Cosmo-torun

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328 discussions

EARA workshop at IAP (fwd)
by boud 30 Sep '03

30 Sep '03

> ---------- Forwarded message ---------- > Date: Mon, 29 Sep 2003 16:02:13 +0200 (CEST) > From: Caroline Terquem <terquem at iap.fr> > Subject: EARA workshop at IAP > > > Dear colleague, > > The IAP will host an EARA workshop entitled: > > The interplay between galaxy interactions, black holes, starbursts > and galaxy formation > > The dates (which we set from people's preferences and local constraints > with other meetings in Paris) are: > > December 4 and 5, 2003 (Thursday & Friday) > > You are invited to attend and present your work. > > Please let us know if you can attend as soon as possible, and send us a title. > > all the best > > Gary Mamon > Andrea Cattaneo > Bruno Guiderdoni > Avishai Dekel

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Re: A Big Rip instead of Big Crunch?
by Jaroslaw Rzepecki 30 Aug '03

30 Aug '03

>About 3 months before the end the solar >system would become undone. About 30 minutes before that the Earth >would explode. And about 10^-19 seconds before the ultimate >moment of doom, atoms would be pulled apart Hi! I never quite understood this... what do you mean by 3 months, 30 min, 10^-19s? Is this the time measured by my local clock? General question is: What would happen to time dimension in such a fast accelerating universe? Cheers Jarek

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A Big Rip instead of Big Crunch?
by Andrzej Marecki 29 Aug '03

29 Aug '03

----- Forwarded message from physnews(a)aip.org ----- PHYSICS NEWS UPDATE The American Institute of Physics Bulletin of Physics News Number 651 August 28, 2003 by Phillip F. Schewe, Ben Stein, and James Riordon THE BIG RIP: A NEW COSMIC DOOMSDAY scenario takes the present acceleration of the expansion of the universe to new extremes. Dartmouth physicist Robert Caldwell and his colleagues Marc Kamionkowski and Nevin Weinberg at Caltech have determined that if the supposed dark energy responsible for the acceleration is potent enough not only will the space between galaxies continue to increase but that the galaxies themselves will fly apart as will, at successive times stars, planets, and even atoms and nuclei. Since the acceleration idea became established with astronomers a few years ago in the wake of observations of distant supernovae, it has been conventional to apportion the supposed energy inventory of the universe as follows: 5% in the form of conventional baryon matter (out of which atoms are made), 25% in the form of dark matter, and the biggest part, 70%, in the form of dark energy. Not a lot is known about dark matter, and even less about dark energy. Cosmologists have taken to discussing the enigmatic properties of the dark energy with the use of a new parameter, w, which is the ratio of its average pressure to energy density. The degree of this runaway expansion impulse is expressed by w. What is the nature of dark energy and how does it overcome the attractive pull of gravitation in order to speed up the cosmic expansion, and what is the proper value of w? In the best known model, the "cosmological constant" in Einstein's famous equations of general relativity corresponds to energy and pressure of the universal quantum vacuum, and is constant in space and time. Here the value of w is -1. In a second popular model, the "quintessence"model, the dark energy is associated with a universal quantum field relaxing towards some final state. Here the energy density and pressure of the dark energy are slowly decreasing with time, and the value of w is somewhere between -1/3 and -1 (w must be smaller than -1/3 in order for cosmic acceleration to occur). In Caldwell's "phantom energy" model, there is no stable vacuum quantum state and the energy density and the expansionary pressure exerted on the universe seems to increase even as the spacetime itself expands (with ordinary gases, pressure falls with expansion). In this scenario w is less than -1. The implications of this new type of cosmology are that bound systems should in the course of time be ripped up (see figure at http://www.aip.org/mgr/png/2003/200.htm ). For example, at a w value of -1.5 the universe would last for 35 billion years before being ripped apart. About 60 million years before the end, the Milky Way would be torn apart. About 3 months before the end the solar system would become undone. About 30 minutes before that the Earth would explode. And about 10^-19 seconds before the ultimate moment of doom, atoms would be pulled apart. Caldwell (robert.r.caldwell(a)dartmouth.edu, 603-646-2742) suggests that deciding between this model and the others might be possible in coming years with much better data coming from microwave background, supernovae, and galaxy measurements. (Caldwell et al., Physical Review Letters, 15 August 2003; text at www.aip.org/physnews/select) [...] ----- End of forwarded message from physnews(a)aip.org -----

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open zwicky proposal - deadline Mon 7 July 2003
by boud 30 Jun '03

30 Jun '03

Hi everyone, I think people have had enough time to see how wiki pages work internally http://adjani.astro.uni.torun.pl:9673/zwicky/ and how they work externally where anybody at all with internet access can modify pages http://pl.wikipedia.org So I think it's time to have some open zwiki (or other wiki software) pages on adjani for organising things like: - cosmic topology research - cosmic standard ruler stuff - OCRA coordination - other research projects - cosmo/extragalactic session at http://www.pta.edu.pl/zjazd - other conferences where there's no point creating a new password for everyone who might want to make a comment or change something. So this is my proposal. Please provide comments, a modified, improved version of the proposal, or if you really think this goes against the purpose of why we are here - observational cosmology research - then you may *block* the proposal, but in that case you take responsibility for having blocked. (This is the style of consensus decision-making, for anyone who forgot...) pozdrawiam boud ********************************************************************** PROPOSAL for open (z)wiki pages. DECISION DEADLINE Mon 7 July 2003 It is proposed to have some wiki pages, separate from the present pages http://adjani.astro.uni.torun.pl:9673/zwicky/ For example, with a name http://adjani.astro.uni.torun.pl:9673/open/ to make it clear that it's an open zwiki. The purpose will be to organise things like - cosmic topology research - cosmic standard ruler stuff - OCRA coordination - other research projects - cosmo/extragalactic session at http://www.pta.edu.pl/zjazd - other conferences where cosmologists (faculty, postdocs, students) from outside of TCfA will be able to contribute to pages, update them, etc. Although hypothetically this means that web surfers might write rubbish on the pages, in practice there will hopefully be enough real cosmology users on the pages that any rubbish will quickly be removed by the real users. The example of http://pl.wikipedia.org shows that this is possible and practical, with good results. **********************************************************************

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H0=75km/s/Mpc
by Andrzej Marecki 12 Jun '03

12 Jun '03

----- Forwarded message from send mail ONLY to astro-ph ----- [...] Paper: astro-ph/0306216 From: L.V.E. Koopmans <leon(a)astro.rug.nl> Date: Wed, 11 Jun 2003 01:59:39 GMT (350kb) Title: The Hubble Constant from the Gravitational Lens B1608+656 Authors: L.V.E. Koopmans (Caltech/STScI), T. Treu (Caltech), C.D. Fassnacht (UC Davis), R.D. Blandford (Caltech), G. Surpi (Caltech) Comments: 16 pages, 6 figures, 5 tables; submitted to ApJ \\ We present a refined gravitational lens model of the four-image lens system B1608+656 based on new and improved observational constraints: [...] A combined gravitational-lens and stellar dynamical analysis leads to a value of the Hubble Constant of H_0=75(+7/-6) km/s/Mpc (68 percent CL; Omega_m=0.3, Omega_Lambda=0.7. [...] ----- End of forwarded message from send mail ONLY to astro-ph ----- It's important to note that originally the same group claimed that H0 might be as low as... 61 km/s/Mpc, see: Fassnacht et al. (2002) ApJ, 581, 823 -- Andrzej

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unofficial unofficial grant results :(
by Boud Roukema 10 Jun '03

10 Jun '03

Hi everyone (on the grant proposal), The unofficial unofficial grants results are negative, sorry. :( The official unofficial results should be found as Konkurs XXV here within a few days: http://www.astrouw.edu.pl/~kst/konkursy.html And the official official results probably within 3-4 weeks. i'll be in Blois next week: http://blois.in2p3.fr/2003/pages/inform2.html but in July and August i'll be more or less in Toruń/Piwnice, though probably working from home more often than from my office. i'm not eager to do the paperwork again, but i guess the funding arithmetic can be the same, we only need to change the scientific plan and translate it to po polsku. IMHO, it's probably not worth trying again in topology, i think we should consider a plan which is more or less: ArFus - galaxy formation modelling + SMBH merger models for inducing AGN formation => RLAGN birth, youth and death observational (phenomenological) population constraints Nothing will stop us doing topology anyway, and this sort of work is something i think we should do anyway - it's the obvious way of combining our best observational and theoretical experience on a subject where it is certain that the objects of interest exist! The difficult question is how Bartek can fit into this. Bartek: any ideas? How about something like the reionisation epoch, around z=10-20? Since WMAP, people are coming up with all sorts of stuff on this. Hmmm... How about predictions for SKA? http://www.skatelescope.org/ That should find star-forming galaxies at redshifts anywhere around z=5-20, and SMBH and AGN formation around then should certainly be affected by when and how reionisation happened, making the link with RLAGN evolution modelling. Anyway, please say what you think, is it realistic to do this during July - including Polish translation etc etc - when everyone would rather be doing theoretical cosmology in the warm sunshine outside? pozd boud

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PTA wrzesnia - can we have a cosmo session?
by boud 10 Jun '03

10 Jun '03

Cześć, Would it be possible for the cosmologists in Poland to organise a session during the PTA in September? Since many of us may be attending anyway, we might as well do this in an organised and open way rather than just as a random meeting among friends who already know each other... My idea would be to use the mailing list cosmo-pl(a)astro.uni.torun.pl so that everybody from Toruń, Warszawa, Kraków and other cosmologists with Polish connections can coordinate, decide on a programme, etc. I would be happy to facilitate (moderować) the discussions. I guess the questions to the LKO would be: (1) How much time can we have in total? half-a-day? a few hours? (2) Would a meeting in the full session be best, or would a parallel session be better? But they would have to evolve depending on how much interest there is to Polish cosmologists. For the moment I'm only cc-ing this to cosmo-torun, so that we have some "local" coordination first, before PL level coordination. I'm not yet a member of the PTA, but of course I would be happy to become a member. pozdrawiam Boud PS: Is there an http: reference to the meeting details?

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SZ - OCRA paper - Battye Weller
by Boud Roukema 30 May '03

30 May '03

http://de.arxiv.org/abs/astro-ph/0305568

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Dark matter - yes, MOND - no.
by Andrzej Marecki 23 May '03

23 May '03

----- Forwarded message from physnews(a)aip.org ----- THE CONVENTIONAL THEORY OF DARK MATTER just got some potent support from a new batch of observations to be reported by scientists from the Sloan Digital Sky Survey (SDSS) this week at a meeting in the Canary Islands. One of the main reasons for believing in the existence of non-luminous matter is that the motions of galaxies within galaxy clusters and the motions of matter around individual galaxies seems to defy conventional celestial mechanics. Either plenty of extra (but unconventional) mass must lurk in the vicinity of the galaxies (the dark matter theory) or the known laws of physics might be in need of amendment (the theory known as modified Newtonian dynamics, or MOND). Scrutinizing a subset of 3000 galaxies (from Sloan's inventory of 250,000 galaxies) with satellite galaxies in tow, the researchers' profile of satellite velocities supported the dark matter theory and discounted the MOND idea. (See the Sloan website at www.sdss.org ) ----- End of forwarded message from physnews(a)aip.org ----- -- Andrzej

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Weyssenhoff fluid article - Szydlowski & Krawiec
by Boud Roukema 21 May '03

21 May '03

Cześć Adam (z Krakowie), Zobaczyłem twoj artykuł z Marekem Szydłowskiego: http://de.arxiv.org/abs/astro-ph/0305364 Chyba już znasz, ale w Toruniu próbujemy rozwijać komunikacji między kosmologów i ekstragalaktyków w Polsce - możesz napisać się na lista mejla cosmo-pl małpa astro.uni.torun.pl tutaj: http://www.astro.uni.torun.pl/sympa/cosmo-pl/index.html SUBSCRIBE: email to sympa(a)astro.uni.torun.pl with "subscribe cosmo-pl" W tej chwili nie są wiele mejlów (ryzyko spam jest bardzo niski, oprócz spam od mnie :), ale kiedy ktoś chce używać ta lista, może być użyteczny. Mniej-więcej są osób z Toruniu + Wwie + Krakowie + kilka na granicą (Bohdan P, Radek Stompor, Krz Górski). Najaktywne listy mejla u nas chyba są http://www.astro.uni.torun.pl/sympa/cosmo-torun/index.html http://www.astro.uni.torun.pl/sympa/shape-univ/index.html i stron Zwicky: http://adjani.astro.uni.torun.pl:9673/zwicky/TCfACosmology Chyba teraz najłatwiejszy okazja dla spotka kosmo w Polsce będzie spotka PTA w Toruniu, widocznie: 8-10.09.2003 http://www.phys.uni.torun.pl/phys/KONFERENCJE/konf-w2003.html ale wiem że potrzebuję iść do Krakowie dla spotykać z wasz... pozdrawiam boud

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