(Proposal ID) S10A-039

(PI) Arnaboldi, Magda

(Proposal Title)
The Suprime-Cam M87 PN survey: testing galaxy formation in clusters

(Abstract)
The long-lasting substructures preserved in the outer halos of giant 
elliptical galaxies are the best records of merger and accretion events that 
took place in the densest regions of the universe. However, little is known 
about them observationally. The motions and chemical compositions of the stars 
in these halos provide vital information, which any galaxy formation theory 
must account for. Here we propose to study the extended halo of the 
prototypical elliptical galaxy M87 in the Virgo cluster and to unveil the 
fossil record caused by past accretion events using Planetary Nebulae (PNe). 
PNe are the only abundant, single stars whose velocities can be measured at 
distances of 15 Mpc, and differently from globular clusters, they trace the 
kinematics of stars. With Subaru & Suprime-Cam, we shall identify and measure 
the [OIII] 5007A fluxes for an unprecedented large number of ~1500 PNe 
distributed between r=4 kpc and 150 kpc in the M87 halo. This dataset 
(position and [OIII] fluxes) will be combined with radial velocities from 
later spectroscopic follow-ups to construct a unique database that represents 
a milestone for understanding the formation history of giant elliptical 
galaxies in general and the mass assembly at the centers of galaxy clusters.