Synergies between SALT and Herschel, Euclid & the SKA: strong gravitational lensing & galaxy evolution

Gravitational lensing has seen a surge of interest in the past few years. The handful of strong lensing systems known in the year 2000 has now been replaced with hundreds, thanks to innovative multi-wavelength selection, and there is an imminent prospect of thousands of lenses from Herschel and other sub-millimetre surveys. Euclid and the Square Kilometre Array promise tens or even hundreds of thousands. Gravitational lensing is one of the very few probes capable of mapping dark matter halo distributions. Lensing also provides independent cosmological parameter estimates and enables the study of galaxy populations that are otherwise too faint for detailed study. SALT is extremely well placed to have an enormous impact with follow-up observations of foreground lenses and background sources from e.g. Herschel, the South Pole Telescope, the Atacama Cosmology Telescope, Euclid and the Square Kilometre Array. This paper reviews the prospects for high-impact SALT science and the many constraints of galaxy evolution that can result

HST imaging of redshift z>0.5 7C and 3C Quasars

We present preliminary results from HST imaging of radio-loud quasar hosts, covering a ~x100 range in radio luminosity but in a narrow redshift range (0.5 to 0.65). The sample was selected from our new, spectroscopically complete 7C survey and the 3CRR catalogue. Despite the very large radio luminosity range, the host luminosities are only weakly correlated (if at all) with radio power, perhaps reflecting a predominance of purely central engine processes in the formation of radio jets, and hence perhaps also in the radio-loud/-quiet dichotomy at these redshifts. The results also contradict naive expectations from several quasar formation theories, but the host magnitudes support radio-loud Unified Schemes.Comment: To appear in the Proceedings of the ESO/IAC Conference on 'Quasar Hosts' - Tenerife 24-27 September 199

IRAS F10214+4724: the inner 100pc

We use new near-infrared spectroscopy and our published optical spectroscopy of the gravitationally-lensed Seyfert-2 galaxy F10214+4724 to study both the links between the starburst and AGN in this object and the properties of the inner narrow-line clouds. The UV spectrum is consistent with a compact, moderately- reddened starburst providing about half the UV light. Spectroscopy of the Halpha /[NII] line blend has enabled us to distinguish emission from the narrow-line region of the Seyfert-2 and a moderately-reddened emission line region which we argue is associated with the starburst. Estimates of the star formation rate from the UV continuum flux and the Halpha flux are broadly consistent. We can explain the unusual emission line properties of F10214+4724 in terms of conventional models for nearby Seyfert-2 galaxies if lensing is preferentially magnifying the side of the inner narrow-line region between the AGN and the observer, and the other side is both less magnified and partially obscured by the torus. The hydrogen densities of clouds in this region are high enough to make the Balmer lines optically thick and to suppress forbidden emission lines with low critical densities. We have deduced the column density of both ionised and neutral gas in the narrow-line clouds, and the density of the ionised gas. Using these we have been able to estimate the mass of the inner narrow-line clouds to be ~ 1 solar mass, and show that the gas:dust ratio NH/E(B-V) in these clouds must be ~1.3x10^{27}m^{-2}mag^{-1}, significantly higher than in the Milky Way. The cloud properties are consistent with the those of the warm absorbers seen in the X-ray spectra of Seyfert-1 galaxies. Our results favour models in which narrow-line clouds start close to the nucleus and flow out.Comment: 13 pages, 5 figures. Accepted by MNRA

GENIE observations of small scale astrophysical processes in star forming regions and quasars

The VLTI/GENIE configuration will operate using at least 4 of the VLTI telescopes (and possibly with one or more of the AT telescopes in the future if adaptive optics become available on them). GENIE effectively can be thought of as a 'smart' coronagraph, enabling high dynamic range imaging to be achieved at moderate spatial resolution, with high rejection of the emission of a central bright point source. However, but this bright source rejection may only provide a rather moderate image quality (due to the few baselines and transfer function on the sky). Operated in this way, only limited image reconstruction is possible since classical radio and millimeter wavelength interferometry techniques are not directly applicable to the outputs of optical interferometers because the absolute phases are generally not measured. However, measurements of visibility and closure phase could lead to situations where image reconstruction becomes possible. This paper addresses the issue of whether there are areas outside of the exoplanet search where it might be able to make a useful impact on astronomy.Comment: Proceedings of the Genie-Darwin Workshop - Hunting for Planet

The local sub-mm luminosity functions and predictions from Spitzer to Herschel

We present new determinations of the local sub-mm luminosity functions, solving the ``sub-mm Olbers' Paradox.'' We also present predictions of source counts and luminosity functions in current and future far-infrared to sub-mm surveys. Using the sub-mm colour temperature relations from the SCUBA Local Universe Galaxy Survey, and the discovery of excess 450 micron excess emission in these galaxies, we interpolate and extrapolate the IRAS detections to make predictions of the SEDs of all 15411 PSC-z galaxies from 50-1300 microns. Despite the long extrapolations we find excellent agreement with (a) the 90 micron luminosity function of Serjeant et al. (2001), (b) the 850 micron luminosity function of Dunne et al. (2000), (c) the mm-wave photometry of Andreani & Franceschini (1996); (d) the asymptotic differential and integral source count predictions at 50-1300 microns by Rowan-Robinson (2001). We find the local 850 micron sub-mm luminosity density converges to (7.3+/-0.2)x10^{19} h_{65} W/Hz/Mpc^3. Remarkably, the local spectral luminosity density and the extragalactic background light together strongly constrain the cosmic star formation history for a wide class of evolutionary assumptions. We find that the extragalactic background light, the 850 micron 8mJy source counts, and the Omega_* constraints all independently point to a decline in the comoving star formation rate at z>1. In order to reconcile this with direct determinations, we suggest either there is a top-heavy initial mass function at high redshifts, and/or there is stronger evolution in the more luminous far-infrared galaxies than seen in the population as a whole.Comment: MNRAS in press. Uses BoxedEPS (included). 16 figure

The future of astronomy with small satellites

The number of small satellites has grown dramatically in the past decade from tens of satellites per year in the mid-2010s to a projection of tens of thousands in orbit by the mid-2020s. This presents both problems and opportunities for observational astronomy. Small satellites offer complementary cost-effective capabilities to both ground-based astronomy and larger space missions. Compared to ground-based astronomy, these advantages are not just in the accessibility of wavelength ranges where the Earth's atmosphere is opaque, but also in stable, high precision photometry, long-term monitoring and improved areal coverage. Astronomy has a long history of new observational parameter spaces leading to major discoveries. Here we discuss the potential for small satellites to explore new parameter spaces in astrophysics, drawing on examples from current and proposed missions, and spanning a wide range of science goals from binary stars, exoplanets and solar system science to the early Universe and fundamental physics.Comment: Nature Astronomy, in press. 2 figures. Smallsats special issue (with separate articles on problems/mitigations for ground-based/space astronomy