HETDEX PILOT SURVEY FOR LYMAN ALPHA EMITTERS AT
2<z<4
Guillermo A. BlancThe University of Texas at Austin
COLABORATORS:
Joshua Adams, Karl Gebhardt, Gary Hill, Niv Drory, Phillip MacQueen, Ralf Koehler, Lei Hao, Jeremy Murphy, and the HETDEX Collaboration.
HETDEX• Hobby-Eberly Telescope Dark Energy eXperiment
• Measure w(z)=pDE(z)/ρDE(z) at 2<z<4 using Baryonic Acoustic Oscillations (BAO)
• Power spectrum of the spatial distribution of 1,000,000 LAEs over a volume of 9 Gpc3
HETDEX• How do you find 1,000,000 LAEs?
You use a VIRUS
Visible Integral-field Replicable Unit Spectrograph
150 replicable IFU = 40 arcmin2 FOV, 37000 fibers (D=1.5”)
VIRUS-P• VIRUS Prototype IFU
• 1.7’x1.7’ FOV at HJST 2.7m
• 1/3 filling factor
• Largest FOV of any existent IFU
• 4.2’’ diameter fibers on sky
• 3500-5800Å wavelength range
• R=1000 @ 5000Å
The VIRUS-P Pilot Survey
• 99 arcmin2 surveyed so far on COSMOS, GOODS-N and MUNICS-S2 fields
• 6 position dither pattern ensures good field coverage
• 5σ flux limit of ~6x10-17 erg/s/cm2 for a point-source emitting and unresolved line
DETECTION OF EMISSION LINES
• GROW DETECTION UNTIL S/N STOPS INCREASING
• POSITION GIVEN BY FIRST MOMENT OF LIGHT DISTRIBUTION
• We have analyze 12 pointings (35 arcmin2) of data in the COSMOS field.
• 99 unique emission line sources detected.
– 45 LAEs – 35 [OII]λ3727 Emitters– 5 [OIII]λ5007 Emitters– 3 Hβ Emitters– 1 AGN– 10 ambiguous
classifications
PRELIMINARY ANALYSIS
LAEs and low-z Galaxies
CONCLUSIONS• 45 to 55 LAE sample over 35 arcmin2 to a median flux limit of ~6 ergs/s/cm2.
~300 LAEs expected over the whole pilot survey area.
• VIRUS-P IFU samples 50 times more volume per arcmin2 than narrow-band survey.
• Number of sources agrees with predictions from previous measurements of the Lyα LF of galaxies.
• Science:
• Evolution of the Lyα LF
• Large scale clustering and bias
• Physical properties of LAEs (SED fitting)
• Candidates for NIR Hα spectroscopy
• VIRUS will be the largest IFU in the world and will be commissioned by the end of 2010. HETDEX will detect ~1,000,000 LAEs in 100 nights.
• HETDEX will measure w at z~3 with ~1% accuracy and measure evolution if DE≠Λ and w(z) evolves more than a 1%.
• www.hetdex.org
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