Diffuse Tidal Structures in the Halos of Virgo Ellipticals

TL;DR

This study uses deep photometry to identify and analyze diffuse tidal features around five Virgo elliptical galaxies, revealing diverse accretion histories and interactions with their environment.

Contribution

It provides detailed observations of tidal structures in galaxy halos, highlighting their origins and implications for galaxy evolution in a cluster environment.

Findings

M49 has an extended shell system indicating satellite accretion.

M89 shows complex shells and plumes from multiple or major mergers.

M87 exhibits long streamers from dwarf galaxy stripping.

Abstract

We use deep V-band surface photometry of five of the brightest elliptical galaxies in the Virgo cluster to search for diffuse tidal streams, shells, and plumes in their outer halos (r > 50 kpc). We fit and subtract elliptical isophotal models from the galaxy images to reveal a variety of substructure, with surface brightnesses in the range mu_V= 26-29 mag/arcsec^2. M49 possesses an extended, interleaved shell system reminiscent of the radial accretion of a satellite companion, while M89's complex system of shells and plumes suggests a more complicated accretion history involving either multiple events or a major merger. M87 has a set of long streamers as might be expected from stripping of low luminosity dwarfs on radial orbits in Virgo. M86 also displays a number of small streams indicative of stripping of dwarf companions, but these comprise much less luminosity than those of M87. Only M84 lacks significant tidal features. We quantify the photometric properties of these structures, and discuss their origins in the context of each galaxy's environment and kinematics within the Virgo cluster.