The WiggleZ Dark Energy Survey: Direct constraints on blue galaxy intrinsic alignments at intermediate redshifts

By Rachel Mandelbaum, C. Blake, Sarah Bridle, Filipe B. Abdalla, S. Brough, M. Colless, W. Couch, Scott M. Croom, T. Davis, Michael Drinkwater and 14 more. 2009

139 citations recorded by the source corpus.

Correlations between the intrinsic shapes of galaxy pairs, and between the intrinsic shapes of galaxies and the large-scale density field, may be induced by tidal fields. These correlations, which have been detected at low redshifts (z < 0.35) for bright red galaxies in the Sloan Digital Sky Survey (SDSS), and for which upper limits exist for blue galaxies at z similar to 0.1, provide a window into galaxy formation and evolution, and are also an important contaminant for current and future weak lensing surveys. Measurements of these alignments at intermediate redshifts (z similar to 0.6) that are more relevant for cosmic shear observations are very important for understanding the origin and redshift evolution of these alignments, and for minimizing their impact on weak lensing measurements. We present the first such intermediate-redshift measurement for blue galaxies, using galaxy shape measurements from SDSS and spectroscopic redshifts from the WiggleZ Dark Energy Survey. Our null detection allows us to place upper limits on the contamination of weak lensing measurements by blue galaxy intrinsic alignments that, for the first time, do not require significant model-dependent extrapolation from the z similar to 0.1 SDSS observations. Also, combining the SDSS and WiggleZ constraints gives us a long redshift baseline with which to constrain intrinsic alignment models and contamination of the cosmic shear power spectrum. Assuming that the alignments can be explained by linear alignment with the smoothed local density field, we find that a measurement of Sigma(8) in a blue-galaxy dominated, CFHTLS-like survey would be contaminated by at most +0.02(-0.03) (95 per cent confidence level, SDSS and WiggleZ) or +/- 0.03 (WiggleZ alone) due to intrinsic alignments. We also allow additional power-law redshift evolution of the intrinsic alignments, due to (for example) effects like interactions and mergers that are not included in the linear alignment model, and find that our constraints on cosmic shear contamination are not significantly weakened if the power-law index is less than similar to 2. The WiggleZ sample (unlike SDSS) has a long enough redshift baseline that the data can rule out the possibility of very strong additional evolution.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/9fa080092deeb963ad5a1accb5f5115d0ee739d3

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Citations in the corpus

KiDS+GAMA : cosmology constraints from a joint analysis of cosmic shear, galaxy-galaxy lensing, and angular clustering (2017, background): “…although intrinsic alignments have been detected for luminous red galaxies (e.g. Joachimi et al. 2011; Singh, Mandelbaum & More 2015), the constraints for less luminous red galaxies and blue galaxies are consistent with zero (Mandelbaum et al. 2006; Hirata et al. 2007; Mandelbaum et al. 2011).”
Spin alignments within the cosmic web: a theory of constrained tidal torques near filaments (2015, background): “…2002; Lee & Pen 2002; Bernstein & Norberg 2002; Heymans et al. 2004; Hirata et al. 2004; Hirata & Seljak 2004; Mandelbaum et al. 2006; Hirata et al. 2007; Mandelbaum et al. 2011; Joachimi et al. 2011, 2013a) efforts have been invested to control the level of in- © 0000 The Authors ar X iv :1 50 4.”
Observational probes of cosmic acceleration (2012, methodology): “We learned that large-scale intrinsic galaxy alignments are strongest for luminous red galaxies (Hirata et al., 2007; Mandelbaum et al., 2011), and that the linear alignment model, once considered a crude analytical tool (Catelan et al., 2001), is in fact an excellent description of the…”
KiDS+VIKING-450 and DES-Y1 combined: Cosmology with cosmic shear (2019, result): “We use a pivot redshift of z0 = 0.3, in agreement with past KiDS analyses and direct measurements of the IA (e.g. Mandelbaum et al. 2011; Joachimi et al. 2011).”
CFHTLenS: combined probe cosmological model comparison using 2D weak gravitational lensing (2012, background): “…correlation with an expected bias for σ 8 which is well within the statistical uncertainty (Kirk, Bridle & Schneider 2010; Joachimi et al. 2011; Mandelbaum et al. 2011), see also a joint lensing and IA tomography analysis over the full available redshift range (Heymans et al., in…”
CFHTLenS tomographic weak lensing cosmological parameter constraints: Mitigating the impact of intrinsic galaxy alignments (2013, methodology): “This model has since been adopted by several observational analyses (Kirk et al. 2010; Joachimi et al. 2011; Mandelbaum et al. 2011), as it has the useful property that with only a single parameter A, both the II and GI contribution to the shear correlation function can be predicted.”
The Intrinsic Alignment of Galaxies and its Impact on Weak Gravitational Lensing in an Era of Precision Cosmology (2014, methodology): “Figure 11: The projected correlation functions wg+(rp), w++(rp), and w××(rp) obtained from the SDSS L3, L4, L5, and L6 galaxy samples using Pipeline II of in Mandelbaum et al. (2006b). Each of the 10 bins contains the same range in rp for all samples, but some of the error bars have been slightly di”
Lensing is Low: Cosmology, Galaxy Formation, or New Physics? (2016, background): “Finally, we remark that clustering measurements also have a specific weight function (because clustering measures pairs of galaxies, see for example Mandelbaum et al. 2011).”
Galaxy Alignments: Observations and Impact on Cosmology (2015, methodology): “Mandelbaum et al. (2011) fit two simple models to their intrinsic alignment measurements: a power-law in transverse separation and the non-linear alignment model with an additional free power-law dependence on redshift (Bridle & King 2007).”