TY - JOUR
T1 - Constraints on z ≈ 10 galaxies from the deepest Hubble Space Telescope NICMOS fields
AU - Bouwens, R. J.
AU - Illingworth, G. D.
AU - Thompson, R. I.
AU - Franx, M.
N1 - Funding Information:
We are grateful to S. Beckwith and the entire STScI science team for their foresight in taking deep NICMOS parallels to the UDF, M. Dickinson and STScI for making their NICMOS reductions available in electronic form, D. Eisenstein, B. Mobasher, and E. Scannapieco for valuable discussions, H. Yan for an electronic copy of a 2.5 Gyr ERO SED, and our referee for valuable comments that substantially improved this manuscript. This research was supported under NASA grants GO-09803.05-A and NAG 5-7697.
PY - 2005/5/1
Y1 - 2005/5/1
N2 - We use all available fields with deep NICMOS imaging to search for J 110-dropouts (H160,AB ≲ 28) at z ≈ 10. Our primary data set for this search is the two J110 + H160 ICMOS fields taken in parallel with the Advanced Camera for Surveys (ACS) Hubble Ultra Deep Field (UDF). The 5 σ limiting magnitudes were ∼28.6 in J 110 and ∼28.5 in H160 (0″.6 apertures). Several shallower fields were also used: J110 + H160 NICMOS frames available over the Hubble Deep Field (HDF) North, the HDF-South NICMOS parallel, and the ACS UDF (with 5 a limiting magnitudes in J110 and H160 ranging from 27.0 to 28.2). The primary selection criterion was (J110-H160)AB > 1-8. Eleven such sources were found in all search fields using this criterion. Eight of these are clearly ruled out as credible z ≈ 10 sources, either as a result of detections (>2 a) blueward of J110 or their colors redward of the break (H160-K ∼ 1.5) (redder than ≳98% of lower redshift dropouts). The nature of the three remaining sources could not be determined from the data. This number appears consistent with the expected contamination from low-redshift interlopers. Analysis of the stacked images for the three candidates also suggests some contamination. Regardless of their true redshifts, the actual number of z ≈ 10 sources must be three or fewer. To assess the significance of these results, two lower redshift samples (a z ∼ 3.8 B-dropout and z ∼ 6 i-dropout sample) were projected to z ∼ 7-13 using a (1 + z) -1 size scaling (for fixed luminosity). They were added to the image frames and the selection was repeated, giving 15.6 and 4.8 J110- dropouts, respectively. This suggests that to the limit of this probe (≈0.3Lz=3*), there has been evolution from z ∼ 3.8 and possibly from z ∼ 6. This is consistent with the strong evolution already noted at z ∼ 6 and z ∼ 7.5 relative to z ∼ 3-4. Even assuming that three sources from this probe are at z ≈ 10, the rest-frame continuum UV (∼1500 ̊) luminosity density at z ∼ 10 (integrated down to 0.3Lz=3*) is just 0.19-0.09+0.13 times that at z ∼ 3.8 (or 0.19-0.10+0.15 times, including the small effect from cosmic variance). However, if none of our sources are at z ≈ 10, this ratio has a 1 σ upper limit of 0.07.
AB - We use all available fields with deep NICMOS imaging to search for J 110-dropouts (H160,AB ≲ 28) at z ≈ 10. Our primary data set for this search is the two J110 + H160 ICMOS fields taken in parallel with the Advanced Camera for Surveys (ACS) Hubble Ultra Deep Field (UDF). The 5 σ limiting magnitudes were ∼28.6 in J 110 and ∼28.5 in H160 (0″.6 apertures). Several shallower fields were also used: J110 + H160 NICMOS frames available over the Hubble Deep Field (HDF) North, the HDF-South NICMOS parallel, and the ACS UDF (with 5 a limiting magnitudes in J110 and H160 ranging from 27.0 to 28.2). The primary selection criterion was (J110-H160)AB > 1-8. Eleven such sources were found in all search fields using this criterion. Eight of these are clearly ruled out as credible z ≈ 10 sources, either as a result of detections (>2 a) blueward of J110 or their colors redward of the break (H160-K ∼ 1.5) (redder than ≳98% of lower redshift dropouts). The nature of the three remaining sources could not be determined from the data. This number appears consistent with the expected contamination from low-redshift interlopers. Analysis of the stacked images for the three candidates also suggests some contamination. Regardless of their true redshifts, the actual number of z ≈ 10 sources must be three or fewer. To assess the significance of these results, two lower redshift samples (a z ∼ 3.8 B-dropout and z ∼ 6 i-dropout sample) were projected to z ∼ 7-13 using a (1 + z) -1 size scaling (for fixed luminosity). They were added to the image frames and the selection was repeated, giving 15.6 and 4.8 J110- dropouts, respectively. This suggests that to the limit of this probe (≈0.3Lz=3*), there has been evolution from z ∼ 3.8 and possibly from z ∼ 6. This is consistent with the strong evolution already noted at z ∼ 6 and z ∼ 7.5 relative to z ∼ 3-4. Even assuming that three sources from this probe are at z ≈ 10, the rest-frame continuum UV (∼1500 ̊) luminosity density at z ∼ 10 (integrated down to 0.3Lz=3*) is just 0.19-0.09+0.13 times that at z ∼ 3.8 (or 0.19-0.10+0.15 times, including the small effect from cosmic variance). However, if none of our sources are at z ≈ 10, this ratio has a 1 σ upper limit of 0.07.
KW - Galaxies: evolution
KW - Galaxies: high-redshift
UR - http://www.scopus.com/inward/record.url?scp=20344374615&partnerID=8YFLogxK
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U2 - 10.1086/430302
DO - 10.1086/430302
M3 - Article
AN - SCOPUS:20344374615
VL - 624
SP - L5-L8
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 1 II
ER -