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.