Galaxy-QSO correlation induced by weak gravitational lensing arising from large-scale structure

Guimarães, Antonio C. C.; Bruck, Carsten van de; Brandenberger, Robert H.

doi:10.1046/j.1365-8711.2001.04451.x

Cited by 12 publications

(17 citation statements)

References 50 publications

(55 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Typical magnifications are of order 10 per cent for moderately distant sources. In addition to QSOs, certain populations of distant galaxies can also be used as sources [305,306,307,308,309,310,311,312,313].…”

Section: Cosmic Magnificationmentioning

confidence: 99%

Weak gravitational lensing

2001

View full text Add to dashboard Cite

According to the theory of general relativity, masses deflect light in a way similar to convex glass lenses. This gravitational lensing effect is astigmatic, giving rise to image distortions. These distortions allow to quantify cosmic structures statistically on a broad range of scales, and to map the spatial distribution of dark and visible matter. We summarise the theory of weak gravitational lensing and review applications to galaxies, galaxy clusters and larger-scale structures in the Universe.

show abstract

Section: Cosmic Magnificationmentioning

confidence: 99%

Weak gravitational lensing

2001

View full text Add to dashboard Cite

show abstract

“…This model is reviewed in the , and described in detail by Gaztañaga (2003, see also Myers 2003). Gaztañaga has shown that a good power‐law expression for scale‐dependent biasing of galaxies is Whilst Gaztañaga assumed that this bias corresponded to the ratio of the galaxy and matter correlation functions (see also Guimãraes et al 2001), b ( r ) =[ξ gg ( r )/ξ mm ( r )] 0.5 , we are in fact comparing the cross‐correlation of QSOs and galaxies with the galaxy autocorrelation function, and so are defining a bias function via b ( r ) =ξ gg ( r )/ξ gm ( r ). Whilst on large scales these two definitions should be equal, one expects the halo of the central galaxy to affect the shape of ξ gm ( r ) on small scales.…”

Section: Statistical Lensing Modelsmentioning

confidence: 99%

On statistical lensing and the anticorrelation between 2dF QSOs and foreground galaxies

Myers

Outram

Shanks

et al. 2005

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We study the cross‐correlation of Automated Plate Measurement and Sloan Digital Sky Survey galaxies with background quasi‐stellar objects (QSOs) taken from the 2dF QSO Redshift Survey, and detect a significant (2.8σ) anticorrelation. The lack of a similar signal between stars in the 2dF survey and our galaxy samples gives us confidence that the anticorrelation is not due to a systematic error. The possibility that dust in the foreground galaxies could produce such an anticorrelation is marginally rejected, at the 2σ level, through consideration of the colours of QSOs behind these galaxies. It is possible that a dust model that obscures QSOs without reddening them, or preferentially discards reddened QSOs from the 2dF survey sample, could produce such an anticorrelation; however, such models are at odds with the positive QSO–galaxy correlations found at bright magnitudes by other authors. Our detection of a galaxy–QSO anticorrelation is consistent with the predictions of statistical lensing theory. When combined with earlier results that have reported a positive galaxy–QSO correlation, a consistent and compelling picture emerges that spans faint and bright QSO samples showing positive or negative correlations according to the QSO N(m) slope. We find that galaxies are highly anti‐biased on small scales. We consider two models that use quite different descriptions of the lensing matter and find that they yield consistent predictions for the strength of galaxy bias on 0.1 h−1 Mpc scales of b∼ 0.1 (for a ΛCDM cosmology). Whilst the slope of our power‐law fit to the QSO–galaxy cross‐correlation does not allow us to rule out a linear bias parameter, when we compare our measurement of b on 100 h−1 kpc scales to independent methods that determine b∼ 1 on h−1 Mpc scales, we conclude that bias, on these small scales, is scale‐dependent. These results indicate that there appears to be more mass present, at least on the 100 h−1 kpc scales probed, than predicted by simple ΛCDM biasing prescriptions, and thus constrain halo occupation models of the galaxy distribution.

show abstract

“…Improvements have recently been made on the theoretical side; i.e., Ménard et al (2003b) went beyond the linearized magnification approximation by including nonlinear corrections to the relation between the magnification and density fluctuations, and then compared their results to numerical simulations. Guimarães et al (2001) introduced a scale-dependent galaxy bias obtained from measurements of galaxy autocorrelation functions. Jain et al (2003) modeled the complex behavior of the galaxy bias using the halo-model approach, and Takada & Hamana (2003) added an estimation of the full nonlinear magnification contribution by including the magnification profile of NFW halos (Navarro, Frenk, & White 1997) in the halo-model formalism.…”

Section: Introductionmentioning

confidence: 99%

Detection of Cosmic Magnification with the Sloan Digital Sky Survey

Scranton

Ménard

Richards

et al. 2005

ApJ

247

286

View full text Add to dashboard Cite

We present an 8 sigma detection of cosmic magnification measured by the variation of quasar density due to gravitational lensing by foreground large scale structure. To make this measurement we used 3800 square degrees of photometric observations from the Sloan Digital Sky Survey (SDSS) containing \~200,000 quasars and 13 million galaxies. Our measurement of the galaxy-quasar cross-correlation function exhibits the amplitude, angular dependence and change in sign as a function of the slope of the observed quasar number counts that is expected from magnification bias due to weak gravitational lensing. We show that observational uncertainties (stellar contamination, Galactic dust extinction, seeing variations and errors in the photometric redshifts) are well controlled and do not significantly affect the lensing signal. By weighting the quasars with the number count slope, we combine the cross-correlation of quasars for our full magnitude range and detect the lensing signal at >4 sigma in all five SDSS filters. Our measurements of cosmic magnification probe scales ranging from 60 kpc/h to 10 Mpc/h and are in good agreement with theoretical predictions based on the WMAP concordance cosmology. As with galaxy-galaxy lensing, future measurements of cosmic magnification will provide useful constraints on the galaxy-mass power spectrum.Comment: 12 pages, 8 figures, 2 tables; accepted for publication in Ap

show abstract

Galaxy-QSO correlation induced by weak gravitational lensing arising from large-scale structure

Cited by 12 publications

References 50 publications

Weak gravitational lensing

Weak gravitational lensing

On statistical lensing and the anticorrelation between 2dF QSOs and foreground galaxies

Detection of Cosmic Magnification with the Sloan Digital Sky Survey

Contact Info

Product

Resources

About