The LBDS Hercules sample of mJy radio sources at 1.4 GHz - II. Redshift distribution, radio luminosity function, and the high-redshift cut-off

{Abridged} A combination of spectroscopy and broadband photometric redshifts has been used to find the complete redshift distribution of the Hercules sample of millijansky radio sources. These data have been used to examine the evolution of the radio luminosity function (RLF) and its high-redshift cut-off. New redshifts have been measured for eleven sources, and a further ten upper limits are given. The total number of sources with known redshifts in the sample is now 47 (65%). We calculated broadband photometric redshifts for the remaining one-third of the sample. For the luminosity range probed by the present study (P_1.4 > 10^24.5 W/Hz/sr), we use the V/V_max test to show conclusively that there is a deficit of high-redshift (z > 2-2.5) objects. Comparison with the model RLFs of Dunlop & Peacock (1990) shows that our data can now exclude pure luminosity evolution. Two of the models of DP90, and the RLF deduced by direct binning of the data, both favour a luminosity dependence for the high-redshift cut-off, with lower-luminosity sources (P_1.4 \simeq 10^24 W/Hz/sr) in decline by z \simeq 1-1.5 while higher-luminosity sources (P_1.4 \simeq 10^{25-26} W/Hz/sr) decline in comoving number density beyond z \simeq 2-2.5.Comment: Revised version submitted to MNRAS. 16 pages, 12 figure

A 1200-micron MAMBO survey of ELAISN2 and the Lockman Hole - I. Maps, sources and number counts

The definitive version is available at www.blackwell-synergy.com '.--Copyright Blackwell Publishing. DOI : 10.1111/j.1365-2966.2004.08235.xWe present a deep, new 1200μm survey of the ELAISN2 and Lockman Hole fields using the Max Planck Millimeter Bolometer array (MAMBO). The areas surveyed are 160 arcmin2 in ELAISN2 and 197 arcmin2 in the Lockman Hole, covering the entire SCUBA ‘8mJy Survey’. In total, 27 (44) sources have been detected at a significance 4.0 ( 3.5 ). The primary goals of the survey were to investigate the reliability of (sub)millimetre galaxy (SMG) samples, to analyse SMGs using flux ratios sensitive to redshift at z > 3, and to search for ‘SCUBA drop-outs’, i.e. galaxies at z >> 3. We present the 1200μm number counts and find evidence of a fall at bright flux levels. Employing parametric models for the evolution of the local 60μm IRAS luminosity function (LF), we are able to account simultaneously for the 1200 and 850μm counts, suggesting that the MAMBO and SCUBA sources trace the same underlying population of high-redshift, dust-enshrouded galaxies. From a nearest-neighbour clustering analysis we find tentative evidence that themost significantMAMBO sources come in pairs, typically separated by 23′′. Our MAMBO observations unambiguously confirm around half of the SCUBA sources. In a robust sub-sample of 13 SMGs detected by both MAMBO and SCUBA at a significance 3.5 , only one has no radio counterpart. Furthermore, the distribution of 850/1200μmflux density ratios for this sub-sample is consistent with the spectroscopic redshift distribution of radio-detected SMGs (Chapman et al. 2003). Finally, we have searched for evidence of a high-redshift tail of SMGs amongst the 18 MAMBO sources which are not detected by SCUBA. While we cannot rule out that some of them are SCUBA drop-outs at z >> 3, their overall 850-to-1200μm flux distribution is statistically indistinguishable from that of the 13 SMGS which were robustly identified by both MAMBO and SCUBA.Peer reviewe

The KMOS Deep Survey (KDS) – I. Dynamical measurements of typical star-forming galaxies at z ≃ 3.5

We present dynamical measurements from the KMOS (K-band Multi-Object Spectrograph) Deep Survey (KDS), which is comprised of 77 typical star-forming galaxies at z z ≃ 3.5 in the mass range 9.0 1), with the sample average VC/σint value much smaller than at lower redshift. After carefully selecting comparable star-forming samples at multiple epochs, we find that the rotation-dominated fraction evolves with redshift with a z−0.2 dependence. The rotation-dominated KDS galaxies show no clear offset from the local rotation velocity-stellar mass (i.e. VC − M⋆) relation, although a smaller fraction of the galaxies are on the relation due to the increase in the dispersion-dominated fraction. These observations are consistent with a simple equilibrium model picture, in which random motions are boosted in high-redshift galaxies by a combination of the increasing gas fractions, accretion efficiency, specific star-formation rate and stellar feedback and which may provide significant pressure support against gravity on the galactic disk scale

The SCUBA Half Degree Extragalactic Survey (SHADES) - III : Identification of radio and mid-infrared counterparts to submillimetre galaxies

Peer reviewe

Open Issues on the Synthesis of Evolved Stellar Populations at Ultraviolet Wavelengths

In this paper we briefly review three topics that have motivated our (and others') investigations in recent years within the context of evolutionary population synthesis techniques. These are: The origin of the FUV up-turn in elliptical galaxies, the age-metallicity degeneracy, and the study of the mid-UV rest-frame spectra of distant red galaxies. We summarize some of our results and present a very preliminary application of a UV grid of theoretical spectra in the analysis of integrated properties of aged stellar populations. At the end, we concisely suggest how these topics can be tackled once the World Space Observatory enters into operation in the midst of this decade.Comment: 8 pages, 4 figures, accepted for publication in Astrophysics & Space Science, UV Universe special issu

Quasars and their host galaxies

This review attempts to describe developments in the fields of quasar and quasar host galaxies in the past five. In this time period, the Sloan and 2dF quasar surveys have added several tens of thousands of quasars, with Sloan quasars being found to z>6. Obscured, or partially obscured quasars have begun to be found in significant numbers. Black hole mass estimates for quasars, and our confidence in them, have improved significantly, allowing a start on relating quasar properties such as radio jet power to fundamental parameters of the quasar such as black hole mass and accretion rate. Quasar host galaxy studies have allowed us to find and characterize the host galaxies of quasars to z>2. Despite these developments, many questions remain unresolved, in particular the origin of the close relationship between black hole mass and galaxy bulge mass/velocity dispersion seen in local galaxies.Comment: Review article, to appear in Astrophysics Update

The SCUBA-2 Cosmology Legacy Survey: the nature of bright submm galaxies from 2 deg2 of 850-μm imaging

We present physical properties [redshifts (z), star-formation rates (SFRs) and stellar masses ( Mstar Mstar )] of bright (S850 ≥ 4 mJy) submm galaxies in the ≃2 deg2 COSMOS and UDS fields selected with SCUBA-2/JCMT. We complete the galaxy identification process for all (≃2000) S/N ≥ 3.5 850-μm sources, but focus our scientific analysis on a high-quality subsample of 651 S/N ≥ 4 sources with complete multiwavelength coverage including 1.1-mm imaging. We check the reliability of our identifications, and the robustness of the SCUBA-2 fluxes by revisiting the recent ALMA follow-up of 29 sources in our sample. Considering >4 mJy ALMA sources, our identification method has a completeness of ≃86 per cent with a reliability of ≃92 per cent, and only ≃15–20 per cent of sources are significantly affected by multiplicity (when a secondary component contributes >1/3 of the primary source flux). The impact of source blending on the 850-μm source counts as determined with SCUBA-2 is modest; scaling the single-dish fluxes by ≃0.9 reproduces the ALMA source counts. For our final SCUBA-2 sample, we find median z=2.40+0.10−0.04 z=2.40−0.04+0.10 , SFR = 287 ± 6 M⊙  yr− 1 and log(Mstar/M⊙)=11.12±0.02 log⁡(Mstar/M⊙)=11.12±0.02 (the latter for 349/651 sources with optical identifications). These properties clearly locate bright submm galaxies on the high-mass end of the ‘main sequence’ of star-forming galaxies out to z ≃ 6, suggesting that major mergers are not a dominant driver of the high-redshift submm-selected population. Their number densities are also consistent with the evolving galaxy stellar mass function. Hence, the submm galaxy population is as expected, albeit reproducing the evolution of the main sequence of star-forming galaxies remains a challenge for theoretical models/simulations

The lifecycle of powerful AGN outflows

During the course of this conference, much evidence was presented that points to an intimate connection between the energetic outflows driven by AGN and the energy budget and quite possibly also the evolution of their gaseous environments. However, it is still not clear if and how the AGN activity is triggered by the cooling gas, how long the activity lasts for and how these effects give rise to the observed distribution of morphologies of the outflows. In this contribution we concentrate on the high radio luminosity end of the AGN population. While most of the heating of the environmental gas may be due to less luminous and energetic outflows, these more powerful objects have a very profound influence on their surroundings. We will describe a simple model for powerful radio galaxies and radio-loud quasars that explains the dichotomy of their large-scale radio morphologies as well as their radio luminosity function.Comment: 6 pages, contribution to 'Heating vs. coooling in galaxies and galaxy clusters', Garching 2006, proceedings to be published by Springer (ESO Astrophysics Symposia), eds. H. Boehringer, P. Schuecker, G.W. Pratt & A. Finogueno