Abstract
We report on the AAT-AAOmega LRG Pilot observing run to establish the
feasibility of a large spectroscopic survey using the new AAOmega
instrument. We have selected luminous red galaxies (LRGs) using single
epoch SDSS riz-photometry to i <20.5 and z <20.2. We have
observed in three fields including the COSMOS field and the COMBO-17 S11
field, obtaining a sample of ~600 redshift z >~ 0.5 LRGs. Exposure
times varied from 1-4 h to determine the minimum exposure for AAOmega to
make an essentially complete LRG redshift survey in average conditions.
We show that LRG redshifts to i <20.5 can be measured in ~1.5h
exposures and present comparisons with 2SLAQ and COMBO-17
(photo)redshifts. Crucially, the riz selection coupled with the three to
four times improved AAOmega throughput is shown to extend the LRG mean
redshift from z = 0.55 for 2SLAQ to z = 0.681 +/- 0.005 for riz-selected
LRGs. This extended range is vital for maximizing the signal-to-noise
ratio for the detection of the baryon acoustic oscillations (BAOs).
Furthermore, we show that the amplitude of LRG clustering is
s0 = 9.9 +/- 0.7h-1Mpc, as high as that seen in
the 2SLAQ LRG Survey. Consistent results for this clustering amplitude
are found from the projected and semi-projected correlation functions.
This high amplitude is consistent with a long-lived population whose
bias evolves as predicted by a simple `high-peak' model. We conclude
that a redshift survey of 360000 LRGs over 3000 deg2, with an
effective volume some four times bigger than previously used to detect
BAO with LRGs, is possible with AAOmega in 170 nights.
Original language | English |
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Pages (from-to) | 1323-1334 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 387 |
DOIs | |
Publication status | Published - 1 Jul 2008 |