Efstathiou, Andreas

We present the 90-μm luminosity function of the Final Analysis of the European Large Area ISO Survey (ELAIS), extending the sample size of our previous analysis (Paper IV) by about a factor of 4. Our sample extends to z = 1.1, ∼50 times the comoving volume of Paper IV, and 10 7.7 < h -2 L/L ⊙ < 10 02.5. From our optical spectroscopy campaigns of the northern ELAIS 90-μm survey (7.4 deg 2 in total, to S 90 μm ≥ 70 mJy), we obtained redshifts for 61 per cent of the sample (151 redshifts) to B < 21 identified at 7 μm, 15 μm, 20 cm or with bright (B < 18.5) optical identifications. The selection function is well-defined, permitting the construction of the 90-μm luminosity function of the Final Analysis catalogue in the ELAIS northern fields, which is in excellent agreement with our Preliminary Analysis luminosity function in the ELAIS S1 field from Paper IV. The luminosity function is also in good agreement with the recent IRAS-based prediction of Serjeant and Harrison - which, if correct, requires luminosity evolution of (1 + z) 3.4±1.0 for consistency with the source counts. This implies an evolution in comoving-volume-averaged star formation rate at z ≲ 1 consistent with that derived from rest-frame optical and ultraviolet surveys.

We present deep imaging at 6.7 and 15 μm from the CAM instrument on the Infrared Space Observatory (ISO), centred on the Hubble Deep Field (HDF). These are the deepest integrations published to date at these wavelengths in any region of sky. We discuss the observational strategy and the data reduction. The observed source density appears to approach the CAM confusion limit at 15 μm, and fluctuations in the 6.7-μm sky background may be identifiable with similar spatial fluctuations in the HDF galaxy counts. ISO appears to be detecting comparable field galaxy populations to the HDF, and our data yield strong evidence that future infrared missions (such as SIRTF, FIRST and WIRE) as well as SCUBA and millimetre arrays will easily detect field galaxies out to comparably high redshifts.

We present the luminosity function of 90-μm-selected galaxies from the European Large Area ISO Survey (ELAIS), extending to z = 0.3. Their luminosities are in the range 109 < h-265L/L⊙ < 1012, i.e. non-ultraluminous. From our sample of 37 reliably detected galaxies in the ELAIS S1 region from the Efstathiou et al. S90 ≥ 100 mJy data base, we have found optical, 15-μm or 1.4-GHz identifications for 24 (65 per cent). We have obtained 2dF and UK Schmidt FLAIR spectroscopy of 89 per cent of identifications to rigid multivariate flux limits. We construct a luminosity function assuming that (i) our spectroscopic subset is an unbiased sparse sample, and (ii) there are no galaxies that would not be represented in our spectroscopic sample at any redshift. We argue that we can be confident of both assumptions. We find that the luminosity function is well described by the local 100-μm luminosity function of Rowan-Robinson, Helou & Walker. Assuming this local normalization, we derive luminosity evolution of (1 + z)2.45±0.85 (95 per cent confidence). We argue that star formation dominates the bolometric luminosities of these galaxies, and we derive comoving star formation rates in broad agreement with the Flores et al. and Rowan-Robinson et al. mid-infrared-based estimates.

We present an extended analysis of the Submillimetre Common User Bolometer Array (SCUBA) observations of the Hubble Deep Field (HDF), expanding the areal coverage of the Hughes et al. study by a factor of ∼1.8 and containing at least three further sources in addition to the five in that study. We also announce the public release of the reduced data products. The map is the deepest ever made in the submillimetre (submm), obtained in excellent conditions (median 850-μm optical depth of 0.16). Two independent reductions were made, one with SURF and the other with a wholly algorithmic IDL analysis which we present in detail here. Of the three new sources, all appear to be at z ≳ 0.9 and one is provisionally associated with an extremely red object (I - K > 5). There appears to be no significant cross-correlation signal between the 850-μm fluctuations and sources detected by ISOCAM, the Very Large Array (VLA) or Chandra, nor with very red objects (I - K > 4), nor quasars and quasar candidates in the HDF (notwithstanding a small number of individual weak candidate detections). This is consistent with interpretations where the 850-μm selected galaxies are at higher redshifts than those currently probed by ISOCAM/VLA, and predominantly not Compton-thin active galactic nuclei (AGN). There are only one or two compelling cases for the radio source being the submm source. Nevertheless, most SCUBA-HDF point sources have a nearby radio source apparently well-separated from the submm centroid.