Theoretical estimates of intrinsic galaxy alignment |
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| Authors: | Jonathan Mackey Martin White Marc Kamionkowski |
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| Institution: | Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, USA and; Mail Code 130-33, California Institute of Technology, Pasadena, CA 91125, USA |
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| Abstract: | It has recently been argued that the observed ellipticities of galaxies may be determined at least in part by the primordial tidal gravitational field in which the galaxy formed. Long-range correlations in the tidal field could thus lead to an ellipticity–ellipticity correlation for widely separated galaxies. We present a new model relating ellipticity to angular momentum, which can be calculated in linear theory. We use this model to calculate the angular power spectrum of intrinsic galaxy shape correlations. We show that, for low-redshift galaxy surveys, our model predicts that intrinsic correlations will dominate correlations induced by weak lensing, in good agreement with previous theoretical work and observations. We find that our model produces ' E -mode' correlations enhanced by a factor of 3.5 over B -modes on small scales, making it harder to disentangle intrinsic correlations from those induced by weak gravitational lensing. |
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| Keywords: | gravitational lensing cosmology: theory large-scale structure of Universe |
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