David Lyth - Academia.edu (original) (raw)

Uploads

Papers by David Lyth

In a recent paper, we suggested that the density fluctuation spectra arising from power-law (or e... more In a recent paper, we suggested that the density fluctuation spectra arising from power-law (or extended) inflation, which are tilted with respect to the Harrison–Zel’dovich spectrum, may provide an explanation for the excess large scale clustering seen in galaxy surveys such as the APM survey. In the light of the new results from COBE, we examine in detail here cold dark matter cosmogonies based on inflationary models predicting power-law spectra. Along with power-law and extended inflation, this class includes natural inflation. The latter is of interest because, unlike the first two, it produces a power-law spectrum without significant gravitational wave production. We examine a range of phenomena, including large angle microwave background fluctuations, clustering in the galaxy distribution, bulk peculiar velocity flows, the formation of high redshift quasars and the epoch of structure formation. Of the three models, only natural inflation seems capable of explaining the large s...

arXiv (Cornell University), Dec 12, 1993

Journal of Cosmology and Astroparticle Physics, 2006

We address the possibility of bounding the spectral index nnn of primordial density fluctuations,... more We address the possibility of bounding the spectral index nnn of primordial density fluctuations, using both the cosmic microwave background (cmb) anisotropy and data on galaxies and clusters. Each piece of galaxy and cluster data is reduced to a value of sigma(R)\sigma(R)sigma(R) (the linearly evolved {\em rms} density contrast with top hat smoothing on scale RRR) which allows data on

The Primordial Density Perturbation

We analyse the implications for inflationary models of the cosmic microwave background (cmb) anis... more We analyse the implications for inflationary models of the cosmic microwave background (cmb) anisotropy measured by COBE. Vacuum fluctuations during inflation generate an adiabatic density perturbation, and also gravitational waves. The ratio of these two contributions to the cmb anisotropy is given for an arbitrary slow-roll inflaton potential. Results from the IRAS/QDOT and POTENT galaxy surveys are used to normalise the spectrum of the density perturbation on the scale 20h Mpc, so that the COBE measurement on the scale 10h Mpc provides a lower bound on the spectral index n. For ‘power law’ and ‘extended’ inflation, gravitational waves are significant and the bound is n > 0.84 at the 2-sigma level. For ‘natural’ inflation, gravitational waves are negligible and the constraint is weakened to n > 0.70, at best marginally consistent with a recent proposal for explaining the excess clustering observed in the APM galaxy survey. Many versions of extended inflation, including those...

Monthly Notices of the Royal Astronomical Society, 1995

Monthly Notices of the Royal Astronomical Society

Cosmology, Inflation and the Origin of Structure, 2009

Cosmological Inflation and Large-Scale Structure, 2000