Subproject A2: Milky Way Satellite Census and Characterization
Eva Grebel (ARI), Norbert Christlieb (LSW)
|
Search for new Galactic satellites and follow-up studies to understand the extreme low-mass end of the process of galaxy formation. This involves the search, structural characterization evolutionary histories, chemistry, kinematics, and dark matter content of faint Milky Way satellites. It will further probe the "sub-structure crisis/issue" in ΛCDM and provide a comparison to the stellar population properties of the Galactic halo.
A prediction of recent cosmological models is that the most significant contributors to the stellar mass of the inner halo were several massive satellites that were accreted early on. The Magellanic Clouds may be present-day counterparts of such early contributors. If so, their old stellar populations should be chemically similar to halo stars. However, since these irregular galaxies are dominated by intermediate-age populations, it is a challenge to identify genuinely old stars. Using RR Lyrae stars, which only occur in old populations, we discovered the most metal-poor stars known in the Magellanic Clouds known so far. We showed that their element abundance ratios are consistent with those of similarly metal-poor stars in the halo. While progress was made on the characterization of Galactic satellites, the work towards the completion of the census of Galactic satellites during the first funding period did not proceed as planned since the photometric survey data from the “Panoramic Survey Telescope and Rapid Response System” (Pan-STARRS) only recently reached a homogeneity sufficient for this purpose.
Publications
Haschke, R., Grebel, E.K., Duffau, S., Jin, S.: "Metallicity Distribution Functions of the Old Populations of the Magellanic Clouds from RR Lyrae Stars"; 2012, AJ, 143, 48
Salucci, P., Wilkinson, M.I., Walker, M.G., Gilmore, G.F., Grebel, E.K., Koch, A., Frigerio Martins, C., & Wyse, R.F.G.: "Dwarf spheroidal galaxy kinematics and spiral galaxy scaling laws"; 2012, MNRAS, 420, 2034
Pasetto, S., Bertelli, G., Grebel, E.K., Chiosi, C., & Fujita, Y.: "Dissipative Phenomena in Extended-Bodies Interactions: Dwarf Galaxies of the Local Group and Their Synthetic CMDs"; 2012, A&A, 542, A17
Frank, M.J., Hilker, M., Baumgardt, H., Cote, P., Grebel, E.K., Haghi, H., Kuepper, A., & Djorgovski, S.L.: "The velocity dispersion and mass function of the outer halo globular cluster Palomar 4"; 2012, MNRAS, 423, 2917
Cignoni, M., Cole, A.A., Tosi, M., Gallagher, J.S., Sabbi, E., Anderson, J., Grebel, E.K., & Nota, A.: "Star Formation History in the Field of the Small Magellanic Cloud. I. The Bar"; 2012, ApJ, 754, 130
Haschke, R., Grebel, E.K., Frebel, A., Duffau, S., Hansen, C.J., & Koch, A.: "Chemical Abundances of Metal-Poor RR Lyrae Stars in the Magellanic Clouds"; 2012, AJ, 144, 88
Lora, V., Just, A., Sanchez-Salcedo, F.J., & Grebel, E.K.: "Dark Matter Subhaloes in the Ursa Minor Dwarf Galaxy"; 2012, ApJ, 757, 87
Haschke, R., Grebel, E.K., Duffau, S.: "Three-Dimensional Maps of the Magellanic Clouds Using RR Lyrae Stars and Cepheids. II. The Small Magellanic Cloud"; 2012, AJ, 144, 107
Haschke R., Grebel, E.K., Duffau, S.: "Three-Dimensional Maps of the Magellanic Clouds Using RR Lyrae Stars and Cepheids. I. The Large Magellanic Cloud"; 2012, AJ, 144, 106
Caliskan, S., Christlieb, N., & Grebel, E.K.: "Abundance analysis of the outer halo globular cluster Palomar 14"; 2012, A&A, 537, 83
Cignoni, M., Cole, A.A., Tosi, M., Gallagher, J.S., Sabbi, E., Anderson, J., Grebel, E.K., & Nota, A.: "Mean age gradient and asymmetry in the star formation history of the Small Magellanic Cloud"; 2013, ApJ, 775, 83
Baumgardt, H., Parmentier, G., Anders, P., & Grebel, E.K.: "The star cluster formation history of the LMC"; 2013, MNRAS, 430, 676
Lora, V., Grebel, E.K., Sanchez-Salcedo, F.J., & Just, A.: "Sextans' Cold Substructures as a Dynamical Judge: Core, Cusp, or MOND?"; 2013, ApJ, 777, 65
