Measurements and implications of the SDSS DR7 galaxy angular power spectrum

Hayes, Brett

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https://hdl.handle.net/2142/34515 Copy

Description

Title

Measurements and implications of the SDSS DR7 galaxy angular power spectrum

Author(s)

Hayes, Brett

Issue Date

2012-09-18T21:23:35Z

Director of Research (if dissertation) or Advisor (if thesis)

Brunner, Robert J.

Doctoral Committee Chair(s)

Brunner, Robert J.

Committee Member(s)

• Fields, Brian D.
• Looney, Leslie W.
• Ricker, Paul M.

Department of Study

Astronomy

Discipline

Astronomy

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

Sloan Digital Sky Survey Data Release 7 (SDSS DR7) Galaxy Angular Power Spectrum

Abstract

We calculate the angular power spectrum of galaxies selected from the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) by using a quadratic estimation method with KL-compression. The primary data sample includes over 18 million galaxies covering more than 5,700 square degrees after masking areas with bright objects, reddening greater than 0.2 magnitudes, and seeing of more than 1.5 arcseconds. We also construct a volume-limited sample of 3.2 million galaxies in the same area, consisting of galaxies with absolute r-band magnitudes Mr < −21.2 and photometric redshifts z < 0.4. We test for systematic effects by calculating the angular power spectrum on simulated data and by SDSS stripe, and we find that these measurements are minimally affected by seeing and reddening. We calculate the angular power spectrum for ℓ ≤ 200 multipoles by using 40 bands for the full area data, ℓ ≤ 1000 multipoles using 50 bands for individual stripes, and ℓ ≤ 1600 multipoles using 64 bands for a selected area near the North Galactic Pole at high resolution. We also calculate the angular power spectra for the main galaxy sample separated into 3 magnitude bins, as well as the volume-limited sample separated into 2 redshift shells and early- and late-type galaxies to examine the evolution of the angular power spectrum. We determine the theoretical linear angular power spectrum by projecting the 3D power spectrum to two dimensions for a basic comparison to our observational results for the SDSS DR7 main galaxy sample and subsamples separated by magnitude. For our high resolution and volume-limited samples, we generate nonlinear angular power spectra using CAMB nonlinear 3D matter power spectra for our projections. By minimizing the χ2 fit between these data and the theoretical angular power spectra, we measure a fit of Omega_m = 0.31+0.18−0.11 with a linear bias of b = 0.94 ± 0.04 for the entire SDSS DR7 main galaxy sample, Omega_m = 0.267 ± 0.038, Omega_b = 0.045 ± 0.012, and Omega_b = 1.075±0.056 for our high resolution sample, and Omega_m = 0.282±0.026, Omega_b = 0.041±0.020, and b = 1.545 ± 0.057 for our full volume-limited sample. Finally, we measure the relative linear bias between early- and late-type galaxies, and find be/bl = 1.375 ± 0.076.

Graduation Semester

2012-08

Permalink

http://hdl.handle.net/2142/34515

Copyright and License Information

Copyright 2012 Brett Hayes

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