We present identifications of Abell/ACO clusters of galaxies with APM clusters using the metric s... more We present identifications of Abell/ACO clusters of galaxies with APM clusters using the metric separation between the APM clusters' coordinates and the nominal Abell cluster positions at both the APM and the (measured or estimated) Abell cluster redshift. Wherever available, we also take into account the positions of the APM galaxies which have redshift measurements. Finally, chance alignments of physically unrelated APM and ACO clusters at discordant redshifts are removed after visual inspection of the corresponding optical UK Schmidt plates. Our compilation contains only truly physical identifications, and so supersedes the identifications listed by Dalton et al. and also their subsequent erratum, which both contain a significant fraction of chance coincidences between clusters at different distances that appear close together in projection on the sky.
We present a correlation function analysis for the catalogue of photometric redshifts obtained fr... more We present a correlation function analysis for the catalogue of photometric redshifts obtained from the Hubble Deep Field image by Fernandez-Soto et al., 1998. By dividing the catalogue into redshift bins of width $\Delta z=0.4$ we measured the angular correlation function $w(\theta)$ as a function of redshift up to $z\sim 4.8$. From these measurements we derive the trend of the correlation length $r_0$. We find that $r_0(z)$ is roughly constant with look-back time up to $z \simeq 2$, and then increases to higher values at $z\simgt 2.4$. We estimate the values of $r_0$, assuming $\xi(r,z)=(r/r_0(z))^{-\gamma}$, $\gamma=1.8$ and different geometries. For $\Omega_0=1$ we find $r_0(z=3)\simeq 7.00\pm 4.87 h^{-1}$ Mpc, in good agreement with the values obtained from analysis of the Lyman Break Galaxies.
We find that radio galaxies are strongly clustered and highly biased tracers of the underlying ma... more We find that radio galaxies are strongly clustered and highly biased tracers of the underlying mass distribution. Models for the angular correlation function $w(\theta)$ show good agreement with the observations if we assume a bias factor $b\simeq 2$ at $z\simeq 0.3$.
We constrain f_nu = Omega_nu / Omega_m, the fractional contribution of neutrinos to the total mas... more We constrain f_nu = Omega_nu / Omega_m, the fractional contribution of neutrinos to the total mass density in the Universe, by comparing the power spectrum of fluctuations derived from the 2dF Galaxy Redshift Survey with power spectra for models with four components: baryons, cold dark matter, massive neutrinos and a cosmological constant. Adding constraints from independent cosmological probes we find f_nu < 0.13 (at 95% confidence) for a prior of 0.1< Omega_m <0.5, and assuming the scalar spectral index n=1. This translates to an upper limit on the total neutrino mass and m_nu,tot < 1.8 eV for "concordance" values of Omega_m and the Hubble constant. Very similar results are obtained with a prior on Omega_m from Type Ia supernovae surveys, and with marginalization over n.
The APM Northern Sky Catalogue, a digitised version of the Palomar sky survey, is accessible on-l... more The APM Northern Sky Catalogue, a digitised version of the Palomar sky survey, is accessible on-line.
We present identifications of Abell/ACO clusters of galaxies with APM clusters using the metric s... more We present identifications of Abell/ACO clusters of galaxies with APM clusters using the metric separation between the APM clusters' coordinates and the nominal Abell cluster positions at both the APM and the (measured or estimated) Abell cluster redshift. Wherever available, we also take into account the positions of the APM galaxies which have redshift measurements. Finally, chance alignments of physically unrelated APM and ACO clusters at discordant redshifts are removed after visual inspection of the corresponding optical UK Schmidt plates. Our compilation contains only truly physical identifications, and so supersedes the identifications listed by Dalton et al. and also their subsequent erratum, which both contain a significant fraction of chance coincidences between clusters at different distances that appear close together in projection on the sky.
We present a correlation function analysis for the catalogue of photometric redshifts obtained fr... more We present a correlation function analysis for the catalogue of photometric redshifts obtained from the Hubble Deep Field image by Fernandez-Soto et al., 1998. By dividing the catalogue into redshift bins of width $\Delta z=0.4$ we measured the angular correlation function $w(\theta)$ as a function of redshift up to $z\sim 4.8$. From these measurements we derive the trend of the correlation length $r_0$. We find that $r_0(z)$ is roughly constant with look-back time up to $z \simeq 2$, and then increases to higher values at $z\simgt 2.4$. We estimate the values of $r_0$, assuming $\xi(r,z)=(r/r_0(z))^{-\gamma}$, $\gamma=1.8$ and different geometries. For $\Omega_0=1$ we find $r_0(z=3)\simeq 7.00\pm 4.87 h^{-1}$ Mpc, in good agreement with the values obtained from analysis of the Lyman Break Galaxies.
We find that radio galaxies are strongly clustered and highly biased tracers of the underlying ma... more We find that radio galaxies are strongly clustered and highly biased tracers of the underlying mass distribution. Models for the angular correlation function $w(\theta)$ show good agreement with the observations if we assume a bias factor $b\simeq 2$ at $z\simeq 0.3$.
We constrain f_nu = Omega_nu / Omega_m, the fractional contribution of neutrinos to the total mas... more We constrain f_nu = Omega_nu / Omega_m, the fractional contribution of neutrinos to the total mass density in the Universe, by comparing the power spectrum of fluctuations derived from the 2dF Galaxy Redshift Survey with power spectra for models with four components: baryons, cold dark matter, massive neutrinos and a cosmological constant. Adding constraints from independent cosmological probes we find f_nu < 0.13 (at 95% confidence) for a prior of 0.1< Omega_m <0.5, and assuming the scalar spectral index n=1. This translates to an upper limit on the total neutrino mass and m_nu,tot < 1.8 eV for "concordance" values of Omega_m and the Hubble constant. Very similar results are obtained with a prior on Omega_m from Type Ia supernovae surveys, and with marginalization over n.
The APM Northern Sky Catalogue, a digitised version of the Palomar sky survey, is accessible on-l... more The APM Northern Sky Catalogue, a digitised version of the Palomar sky survey, is accessible on-line.
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Papers by Steve Maddox