![]() ![]() ![]() Before applying to data, this method was initially used to model the void-galaxy correlation in the Big MultiDark simulation and consistently recovered the fiducial growth rate to a precision of 3.4% for a (2:5h□1Gpc)3 volume (Nadathur et al., 2019a). Although not available from observations directly, a component of density field reconstruction allows for the removal of the linear RSD from the galaxy field, enabling voids to be found in real space. Valid modelling of the cross-correlation between voids and surrounding galaxies requires the real space position of the voids to be known (Nadathur & Percival, 2019). As such, they have the potential for being able to decouple the degeneracy between RSD and the Alcock-Paczynski (AP) effect. Purely linear dynamics can readily describe these low-density environments. This resulted in a negligible effect, of shifting the peak by < 0:1%, suggesting that for the next generation of surveys incorrect assumptions of fiducial cosmology will be unlikely to cause biases in measurements (Carter et al., 2019).Cosmic voids offer an emerging probe of cosmology within Large Scale Structure. Using a suite of wCDM simulations, the potential systematic uncertainties were tested across a wide range of cosmologies. These surveys will push the statistical uncertainty on the measurement of the BAO to sub-percent levels, in multiple redshift bins. Improving distance constraints at low redshift (z < 0:3), to enhance current constraints on H 0, will be crucial to further shed light on the ongoing tension between dierent datasets (Riess et al., 2018 Planck Collaboration et al., 2018).Systematics that could manifest through an incorrect assumption of fiducial cosmology, during the process of BAO measurement, are of critical importance to understand in future surveys, such as DESI and Euclid (Laureijs et al., 2011). Later in the thesis, reconstruction was applied to mock catalogues for both surveys, demonstrating the potential of these data. These surveys will provide complementary ∼ 1% measurements in the northern and southern hemisphere, respectively. In the future, both the Dark Energy Spectroscopic Instrument (DESI Collaboration et al., 2016) Bright Galaxy Survey (DESI BGS) and Taipan (da Cunha et al., 2017), will update the BAO constraint in this low redshift regime. (2015) yields a measurement of the Hubble constant of H 0 = 64☐3:5kms -1Mpc -1 (Carter et al., 2018). This result is consistent with the currently accepted ΛCDM model and fixing the standard ruler using a Ω mh 2 prior from Planck Collaboration et al. By combining with post-reconstruction result of the Sloan Digital Sky Survey Main Galaxy Sample (SDSS MGS) (Ross et al., 2015) the currently best distance constraint at z < 0:3 from BAO was provided DV (z eff ) = (r s/r fid s )Mpc, a ∼3% measurement. In cases where it has been applied, reconstruction has offered up to a factor of two improvement in constraining power, dependent on redshift.This thesis makes use of a Fast Fourier Transform (FFT) application of density field reconstruction (Burden et al., 2014, 2015) to perform BAO measurements, test for systematic effects due to assumptions inherent to the current standard analysis and provide a vital component of a novel void galaxy cross-correlation analysis.ĭensity field reconstruction was applied during a reanalysis of the 6-degree Field Galaxy Survey (6dFGS). This sharpens the peak in the correlation function and enhances the oscillations in the power spectrum. This method acts to remove the non-linear damping of the baryon acoustic oscillation peak, due to bulk flows, from the galaxy field. The current standard procedure to measure baryon acoustic oscillations makes use of a step, to linearise the density field, known as density field reconstruction. Baryon acoustic oscillations (BAO) provide a standard ruler to measure the expansion rate, and redshift space distortions (RSD) allow for an understanding of the growth rate of structure. AbstractMeasurements of the large-scale structure traced by galaxies, in galaxy redshift surveys, have matured into a critical probe of the underlying cosmological model. ![]()
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