The build-up of the cD halo of M87 - evidence for accretion in the last Gyr

Understand

We present kinematic and photometric evidence for an accretion event in the halo of the cD galaxy M87 in the last Gyr.

• Using velocities for ~300 planetary nebulas (PNs) in the M87 halo, we identify a chevron-like substructure in the PN phase-space.
• We implement a probabilistic Gaussian mixture model to identify the PNs that belong to the chevron.
• From analysis of deep V-band images of M87, we find that the region with the highest density of PNs associated to the chevron, is a crown-shaped substructure in the optical light.