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John M. Dickey

Publications and source records attributed to John M. Dickey.

74 records · Page 5Linked to original sources

Determination of Galaxy Spin Vectors in the Pisces-Perseus Supercluster with the Arecibo Telescope

We use HI observations made with the upgraded Arecibo 305M Telescope in August 1998 to obtain accurate spin vector determinations for 54 nearly edge-on galaxies in the Minnesota Automated Plate Scanner Pisces-Perseus Survey (MAPS-PP). We introduce a simple observational technique of determining the sense of rotation for galaxies, even when their HI disks are not fully resolved. We examined the spin vector distribution of these 54 galaxies for evidence of preferential galaxy alignments. We use the Kuiper statistic, a variant of the Kolmogorov--Smirnov statistic, to determine the significance of any anisotropies in the distribution of galaxy spin vectors. The possibility of ``spin vector domains'' is also investigated. We find no significant evidence of preferential galaxy alignments in this sample. However, we show tha t the small sample size places weak limits on the level of galaxy alignments.

astro-ph↗

Absorption of the Linear Polarization of the Galactic Background Radiation by the $λ$21-cm Line of HI

Absorption lines at $λ$ 21-cm are detected in the Stokes Q and U components of the Galactic synchrotron background. The lower limit distance implied for the emission region is 2 kpc in the direction (l,b) = (329.5$^{\circ}$,+1.15$^{\circ}$). The Australia Telescope Compact Array has the capability of mapping this absorption over large areas of the Galactic plane. Observations like these have the potential to reveal the three dimensional structure of the Galactic synchrotron emission throughout the Milky Way disk.

astro-ph↗