ADMX Run 1c: A High-Resolution Search*

The Axion Dark Matter eXperiment (ADMX) searches for axions bound in the dark matter halo in the Milky Way galaxy. To date, ADMX has ruled out the QCD axion in the frequency range of approximately 650 MHz to 1 GHz (masses of 2.7 to 4.1 $\mu$eV, for both the KSVZ and DFSZ models. However, this analysis was done with respect to the expected signal from the isothermal halo model. A component of the halo of axions could be cold, nonvirialized flows predicted by the caustic ring model. The key characterstic of these flows is their signal would be sharp in frequency space, such that the main analysis is insensitive to them. The signal to noise ratio of a signal with a certain frequency width depends on the frequency resolution of the analysis. Thus, a follow-up analysis for frequency resolutions of 20 mHz, 40 mHz, 200 mHz, and 1 Hz was performed searching for these nonvirialized flows. This talk will discuss the motivation, methods, and preliminary results of this high resolution search.