Astro::Cosmology 0.90

Astro::Cosmology is a Perl module that can calculate cosmological distances, volumes, and times.

This module provides a set of routines to calculate a number of cosmological quantities based on distance and time. Some are a bit complex - e.g. the volume element at a given redshift - while some, such as the conversion between flux and luminosity, are more mundane.

To calculate results for a given cosmology you create an Astro::Cosmology object with the desired cosmological parameters, and then call the object's methods to perform the actual calculations. If you aren't used to objects, it may sound confusing; hopefully the SYNOPSIS section below will help (after all, a bit of code is worth a thousand words). The advantage of using an object-orientated interface is that the object can carry around the cosmological parameters, so you don't need to keep on specifying them whenever you want to calculate anything; it also means you can write routines which can just accept an Astro::Cosmology object rather than all the cosmological parameters.

This module requires that the PDL distribution is installed on your machine; PDL is available from CPAN or http://pdl.perl.org/

WARNING

Whilst I believe the results are accurate, I do not guarantee this. Caveat emptor, as the Romans used to say...

SYNOPSIS

use Astro::Cosmology qw( :constants );

# what is the luminosity distance, in metres, for
# a couple of cosmologies
#
my $z = sequence(10) / 10;
my $eds = Astro::Cosmology->new;
my $sn = Astro::Cosmology->new( matter => 0.3, lambda => 0.7 );

my $de = 1.0e6 * PARSEC * $eds->lum_dist($z);
my $ds = 1.0e6 * PARSEC * $sn->lum_dist($z);

# let's change the parameters of the $sn cosmology
$sn->setvars( lambda=>0.6, matter=>0.2 );

UNITS

If H0 is set to 0, then the units used are the Hubble distance, volume per steradian, or time. If greater than zero, distances are measured in Mpc, volumes in Mpc^3/steradian, and time in years.

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Requirements:

· Perl