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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. The Galaxy Evolution Explorer (GALEX).
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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
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 deg2 • Slitless Spectroscopy • 1350-2800Å • Spectral resolution R=80-300 • Conducting several surveys of varying depth and area, as well as pointed observations GALEX-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) GALEX-NDWFS Investigation of Galaxies at z=1-2
Lyman Break Galaxies at z>3: U-band dropouts GALEX-NDWFS Investigation of Galaxies at z=1-2
Lyman Break Galaxies at z>3: U-band dropouts GALEX-NDWFS Investigation of Galaxies at z=1-2
GALEX Observations of Bootes Region • Deep Imaging Survey • 80 deg2, including the 9 deg2 Bootes region of the NDWFS. • Limiting magnitude AB=25 • 1 deg2 observed in 2003 (the “00” field - 43 ksec) • 2 more deg2 coming this week • Ultra-Deep Imaging Survey • 4 deg2, including the “00” field in Bootes • Limiting magnitude AB=26 • 200 ksec planned (100 in 2004) • Deep Spectroscopic Survey • 2 deg2, including the “00” field • Limiting magnitude AB=22.5-24 Supplemented NDWFS data with deep U observations (AB=26) in the “00” field GALEX-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.) GALEX-NDWFS Investigation of Galaxies at z=1-2
z=2: NUV Dropouts • SExtractor single-band catalogs matched in Bw, U, NUV • Spatial resolution problems remains • Compare colors to model colors of redshifted starburst spectra (following Steidel et al.) GALEX-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. 2004 in GALEX edition of APJL L* for LBGs from Giavalisco 2002 GALEX-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. 2004 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) GALEX-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 GALEX-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 GALEX-NDWFS Investigation of Galaxies at z=1-2