The Curious Case of Centaurus A II: On the Subject of the Quenched satellites

TL;DR

This study investigates why Centaurus A has fewer luminous satellite galaxies in its inner regions, proposing that AGN feedback may quench star formation in satellites, aligning models with observations.

Contribution

It introduces a semi-analytic model incorporating AGN feedback to explain the satellite luminosity deficit in Centaurus A's inner halo.

Findings

AGN-driven thermal feedback can suppress star formation in satellites.

Models overpredict bright satellites without environmental effects.

Environmental factors like radio lobes influence satellite survival.

Abstract

The satellite system of Centaurus A presents a curious cosmological puzzle: while the global population is consistent with theoretical expectations, its inner regions (d<150 kpc) exhibit a deficit of luminous satellite galaxies. Using the Galacticus semi-analytic model applied to high-resolution N-body merger trees, we investigate potential quenching mechanisms to explain this trend. Our fiducial models, calibrated to the Milky Way, reproduce the overall Cen A population but overpredict the number of bright inner-halo satellites by a factor of 4 +- 1 at Mv < -15.8. We find that this is not due to statistical variance. Instead, the spatial coincidence of this deficiency with Cen A's massive, kiloparsec-scale radio lobes suggests a powerful environmental driver. We explore a range of physical scenarios, including enhanced tidal disruption, reionization quenching, and suppressed accretion into halos from the surrounding intergalactic medium. Our results indicate that AGN-driven thermal feedback at z < 5 can significantly suppress star formation in satellites, effectively truncating the bright end of the inner luminosity function. Our work suggests that the "Curious Case of Centaurus A" may provide evidence of AGN feedback within the host galaxy that regulates the survival and evolution of its dwarf galaxy satellites.