Neil deGrasse Tyson and Harvard graduate student Cullen Blake are currently working to measure spatial correlations in the angular momenta of galaxies using the COSMOS data. Tyson is Co-I on COSMOS, an international collaboration of more than 30 astrophysicists to obtain deep, single-band data from the Hubble Space Telescope over two square degrees on the sky - the largest observing program ever conducted on the Hubble Telescopse. When supplemented by multi-wavelength ground-based data, the COSMOS project will contribute significantly to the large scale structure of the universe, with sub-projects on the weak-lensing search for dark matter, star formation history, galaxy clustering, and morphology evolution.

The Tyson and Blake seek to understand the degree to which the spins of galaxies align, which is important for theories of galaxy formation. Galaxy spin alignments may also present a significant source of noise for measurements of cosmic shear through weak gravitational lensing. There are several theoretical examinations of this topic in the literature, but comparatively few observational results. As the COSMOS data have been accumulating, they have been developing the computational tools necessary to analyze the data by examining data from the Sloan Digitized Sky Survey (Data Release 2). While these two data sets are very different in scope, the techniques used for extracting the galaxy angular momentum correlation signal are very similar. Furthermore, these two data sets should provide complimentary results by exploring different redshift regimes. Their analysis consists of measuring the angular correlation function of galaxy shapes over a range of scales. The measurement of a galaxy's observed shape, and the correction for the effects of the PSF, is central to both the weak lensing and the angular momentum studies. The measured shape-shape correlations can be directly related to predictions from theories of galaxy formation that relate the angular momentum of an early or late type galaxy to its observed shape. This shape-shape correlation function can also directly compared to measurements and predictions of shape correlations induced by weak gravitational lensing. We presented preliminary results from the analysis of the Sloan data in July at the International Astronomical Union meeting #225 on gravitational lensing.

With the experience gained through studying the Sloan data, the analysis of the COSMOS data will proceed in parallel with the COSMOS weak lensing analysis in the coming months.