Abstract
Context. We present ASTRODEEP-GS43, a new multi-wavelength photometric catalogue of the GOODS-South field, which builds and improves upon the previously released CANDELS catalogue. Aims. We provide photometric fluxes and corresponding uncertainties in 43 optical and infrared bands (25 wide and 18 medium filters), as well as the photometric redshifts and physical properties of the 34930 CANDELS H-detected objects, plus an additional sample of 178 H-dropout sources, of which 173 are Ks-detected and five are IRAC-detected. Methods. We keep the CANDELS photometry in seven bands (CTIO U, Hubble Space Telescope WFC3, and ISAAC-K) and measure from scratch the fluxes in the other 36 (23 from Subaru SuprimeCAM and Magellan Baade FourStar and the rest from VIMOS, HST ACS, HAWK-I Ks, and Spitzer IRAC) with state-of-the-art template-fitting techniques. We then compute new photometric redshifts with three different software tools and take the median value as a best estimate. We finally evaluate new physical parameters from spectral energy distribution (SED) fitting, comparing them to previously published ones. Results. Comparing to a sample of 3931 high quality spectroscopic redshifts, for the new photometric redshifts we obtain a normalised median absolute deviation of 0.015, with 3.01% of outliers on the full catalogue (0.011 and 0.22% on the bright end at I814 < 22.5). This is similar to the best available published samples of photometric redshifts, such as the COSMOS UltraVISTA catalogue. Conclusions. The ASTRODEEP-GS43 results are in qualitative agreement with previously published catalogues of the GOODS-South field, improving on them particularly in terms of SED sampling and photometric redshift estimates. The catalogue is available for download from the ASTRODEEP website.
Highlights
Multi-wavelength extragalactic astronomy targeting the highredshift Universe has matured to the status of precision science over the past decade
To compile the final list of K-selected sources we reviewed all the new candidates with S /NK > 5σ, and we considered as valid sources only those that were visible by eye inspection in multiple bands (i.e. K s plus IRAC and/or some HST band), or which had at least a very solid detection in the K s band
We combined the estimates from LePhare, EAzY, and z-phot, taking the median value of the three; we found that the median reduces both the fraction of outliers η (defined as the sources having |zphot −zspec|/(1+zspec) > 0.15) and the normalised median absolute deviation (NMAD)6 on the spectroscopic sample with respect to any of the single runs taken alone
Summary
Multi-wavelength extragalactic astronomy targeting the highredshift Universe has matured to the status of precision science over the past decade. We exploited the template-fitting code t-phot v2.0 to extract new photometry from the images of ground-based medium bands and Spitzer bands using three substantial algorithmic improvements with respect to the standard methods of v1.0: (i) the use of priors from the closest-wavelength high-resolution band for all the medium bands, as opposed to only priors from the H-detection band, (ii) background subtraction during the fitting process and (iii) individual locally variable PSFs for IRAC
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