Lunch talk on Mar. 25th, 2019

The formation of compact elliptical galaxies in the vicinity of a massive galaxy

Speaker: Min Du (Peking University)

Venue: Gewu 2107

Time: 12:30 PM, Monday, 25th March, 2019

Abstract: 

Compact ellipticals (cEs) are outliers from the scaling relations of early-type galaxies, particularly the mass-metallicity relation which is an important outcome of feedback. M32 of the Andromeda system is a typical cE. The formation of such low-mass, but metal-rich and compact, objects is a long-standing puzzle. Using a pair of high-resolution N-body+gas simulations, we investigate the evolution of a gas-rich low-mass galaxy on a highly radial orbit around a massive host galaxy. As the infalling low-mass galaxy passes through the host’s corona at supersonic speeds, we successfully generate a metal-rich cE that is consistent with observations. The metal-rich gas produced by supernovae and stellar winds is confined by the ram pressure from the surrounding environment, leading to subsequent generations of stars being more metal-rich. These results argue that classical cEs are neither the stripped remnants of much more massive galaxies nor the merger remnants of normal dwarfs.