SIMBAD references

The Las Campanas Infrared (LCIR) Survey, using the Cambridge Infra-Red Survey Instrument (CIRSI), reaches H ∼21 over nearly 1deg² . In this paper we present results from 744arcmin² centred on the Hubble Deep Field South for which UBVRI optical data are publicly available. Making conservative magnitude cuts to ensure spatial uniformity, we detect 3177 galaxies to H =20.0 in 744arcmin² and a further 842 to H =20.5 in a deeper subregion of 407arcmin² . We compare the observed optical-infrared (IR) colour distributions with the predictions of semi-analytic hierarchical models and find reasonable agreement. We also determine photometric redshifts, finding a median redshift of ∼0.55. We compare the redshift distributions N (z ) of E, Sbc, Scd and Im spectral types with models, showing that the observations are inconsistent with simple passive-evolution models while semi-analytic models provide a reasonable fit to the total N (z ) but underestimate the number of z ∼1 red spectral types relative to bluer spectral types. We also present N (z ) for samples of extremely red objects (EROs) defined by optical-IR colours. We find that EROs with R -H >4 and H <20.5 have a median redshift z _m ∼1 while redder colour cuts have slightly higher z _m . In the magnitude range 19<H <20 we find that EROs with R -H >4 comprise ∼18 per cent of the observed galaxy population, while in semi-analytic models they contribute only ∼4 per cent.

We also determine the angular correlation function w (θ ) for magnitude, colour, spectral type and photometric redshift-selected subsamples of the data and use the photometric redshift distributions to derive the spatial clustering statistic ξ (r ) as a function of spectral type and redshift out to z ∼1.2. Parametrizing ξ (r ) by ξ (r _c ,z )=[r _c/r ∗(z )]^–1.8 , where r _c is in comoving coordinates, we find that r ∗(z ) increases by a factor of 1.5-2 from z =0 to z ∼1.2. We interpret this as a selection effect - the galaxies selected at z ∼1.2 are intrinsically very luminous, about 1-1.5mag brighter than L ∗. When galaxies are selected by absolute magnitude, we find no evidence for evolution in r ∗ over this redshift range. Extrapolated to z =0, we find r ∗(z =0)∼6.5h ^–1 Mpc for red galaxies and r ∗(z =0)∼2-4h ^–1 Mpc for blue galaxies. We also find that, while the angular clustering amplitude of EROs with R -H >4 or I -H >3 is up to four times that of the whole galaxy population, the spatial clustering length r ∗(z =1) is ∼7.5-10.5h ^–1 Mpc, which is only a factor of ∼1.7 times r ∗(z =1) for R -H <4 and I -H <3 galaxies lying in a similar redshift and luminosity range. This difference is similar to that observed between red and blue galaxies at low redshifts.