TY - JOUR
T1 - Kinematic evidence for halo substructure in spiral galaxies
AU - Herrmann, Kimberly A.
AU - Ciardullo, Robin
AU - Sigurdsson, Steinn
N1 - Funding Information:
We thank Fabian Walter and Erwin de Blok for giving us access to the THINGS data prior to publication. We also thank our anonymous referee for useful comments. This research has made use of NASA’s Astrophysics Data System and the NASA/ IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. This work was supported by NSF grant AST 06-07416 and a Pennsylvania Space Grant Fellowship.
PY - 2009
Y1 - 2009
N2 - We present the results of a kinematic study of planetary nebulae in the extreme outskirts of two spiral galaxies, M83 (NGC 5236) and M94 (NGC 4736). We find that in the inner regions of the galaxies, the vertical velocity dispersion (σz) falls off exponentially with the light, as expected for a constant mass-to-light ratio, constant thickness disk. However, starting at four optical scale lengths, σz asymptotes out at roughly 20 km s-1. Our analysis finds evidence for significant flaring in the outer regions as well, especially in M94. These observations are in excellent agreement with predictions derived from models of disk heating by halo substructure, and demonstrate how kinematic surveys in the outer disks of spirals can be used to test hierarchical models of galaxy formation.
AB - We present the results of a kinematic study of planetary nebulae in the extreme outskirts of two spiral galaxies, M83 (NGC 5236) and M94 (NGC 4736). We find that in the inner regions of the galaxies, the vertical velocity dispersion (σz) falls off exponentially with the light, as expected for a constant mass-to-light ratio, constant thickness disk. However, starting at four optical scale lengths, σz asymptotes out at roughly 20 km s-1. Our analysis finds evidence for significant flaring in the outer regions as well, especially in M94. These observations are in excellent agreement with predictions derived from models of disk heating by halo substructure, and demonstrate how kinematic surveys in the outer disks of spirals can be used to test hierarchical models of galaxy formation.
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U2 - 10.1088/0004-637X/693/1/L19
DO - 10.1088/0004-637X/693/1/L19
M3 - Article
AN - SCOPUS:64949095452
SN - 0004-637X
VL - 693
SP - L19-L22
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1 PART 2
ER -