On the environmental influence of groups and clusters of galaxies beyond the virial radius: Galactic conformity at few Mpc scales

LACERNA, IVÁN; RODRIGUEZ, FACUNDO; MONTERO-DORTA, ANTONIO; O'MILL, ANA LAURA; CORA, SOFÍA; RUIZ, ANDRÉS; HOUGH, TOMÁS; VEGA-MARTINEZ, CRISTIAN

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2022

0035-8711

The environment within dark matter haloes can quench the star formation of galaxies. However, environmental effects beyond the virial radius of haloes (& 1 Mpc) areless evident. An example is the debated correlation between colour or star formationin central galaxies and neighbour galaxies in adjacent haloes at large separations ofseveral Mpc, referred to as two-halo galactic conformity. We use two galaxy catalogues generated from different versions of the semi-analytic model sag applied tothe mdpl2 cosmological simulation and the IllustrisTNG300 cosmological hydrodynamical simulation to study the two-halo conformity by measuring the quenchedfraction of neighbouring galaxies as a function of the real-space distance from centralgalaxies. We find that low-mass central galaxies in the vicinity of massive systems(M200c > 1013 h−1 M) out to 5 h−1 Mpc are preferentially quenched compared toother central galaxies at fixed stellar mass M? or fixed host halo mass M200c at z ∼ 0. Inall the galaxy catalogues is consistent that the low-mass (M? < 1010 h−1 M or M200c< 1011.8 h−1 M) central galaxies in the vicinity of clusters and, especially, groups ofgalaxies mostly produce the two-halo galactic conformity. On average, the quenchedlow-mass central galaxies are much closer to massive haloes than star-forming centralgalaxies of the same mass (by a factor of ∼ 5). Our results agree with other worksregarding the environmental influence of massive haloes that can extend beyond thevirial radius and affect nearby low-mass central galaxies.