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