Hintze Centre for Astrophysical Surveys

Abstract:

We measured the harmonic-space power spectrum of galaxy clustering auto-correlation from the Evolutionary Map of the Universe Pilot Survey 1 data (EMU PS1) and its cross-correlation with the lensing convergence map of cosmic microwave background (CMB) from Planck Public Release 4 at the linear scale range from ℓ = 2 to 500. We applied two flux density cuts at 0.18 and 0.4mJy on the radio galaxies observed at 944MHz and considered two source detection algorithms. We found the auto-correlation measurements from the two algorithms at the 0.18mJy cut to deviate for ℓ ≥ 250 due to the different criteria assumed on the source detection and decided to ignore data above this scale. We report a cross-correlation detection of EMU PS1 with CMB lensing at ∼5.5σ, irrespective of flux density cut. In our theoretical modelling we considered the SKADS and T-RECS redshift distribution simulation models that yield consistent results, a linear and a non-linear matter power spectrum, and two linear galaxy bias models. That is a constant redshift-independent galaxy bias b(z) = bg and a constant amplitude galaxy bias b(z) = bg/D(z). By fixing a cosmology model and considering a non-linear matter power spectrum with SKADS, we measured a constant galaxy bias at 0.18mJy (0.4mJy) with bg = 2.32-0.33^+0.41 (2.18-0.25^+0.17) and a constant amplitude bias with bg = 1.72-0.21^+0.31 (1.78-0.15^+0.22). When σ8 is a free parameter for the same models at 0.18mJy (0.4mJy) with the constant model we found σ8 = 0.68-0.14^+0.16 (0.82 ±0.10), while with the constant amplitude model we measured σ8 = 0.61-0.20^+0.18 (0.78-0.09^+0.11), respectively. Our results agree at 1σ with the measurements from Planck CMB and the weak lensing surveys and also show the potential of cosmology studies with future radio continuum survey data.

Abstract:

Almost every galaxy in the local Universe is observed to have a massive black hole in the center. The properties of these black holes are observed to tightly correlate with those of their host galaxy which has been interpreted as coevolution regulated by black hole feedback. This coevolution spans most of cosmic history, as the first active black holes, so-called active galactic nuclei, are already observed as early as z∼10. In this chapter, we lay out how we can find supermassive black holes, review what we know about the population of black holes and their host galaxies from observations, and summarize what we have learned about their coevolution across cosmic time from both observations and simulations.

Abstract:

This repository contains the grizy-band reference frame stacks that were utilised by Gillanders et al. (2025) for accurate reference image subtraction of the field of SN2025ulz.

If one makes use of these data, the work of Gillanders et al. (2025) must be credited.

Abstract:

Strong gravitational lensing has emerged as one of the most versatile tools to explore a range of open questions in astrophysics and cosmology. In this chapter, we focus on the significant contribution of strong lensing in the fields of galaxy structure and evolution. This includes the distribution of luminous and dark matter in galaxies, dark matter substructure, the initial mass function in intermediate redshift massive galaxies and the nature of high redshift galaxies. The impact of this probe has been significant, despite the rarity of known gravitational lens systems. In the imminent era of wide-area sensitive sky surveys, that will reveal 105 strong lensing systems, the full potential of strongly lensed galaxies as an essential and versatile probe of the nature of galaxies will be realized.