Abstract
We present a catalog of high-redshift star-forming galaxies selected to lie within the redshift range z ≃ 7-8 using the Ultra Deep Field 2012 (UDF12), the deepest near-infrared (near-IR) exposures yet taken with the Hubble Space Telescope (HST). As a result of the increased near-IR exposure time compared to previous HST imaging in this field, we probe ∼0.65 (0.25) mag fainter in absolute UV magnitude, at z ∼ 7 (8), which increases confidence in a measurement of the faint end slope of the galaxy luminosity function. Through a 0.7 mag deeper limit in the key F105W filter that encompasses or lies just longward of the Lyman break, we also achieve a much-refined color-color selection that balances high redshift completeness and a low expected contamination fraction. We improve the number of dropout-selected UDF sources to 47 at z ∼ 7 and 27 at z ∼ 8. Incorporating brighter archival and ground-based samples, we measure the z ≃ 7 UV luminosity function to an absolute magnitude limit of M UV = -17 and find a faint end Schechter slope of . Using a similar color-color selection at z ≃ 8 that takes our newly added imaging in the F140W filter into account, and incorporating archival data from the HIPPIES and BoRG campaigns, we provide a robust estimate of the faint end slope at z ≃ 8, . We briefly discuss our results in the context of earlier work and that derived using the same UDF12 data but with an independent photometric redshift technique.
Original language | English (US) |
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Article number | 196 |
Journal | Astrophysical Journal |
Volume | 768 |
Issue number | 2 |
DOIs | |
State | Published - May 10 2013 |
Keywords
- dark ages
- first stars
- galaxies: evolution
- galaxies: formation
- reionization
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science