The ASTRODEEP Frontier Fields Catalogues: II - Photometric redshifts and rest-frame properties in Abell-2744 and MACS-J0416

TL;DR

This paper provides the first public catalog of photometric redshifts and galaxy properties in the Abell-2744 and MACS-J0416 Frontier Fields, enabling studies of faint, high-redshift galaxies through multi-wavelength data and lensing models.

Contribution

It introduces a comprehensive catalog with accurate photometric redshifts and physical properties, leveraging multi-band data and advanced lensing models in the first two Frontier Fields.

Findings

Photometric redshifts reach 3-5% accuracy.

Galaxy counts extend to very faint magnitudes due to lensing.

Probing lower stellar masses and SFRs at high redshift.

Abstract

We present the first public release of photometric redshifts, galaxy rest-frame properties and associated magnification values in the cluster and parallel pointings of the first two Frontier Fields, Abell-2744 and MACS-J0416. We exploit a multi-wavelength catalogue ranging from HST to ground-based K and Spitzer IRAC which is specifically designed to enable detection and measurement of accurate fluxes in crowded cluster regions. The multi-band information is used to derive photometric redshifts and physical properties of sources detected either in the H-band image alone or from a stack of four WFC3 bands. To minimize systematics median photometric redshifts are assembled from six different approaches to photo-z estimates. Their reliability is assessed through a comparison with available spectroscopic samples. State of the art lensing models are used to derive magnification values on an object-by-object basis by taking into account sources positions and redshifts. We show that photometric redshifts reach a remarkable ~3-5% accuracy. After accounting for magnification the H band number counts are found in agreement at bright magnitudes with number counts from the CANDELS fields, while extending the presently available samples to galaxies intrinsically as faint as H160~32-33 thanks to strong gravitational lensing. The Frontier Fields allow to probe the galaxy stellar mass distribution at 0.5-1.5 dex lower masses, depending on magnification, with respect to extragalactic wide fields, including sources at Mstar~ 10^7-10^8 Msun at z>5. Similarly, they allow the detection of objects with intrinsic SFRs>1dex lower than in the CANDELS fields reaching 0.1-1 Msun/yr at z~6-10. [abridged]