Particle horizon in Lemaître model

[EhsanZ]

What is the exact calculation of Particle horizon in Lemaître model? Does it exist? Is it finite or infinite?
Can anyone calculate that integral?
Thanks

 

[Markus Hanke]

What is the exact calculation of Particle horizon in Lemaître model? Does it exist? Is it finite or infinite?
Can anyone calculate that integral?
Thanks

The particle horizon marks the boundary between observable and un-observable parts of the universe, and yes, this integral can be calculated using the time-dependent scale factor function taken from the FLRW metric, as well as observational parameters. So far as I could find ( these things change pretty regularly ) the furthest know object to date has a redshift factor of z=8.2 which would be equivalent to a proper distance ( remember, this is not the same as light-travel distance due to the dynamic expansion of spacetime ) of about 30 billion light years. Reference :

http://en.wikipedia.org/wiki/Observable_universe

If you do the maths from the integral you arrive at a figure of about 46 billion light years.