3D-HST WFC3-selected Photometric Catalogs in the Five CANDELS/3D-HST Fields: Photometry, Photometric Redshifts and Stellar Masses

Abstract: The 3D-HST and CANDELS programs have provided WFC3 and ACS spectroscopy and photometry over ~900 square arcminutes in five fields: AEGIS, COSMOS, GOODS-North, GOODS-South, and the UKIDSS UDS field. All these fields have a wealth of publicly available imaging datasets in addition to the HST data, which makes it possible to construct the spectral energy distributions (SEDs) of objects over a wide wavelength range. In this paper we describe a photometric analysis of the CANDELS and 3D-HST HST imaging and the ancillary imaging data at wavelengths 0.3um to 8um. Objects were selected in the WFC3 near-IR bands, and their SEDs were determined by carefully taking the effects of the point spread function in each observation into account. A total of 147 distinct imaging datasets were used in the analysis. The photometry is made available in the form of six catalogs: one for each field, as well as a master catalog containing all objects in the entire survey. We also provide derived data products: photometric redshifts, determined with the EAZY code, and stellar population parameters determined with the FAST code. We make all the imaging data that were used in the analysis available, including our reductions of the WFC3 imaging in all five fields. 3D-HST is a spectroscopic survey with the WFC3 and ACS grisms, and the photometric catalogs presented here constitute a necessary first step in the analysis of these grism data. All the data presented in this paper are available through the 3D-HST website.

• The paper presents a comprehensive photometric catalog combining HST/WFC3 and ancillary data to deliver accurate redshift and stellar mass estimates.
• It employs multi-wavelength SED fitting using EAZY and FAST codes on 147 imaging datasets covering 900 arcmin² of sky.
• The catalog’s redshift precision (NMAD ~2.7%) enables detailed analyses of galaxy evolution and clustering across key extragalactic fields.

Overview of "3D-HST WFC3-selected Photometric Catalogs in the Five CANDELS/3D-HST Fields" by Skelton et al.

The paper "3D-HST WFC3-selected Photometric Catalogs in the Five CANDELS/3D-HST Fields: Photometry, Photometric Redshifts and Stellar Masses" by Skelton et al. presents an extensive analysis and cataloging effort that combines the powerful imaging capabilities of the Hubble Space Telescope (HST) with extensive ground-based data. This collaboration between the HST/WFC3 3D-HST grism survey and the CANDELS project has led to the creation of a comprehensive photometric catalog covering five key extragalactic fields: AEGIS, COSMOS, GOODS-North, GOODS-South, and UDS. The effort leverages roughly 900 arcmin² of sky to provide photophysics of galaxies over significant cosmic time, enhancing our understanding of galaxy evolution, star formation, and mass assembly processes.

Methodology and Data Utilized

The study employs a multi-wavelength photometric approach, integrating spectral energy distributions (SEDs) from the WFC3 near-infrared observations with ancillary datasets ranging from ultraviolet to infrared. At the heart of these catalogs are observations in the WFC3 F125W, F140W, and F160W bands, alongside ACS data, all processed to achieve uniform photometric measurements across the fields. The study's analysis draws upon a total of 147 imaging datasets, demonstrating an impressive ability to synthesize diverse data sources and telescope capabilities.

These observations are instrumental in the team’s development of photometric redshifts and estimations of stellar masses through the EAZY and FAST codes. This is of paramount importance as it allows for the investigation of galaxies' evolution without the need for spectroscopic redshifts, which are more resource-intensive to obtain.

Key Findings and Implications

The robust catalog devised by the authors shows an ability to accurately estimate the photometric redshifts across various conditions, achieving an NMAD scatter of approximately 2.7% when compared with available spectroscopic redshifts. This level of accuracy is notably enhanced in the COSMOS and GOODS-S fields, where medium-band data are available.

The photometric catalogs allow for significant scientific inquiries, such as the construction of rest-frame color diagrams and star formation histories, facilitating deeper insights into galaxy formation theories. By enabling accurate redshift determination across extensive fields, the data offers a way to identify and study galaxy clusters, dual AGN systems, and potentially unique astrophysical phenomena across cosmic time and varying environments.

Speculative Outlook on Future Developments

The methods and outcomes described in the paper lay the groundwork for integrating even more sophisticated data processing techniques and the further synergy between imaging and spectral data. As future observations, including those from the upcoming James Webb Space Telescope (JWST), become available, such synergistic approaches will likely remain crucial. They will enhance the depth, resolution, and quality of cosmological data and allow for more refined studies of the universe's fabric.

The ongoing catalog updates and the integration of grism spectroscopy from 3D-HST will improve the precision of redshifts and physical properties of galaxies, which holds the potential to resolve outstanding questions about galaxy dynamics and dark matter distribution.

Conclusion

Skelton et al.'s comprehensive cataloging of five CANDELS/3D-HST fields sets a high standard for astronomical surveying and data synthesis, illustrating the power of combining multi-instrument observations to advance our understanding of the universe significantly. The meticulous approach to calibration, data reduction, and validation as presented forms a solid foundation for subsequent analyses aimed at unraveling the complexities of cosmic evolution and structure formation.