From boud w astro.uni.torun.pl  Mon Feb 27 12:26:05 2012
From: boud w astro.uni.torun.pl (Boud Roukema)
Date: Mon, 27 Feb 2012 12:26:05 +0100 (CET)
Subject: [Cosmo-torun] grey extinction
Message-ID: <alpine.DEB.1.10.1202271213190.17287@adjani.astro.uni.torun.pl>

Witam

After this morning's seminar, here seem to be a few articles on grey extinction
and the \ddot{a}/a > 0 interpretation of the SNe Ia experiments:

http://arxiv.org/abs/0909.0231
Grey Milky Way Extinction from SDSS Stellar Photometry
Authors: Evgeny Gorbikov, Noah Brosch

http://arxiv.org/abs/astro-ph/0701259
Redshift-distance relations from type Ia supernova observations. New constraints on grey dust models
Authors: A.R. Robaina, J. Cepa

http://arxiv.org/abs/astro-ph/0603833
The Impact of Cosmic Dust on Supernova Cosmology
Authors: Pier Stefano Corasaniti

http://arxiv.org/abs/astro-ph/0505446
No evidence of "gray" dust from composite quasar spectra
Authors: Chris J. Willott

http://arxiv.org/abs/astro-ph/0410501
Limiting the dimming of distant type Ia supernovae
Authors: Linda Ostman, Edvard Mortsell

http://arxiv.org/abs/astro-ph/0306459
Extinction by grey dust in the intergalactic medium
Authors: Ernst Fischer

pozdr
boud



From boud w astro.uni.torun.pl  Wed Feb 29 20:20:54 2012
From: boud w astro.uni.torun.pl (Boud Roukema)
Date: Wed, 29 Feb 2012 20:20:54 +0100 (CET)
Subject: [Cosmo-torun] cosmo workshop Fri 2 March @15.00 @KRA: Jan Ostrowski
 on Cactus: numerical relativity
Message-ID: <alpine.DEB.1.10.1202292005270.29578@adjani.astro.uni.torun.pl>

hi cosmo-torun

   Cactus: numerical relativity
   cosmo workshop Fri 2 March @15.00 @KRA
   Jan Ostrowski


Jan is doing very interesting work in finding out how to do numerical
relativity. One way of saying it is the following:

"Normal" cosmological N-body simulations consist of *Newtonian*
gravity simulated on a highly simplified (perfectly homogeneous)
relativistic "background". In formal scientific language, this is
called a "heuristic" approach; in informal language, it's called "a
fudge" - it's a mathematical shortcut that seems like it should work
and lets us quickly compare some sort of "model" to observations
instead of waiting 50 years for the mathematics to be solved. In
principle, every scientist using the heuristic/fudge is aware of
this. Pure theory is very difficult to apply to the real world.

Relativistic cosmological simulations should be "directly"
relativistic, consistent with the Einstein equations, without using
the heuristic/fudge of adding "perturbations" that obey Newtonian
gravity to a relativistic "background". So these simulations can be called
"background-free".

How can we do background-free cosmology simulations?

Jan will present a discussion on this.

pozdr
boud



From faithlesstomas w gmail.com  Wed Feb 29 23:37:40 2012
From: faithlesstomas w gmail.com (Tomasz Kazimierczak)
Date: Wed, 29 Feb 2012 23:37:40 +0100
Subject: [Cosmo-torun] cosmo workshop Fri 2 March @15.00 @KRA: Jan
 Ostrowski on Cactus: numerical relativity
In-Reply-To: <alpine.DEB.1.10.1202292005270.29578@adjani.astro.uni.torun.pl>
References: <alpine.DEB.1.10.1202292005270.29578@adjani.astro.uni.torun.pl>
Message-ID: <CANMnsZJZZ0tqMpP7S7wAnajYLF5HRDTfzrtvA8nzvDXS-BpsxA@mail.gmail.com>

hello cosmo-torun

Could we start a little bit ealier,
for example @14:00?

I have "dyżur" at control room starting at 16:00.

2012/2/29 Boud Roukema <boud w astro.uni.torun.pl>

> hi cosmo-torun
>
>  Cactus: numerical relativity
>  cosmo workshop Fri 2 March @15.00 @KRA
>  Jan Ostrowski
>
>
> Jan is doing very interesting work in finding out how to do numerical
> relativity. One way of saying it is the following:
>
> "Normal" cosmological N-body simulations consist of *Newtonian*
> gravity simulated on a highly simplified (perfectly homogeneous)
> relativistic "background". In formal scientific language, this is
> called a "heuristic" approach; in informal language, it's called "a
> fudge" - it's a mathematical shortcut that seems like it should work
> and lets us quickly compare some sort of "model" to observations
> instead of waiting 50 years for the mathematics to be solved. In
> principle, every scientist using the heuristic/fudge is aware of
> this. Pure theory is very difficult to apply to the real world.
>
> Relativistic cosmological simulations should be "directly"
> relativistic, consistent with the Einstein equations, without using
> the heuristic/fudge of adding "perturbations" that obey Newtonian
> gravity to a relativistic "background". So these simulations can be called
> "background-free".
>
> How can we do background-free cosmology simulations?
>
> Jan will present a discussion on this.
>
> pozdr
> boud
>
> ______________________________**_________________
> Cosmo-torun mailing list
> Cosmo-torun w cosmo.torun.pl
> http://cosmo.torun.pl/mailman/**listinfo/cosmo-torun<http://cosmo.torun.pl/mailman/listinfo/cosmo-torun>
>
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