Tidal Streams in Newly Discovered Compact Elliptical (cE) Galaxies

TL;DR

This paper reports the discovery of two compact elliptical galaxies with tidal streams, providing direct evidence for their formation via tidal stripping in small galaxy groups.

Contribution

It presents the first direct observational evidence of tidal streams in newly discovered cE galaxies, supporting the tidal stripping formation scenario.

Findings

Both cEs show clear tidal streams.

The cEs have effective radii less than 400 pc.

They possess young to intermediate-age stellar populations.

Abstract

We present two newly-discovered, compact elliptical (cE) galaxies, which exhibit clear evidence of tidal steams, found in a search of SDSS DR7. The structural parameters of the cEs are derived using GALFIT and give effective radii < 400 pc. They also possess young to intermediate-age stellar populations. These two cEs provide direct evidence, a "smoking gun", for the process of tidal stripping that is believed to be the origin of M32-type galaxies. Both are found in small group environments with many late-type galaxies, suggesting that we may be seeing the formation of such galaxies in dynamically young galaxy groups.