TY - JOUR
T1 - Deep galaxy counts in the K band with the Keck telescope
AU - Djorgovski, S.
AU - Soifer, B. T.
AU - Pahre, M. A.
AU - Larkin, J. E.
AU - Smith, J. D.
AU - Neugebauer, G.
AU - Smail, I.
AU - Matthews, K.
AU - Hogg, D. W.
AU - Blandford, R. D.
AU - Cohen, J.
AU - Harrison, W.
AU - Nelson, J.
PY - 1995/1/1
Y1 - 1995/1/1
N2 - We present deep galaxy counts in the K (λ2.2 μm) band, obtained at the W. M. Keck 10 m telescope. The data reach limiting magnitudes K ∼ 24 mag, about 5 times deeper than the deepest published K-band images to date. The counts are performed in three small (∼1′), widely separated high-latitude fields. Extensive Monte Carlo tests were used to derive the completeness corrections and minimize photometric biases. The counts continue to rise, with no sign of a turnover, down to the limits of our data, with the logarithmic slope of d log N/dm = 0.315 ± 0.02 between K = 20 and 24 mag. This implies a cumulative surface density of ∼5 × 105 galaxies deg-2, or ∼2 × 1010 over the entire sky, down to K = 24 mag. Our counts are in good agreement with, although slightly lower than, those from the Hawaii Deep Survey by Cowie and collaborators; the discrepancies may be due to the small differences in the aperture corrections. The observed field-to-field variations are as expected from the Poissonian noise and galaxy clustering as described by the angular two-point correlation function for faint galaxies. We compare our counts with some of the available theoretical predictions. The data do not require models with a high value of Ω0, but can be well fitted by models with no (or little) evolution, and cosmologies with a low value Ω0. Given the uncertainties in the models, it may be premature to put useful constrains on the value of Ω0 from the counts alone. Optical-to-IR colors are computed, using CCD data obtained previously at Palomar. We find a few red galaxies with (r - K) ≳ 5 mag, or (i - K) ≳ 5 mag; these may be ellipticals at z ∼ 1. While the redshift distribution of galaxies in our counts is still unknown, the flux limits reached would allow us to detect unobscured L* galaxies out to substantial redshifts (z > 3?).
AB - We present deep galaxy counts in the K (λ2.2 μm) band, obtained at the W. M. Keck 10 m telescope. The data reach limiting magnitudes K ∼ 24 mag, about 5 times deeper than the deepest published K-band images to date. The counts are performed in three small (∼1′), widely separated high-latitude fields. Extensive Monte Carlo tests were used to derive the completeness corrections and minimize photometric biases. The counts continue to rise, with no sign of a turnover, down to the limits of our data, with the logarithmic slope of d log N/dm = 0.315 ± 0.02 between K = 20 and 24 mag. This implies a cumulative surface density of ∼5 × 105 galaxies deg-2, or ∼2 × 1010 over the entire sky, down to K = 24 mag. Our counts are in good agreement with, although slightly lower than, those from the Hawaii Deep Survey by Cowie and collaborators; the discrepancies may be due to the small differences in the aperture corrections. The observed field-to-field variations are as expected from the Poissonian noise and galaxy clustering as described by the angular two-point correlation function for faint galaxies. We compare our counts with some of the available theoretical predictions. The data do not require models with a high value of Ω0, but can be well fitted by models with no (or little) evolution, and cosmologies with a low value Ω0. Given the uncertainties in the models, it may be premature to put useful constrains on the value of Ω0 from the counts alone. Optical-to-IR colors are computed, using CCD data obtained previously at Palomar. We find a few red galaxies with (r - K) ≳ 5 mag, or (i - K) ≳ 5 mag; these may be ellipticals at z ∼ 1. While the redshift distribution of galaxies in our counts is still unknown, the flux limits reached would allow us to detect unobscured L* galaxies out to substantial redshifts (z > 3?).
KW - Cosmology: observations
KW - Galaxies: evolution
KW - Galaxies: photometry
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U2 - 10.1086/187703
DO - 10.1086/187703
M3 - Article
AN - SCOPUS:11944258210
SN - 0004-637X
VL - 438
SP - L13-L16
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1 PART 2
ER -