R-H color  strong relation between effective radius R e and stellar mass M * Relation may persist over 2 decades in M * down to 10 9 M  Color-radius and mass-radius relation for z ~ 2-3 star forming galaxies. (Red: z>2.5, Blue: z<1.9)

Summary Star-forming galaxies have globally high  Galaxies with M * < M  have little velocity shear Galaxies with M * > M  show more pronounced shear Recent Gemini/NIFS observations will test  limits Rest UV/optical morphologies similar for low M *, differ over M  Strong mass-radius relation What are the spatially resolved properties of z~2-3 galaxies?