Theoretical estimates of intrinsic galaxy alignment
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.
Additional Information© 2002 RAS. Received: 14 January 2002. Accepted: 16 January 2002. Published: 01 June 2002. We thank U.-L. Pen, C. Metzler, R. Croft, R. Crittenden, P. Natarajan, A. Heavens and A. Refregier for useful discussions on intrinsic alignments. JM thanks R. Narayan and J. Huchra for helpful comments on an earlier draft. This work was supported in part by the Alfred P. Sloan Foundation and the National Science Foundation, through grants PHY-0096151, ACI96-19019 and AST-9803137. MK was supported at Caltech by NSF AST-0096023, NASA NAG5-8506, and DoE DE-FG03-92-ER40701. We are grateful to Lindsay King for pointing out an error in our calculation.
Published - 332-4-788.pdf
Accepted Version - 0106364.pdf