The Effectiveness of Mid/Far IR Blind, Wide Area, Spectral Surveys in Breaking the Confusion Limit

Abstract

Source confusion determines the useful depth to which to take large-area extragalactic surveys. 3D imaging spectrometers, with positional as well as spectral information, however, can potentially provide a means by which to break the traditional confusion limit.In this poster we present the results of our investigation into the effectiveness of mid/far infrared, blind, wide area spectroscopic surveys with SAFARI in breaking through the confusion limit. We generate an artificial sky representative of 100 SAFARI footprints based on two galaxy evolution models: bright-end and burst-mode. Using a fully automated redshift determination method we find we can accurately estimate redshifts for 37 and 53% of sources with continuum fluxes that are as much as an order of magnitude below the traditional continuum confusion limit (at 120 μm) for the bright-end and burst-mode evolution models respectively. Our results suggest that deep, blind spectral line surveys with SAFARI will be able to break the traditional photometric confusion limit, allowing us to resolve a significant number of previously inaccessible galaxies, and so potentially to differentiate between different galaxy evolution models.

Spectral Line Confusion in SAFARI Surveys (work in progress)

“…The spectra used in this work are a sub-sample of those used in Raymond et al (2009) and are shown in Figure 1. We selected the following 6 spectra to represent each of the principle classes of object; normal (eg.…”

“…These spectra are highlighted in Figure 1 by a thicker line. Details as to how the spectra were compiled are given Raymond et al (2009).…”

“…Spectra used in this work and in Raymond et al (2009) and redshifted in steps of Δz = 0.2, between 0.2 < z < 4. We approximate the resolution of SAFARI as a wavelengthindependent value of R ∼ 1000.…”

“…Work presented in Clements et al (2007), Raymond et al (2009) and Raymond et al these proceedings, modeled artificial skies matched to the instrumental parameters of SAFARI, the proposed FIR imaging spectrometer for SPICA (Swinyard et al, 2006). These were populated with sources based on the evolutionary models of Pearson (2005) and Pearson et al (2007).…”

“…As a result, source redshifts become hard to extract. Raymond et al (2009) attempted to extract redshifts from spectrally confused spectra, however no systematic analysis was performed on estimating redshifts from confused spectra. In this work we rectify this, and present the preliminary results of a systematic analysis of our ability to extract redshifts from scrambled spectra.…”