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Paper: Large Scale Structure at 24 Microns in the SWIRE Survey
Volume: 357, The Spitzer Space Telescope: New Views of the Cosmos
Page: 271
Authors: Masci, F.; the SWIRE Team
Abstract: We present initial results of galaxy clustering at 24μm by analyzing statistics of the projected galaxy distribution from counts-in-cells. This study focuses on the ELAIS-North1 SWIRE field. The sample covers ≅ 5.9 deg2 and contains 24,715 sources detected at 24μm to a 5.6σ limit of 250μJy (in the lowest coverage regions). We have explored clustering as a function of 3.6 - 24μm color and 24μm flux density using angular-averaged two-point correlation functions derived from the variance of counts-in-cells on scales 0°.05−0°.7. Using a power-law parameterization, w2(θ) = A(θ/deg)1−γ, we find [A, γ] = [(5.43 ± 0.20) × 10−4, 2.01 ± 0.02] for the full sample (1σ errors throughout). We have inverted Limber's equation and estimated a spatial correlation length of r0 = 3.32 ± 0.19 h−1Mpc for the full sample, assuming stable clustering and a redshift model consistent with observed 24μm counts. We also find that blue [fv(24)/fv(3.6) ≤ 5.5] and red [fv(24)/fv(3.6) ≥ 6.5] galaxies have the lowest and highest r0 values respectively, implying that redder galaxies are more clustered (by a factor of ≈ 3 on scales ≥ 0°.2). Overall, the clustering estimates are smaller than those derived from optical surveys, but in agreement with results from IRAS and ISO in the mid-infrared. This extends the notion to higher redshifts that infrared selected surveys show weaker clustering than optical surveys.
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