Galaxy clustering and feedback

• Main Author: Bielby, Richard
• Published: Durham University 2008
• Subjects: 523.112
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492963

I cross-correlate the WMAP third year data with the АСО, АРМ and 2MASS galaxy and cluster catalogues, confirming the presence of the SZ effect in the WMAP 3rd year data around АСО, АРМ and 2MASS clusters, showing an increase in detection significance compared to previous analyses of the 1-year WMAP data release. I compare the cross-correlation results for a number of clusters to their SZ β-model profiles estimated from ROSAT and Chandra X-ray data. I conclude that the SZ profiles estimated from the β -model over-predict the observed SZ effect in the cluster samples. Additionally, I develop colour cuts using the SDSS optical bands to photometrically select emission line galaxies at redshifts of z < 0.35, 0.35 < z < 0.55 and z > 0.55. The selections have been calibrated using a combination of photometric redshifts from the COMBO-17 survey and spectroscopic observations. I estimate correlation lengths of rо = 2.64 (^+2.64_-0.08) h (^-1) Mpc, ro = 3.62 > ± 0.06h (^-1) and rо = 5.88 ± 0.12h (^-1)Mpc for the low, mid and high redshift samples respectively. Using these photometric samples I search for the Integrated Sachs- Wolfe signal in the WMAP 5yr data, but find no significant detection. I also present a survey of star-forming galaxies at z ≈ 3. Using Lyman Break and U-dropout photometric elections, we identify a total of ≈ 21,000 candidate z > 2 galaxies and perform spectroscopic observations of a selection of these candidates with integration times of 10,000s with the VLT VIMOS. In total this survey has so far produced a total of 1149 LBGs at redshifts of 2 < z < 3.5 over a total area of l.18deg(^2), with a mean redshift of ž = 2.87 ± 0.34. Using both the photometric and spectroscopic LBG catalogues, I investigate the clustering properties of the z > 2 galaxy sample using the angular correlation function, measuring a clustering amplitude of rо = 4.32(^+0.13_-0.12)h (^-1) Mpc with a slope of ϒ2 = 1.90 (^+0.09_-0.14) at separations of r > 0.4h(+-1) Mpc. We then measure the redshift space clustering based on the spectroscopically observed sample and estimate the infall parameter, β, of the sample by fitting a redshift space distortion model to the ع (σ, π). To conclude this work, I analyze the correlation of LBGs with the Lya forest transmissivity of a number of z ~ 3 QSOs, with the aim of looking for the imprint of high velocity winds on the IGM. The data show a fall in the transmissivity in the Lya forest at scales of 5h(^-1)Mpc < r < 10h(^-1)Mpc away from LBGs, indicating an increase in gas densities at these scales. However we find no significant change from the mean transmissivity at scales of <3h(^-1)Mpc, potentially signifying the presence of low density ionised regions close to LBGs.