2015
DOI: 10.1051/0004-6361/201425016
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On the origin of intrinsic alignment in cosmic shear measurements: an analytic argument

Abstract: Galaxy intrinsic alignment can be a severe source of error in weak-lensing studies. The problem has been widely studied by numerical simulations and with heuristic models, but without a clear theoretical justification of its origin and amplitude. In particular, it is still unclear whether intrinsic alignment of galaxies is dominated by formation and accretion processes or by the effects of the instantaneous tidal field acting upon them. We investigate this question by developing a simple model of intrinsic ali… Show more

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Cited by 15 publications
(15 citation statements)
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References 47 publications
(108 reference statements)
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“…Furthermore, the potential of the system needs to be consistent with the particle distribution in configuration-and velocity-space, and cannot be chosen independently. These are two points in which we hope to improve the investigation by Camelio & Lombardi (2015).…”
Section: Theoretical Backgroundmentioning
confidence: 88%
See 1 more Smart Citation
“…Furthermore, the potential of the system needs to be consistent with the particle distribution in configuration-and velocity-space, and cannot be chosen independently. These are two points in which we hope to improve the investigation by Camelio & Lombardi (2015).…”
Section: Theoretical Backgroundmentioning
confidence: 88%
“…We also emphasise that our model assumes a spherically symmetric, self-gravitating halo in virial equilibrium, with an isotropic velocity distribution with constant dispersion. A consistent solution for such a system would be the singular isothermal sphere with a density profile ρ ∝ 1/r 2 , for which we need to assume a cut-off radius in order to obtain finite values for the quadrupole moments, similarly to Camelio & Lombardi (2015). Our virial argument, on the other hand, does not differentiate between the dark matter and stellar components and, in particular, does not assume a potential of the unperturbed galaxy.…”
Section: Theoretical Backgroundmentioning
confidence: 99%
“…If there is dynamical equilibration between the dark matter and the stellar components, one can expect that the shape of the luminous component reflects the shape of the dark matter halo. If the halo is now embedded into the large-scale structure, gravitational tidal fields will distort the potential of the halo and the luminous component rearranges itself while maintaining virial equilibrium as long as the gravitational shear is not strong enough to disrupt the halo (Camelio & Lombardi 2015). For sufficiently small tidal shears one can expect a linear relationship between the observed (projected) shape and the strength of the tidal fields.…”
Section: Early-type Galaxiesmentioning
confidence: 99%
“…The limiting case of z IA = z obs is the "instantaneous alignment" scenario. For further discussion on this topic, see [10,22,31]. At leading order, the impact of alignment epoch can be absorbed into a redshiftdependent amplitude, A(z), and eq.…”
Section: Alignment Epochmentioning
confidence: 99%