In Space Science Reviews
For a PDF version of the article, click here.
http://arxiv.org/abs/1504.05465
1 Department of Physics & Astronomy,
University College
London, Gower Street, London, WC1E 6BT, UK
2 Jodrell Bank Centre for Astrophysics,
School of Physics and Astronomy,
University of
Manchester, Oxford Road, Manchester M13 9PL, UK
3 Leiden Observatory,
Leiden University,
PO Box 9513, NL-2300 RA Leiden, Netherlands
4 Mullard
Space Science Laboratory,
University College
London, Holmbury St Mary, Dorking, Surrey RH5 6NT, UK
5 McWilliams Center for Cosmology,
Department of
Physics, Carnegie
Mellon University, Pittsburgh, PA 15213, USA
6 Scottish
Universities Physics Alliance,
Institute for
Astronomy,
University of
Edinburgh,
Royal Observatory,
Blackford Hill, Edinburgh EH9 3HJ, UK
7 Jet
Propulsion Laboratory,
California Institute
of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
8 Laboratoire
d'astrophysique (LASTRO),
Ecole Polytechnique
Fédérale de Lausanne (EPFL),
Observatoire de Sauverny, CH-1290
Versoix, Switzerland
9 Astronomisches Recheninstitut,
Zentrum für Astronomie der Universität
Heidelberg, Philosophenweg 12, 69120 Heidelberg,
Germany
Abstract: Galaxy shapes are not randomly oriented, rather they are statistically aligned in a way that can depend on formation environment, history and galaxy type. Studying the alignment of galaxies can therefore deliver important information about the astrophysics of galaxy formation and evolution as well as the growth of structure in the Universe. In this review paper we summarise key measurements of intrinsic alignments, divided by galaxy type, scale and environment. We also cover the statistics and formalism necessary to understand the observations in the literature. With the emergence of weak gravitational lensing as a precision probe of cosmology, galaxy alignments took on an added importance because they can mimic cosmic shear, the effect of gravitational lensing by large-scale structure on observed galaxy shapes. This makes intrinsic alignments an important systematic effect in weak lensing studies. We quantify the impact of intrinsic alignments on cosmic shear surveys and finish by reviewing practical mitigation techniques which attempt to remove contamination by intrinsic alignments.
Keywords: galaxies: evolution; galaxies: haloes; galaxies: interactions; large-scale structure of Universe; gravitational lensing: weak
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