Power spectrum Analysis of Far - IR Background Fluctuations in Spitzer maps at 160 μ

We describe data reduction and analysis of fluctuations in the Cosmic Far-IR Background (CFIB) in large maps observed with the Multiband Imaging Photometer for Spitzer (MIPS) instrument 160 μm detectors. We analyzed the extragalactic First Look Survey (FLS) and the Spitzer Wide-area Infrared Extragalactic Survey (SWIRE) Lockman Hole observations, the latter being the largest low-cirrus mapping observation available. In the Lockman Hole map, we measured the power spectrum of the CFIB by fitting a power law to the IR cirrus component, the dominant foreground contaminant, and subtracting this cirrus signal. The CFIB power spectrum at mid -high k (k ∼ (2 5) × 10 arc min) is consistent with previous measurements of a relatively flat component. At lower k, however, the power spectrum is clearly not flat, decreasing from our lowest frequencies (k ∼ 3 × 10−2 arc min−1) and flattening at mid-frequencies (k ≥ (1 2) × 10−1 arc min−1). This behavior is consistent with the gross characteristics of predictions of a source clustering “signature” in CFIB power spectra, and this is the first report of such