WUNA Lunch Talk:

David Martinez-Delgado


A Survey of Stellar Tidal Streams in Nearby Spiral Galaxies

April 22

12:10PM, Room 230, NRAO, Edgemont Road


Within the hierarchical framework for galaxy formation, merging and tidal interactions are expected to shape large galaxies to this day. While major mergers are quite rare at present, minor mergers and satellite disruptions - that result in stellar streams - should be common, and are indeed seen in both the Milky Way and the Andromeda Galaxy.

As a pilot study, we have carried out ultra-deep, wide-field imaging of some spiral galaxies in the Local Volume, which has revealed external views of such stellar tidal streams at unprecedented sensitivity and detail, with data taken at small robotic telescopes (0.1-0.5-meter) that provide exquisite surface brightness sensitivity.

The goal of our project is to undertake the first systematic and comprehensive imaging survey of stellar tidal streams for a sample of 50 nearby Milky-Way-like spiral galaxies within 15 Mpc, with a surface brightness sensitivity of 29-30 mag/arcsec2. The survey will result in estimates of the incidence, size/geometry and stellar luminosity/mass distribution of such streams. This will not only to put our Milky Way and M31 in context, but also provide for the first time an extensive statistical basis for comparison with state-of-art, self-consistent Lambda-CDM cosmological simulations of this phenomenon. The results of the project will provide a direct and stringent test of hierarchical structure formation on this scale, will constrain the present-epoch (minor) interaction rate and probe the minor-merger resilience of stellar disks.