Abstract
A&A 590, A31 (2016) 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]
