Galaxy Environment

The environment of a galaxy can be a key factor in determining the evolution of galaxies. The environment of a galaxy is a multi-faceted property and can be quantified and interpreted in a large number of different ways depending on observations available and given science goal.

Partial List of Probes of Environment

- N-th Nearest Neighbour

- Fixed Aperture Measures

- Correlation Functions, power spectra, counts-in-cells

- Identifying Groups, Clusters, Filaments, Voids

- Complementary observations of local gas content etc.

Galaxy Halo Connection

One key perspective on environment is the galaxy-halo connection; how the dark matter halo that a galaxy is in affects its evolution and determines its properties.

Typically this requires assuming some knowledge of the underlying dark matter halo distribution, and then measuring some properties of the galaxy population and constraining what the relationship could be.

This can be probed in a number of ways:

- Galaxy number counts; the comoving number density of galaxies

- Galaxy-galaxy clustering; measuring the correlation function/power spectrum of galaxies, often in angular space

- Galaxy-galaxy lensing; measure the correlation between galaxies and the shear on background galaxies from gravitational lensing

Very broadly, measurements of clustering contain information about information about galaxy environment on small (~<1Mpc) scales, and information about cosmology on large (~>1Mpc) scales

Some broader notes about galaxy clustering and correlation functions: File:Clustering notes small PH.pdf

Examples of Work by Current or Former Group Members in this Area

Cross-correlating radio continuum surveys and CMB lensing: constraining redshift distributions, galaxy bias and cosmology

Formation of S0s in extreme environments II: the star-formation histories of bulges, discs and lenses

Comparing Galaxy Clustering in Horizon-AGN Simulated Lightcone Mocks and VIDEO Observations

The clustering and bias of radio-selected AGN and star-forming galaxies in the COSMOS field

PKSB1740-517: An ALMA view of the cold gas feeding a distant interacting young radio galaxy

The environment and host haloes of the brightest z~6 Lyman-break galaxies

Environmental Quenching and Galactic Conformity in the Galaxy Cross-Correlation Signal

The galaxy-halo connection in the VIDEO Survey at 0.5<z<1.7

Tracing the neutral gas environments of young radio AGN with ASKAP

Evolution in the bias of faint radio sources to z ~ 2.2

Galaxy and Mass Assembly (GAMA): The evolution of bias in the radio source population to z ~ 1.5

Sample variance, source clustering and their influence on the counts of faint radio sources

The environments of hyperluminous infrared galaxies at 0.44<z<1.55