# Dark Energy Survey Year 1 results: measurement of the galaxy angular power spectrum

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**Dark Energy Survey Year 1 results: measurement of the galaxy angular power spectrum.** / DES Collaboration; Avila Perez, Santiago Javier; Ross, Ashley Jacob; D'Andrea, Christopher Brian; Percival, Will; Thomas, Daniel.

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*Monthly Notices of the Royal Astronomical Society: Letters*, vol. 487, no. 3, pp. 3870-3883. https://doi.org/10.1093/mnras/stz1514

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*Monthly Notices of the Royal Astronomical Society: Letters*,

*487*(3), 3870-3883. https://doi.org/10.1093/mnras/stz1514

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TY - JOUR

T1 - Dark Energy Survey Year 1 results: measurement of the galaxy angular power spectrum

AU - DES Collaboration

AU - Avila Perez, Santiago Javier

AU - Ross, Ashley Jacob

AU - D'Andrea, Christopher Brian

AU - Percival, Will

AU - Thomas, Daniel

PY - 2019/8/1

Y1 - 2019/8/1

N2 - We use data from the first-year observations of the DES collaboration to measure the galaxy angular power spectrum (APS), and search for its BAO feature. We test our methodology in a sample of 1800 DES Y1-like mock catalogues. We use the pseudo-Cℓ method to estimate the APS and the mock catalogues to estimate its covariance matrix. We use templates to model the measured spectra and estimate template parameters firstly from the Cℓ’s of the mocks using two different methods, a maximum likelihood estimator and a Markov Chain Monte Carlo, finding consistent results with a good reduced χ2. Robustness tests are performed to estimate the impact of different choices of settings used in our analysis. Finally, we apply our method to a galaxy sample constructed from DES Y1 data specifically for LSS studies. This catalogue comprises galaxies within an effective area of 1318 deg2 and 0.6 < z < 1.0. We find that the DES Y1 data favour a model with BAO at the 2.6σ C.L. However, the goodness of fit is somewhat poor, with χ2/(d.o.f.) = 1.49. We identify a possible cause showing that using a theoretical covariance matrix obtained from Cℓ’s that are better adjusted to data results in an improved value of χ2/(dof) = 1.36 which is similar to the value obtained with the real-space analysis. Our results correspond to a distance measurement of DA(zeff = 0.81)/rd = 10.65 ± 0.49, consistent with the main DES BAO findings. This is a companion paper to the main DES BAO article showing the details of the harmonic space analysis.

AB - We use data from the first-year observations of the DES collaboration to measure the galaxy angular power spectrum (APS), and search for its BAO feature. We test our methodology in a sample of 1800 DES Y1-like mock catalogues. We use the pseudo-Cℓ method to estimate the APS and the mock catalogues to estimate its covariance matrix. We use templates to model the measured spectra and estimate template parameters firstly from the Cℓ’s of the mocks using two different methods, a maximum likelihood estimator and a Markov Chain Monte Carlo, finding consistent results with a good reduced χ2. Robustness tests are performed to estimate the impact of different choices of settings used in our analysis. Finally, we apply our method to a galaxy sample constructed from DES Y1 data specifically for LSS studies. This catalogue comprises galaxies within an effective area of 1318 deg2 and 0.6 < z < 1.0. We find that the DES Y1 data favour a model with BAO at the 2.6σ C.L. However, the goodness of fit is somewhat poor, with χ2/(d.o.f.) = 1.49. We identify a possible cause showing that using a theoretical covariance matrix obtained from Cℓ’s that are better adjusted to data results in an improved value of χ2/(dof) = 1.36 which is similar to the value obtained with the real-space analysis. Our results correspond to a distance measurement of DA(zeff = 0.81)/rd = 10.65 ± 0.49, consistent with the main DES BAO findings. This is a companion paper to the main DES BAO article showing the details of the harmonic space analysis.

KW - RCUK

KW - STFC

KW - cosmology: observations

KW - large-scale structure of Universe

U2 - 10.1093/mnras/stz1514

DO - 10.1093/mnras/stz1514

M3 - Article

VL - 487

SP - 3870

EP - 3883

JO - Monthly Notices of the Royal Astronomical Society: Letters

JF - Monthly Notices of the Royal Astronomical Society: Letters

SN - 1745-3925

IS - 3

ER -

ID: 15702371