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Title: Anisotropic magnification distortion of the 3D galaxy correlation. I. Real space

Abstract

It has long been known that gravitational lensing, primarily via magnification bias, modifies the observed galaxy (or quasar) clustering. Such discussions have largely focused on the 2D angular correlation function. Here and in paper II [L. Hui, E. Gaztanaga, and M. LoVerde, arXiv:0710.4191] we explore how magnification bias distorts the 3D correlation function and power spectrum, as first considered by Matsubara [Astrophys. J. Lett. 537, L77 (2000).]. The interesting point is that the distortion is anisotropic. Magnification bias in general preferentially enhances the observed correlation in the line-of-sight (LOS) orientation, especially on large scales. For instance, at a LOS separation of {approx}100 Mpc/h, where the intrinsic galaxy-galaxy correlation is rather weak, the observed correlation can be enhanced by lensing by a factor of a few, even at a modest redshift of z{approx}0.35. This effect presents an interesting opportunity as well as a challenge. The opportunity: this lensing anisotropy is distinctive, making it possible to separately measure the galaxy-galaxy, galaxy-magnification, and magnification-magnification correlations, without measuring galaxy shapes. The anisotropy is distinguishable from the well-known distortion due to peculiar motions, as will be discussed in paper II. The challenge: the magnification distortion of the galaxy correlation must be accounted for in interpretingmore » data as precision improves. For instance, the {approx}100 Mpc/h baryon acoustic oscillation scale in the correlation function is shifted by up to {approx}3% in the LOS orientation, and up to {approx}0.6% in the monopole, depending on the galaxy bias, redshift, and number count slope. The corresponding shifts in the inferred Hubble parameter and angular diameter distance, if ignored, could significantly bias measurements of the dark energy equation of state. Lastly, magnification distortion offers a plausible explanation for the well-known excess correlations seen in pencil beam surveys.« less

Authors:
;  [1];  [2];  [3]
  1. Institute for Strings, Cosmology and Astroparticle Physics (ISCAP), Columbia University, New York, New York 10027 (United States)
  2. (United States)
  3. Institut de Ciencies de l'Espai, IEEC-CSIC, Campus UAB, F. de Ciencies, Torre C5 par-2, Barcelona 08193 (Spain)
Publication Date:
OSTI Identifier:
21027795
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. D, Particles Fields; Journal Volume: 76; Journal Issue: 10; Other Information: DOI: 10.1103/PhysRevD.76.103502; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ACCURACY; ANGULAR CORRELATION; ANISOTROPY; BARYONS; CORRELATION FUNCTIONS; COSMOLOGY; ENERGY SPECTRA; EQUATIONS OF STATE; GALAXIES; MONOPOLES; NONLUMINOUS MATTER; QUASARS; RED SHIFT; SPACE

Citation Formats

Hui, Lam, LoVerde, Marilena, Department of Physics, Columbia University, New York, New York 10027, and Gaztanaga, Enrique. Anisotropic magnification distortion of the 3D galaxy correlation. I. Real space. United States: N. p., 2007. Web. doi:10.1103/PHYSREVD.76.103502.
Hui, Lam, LoVerde, Marilena, Department of Physics, Columbia University, New York, New York 10027, & Gaztanaga, Enrique. Anisotropic magnification distortion of the 3D galaxy correlation. I. Real space. United States. doi:10.1103/PHYSREVD.76.103502.
Hui, Lam, LoVerde, Marilena, Department of Physics, Columbia University, New York, New York 10027, and Gaztanaga, Enrique. Thu . "Anisotropic magnification distortion of the 3D galaxy correlation. I. Real space". United States. doi:10.1103/PHYSREVD.76.103502.
@article{osti_21027795,
title = {Anisotropic magnification distortion of the 3D galaxy correlation. I. Real space},
author = {Hui, Lam and LoVerde, Marilena and Department of Physics, Columbia University, New York, New York 10027 and Gaztanaga, Enrique},
abstractNote = {It has long been known that gravitational lensing, primarily via magnification bias, modifies the observed galaxy (or quasar) clustering. Such discussions have largely focused on the 2D angular correlation function. Here and in paper II [L. Hui, E. Gaztanaga, and M. LoVerde, arXiv:0710.4191] we explore how magnification bias distorts the 3D correlation function and power spectrum, as first considered by Matsubara [Astrophys. J. Lett. 537, L77 (2000).]. The interesting point is that the distortion is anisotropic. Magnification bias in general preferentially enhances the observed correlation in the line-of-sight (LOS) orientation, especially on large scales. For instance, at a LOS separation of {approx}100 Mpc/h, where the intrinsic galaxy-galaxy correlation is rather weak, the observed correlation can be enhanced by lensing by a factor of a few, even at a modest redshift of z{approx}0.35. This effect presents an interesting opportunity as well as a challenge. The opportunity: this lensing anisotropy is distinctive, making it possible to separately measure the galaxy-galaxy, galaxy-magnification, and magnification-magnification correlations, without measuring galaxy shapes. The anisotropy is distinguishable from the well-known distortion due to peculiar motions, as will be discussed in paper II. The challenge: the magnification distortion of the galaxy correlation must be accounted for in interpreting data as precision improves. For instance, the {approx}100 Mpc/h baryon acoustic oscillation scale in the correlation function is shifted by up to {approx}3% in the LOS orientation, and up to {approx}0.6% in the monopole, depending on the galaxy bias, redshift, and number count slope. The corresponding shifts in the inferred Hubble parameter and angular diameter distance, if ignored, could significantly bias measurements of the dark energy equation of state. Lastly, magnification distortion offers a plausible explanation for the well-known excess correlations seen in pencil beam surveys.},
doi = {10.1103/PHYSREVD.76.103502},
journal = {Physical Review. D, Particles Fields},
number = 10,
volume = 76,
place = {United States},
year = {Thu Nov 15 00:00:00 EST 2007},
month = {Thu Nov 15 00:00:00 EST 2007}
}