The missing light of the Hubble Ultra Deep Field

Borlaff, A.; Trujillo, I.; Román, J.r; Beckman, J. E.; Eliche-Moral, M. C.; Infante-Sáinz, R.; Lumbreras-Calle, A.; de Almagro, Rodrigo Takuro Sato Martín; Gómez-Guijarro, Carlos; Cebrián, M.; Dorta, A.; Cardiel, Nicolás; Akhlaghi, Mohammad; Martínez-Lombilla, C.
Bibliographical reference

Astronomy and Astrophysics, Volume 621, id.A133, 34 pp.

Advertised on:
Number of authors
IAC number of authors
Refereed citations
Context. The Hubble Ultra Deep field (HUDF) is the deepest region ever observed with the Hubble Space Telescope. With the main objective of unveiling the nature of galaxies up to z ˜ 7 - 8, the observing and reduction strategy have focused on the properties of small and unresolved objects, rather than the outskirts of the largest objects, which are usually over-subtracted. Aims: We aim to create a new set of WFC3 IR mosaics of the HUDF using novel techniques to preserve the properties of the low surface brightness regions. Methods: We created ABYSS: a pipeline that optimises the estimate and modelling of low-level systematic effects to obtain a robust background subtraction. We have improved four key points in the reduction: 1) creation of new absolute sky flat fields, 2) extended persistence models, 3) dedicated sky background subtraction and 4) robust co-adding. Results: The new mosaics successfully recover the low surface brightness structure removed on the previous HUDF published reductions. The amount of light recovered with a mean surface brightness dimmer than μ¯ = 26 mag arcsec-2 is equivalent to a m = 19 mag source when compared to the XDF and a m = 20 mag compared to the HUDF12. Conclusions: We present a set of techniques to reduce ultra-deep images (μ > 32.5 mag arcsec-2, 3σ in 10 × 10 arcsec boxes), that successfully allow us to detect the low surface brightness structure of extended sources on ultra deep surveys. The developed procedures are applicable to HST, JWST, EUCLID and many other space and ground-based observatories. The final ABYSS WFC3 IR HUDF mosaics are only available at and at the CDS via anonymous ftp to ( or via
Related projects
Poster Almeria Astronomy week
Kinematic, Structural and Composition Studies of the Interstellar and Intergalactic Media

The basic objective of the broject is to investigate the evolution of galaxies by deepening our understanding of the interaction between the insterstellar medium and the stars.The main technique which we use is the two-dimensional kinematic study of whole galaxies observed using our instrument:GHaFaS, a Fabry-Perot interferometer on the William

John E. Beckman
Group members
Traces of Galaxy Formation: Stellar populations, Dynamics and Morphology

We are a large, diverse, and very active research group aiming to provide a comprehensive picture for the formation of galaxies in the Universe. Rooted in detailed stellar population analysis, we are constantly exploring and developing new tools and ideas to understand how galaxies came to be what we now observe.

Martín Navarro
Project Image
Spiral Galaxies: Evolution and Consequences

Our small group is well known and respected internationally for our innovative and important work on various aspects of the structure and evolution of nearby spiral galaxies. We primarily use observations at various wavelengths, exploiting synergies that allow us to answer the most pertinent questions relating to what the main properties of

Johan Hendrik
Knapen Koelstra