A GALEX and NDWFS Investigation of Star Forming Galaxies at z=1 and 2 Charles G. Hoopes, Timothy M. Heckman (JHU) Buell T. Jannuzi, Arjun Dey, Michael J. I. Brown, Alison Ford (NOAO) and Davis Schiminovich (Columbia) June 2, 2004

GALEX-NDWFS Investigation of Galaxies at z=1-2 The Galaxy Evolution Explorer (GALEX) Launched April 28, 2003 Imaging in two UV bands –FUV: λ=1516Å, Δλ=268Å –NUV: λ=2267Å, Δλ=732Å –Spatial resolution ~5” –FOV ~1.2 deg 2 Slitless Spectroscopy – Å –Spectral resolution R= Conducting several surveys of varying depth and area, as well as pointed observations

June 2, 2004GALEX-NDWFS Investigation of Galaxies at z=1-2 Mapping the History of Star Formation in the Universe SF history of universe mapped out to z>5 Relatively little known about z<3 Different techniques used for different redshift intervals (From Giavalisco 2002 and Barger et al 2000)

June 2, 2004GALEX-NDWFS Investigation of Galaxies at z=1-2 Lyman Break Galaxies at z>3: U-band dropouts

June 2, 2004GALEX-NDWFS Investigation of Galaxies at z=1-2 Lyman Break Galaxies at z>3: U-band dropouts

June 2, 2004GALEX-NDWFS Investigation of Galaxies at z=1-2 GALEX Observations of Bootes Region Deep Imaging Survey –80 deg 2, including the 9 deg 2 Bootes region of the NDWFS. –Limiting magnitude AB=25 –1 deg 2 observed in 2003 (the “00” field - 43 ksec) –2 more deg 2 coming this week Ultra-Deep Imaging Survey –4 deg 2, including the “00” field in Bootes –Limiting magnitude AB=26 –200 ksec planned (100 in 2004) Deep Spectroscopic Survey –2 deg 2, including the “00” field –Limiting magnitude AB= Supplemented NDWFS data with deep U observations (AB=26) in the “00” field

June 2, 2004GALEX-NDWFS Investigation of Galaxies at z=1-2 z=1: FUV Dropouts SExtractor (Bertin & Arnouts 1996) dual band catalog in NUV/FUV matched with U-band Spatial resolution difference (~5” for GALEX, <1” for U-band) creates identification problems Compare colors to model colors of redshifted starburst spectra (following Steidel et al.)

June 2, 2004GALEX-NDWFS Investigation of Galaxies at z=1-2 z=2: NUV Dropouts SExtractor single-band catalogs matched in B w, U, NUV Spatial resolution problems remains Compare colors to model colors of redshifted starburst spectra (following Steidel et al.)

June 2, 2004GALEX-NDWFS Investigation of Galaxies at z=1-2 UV Luminosity Luminosities calculated from filter redward of Lyman break Fainter z=2 galaxies selected against, but bright z=1 galaxies would be detected Indicates that most luminous galaxies at z=2 have faded by z=1 L* at z=0 from Treyer et al in GALEX edition of APJL L* for LBGs from Giavalisco 2002

June 2, 2004GALEX-NDWFS Investigation of Galaxies at z=1-2 Star Formation and Extinction We may be seeing the transition in star formation rates from LBGs to present-day starbursts (see also Arnouts et al in GALEX edition of ApJL) Mean extinction implied by UV slope is E(B-V)~0.1 for z=1 E(B-V)~0.2 for z=2 (but there is a degeneracy between redshift and UV slope, and only sensitive to E(B-V)<0.4)

June 2, 2004GALEX-NDWFS Investigation of Galaxies at z=1-2 Future Work Improved matching techniques, photo-z Further GALEX observations Spitzer observations of this region are planned Spectroscopic follow up

June 2, 2004GALEX-NDWFS Investigation of Galaxies at z=1-2 Summary GALEX-NDWFS collaboration will shed light on galaxy evolution at z=1-2 Large amount of GALEX data in the Bootes region is coming Initial results show the vigorous star formation of Lyman Break Galaxies fading from z=2 to z=1