The physical origin of the large-scale conformity in the colours and specific
star formation rates of isolated low mass central galaxies and their neighbours
on scales in excess of 1 Mpc is still under debate. One possible scenario is
that gas is heated over large scales by feedback from active galactic nuclei
(AGN), leading to coherent modulation of cooling and star formation between
well-separated galaxies. In this Letter, the metal line absorption catalogue of
Zhu & Menard (2013) is used to probe gas out to large projected radii around a
sample of a million galaxies with stellar masses ~10^{10} M_{sun} and
photometric redshifts in the range 0.4<z<0.8 selected from Sloan Digital Sky
Survey imaging data. This galaxy sample covers an effective volume of 2.2
Gpc^3. A statistically significant excess of MgII absorbers is present around
the red low mass galaxies compared to their blue counterparts out to projected
radii of 10 Mpc. In addition, the equivalent width distribution function of
MgII absorbers around low mass galaxies is shown to be strongly affected by the
presence of a nearby (R_p<2 Mpc) radio-loud AGN out to projected radii of 5
Mpc.Comment: 5 pages, accepted in MNRAS Letter
