Galaxy evolution at high redshift: the legacy of deep near-infrared surveys
Galactic conformity and central / satellite quenching at redshifts 0.4 to 1.9 in the UKIDSS UDS
William Hartley
Christopher Conselice
A curious correlation exists between the star-formation activities of central galaxies and their satellites. The tendency for passive central galaxies to have an enhanced fraction of passive satellites (and vice-versa) has been dubbed 'galactic conformity', and has been demonstrated at group and sub-group halo masses. Theoretical models that include only halo-mass dependent quenching mechanisms are unable to reproduce this behaviour. Understanding how conformity arises may therefore lead us to new discoveries regarding the physical processes that govern the termination of star-formation in satellite galaxies. A vital, but currently unknown, aspect of the conformity effect is how it evolves with redshift. Thus far the correlation has only been identified at low redshift (z~0.1). In this contribution I use the UKIDSS Ultra Deep Survey to investigate the properties and radial distribution of satellite galaxies around typical mass (M*) galaxies over redshift 0.4 to 1.9. I show that
galactic conformity is present to at least z~2 and is not a simple manifestation of halo-mass-driven effects. Finally, I discuss some of the possible implications of conformity for the quenching of central and satellite galaxies.


16:30 - 18:00
EX - LT2 (200)