Weak gravitational lensing of distant galaxies

Kaiser, Nick

doi:10.1086/171151

Cited by 779 publications

(957 citation statements)

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“…The gravitational lensing contribution to the shear power spectrum can be obtained on small scales (' 1) by Limber integration [43], which computes the power spectrum of a radially projected quantity. In this case we integrate Eq.…”

Section: Shear Power Spectramentioning

confidence: 99%

Intrinsic alignment-lensing interference as a contaminant of cosmic shear

2004

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Cosmic shear surveys have great promise as tools for precision cosmology, but can be subject to systematic errors including intrinsic ellipticity correlations of the source galaxies. The intrinsic alignments are believed to be small for deep surveys, but this is based on intrinsic and lensing distortions being uncorrelated. Here we show that the gravitational lensing shear and intrinsic shear need not be independent: correlations between the tidal field and the intrinsic shear cause the intrinsic shear of nearby galaxies to be correlated with the gravitational shear acting on more distant galaxies. We estimate the magnitude of this effect for two simple intrinsic-alignment models: one in which the galaxy ellipticity is linearly related to the tidal field, and one in which it is quadratic in the tidal field as suggested by tidal torque theory. The first model predicts a gravitational-intrinsic (GI) correlation that can be much greater than the intrinsic-intrinsic (II) correlation for broad redshift distributions, and that remains when galaxies pairs at similar redshifts are rejected. The second model, in its simplest form, predicts no gravitational-intrinsic correlation. In the first model, and assuming a normalization consistent with recently claimed detections of intrinsic correlations, we find that the GI correlation term can exceed the usual II term by >1 order of magnitude and the intrinsic correlation induced B-mode by 2 orders of magnitude. These interference effects can suppress the lensing power spectrum for a single broad redshift bin by of order 10% at z s 1 and 30% at z s 0:5. We conclude that, depending on the intrinsic-alignment model, the GI correlation may be the dominant contaminant of the lensing signal and can even affect cross spectra between widely separated bins. We describe two ways to constrain this effect, one based on density-shear correlations and one based on scaling of the cross correlation tomography signal with redshift.

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Section: Shear Power Spectramentioning

confidence: 99%

Intrinsic alignment-lensing interference as a contaminant of cosmic shear

2004

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“…The modern theoretical formalism of weak lensing traces back largely to the papers of Blandford et al (1991), Miralda-Escudé (1991), and Kaiser (1992), though one can find roots in the much earlier papers of Kristian and Sachs (1966) and Gunn (1967).…”

Section: Weak Lensing Principles: Mathematical Discussionmentioning

confidence: 99%

Observational probes of cosmic acceleration

et al. 2013

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The accelerating expansion of the universe is the most surprising cosmological discovery in many decades, implying that the universe is dominated by some form of "dark energy" with exotic physical properties, or that Einstein's theory of gravity breaks down on cosmological scales. The profound implications of cosmic acceleration have inspired ambitious efforts to understand its origin, with experiments that aim to measure the history of expansion and growth of structure with percent-level precision or higher. We review in detail the four most well established methods for making such measurements: Type Ia supernovae, baryon acoustic oscillations (BAO), weak gravitational lensing, and the abundance of galaxy clusters. We pay particular attention to the systematic uncertainties in these techniques and to strategies for controlling them at the level needed to exploit "Stage IV" dark energy facilities such as BigBOSS, LSST, Euclid, and WFIRST. We briefly review a number of other approaches including redshift-space distortions, the Alcock-Paczynski effect, and direct measurements of the Hubble constant H 0 . We present extensive forecasts for constraints on the dark energy equation of state and parameterized deviations from General Relativity, achievable with Stage III and Stage IV experimental programs that incorporate supernovae, BAO, weak lensing, and cosmic microwave background data. We also show the level of precision required for clusters or other methods to provide constraints competitive with those of these fiducial programs. We emphasize the value of a balanced program that employs several of the most powerful methods in combination, both to cross-check systematic uncertainties and to take advantage of complementary information. Surveys to probe cosmic acceleration produce data sets that support a wide range of scientific investigations, and they continue the longstanding astronomical tradition of mapping the universe in ever greater detail over ever larger scales.

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“…At small angular scales, the Limber approximation (Limber 1953;Kaiser 1992) is valid and we can relate C κg ℓ to the matter power spectrum, P (k, χ), through…”

Section: Formalismmentioning

confidence: 99%

Joint measurement of lensing–galaxy correlations using SPT and DES SV data

Baxter

Clampitt

Giannantonio

et al. 2016

Mon. Not. R. Astron. Soc.

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We measure the correlation of galaxy lensing and cosmic microwave background lensing with a set of galaxies expected to trace the matter density field. The measurements are performed using pre-survey Dark Energy Survey (DES) Science Verification optical imaging data and millimeter-wave data from the 2500 square degree South Pole Telescope Sunyaev-Zel'dovich (SPT-SZ) survey. The two lensing-galaxy correlations are jointly fit to extract constraints on cosmological parameters, constraints on the redshift distribution of the lens galaxies, and constraints on the absolute shear calibration of DES galaxy lensing measurements. We show that an attractive feature of these fits is that they are fairly insensitive to the clustering bias of the galaxies used as matter tracers. The measurement presented in this work confirms that DES and SPT data are consistent with each other and with the currently favored ΛCDM cosmological model. It also demonstrates that joint lensing-galaxy correlation measurement considered here contains a wealth of information that can be extracted using current and future surveys.

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Weak gravitational lensing of distant galaxies

Cited by 779 publications

References 0 publications

Intrinsic alignment-lensing interference as a contaminant of cosmic shear

Intrinsic alignment-lensing interference as a contaminant of cosmic shear

Observational probes of cosmic acceleration

Joint measurement of lensing–galaxy correlations using SPT and DES SV data

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