The DECam Ecliptic Exploration Project (DEEP) III: Survey characterization and simulation methods

TL;DR

This paper characterizes the observational biases of the DEEP survey, develops simulation methods to estimate survey completeness, and provides insights into the population of distant objects beyond Neptune.

Contribution

It introduces a new survey simulation software and methodology for characterizing detection efficiencies and biases in the DEEP survey data.

Findings

Peak survey completeness is approximately 80%.

Magnitude limit at 25% efficiency is around 26.22 mag.

Estimated effective search area for 40 au objects is 14.8 deg².

Abstract

We present a detailed study of the observational biases of the DECam Ecliptic Exploration Project's (DEEP) B1 data release and survey simulation software that enables direct statistical comparisons between models and our data. We inject a synthetic population of objects into the images, and then subsequently recover them in the same processing as our real detections. This enables us to characterize the survey's completeness as a function of apparent magnitudes and on-sky rates of motion. We study the statistically optimal functional form for the magnitude, and develop a methodology that can estimate the magnitude and rate efficiencies for all survey's pointing groups simultaneously. We have determined that our peak completeness is on average 80\% in each pointing group, and our magnitude drops to $25\%$ of this value at $m_{25} = 26.22$. We describe the freely available survey simulation software and its methodology. We conclude by using it to infer that our effective search area for objects at 40 au is $14.8\deg^2$, and that our lack of dynamically cold distant objects means that there at most $8\times 10^3$ objects with $60 < a < 80$ au and absolute magnitudes $H \leq 8$.