Structural Parameters of Galaxies in CANDELS

TL;DR

This paper provides detailed structural parameter measurements for over 100,000 galaxies from the CANDELS survey, using Sersic model fits across multiple near-infrared filters, and assesses measurement uncertainties.

Contribution

It introduces a comprehensive catalog of galaxy structural parameters with systematic and random uncertainty estimates, based on extensive modeling and simulations.

Findings

Accurate structural parameters can be obtained for galaxies brighter than H_F160W < 23.

Size and shape measurements remain reliable up to H_F160W ~ 24.5.

Systematic uncertainties are quantified through simulated galaxy mosaics.

Abstract

We present global structural parameter measurements of 109,533 unique, H_F160W-selected objects from the CANDELS multi-cycle treasury program. Sersic model fits for these objects are produced with GALFIT in all available near-infrared filters (H_F160W, J_F125W and, for a subset, Y_F105W). The parameters of the best-fitting Sersic models (total magnitude, half-light radius, Sersic index, axis ratio, and position angle) are made public, along with newly constructed point spread functions for each field and filter. Random uncertainties in the measured parameters are estimated for each individual object based on a comparison between multiple, independent measurements of the same set of objects. To quantify systematic uncertainties we create a mosaic with simulated galaxy images with a realistic distribution of input parameters and then process and analyze the mosaic in an identical manner as the real data. We find that accurate and precise measurements -- to 10% or better -- of all structural parameters can typically be obtained for galaxies with H_F160W < 23, with comparable fidelity for basic size and shape measurements for galaxies to H_F160W ~ 24.5.