Cosmo-torun

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328 discussions

The Bohdan Paczynski Memorial Colloquium (fwd) - pierwszy wykład 16.11.2012 (fwd)
by Boud Roukema 07 Nov '12

07 Nov '12

> Szanowni Panstwo, > > Centrum Astronomiczne im. M. Kopernika PAN w Warszawie otwiera serię wykładów "The Bohdan Paczyński Memorial Colloquium". > Szczegoly na stronie: www.camk.edu.pl/PaczynskiColloquium > > Zapraszamy na pierwszy wykład, który odbędzie się 16 listopada o 15:00, > w Warszawie, ul. Bartycka 18: > > Rashid Sunyaev > > Max-Planck Institute for Astrophysics, Space Research Institute, Moscow, > Institute for Advanced Study, Princeton > > Hot Intergalactic Gas in Clusters of Galaxies,Cosmic Microwave Background Radiation and Cosmology > > Marek Abramowicz > Joanna Mikolajewska > > -------------------------------------------------------------------- > Prof. Joanna Mikolajewska Phone: +48 22 3296134 > N. Copernicus Astronomical Center Fax: +48 22 8410046 > Bartycka 18 E-mail: mikolaj camk.edu.pl > 00-716 Warszawa, Poland Web: www.camk.edu.pl > -------------------------------------------------------------------- _______________________________________________ Cosmo-torun mailing list Cosmo-torun(a)cosmo.torun.pl http://cosmo.torun.pl/mailman/listinfo/cosmo-torun

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The Bohdan Paczynski Memorial Colloquium (fwd) - pierwszy wykład 16.11.2012
by Paweł Grochowalski 06 Nov '12

06 Nov '12

Szanowni Panstwo, Centrum Astronomiczne im. M. Kopernika PAN w Warszawie otwiera serię wykładów "The Bohdan Paczyński Memorial Colloquium". Szczegoly na stronie: www.camk.edu.pl/PaczynskiColloquium Zapraszamy na pierwszy wykład, który odbędzie się 16 listopada o 15:00, w Warszawie, ul. Bartycka 18: *Rashid Sunyaev* Max-Planck Institute for Astrophysics, Space Research Institute, Moscow, Institute for Advanced Study, Princeton *Hot Intergalactic Gas in Clusters of Galaxies,Cosmic Microwave Background Radiation and Cosmology* Marek Abramowicz Joanna Mikolajewska -------------------------------------------------------------------- Prof. Joanna Mikolajewska Phone: +48 22 3296134 N. Copernicus Astronomical Center Fax: +48 22 8410046 Bartycka 18 E-mail: mikolaj(a)camk.edu.pl 00-716 Warszawa, Poland Web: www.camk.edu.pl -------------------------------------------------------------------- _______________________________________________ Cosmo-torun mailing list Cosmo-torun(a)cosmo.torun.pl http://cosmo.torun.pl/mailman/listinfo/cosmo-torun

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Newtonian N-body wrong in EdS relativistic 2nd order perturbation theory above 10 Mpc
by Boud Roukema 04 Nov '12

04 Nov '12

hi everyone http://arxiv.org/abs/1207.2035 Newtonian versus relativistic cosmology Authors: Samuel F. Flender, Dominik J. Schwarz Abstract: We show how the relativistic matter and velocity power spectra behave in different gauges. We construct a new gauge where both spectra coincide with Newtonian theory on all scales. However, in this gauge there are geometric quantities present which do not exist in Newtonian theory, for example the local variation of the Hubble parameter. Comparing this quantity to second order Newtonian quantities, we find that Newtonian theory is wrong on scales larger than 10 Mpc. This undermines the reliability of Newtonian cosmological N-body simulations on these scales. What's surprising is that this is still only *perturbation* theory, it's not fully relativistic, if I understand the paper correctly. Fully relativistic calculations still remain to be done. pozdr boud _______________________________________________ Cosmo-torun mailing list Cosmo-torun(a)cosmo.torun.pl http://cosmo.torun.pl/mailman/listinfo/cosmo-torun

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A spiral galaxy at z=2.18
by Andrzej Marecki 20 Jul '12

20 Jul '12

Can a grand-design *spiral* galaxy be located at a redshift z=2.18? Yes it can! http://www.nature.com/nature/journal/v487/n7407/full/nature11256.html -- am _______________________________________________ Cosmo-torun mailing list Cosmo-torun(a)cosmo.torun.pl http://cosmo.torun.pl/mailman/listinfo/cosmo-torun

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cosmo-discussion 14:30 Fri 13 May @KRA - Narlikar visit
by Boud Roukema 19 Apr '12

19 Apr '12

hi cosmo-torun, For people who are at KRA tomorrow afternoon, i propose a brief discussion - 14:30 Fri 13 May @KRA - about suggestions/preferences for a seminar and/or workshop during Jayant Narlikar's visit to Toruń during late May. pozdr boud PS: Coming up for Fri 20 May: Karolina on reionisation.

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11:00 Mon 28 May 2012: Narlikar - Highlights of an alternative cosmology
by Boud Roukema 16 Apr '12

16 Apr '12

hi cosmo-torun, Here are the details of Jayant's seminar: Title: Highlights of an alternative cosmology Speaker: Jayant Narlikar [1] Abstract: (tbd) Time/date: 11:00 Monday 28 May 2012 Place: KRA, Torun Centre for Astronomy [2] [1] http://www.iucaa.ernet.in/~jvn [2] http://www.astro.umk.pl/?lang=en cheers boud

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ok
by ostjan＠stud.umk.pl 22 Mar '12

22 Mar '12

fine with me

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cosmo books [was: Re: Fw: Kosmos]
by Boud Roukema 22 Mar '12

22 Mar '12

witam cosmo-torun On Thu, 22 Mar 2012, Biblioteka CA UMK wrote: > Mam prosbe o popatrzenie na zalacznik - czy taka ksiazka-album o Kosmosie > znajdzie wsrod Panstwa czytelnikow. ... >> W nawiazaniu do rozmowy telefonicznej przesyłam w załączniku dodatkowe >> informacje na temat wspaniałego albumu Gilesa Sparrowa - KOSMOS. >> Zapraszam na www.kmktychy.pl Talking about the "edge of space" in an abstract to a popular astronomy+cosmology book http://www.amazon.com/Cosmos-Giles-Sparrow/dp/1905204299 seems like a bad pedagogical strategy to me. We need to understand the observer's point of view, but our standard model is based on an underlying spacetime (pseudo-4-manifold + metric that solve the Einstein equations), not just a past time cone. It might be nice as a "coffee table book" - it's motivational to see big beautiful pictures. On the other hand with a small (zero) budget, i would tend to go for research/teaching-level books. At the moment we have three books listed on our wiki - please anyone update the wiki page: http://cosmo.torun.pl/foswiki/bin/view/Cosmo/BibliotekaCosmo what we want * Padmanabhan, 1993 Structure Formation in the Universe * Schilpp 1949 Albert Einstein: philosopher-scientist * Bolejko et al 2009 Structures in the Universe by Exact Methods Schilpp 1949 has the Infeld cosmic topology comment about electromagnetism - apparently the first person to talk about physical "effects" of cosmic topology. pozdr boud

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kashlinsky large-scale flow
by Boud Roukema 16 Mar '12

16 Mar '12

hi cosmo-torun, During today's Sprawozdanie, Bronek asked about the Kashlinsky large-scale high-velocity flow. You'll find Kashlinky's work referred to in the paper below, which is an interesting observational analysis according to which the flow is due to using an incorrect choice of the comoving coordinate reference frame. Wiltshire et al's argument is based on Wiltshire's approach to modelling the Universe in a more relativistically correct way than the FLRW ("standard") metric, i.e. one of the "inhomogeneous" approaches to cosmology (according to which the Earth is assumed to exist). http://arxiv.org/abs/1201.5371 Hubble flow variance and the cosmic rest frame Authors: David L. Wiltshire, Peter R. Smale, Teppo Mattsson, Richard Watkins pozdr boud

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cosmo workshop Fri 2 March @15.00 @KRA: Jan Ostrowski on Cactus: numerical relativity
by Boud Roukema 02 Mar '12

02 Mar '12

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

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