Correlation between Galaxies and Quasi‐stellar Objects in the Sloan Digital Sky Survey: A Signal from Gravitational Lensing Magnification?

Gaztañaga, E.

doi:10.1086/374616

Cited by 46 publications

(102 citation statements)

References 79 publications

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“…(Hereafter, the terms 'galaxy' and 'quasar' can be considered synonymous.) It is well known that magnification bias modifies the galaxy angular correlation function [21,22,23,24,25,26,28,29]. In this paper we extend the previous analyses by investigating and quantifying how magnification bias changes the shape of the angular two point correlation function, and its spherical harmonic transform the angular power spectrum, paying special attention to important features such as the turnover in the power spectrum and the BAO.…”

Section: Introductionmentioning

confidence: 65%

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Lensing corrections to features in the angular two-point correlation function and power spectrum

2008

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It is well known that magnification bias, the modulation of galaxy or quasar source counts by gravitational lensing, can change the observed angular correlation function. We investigate magnification-induced changes to the shape of the observed correlation function w(θ), and the angular power spectrum C ℓ , paying special attention to the matter-radiation equality peak and the baryon wiggles. Lensing effectively mixes the correlation function of the source galaxies with that of the matter correlation at the lower redshifts of the lenses distorting the observed correlation function. We quantify how the lensing corrections depend on the width of the selection function, the galaxy bias b, and the number count slope s. The lensing correction increases with redshift and larger corrections are present for sources with steep number count slopes and/or broad redshift distributions. The most drastic changes to C ℓ occur for measurements at high redshifts (z ∼ > 1.5) and low multipole moment (ℓ ∼ < 100). For the source distributions we consider, magnification bias can shift the location of the matter-radiation equality scale by 1-6% at z ∼ 1.5 and by z ∼ 3.5 the shift can be as large as 30%. The baryon bump in θ 2 w(θ) is shifted by ∼ < 1% and the width is typically increased by ∼ 10%. Shifts of ∼ > 0.5% and broadening ∼ > 20% occur only for very broad selection functions and/or galaxies with (5s − 2)/b ∼ > 2. However, near the baryon bump the magnification correction is not constant but is a gently varying function which depends on the source population. Depending on how the w(θ) data is fitted, this correction may need to be accounted for when using the baryon acoustic scale for precision cosmology.

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Section: Introductionmentioning

confidence: 65%

“…The lensing of high redshift quasars by low redshift galaxies have been detected confirming the presence of magnification bias for these systems. The most recent measurements of this effect are discussed in [25,26,29] (see also [27]). Discussions of earlier measurements can be found in the references therein.…”

Section: Introductionmentioning

confidence: 99%

Lensing corrections to features in the angular two-point correlation function and power spectrum

2008

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“…There are plenty of statistical analyses [128,135,136,137,138,139,140,141,142,143,144] showing an excess of high redshift sources near low redshift galaxies, positive and very significant cross-correlations between surveys of galaxies and QSOs, an excess of pairs of QSOs with very different redshifts, etc.…”

Section: Anomalous Redshiftsmentioning

confidence: 99%

Tests and Problems of the Standard Model in Cosmology

López-Corredoira

2017

Preprint

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The main foundations of the standard ΛCDM model of cosmology are that: 1) The redshifts of the galaxies are due to the expansion of the Universe plus peculiar motions; 2) The cosmic microwave background radiation and its anisotropies derive from the high energy primordial Universe when matter and radiation became decoupled; 3) The abundance pattern of the light elements is explained in terms of primordial nucleosynthesis; and 4) The formation and evolution of galaxies can be explained only in terms of gravitation within a inflation+dark matter+dark energy scenario. Numerous tests have been carried out on these ideas and, although the standard model works pretty well in fitting many observations, there are also many data that present apparent caveats to be understood with it. In this paper, I offer a review of these tests and problems, as well as some examples of alternative models.Keywords Cosmology · Observational cosmology · Origin, formation, and abundances of the elements · dark matter · dark energy · superclusters and large-scale structure of the Universe

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“…Such cross-correlations have been measured using samples of distant quasars magnified by low redshift galaxies (e.g., Benitez & Martinez- Gonzalez (1997); Gaztañaga (2003); Myers et al (2005); Scranton et al (2005)), that can be used to put constraints on the galaxy-mass power spectrum (Jain et al 2003). For a magnitude limited survey, the cumulative number of galaxies above a flux limit f scales as N0(> f ) ∼ Af α , where A is the area of the survey, and α is the power-law slope of the background number counts.…”

Section: Magnification From Galaxy Cross-correlationsmentioning

confidence: 99%

The MICE Grand Challenge light-cone simulation – III. Galaxy lensing mocks from all-sky lensing maps

Fosalba¹,

Gaztañaga²,

Castander³

et al. 2014

Monthly Notices of the Royal Astronomical Society

167

142

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In paper I of this series , we presented a new N-body lightcone simulation from the MICE collaboration, the MICE Grand Challenge (MICE-GC), containing about 70 billion dark-matter particles in a (3 h −1 Gpc) 3 comoving volume, from which we built halo and galaxy catalogues using a Halo Occupation Distribution and Halo Abundance Matching technique, as presented in the companion Paper II . Given its large volume and fine mass resolution, the MICE-GC simulation also allows an accurate modeling of the lensing observables from upcoming wide and deep galaxy surveys. In the last paper of this series (Paper III), we describe the construction of all-sky lensing maps, following the "Onion Universe" approach (Fosalba et al. 2008), and discuss their properties in the lightcone up to z = 1.4 with sub-arcmin spatial resolution. By comparing the convergence power spectrum in the MICE-GC to lower mass-resolution (i.e., particle mass ∼ 10 11 h −1 M ) simulations, we find that resolution effects are at the 5% level for multipoles ∼ 10 3 and 20 % for ∼ 10 4 . Resolution effects have a much lower impact on our simulation, as shown by comparing the MICE-GC to recent numerical fits by Takahashi et al 2012. We use the all-sky lensing maps to model galaxy lensing properties, such as the convergence, shear, and lensed magnitudes and positions, and validate them thoroughly using galaxy shear auto and cross-correlations in harmonic and configuration space. Our results show that the galaxy lensing mocks here presented can be used to accurately model lensing observables down to arc-minute scales. Accompanying this series of papers, we make a first public data release of the MICE-GC galaxy mock, the MICECAT v1.0, through a dedicated web-portal for the MICE simulations: http://cosmohub.pic.es, to help developing and exploiting the new generation of astronomical surveys.

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Correlation between Galaxies and Quasi‐stellar Objects in the Sloan Digital Sky Survey: A Signal from Gravitational Lensing Magnification?

Cited by 46 publications

References 79 publications

Lensing corrections to features in the angular two-point correlation function and power spectrum

Lensing corrections to features in the angular two-point correlation function and power spectrum

Tests and Problems of the Standard Model in Cosmology

The MICE Grand Challenge light-cone simulation – III. Galaxy lensing mocks from all-sky lensing maps

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