COSMIC INFRARED BACKGROUND FLUCTUATIONS IN DEEP SPITZER INFRARED ARRAY CAMERA IMAGES: DATA PROCESSING AND ANALYSIS

Abstract

This paper provides a detailed description of the data reduction and analysis procedures that have been employed in our previous studies of spatial fluctuation of the cosmic infrared background (CIB) using deep Spitzer Infrared Array Camera observations. The self-calibration we apply removes a strong instrumental signal from the fluctuations that would otherwise corrupt the results. The procedures and results for masking bright sources and modeling faint sources down to levels set by the instrumental noise are presented. Various tests are performed to demonstrate that the resulting power spectra of these fields are not dominated by instrumental or procedural effects. These tests indicate that the large-scale ( 30 ) fluctuations that remain in the deepest fields are not directly related to the galaxies that are bright enough to be individually detected. We provide the parameterization of these power spectra in terms of separate instrument noise, shot noise, and power-law components. We discuss the relationship between fluctuations measured at different wavelengths and depths, and the relations between constraints on the mean intensity of the CIB and its fluctuation spectrum. Consistent with growing evidence that the ∼1-5 μm mean intensity of the CIB may not be as far above the integrated emission of resolved galaxies as has been reported in some analyses of DIRBE and IRTS observations, our measurements of spatial fluctuations of the CIB intensity indicate the mean emission from the objects producing the fluctuations is quite low ( 1 nW m −2 sr −1 at 3-5 μm), and thus consistent with current γ -ray absorption constraints. The source of the fluctuations may be high-z Population III objects, or a more local component of very low luminosity objects with clustering properties that differ from the resolved galaxies. Finally, we discuss the prospects of the upcoming space-based surveys to directly measure the epochs inhabited by the populations producing these source-subtracted CIB fluctuations, and to isolate the individual fluxes of these populations.

Contribution of the first galaxies to the cosmic far-infrared/sub-millimeter background – I. Mean background level

“…Thus, absolute flux measurements of the FIR-EBL constitutes a very challenging task. Although the low contribution to the net flux might prevent such absolute measurements of primordial dust emission, it might still be possible to obtain information about it by exploring the EBL angular power spectrum Kashlinsky & Odenwald 2000;Arendt et al 2010;Mitchell-Wynne et al 2015), which we will investigate in a separate paper. According to our model, these signatures should be detected at ∼ 500µm, close to the peak of dust emission from primeval sources.…”

Cross-Correlating Cosmic Infrared and X-Ray Background Fluctuations: Evidence of Significant Black Hole Populations Among the Cib Sources

“…The procedure for map assembly is described in our previous papers (Kashlinsky et al , 2007a with an extensive summary, including all the tests, given in Arendt et al (2010). Our IRAC mosaics are prepared from the basic calibrated data (BCD) product using the least-squares self-calibration procedure described by Fixsen et al (2000).…”

The contribution of faint galaxy wings to source-subtracted near-infrared background fluctuations

“…Mean-square fluctuations, F 2 (θ) ≈ q 2 P2/(2π), is then calculated, where θ is 2π/q converted into arcsec. Mean-square fluctuations are divided by the fraction of unsubtracted pixels in the image to compensate for area lost by masking (Arendt et al 2010). Unless otherwise noted, error bars shown in figures represent one standard deviation of the Poisson errors, P2/ Nq, where Nq is the number of Fourier elements in the associated bin.…”

“…The masking process itself can cause a distortion of fluctuation spectra that must be considered when making comparisons (Arendt et al 2010;Kashlinsky et al 2012). Images are masked by multiplying the image field by a separate mask with pixel values of one everywhere except for sourcesubtracted regions that have pixel values of zero or, as shown in Fig.…”