Galaxy formation and evolution

Abstract:

We propose to build a NIR imager/spectrograph for the LET which will support (1) seeing and diffraction limited direct imaging, (2) seeing and diffraction limited long-slit spectroscopy, (3) integral field spectroscopy and (4) tin small fields) OH-suppressed imaging of very faint objects. The instrument will cover the zJHK spectral bands with optimization for the K band. Therefore the optics will be cold (77 K). Whether the wavelength coverage can be extended to 5 mu without seriously compromising the K-band performance will be investigated during the design phase. At present a 2048 x 2048 HgCdTe array is foreseen as detector. Space will be reserved for the possibility of adding a (cold) multiple object spectroscopy unit. The feasibility of such a device will be investigated in parallel to the development of the main instrument. Six German institutes will cooperate to develop this LBT instrument.

Abstract:

We use three samples (3CRR, 6CE and 6C*) to investigate the radio luminosity function (RLF) for the 'most powerful' low-frequency selected radio sources. We find that the data are well fitted by a model with a constant ca-moving space density at high redshift as well as by one with a declining co-moving space density above some particular redshift. This behaviour is very similar to that inferred for steep-spectrum radio quasars by Willott et al (1998) in Line with the expectations of Unified Schemes. We conclude that there is as yet no evidence for a 'redshift cutoff' in the co-moving space densities of powerful classical double radio sources, and rule out a art-off at z less than or similar to 2.5.