- Shape-univ - cosmo.torun.pl

cfitsio on christo
by Boud Roukema 20 Nov '03

20 Nov '03

Hi Krzyszek, i'm having problems using the cfitsio library on christo. Would you be able to install it on christo etc please? This is so that the Shape of The Universe monograph class: http://adjani.astro.uni.torun.pl/cgi-bin/twiki/view/Cosmo/MonographCosmo can work on some cosmology software. i tried the version installed (as user) by Andrzej Marecki, but i had problems with compiling the header files (1) printerror.c is a program unit which compiles OK on adjani gcc -D__USE_FIXED_PROTOTYPES__ -Wall -c -o printerror.o printerror.c printerror.c:14: fitsio.h: Nie ma takiego pliku ani katalogu i tried gcc -D__USE_FIXED_PROTOTYPES__ -Wall -c -o printerror.o printerror.c -I/home2/boud/include where i have a copy of /home2/amr/cwicz/fitsio/cfitsio.h renamed to fitsio.h since /home2/amr/cwicz/fitsio/fitsio.h is a header file for iraf, not for C. This gives In file included from /home2/boud/include/fitsio.h:227, from printerror.c:14: /home2/boud/include/cfortran.h:115: parse error before `?' printerror.c:28: warning: type defaults to `int' in declaration of `exit' printerror.c:28: warning: parameter names (without types) in function declaration printerror.c:28: conflicting types for `exit' /usr/include/stdlib.h:520: previous declaration of `exit' printerror.c:28: warning: data definition has no type or storage class printerror.c:29: parse error before `}' (2) i tried compiling the package myself Version 2.470 - 18 August 2003 http://heasarc.gsfc.nasa.gov/docs/software/fitsio/fitsio.html but had problems with included header files like <linux/limits.h> (seems to be a general problem on christo) which are not found automatically: ./configure loading cache ./config.cache checking for uname... (cached) 1 checking for cc... (cached) cc checking for gcc... (cached) cc checking whether the C compiler (cc ) works... yes checking whether the C compiler (cc ) is a cross-compiler... no checking whether we are using GNU C... (cached) yes checking whether cc accepts -g... (cached) yes checking for f77... (cached) f77 checking whether we are using GNU Fortran... yes cfitsio: == Adding wrapper support for GNU Fortran... done checking for ranlib... (cached) ranlib checking how to run the C preprocessor... (cached) cc -E checking for stdlib.h... (cached) yes checking for string.h... (cached) yes checking for math.h... (cached) yes checking for limits.h... no *********** WARNING: CFITSIO CONFIGURE FAILURE ************ cfitsio: ANSI C environment NOT found. Aborting cfitsio configure. cfitsio: You're missing a needed ANSI header file. cfitsio: You need an ANSI C compiler and all ANSI trappings cfitsio: to build cfitsio. ******************************************************* Even when i add this in manually, i just get more similar problems... So it might be easier if this is installed by someone who knows the system. thanks boud

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pamietamy: wyklad monog dzis *w sal komputerze KA&A* !!!
by Boud Roukema 30 Oct '03

30 Oct '03

witam, pamietamy: wykład monog dziś 30.10.2003 *w sal komputerze KA&A* na 15.15 pozd boud http://adjani.astro.uni.torun.pl/cgi-bin/twiki/view/Cosmo/MonographCosmo

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nastepny wyklad monograficzny czwartek 30.10.2003 (nie jutro!)
by Boud Roukema 22 Oct '03

22 Oct '03

http://adjani.astro.uni.torun.pl/cgi-bin/twiki/view/Cosmo/MonographCosmo jest seminar (cafeplus) jutro, ale nie ma wyklad monograficzny. pozd boud

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regards
by Alhaja Mariam Abacha 22 Oct '03

22 Oct '03

Dear friend, A very Good day to you.I am by name,Alhaja mariam sani Abacha,the former firstlady and also the wife of the former late head of state of the federal republic of Nigeria,Late Gen.Sani Abacha whose sudden death came on the 8th of June,1998.Since his death,I have been thrown into a state of utter confusion, frustration and hopelessness by the present civilian administration, I have been subjected tophysical and psychological torture by the security agents in the country. My son Mohammed was under detention arraigned before the federal high court of Nigeria for an offence he did not commit.Though he has been released since on the 23rd of september,2002 based on certain conditions,but he is not allowed to move around to any where.He has been restricted to his own town only and also been placed under the government watch.As a widow that is so traumatized, I have lost confidence with anybody within the country. You must have heard over the media reports and the internet on the recovery of various huge sums of money deposited by my husband in different security firms abroad, some companies willingly gave up their secrets and disclosed our money confidently lodged there while many out right blackmail. In fact the total sum discovered by the government so far is in the tune of$700.Million dollars. And they are not relenting to make me poor for life. I got your contacts through my personal research,and out of desperation decided to reach you through this medium.I will give you more information as to this regard as soon as you reply. I repose great confidence in you hence my approach to you dueto security network placed on my day to day affairs I cannot afford to visit the embassy so that is why I decided to contact you and I hope you will not betray my confidence in you. I have deposited the sum of $30 million dollars with a security firm abroad whose name is witheld for now until we open communication. I shall be grateful if you could receive this fund into your account for safe keeping. This arrangement is known to you and my son Abba alone, so my son will deal directly with you as security is up my wholebeing.I am seriously considering to settle down abroad in a friendly atmosphere like yours as soon as this fund get into your account so that I can start all over again if only you wish,but if it is impossible,just help me keep this funds in your account which will accrue you 30% of this fund . Please honesty is the watch word in this transaction.I will require your telephone and fax numbers so that we can commence communication immediately and I will give you a more detail picture of things.In case you don`t accept please do not let me out to the security as I am giving ou this information in total trust and confidence, I ill greatly appreciate if you accept my proposal in good faith.Please expedite action. Sincerely yours, Alhaja Mariam Abacha.

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nowy dzien/godzin wyklad monogr: pon. 16.10-17.40
by Boud Roukema 18 Oct '03

18 Oct '03

Witam, Czwartek była propozycja nowa dzień/godz wykład monograficzne: każdy poniedziałek 16.10-17.40 Proszę zobacz: http://adjani.astro.uni.torun.pl/cgi-bin/twiki/view/Cosmo/MonographCosmo pozd boud

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Re: Dodecahedral space topology
by Boud Roukema 10 Oct '03

10 Oct '03

here's the full article: http://arxiv.org/abs/astro-ph/0310253 On Thu, 9 Oct 2003, Boud Roukema wrote: > On Thu, 9 Oct 2003, Andrzej Marecki wrote: > > > ----- Forwarded message from NatureAlert ----- > > > > [...] > > > > Dodecahedral space topology as an explanation for weak wide-angle > > temperature correlations in the cosmic microwave background > > JEAN-PIERRE LUMINET, JEFFREY R. WEEKS, ALAIN RIAZUELO, ROLAND LEHOUCQ > > & JEAN-PHILIPPE UZAN > > http://info.nature.com/cgi-bin24/DM/y/eMJG0BfWLH0Ch0EeW0Ay >

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l_p ~ \Omega_tot^-1/2
by szajtan odwieczny 08 Oct '03

08 Oct '03

for those who are not in the topic it is about the question why is l_p (which is the number of the multipole on which there is the first peak - so called acustic peak - in the angular power spectrum of CMB fluctuations) proportional to \Omega_tot^-1/2 (which is the unitless total density of the Universe) ? Lately I was thinking about such explanation but don't know if this mae be correct. l_p \approx EH_LSS / SH_LSS where EH_LSS is (say *) the event horizon at the time of last scattering and SH_LSS is the sonic horizon at the last scattering (t=t_LSS). EH_LSS = c * \int_{t_LSS}^{t_0} dt/S(t) SH_LSS = c_s * \int_{0}^{t_LSS} dt/S(t) where c - speed of light, c_s - speed of sound, S(t) - is scale factor. So it's just the angle under which today we see the sonic horizon as it was at the time of last scattering. so from the above it would be that: l_p ~ c_s^-1 (~ means "proportional" here) the speed of sound is defined by: c_s = \sqrt{ (P/\rho)_S } (while entropy - S is constant) (P- pressure, \rho - density) for adiabatic transformation the entropy is or mae be conserved and the equation of state is: P\rho^-\gamma = const where \gamma is the adiabatic index So in short we have c_s ~ \rho^{ (\gamma - 1)/2 } and thus l_p ~ \rho^{ (1-\gamma)/2 } ~ \Omega_{tot}^{ (1-\gamma)/2 } so if the adiabatic index gamma for primordinal plasma is 2 then this consideration mae answer the quiestion, however gamma for nonrelatistic, in moderate temperatures, single-atom gases is something like 1.67 - not 2. Don't know how it is with hydrogen plasma in temperature of few thousand K. Any comments much appreciated. like it might be ok. or this is complete nonsense. ------------ Boud: * - this is the comment about the event horizon. sure that the event horizon is the maximal distance from which, say some light, will ever reach us - and because of that I agree there should be infinity in the top limit of integration in the above formula for event horizon, but I guess if it comes about the event horizon at the time t=t_LSS then wheather there is \infty or just t=t_0 doesn't change the integral much, because from the t=t_LSS point of view the time like 14,2*10^9 y is like infinity. (Because the cones of light of some simultanous events at the time t_LSS drown in "normal" (proper ?) coordinates (not comoving) which are separated (the events) by the distance of event hirizon at the time t=t_LSS, become almost paralel.**) So in other words the size of the event horizon given by the above formula will probably be just a little smaller than the real event horizon at the time in case when integrated to infinity. bart. ----- btw. It is interesting that: If calculate l_p for dust universe where S(t) ~ t^2/3 it is easy to show that l_p \approx 35,2 * c/c_s and thus for l_p=220 where it is observed, we see that at the time of last scattering the sound of speed was about 6,25 times smaller than the speed of light which sounds resonable ;) (oh, this is for flat univ.) ** - this requires some more work to think, and mae be not precise explanation.

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Shape of the Universe IV+V rok monograph course 15:15 today !
by Boud Roukema 02 Oct '03

02 Oct '03

Cześć wszystkim, The teaching responsibilities that Andrzej Strobel offered to me are presented here: http://adjani.astro.uni.torun.pl/cgi-bin/twiki/view/Cosmo/CosmoTeaching2003… ** Monograph course: It seems that the IV+V monograph course officially starts today (czwartek 02.10.2003) at 15:15 in the Radio building. Anyone interested please come along today and/or subscribe to the shape-univ mailing list: SUBSCRIBE: email to sympa(a)astro.uni.torun.pl with "subscribe shape-univ" ** "IV+V Seminar": This is compatible with CafePlus, but 17:00 czwartek is clearly not the best time. Day/time: You can join the cosmo-spotka mailing list for trying to find the best day/time for this. Place: It would be best to alternate between Piwnice (radio building) and CAMK (rabiańska). SUBSCRIBE: email to sympa(a)astro.uni.torun.pl with "subscribe cosmo-spotka" Proszę odpowiedź do: cosmo-spotka at astro.uni.torun.pl pozdrawiam boud

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Re: Re: inflation vs topology (fwd)
by Pawel Bielewicz 19 Jun '03

19 Jun '03

hi boud, everyone On Mon, 18 Apr 2003, boud wrote: > > > > > (So far there is no evidence for > > > deviations from gaussianity). > > > > There were several COBE analyses such as Pando, Valls-Gabaud & Fang: > > > > http://de.arxiv.org/abs/astro-ph/9810165 > > > > that showed non-Gaussianity. Since the WMAP map looks similar to COBE > > on large scales, i guess there should still be the same non-Gaussianity. > > > > Do you know of an article that claims Pando et al were wrong? >> I didn't read that paper, but I just rely, on the papers released >> along with WMAP data (eg. astro-ph/0302223 and many references therein >> among others the one of Pando 98) so maeybe I should write "so far there >> is no significant cosmological non-Gaussianity". And WMAP data are found >> to be consistent with assumption of Gaussian primordinal fluctuations. >Don't believe everything you watch/read on/in CNN/BBC/ApJ/MNRAS/A&A/... >In professional astronomy research articles, people often write sentences >which sound good, but are vague, misleading and sometimes simply wrong. >It's not because they want to be wrong, it's just that they don't have >the time to do the analysis properly and they're under pressure to publish >and to conform. >If you can find a WMAP analysis which shows that Pando et al 9810165 are >wrong, that would be interesting. there is a paper http://de.arxiv.org/abs/astro-ph/9908070 where non-Gaussianity in the COBE data is explained by the so called 'eclipse effect'.

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URGENT BUSINESS ASSISTANCE
by Anorld Peter Johnson 30 May '03

30 May '03

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Physics News Update 638 (fwd) - ABOUT CONVENTIONAL THEORY OF DM
by Sebastian Soberski 23 May '03

23 May '03

PINE 4.44 MESSAGE INDEX Folder: INBOX Message 173 of 173 PINE 4.44 FOLDER LIST Folder: INBOX 174 Messages Mailbox is '/var/mail/ssober' with 0 messages [ELM 2.4ME+ PL99 (25)] PINE 4.4F ATTACHED MESSAGE Folder: INBOX Message 174 of 174 36% Date: Fri, 23 May 2003 09:37:55 +0200 (MET DST) From: Sebastian Soberski <ssober(a)astro.uni.torun.pl> To: shspe-univ(a)astro.uni.torun.pl Subject: Physics News Update 638 (fwd)...ABOUT CONVENTIONAL THEORY OF DM. ---------- Forwarded message ---------- Date: Thu, 22 May 2003 13:55:27 -0400 From: physnews(a)aip.org To: ssober(a)ASTRO.UNI.TORUN.PL Subject: Physics News Update 638 PHYSICS NEWS UPDATE The American Institute of Physics Bulletin of Physics News Number 638 May 22, 2003 by Phillip F. Schewe, Ben Stein, and James Riordon (...) 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) (...) *********** PHYSICS NEWS UPDATE is a digest of physics news items arising from physics meetings, physics journals, newspapers and magazines, and other news sources. It is provided free of charge as a way of broadly disseminating information about physics and physicists. For that reason, you are free to post it, if you like, where others can read it, providing only that you credit AIP. Physics News Update appears approximately once a week. AUTO-SUBSCRIPTION OR DELETION: By using the expression "subscribe physnews" in your e-mail message, you will have automatically added the address from which your message was sent to the distribution list for Physics News Update. If you use the "signoff physnews" expression in your e-mail message, the address in your message header will be deleted from the distribution list. Please send your message to: listserv(a)listserv.aip.org

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Ten Major Challenges in Cosmology
by Andrzej Marecki 22 Apr '03

22 Apr '03

Paper: astro-ph/0304369 From: Reuven Opher <opher(a)astro.iag.usp.br> Date: Mon, 21 Apr 2003 19:47:31 GMT (16kb) Title: Ten Major Challenges in Cosmology Authors: Reuven Opher Comments: 11 pages, invited talk at Xth Brazilian School of Cosmology and Gravitation, Rio de Janeiro, July 29 - Aug. 9, 2002 [...] ----- End of forwarded message from astro-ph ----- Interesting is that "geometry and topology" is number ONE on author's (biased) list of "Ten Major Challenges in Cosmology". Seems like topology is becoming more and more "fashionable". ;) -- Andrzej

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Re: inflation vs topology (fwd)
by Boud Roukema 18 Apr '03

18 Apr '03

> ---------- Forwarded message ---------- > Date: Thu, 17 Apr 2003 13:34:35 +0200 (CEST) > From: Boud Roukema <boud... > To: szajtan... > Subject: Re: inflation vs topology * Shouldn't this be on shape-univ ? i think this could be interesting for others. hi, On Wed, 16 Apr 2003, szajtan odwieczny wrote: > > > > I'm wandering if inflation scenaries of cosmological evolution, > > > discriminate the possibility for non trivial topology of the > > > universe (eg. some torus topology) of circumference smaller than > > > the hubble radius. I had short talk about that with Boud but perhaps > > > it was too short. If I understand well, in case of such non trivial > > > topolology, there should be some, outstanding (special) directions > > > in the CMB sky seen in multipole distribution just for the few > > > lowest multipoles (on the biggest anular scales). On the other hand, > > > > Well, multipoles are a *bad* way of trying to detect topology, but > > it's correct that there should be something funny in the low l > > multipoles for a multiply connected universe. > > Well, you observed the maps composed of the sum of some few first > multipoles, and ..."saw the thing". Thats what I ment. There > mae be several sky maps resulting in the same C_l spectra, and that's > why it can be difficult or impossible to get the direction from C_l > (but that's not importand.) i think we agree here. The "bad" is only a criticism of Tegmark et al's approach. Maybe "bad" is too strong. The sky maps are a little bit better than C_l spectra, and they give a hint ("clue") to topology, but not a good analysis. > > > > > one of the predictions of the inflationary models is that > > > fluctuations in gravitational potetial ( in the biggest angular > > > scales ) are gaussian and have random phases - so there should be no > > > outstanding directions in CMB. > > > > Up to the scale of the inflationary bubble, yes. > > Could you put this in full sentence ? > Do you mean that the topological radius (of eg. n-torus) is to be at least > as big as the radius of the inflationary bubble ? Yes. The physical Universe cannot be bigger than itself. > (That would be really > large radius). Maybe, maybe not. There are many, many inflationary models. > > > > > (So far there is no evidence for > > > deviations from gaussianity). > > > > There were several COBE analyses such as Pando, Valls-Gabaud & Fang: > > > > http://de.arxiv.org/abs/astro-ph/9810165 > > > > that showed non-Gaussianity. Since the WMAP map looks similar to COBE > > on large scales, i guess there should still be the same non-Gaussianity. > > > > Do you know of an article that claims Pando et al were wrong? > I didn't read that paper, but I just rely, on the papers released > along with WMAP data (eg. astro-ph/0302223 and many references therein > among others the one of Pando 98) so maeybe I should write "so far there > is no significant cosmological non-Gaussianity". And WMAP data are found > to be consistent with assumption of Gaussian primordinal fluctuations. Don't believe everything you watch/read on/in CNN/BBC/ApJ/MNRAS/A&A/... In professional astronomy research articles, people often write sentences which sound good, but are vague, misleading and sometimes simply wrong. It's not because they want to be wrong, it's just that they don't have the time to do the analysis properly and they're under pressure to publish and to conform. If you can find a WMAP analysis which shows that Pando et al 9810165 are wrong, that would be interesting. > btw. if the non-gaussianity is found then whole my work with masterthesis > is "o kant" - in a way useless - ;) If I remember well that would > be inconsistent with one of the assumptions of the cmbfast. (I don't know > about the size of the effect), but C_l couldn't be a good fluctuations > tracer, and the probability of model must have been computed directly > from the map. For an exact calculation, it's true that your analysis is probably *slightly* wrong if it assumes gaussianity on all scales. So you have to choose whether to live life in the real world and accept that your results may be nearly right, but a little bit wrong, or you could wait until there is a definite answer on topology, but this might be long after the deadline to write your master's thesis. In fact, Spergel et al 0302209 and Tegmark et al 0302496 seem to show a definite non-gaussianity on the biggest observable scales. I'm not sure if there is a way that you could include this in your analysis *without* making an assumption on the physical origin of the non-gaussianity. But maybe there is. IMHO, non-gaussianity on a big scale is not a big problem for your analysis. > > > > > > > > To me these two things are contrary to each other. Mae they exist > > > together ? Can anybody shed some light on this ? > > > > If there is detectable non-trivial topology, then it's likely that if > > the data is analysed *assuming* trivial topology, then there is a > > non-Gaussian signal. > > > > > Another thing is about the size of the universe. I mean, how it is possible > > > for the universe to have topological circumferece smaller than (for example) > > > the hubble radius, when we assume that every distance has been blown by the > > > factor of 10^54 ever since the world begun ? Or maeybe these two facts also > > > remain without any mutual confict ? > > > > This is the fine-tuning problem. How is it possible for the cosmological > > constant/quintessence parameter to be approximately equal to the matter > > density parameter today (a factor of 2.3 is not much ;) rather than at > > some more "random" time in the past or future? > > "Another thing" was the same problem as the first one but attacked from > another side. My point was rather like: does the topological radius ( > circumference) grows with the inflation ? The injectivity diameter (what you call "topological radius") is comoving. So it grows with inflation. > Or it was once set by > something and doen't change in time. No, it's comoving. > ...hm, you write about the quintessence. But what does it have to do with > the inflation, and to the problem ? Let's assume the inflation is > already finished. the "graceful exit problem" suggests that we mae > consider it as finished by the time of some 10^-33 s, and in this case > dark energy has nothing to do with activity of false vacum. In the early > universe (even in radiation dominated era) the density of dark energy was > negligible small. Unitl now when it starts to be importand. I don't know > about > some fine tuning with inflation ? It's rather cosmological constant that > should be tuned. I don't know maeybe false vacum was the priomridal origin > of the quinessence which starts dominating our universe recenly :), and > this is interesting topic itself, but it wasn't the point of my question. I was including cosmological constant and quintessence together. Let's call it dark energy. Even if it was "negligibly small" at 10^-33s, it had to be just big enough, and not too big, so that today it is 2.3 times bigger than Omega_m. > > > > First some corrections: > > > > - the Guth value was (i think) 55 e-foldings, i.e. e^55 \approx 10^{24} > I wrote it from memory, but you're right, the factor is some 10^29. It > depands on how long we assume the inflation lasts. OK. > > > > - it's not "since the world begun", it's since some early time such > > as t = 10^{-33}s > of course but even if it was from the beginning (whatever that means) or > from 10^-43 s it wouldn't change anything in sizes. > 10^-33 s - 10^-43 s = 10^-33 s - 10^-35 s = 10^-33 s (approxiamately) > (but these are details) OK > > Answer: It's sufficient that the injectivity diameter ("topological > > circumference") was just a bit smaller than > > 10h^-1 Gpc/10^24 \approx 500m at t = 10^-{33}s. > Where does it come from ? (any references to read?). Do you mean "where does the injectivity diameter come from"? If you mean some ideas on quantum gravity or quantum cosmology (apparently quantum cosmology is *simpler* than quantum gravity), look up the references in the 2nd last paragraph of Section 2 of Luminet & Roukema astro-ph/9901364 > So from this I assume > that the injectivity diameter grows with time. Is that right ? > And btw. (probably it's another word, with no polish translation), but is > there some polish equivalent for injectivity diameter ? (and btw. for > fundamental polyhydron > (or something like that) as well. Request for polish translation - > anyone ? ) > > > > > Fine-tuning inflation is required to get Om_Lambda/Om_m \approx 10^0; > mmm, isn't it the problem of quintessence tuning not inflation? I guess it could be either. > > fine-tuning inflation is required for observable topology. > What do you mean ? I mean just what you're saying ;). The amount of inflation needs to be enough so that the injectivity diameter is not too big, not too small, today. Just as quintessence/cosmological constant needs to be fine-tuned (either from inflation or independently) so that it's not too big, not too small, today. > > Fine-tuning inflation is also needed for observable curvature > > (e.g. Om_total = 1.02). > fine tuning here ? probably yes, maeybe just tuning is ok. I disagree. Again this a question over many, many orders of magnitude. > As just for the flatness problem, there is no lower limit set for flatness > (upper limit for inflation duration), but if inflation lasts too > long it would never stop, or universe might get too heavy or so, and we > wouln't have cmb fluctuations at level 10^-5 which in turn might would > have catastrofical consequencies for us :). > > > > > We only know that the first one is correct - so far - but maybe all > > three are correct, and are linked. > > > ...it's a long road, just to come to terms with the above. > > b. Last time i tried to understand inflation, i ended up discovering that there was a fundamental thing that most people had forgotten - topology. Maybe if you try to understand the above, you'll come up with something else that most people (including me) have forgotten... b

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Remake of Fagundes & Wichoski (1987)
by Andrzej Marecki 17 Apr '03

17 Apr '03

Paper: astro-ph/0304290 From: Stephen Weatherley <stephen.weatherley(a)imperial.ac.uk> Date: Tue, 15 Apr 2003 20:02:03 GMT (254kb) Title: Ghosts of the Milky Way: a search for topology in new quasar catalogues Authors: S.J. Weatherley (1), S.J. Warren (1), S.M. Croom (2), R.J. Smith (3), B.J. Boyle (2), T. Shanks (4), L. Millar (5), M.P. Baltovic (1) ((1) Imperial College London, (2) AAO, (3) Liverpool John Moores, (4) Durham, (5) Oxford) Comments: MNRAS Letters, Accepted, 5 pages, 3 figures \\ We revisit the possibility that we inhabit a compact multi-connected flat, or nearly-flat, Universe. Analysis of COBE data has shown that, for such a case, the size of the fundamental domain must be a substantial fraction of the horizon size. Nevertheless, there could be several copies of the Universe within the horizon. If the Milky Way was once a quasar we might detect its `ghost' images. Using new large quasar catalogues we repeat the search by Fagundes & Wichoski for antipodal quasar pairs. By applying linear theory to account for the peculiar velocity of the local group, we are able to narrow the search radius to 134 arcsec. We find seven candidate antipodal quasar pairs within this search radius. However, a similar number would be expected by chance. We argue that, even with larger quasar catalogues, and more accurate values of the cosmological parameters, it is unlikely to be possible to identify putative ghost pairs unambiguously, because of the uncertainty of the correction for peculiar motion of the Milky Way. \\ ( http://de.arXiv.org/abs/astro-ph/0304290 , 254kb) ------------------------------------------------------------------------------ At first sight it's rather a dicouraging result - see the last sentence above. :-( but... Let's explore other approaches! :-) -- Andrzej

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Re: inflation vs topology
by szajtan odwieczny 16 Apr '03

16 Apr '03

> > I'm wandering if inflation scenaries of cosmological evolution, > > discriminate the possibility for non trivial topology of the > > universe (eg. some torus topology) of circumference smaller than > > the hubble radius. I had short talk about that with Boud but perhaps > > it was too short. If I understand well, in case of such non trivial > > topolology, there should be some, outstanding (special) directions > > in the CMB sky seen in multipole distribution just for the few > > lowest multipoles (on the biggest anular scales). On the other hand, > > Well, multipoles are a *bad* way of trying to detect topology, but > it's correct that there should be something funny in the low l > multipoles for a multiply connected universe. Well, you observed the maps composed of the sum of some few first multipoles, and ..."saw the thing". Thats what I ment. There mae be several sky maps resulting in the same C_l spectra, and that's why it can be difficult or impossible to get the direction from C_l (but that's not importand.) > > > one of the predictions of the inflationary models is that > > fluctuations in gravitational potetial ( in the biggest angular > > scales ) are gaussian and have random phases - so there should be no > > outstanding directions in CMB. > > Up to the scale of the inflationary bubble, yes. Could you put this in full sentence ? Do you mean that the topological radius (of eg. n-torus) is to be at least as big as the radius of the inflationary bubble ? (That would be really large radius). > > > (So far there is no evidence for > > deviations from gaussianity). > > There were several COBE analyses such as Pando, Valls-Gabaud & Fang: > > http://de.arxiv.org/abs/astro-ph/9810165 > > that showed non-Gaussianity. Since the WMAP map looks similar to COBE > on large scales, i guess there should still be the same non-Gaussianity. > > Do you know of an article that claims Pando et al were wrong? I didn't read that paper, but I just rely, on the papers released along with WMAP data (eg. astro-ph/0302223 and many references therein among others the one of Pando 98) so maeybe I should write "so far there is no significant cosmological non-Gaussianity". And WMAP data are found to be consistent with assumption of Gaussian primordinal fluctuations. btw. if the non-gaussianity is found then whole my work with masterthesis is "o kant" - in a way useless - ;) If I remember well that would be inconsistent with one of the assumptions of the cmbfast. (I don't know about the size of the effect), but C_l couldn't be a good fluctuations tracer, and the probability of model must have been computed directly from the map. > > > > To me these two things are contrary to each other. Mae they exist > > together ? Can anybody shed some light on this ? > > If there is detectable non-trivial topology, then it's likely that if > the data is analysed *assuming* trivial topology, then there is a > non-Gaussian signal. > > > Another thing is about the size of the universe. I mean, how it is possible > > for the universe to have topological circumferece smaller than (for example) > > the hubble radius, when we assume that every distance has been blown by the > > factor of 10^54 ever since the world begun ? Or maeybe these two facts also > > remain without any mutual confict ? > > This is the fine-tuning problem. How is it possible for the cosmological > constant/quintessence parameter to be approximately equal to the matter > density parameter today (a factor of 2.3 is not much ;) rather than at > some more "random" time in the past or future? "Another thing" was the same problem as the first one but attacked from another side. My point was rather like: does the topological radius ( circumference) grows with the inflation ? Or it was once set by something and doen't change in time. ...hm, you write about the quintessence. But what does it have to do with the inflation, and to the problem ? Let's assume the inflation is already finished. the "graceful exit problem" suggests that we mae consider it as finished by the time of some 10^-33 s, and in this case dark energy has nothing to do with activity of false vacum. In the early universe (even in radiation dominated era) the density of dark energy was negligible small. Unitl now when it starts to be importand. I don't know about some fine tuning with inflation ? It's rather cosmological constant that should be tuned. I don't know maeybe false vacum was the priomridal origin of the quinessence which starts dominating our universe recenly :), and this is interesting topic itself, but it wasn't the point of my question. > > First some corrections: > > - the Guth value was (i think) 55 e-foldings, i.e. e^55 \approx 10^{24} I wrote it from memory, but you're right, the factor is some 10^29. It depands on how long we assume the inflation lasts. > > - it's not "since the world begun", it's since some early time such > as t = 10^{-33}s of course but even if it was from the beginning (whatever that means) or from 10^-43 s it wouldn't change anything in sizes. 10^-33 s - 10^-43 s = 10^-33 s - 10^-35 s = 10^-33 s (approxiamately) (but these are details) > > Answer: It's sufficient that the injectivity diameter ("topological > circumference") was just a bit smaller than > 10h^-1 Gpc/10^24 \approx 500m at t = 10^-{33}s. Where does it come from ? (any references to read?). So from this I assume that the injectivity diameter grows with time. Is that right ? And btw. (probably it's another word, with no polish translation), but is there some polish equivalent for injectivity diameter ? (and btw. for fundamental polyhydron (or something like that) as well. Request for polish translation - anyone ? ) > > Fine-tuning inflation is required to get Om_Lambda/Om_m \approx 10^0; mmm, isn't it the problem of quintessence tuning not inflation? > fine-tuning inflation is required for observable topology. What do you mean ? > > Fine-tuning inflation is also needed for observable curvature > (e.g. Om_total = 1.02). fine tuning here ? probably yes, maeybe just tuning is ok. As just for the flatness problem, there is no lower limit set for flatness (upper limit for inflation duration), but if inflation lasts too long it would never stop, or universe might get too heavy or so, and we wouln't have cmb fluctuations at level 10^-5 which in turn might would have catastrofical consequencies for us :). > > We only know that the first one is correct - so far - but maybe all > three are correct, and are linked. > ...it's a long road, just to come to terms with the above. b.

1 0

inflation vs topology
by szajtan odwieczny 15 Apr '03

15 Apr '03

I'm wandering if inflation scenaries of cosmological evolution, discriminate the possibility for non trivial topology of the universe (eg. some torus topology) of circumference smaller than the hubble radius. I had short talk about that with Boud but perhaps it was too short. If I understand well, in case of such non trivial topolology, there should be some, outstanding (special) directions in the CMB sky seen in multipole distribution just for the few lowest multipoles (on the biggest anular scales). On the other hand, one of the predictions of the inflationary models is that fluctuations in gravitational potetial ( in the biggest angular scales ) are gaussian and have random phases - so there should be no outstanding directions in CMB. (So far there is no evidence for deviations from gaussianity). To me these two things are contrary to each other. Mae they exist together ? Can anybody shed some light on this ? Another thing is about the size of the universe. I mean, how it is possible for the universe to have topological circumferece smaller than (for example) the hubble radius, when we assume that every distance has been blown by the factor of 10^54 ever since the world begun ? Or maeybe these two facts also remain without any mutual confict ? bartek

2 1

where the WMAP map is (the linear combination)
by boud 02 Apr '03

02 Apr '03

The linear combination WMAP map is here: http://lambda.gsfc.nasa.gov/data/map/ilc/ http://lambda.gsfc.nasa.gov/data/map/ilc/map_ilc_yr1_v1.fits I can email anyone packages for reading this in - the "healpix" software is non-free software - i haven't put my version online since it's "non-free" in the Debian sense, though i would be happy for help to make it "free" (GPL compatible etc) if someone had the time... (or if i have 2-3 days free) For now, it's probably not a priority. boud

1 0

Matched circles on WMAP data
by Andrzej Marecki 27 Mar '03

27 Mar '03

Paper: astro-ph/0303580 From: Alain Riazuelo <riazuelo(a)spht.saclay.cea.fr> Date: Wed, 26 Mar 2003 17:20:20 GMT (641kb) Title: Cosmic microwave background constraints on multi-connected spherical spaces Authors: Jean-Philippe Uzan, Alain Riazuelo, Roland Lehoucq, Jeffrey Weeks Comments: 4 pages, submitted to PRL \\ This letter describes the Cosmic Microwave Background anisotropies of multi-connected spherical spaces in a closed universe with density parameter Omega_0 close to 1. [...] -- A.

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files,files,files
by szajtan odwieczny 20 Mar '03

20 Mar '03

hello everyone, Does anybody know theoreticaly how many files can there be on ext2 fs in one directory, on on fat32 filesystem in one directory ? bartek

3 2

topology - WMAP
by Boud Roukema 19 Mar '03

19 Mar '03

Please follow the WMAP thread on cosmo-torun http://www.astro.uni.torun.pl/sympa/cosmo-torun/2003-03/msg00001.html Thanks boud

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Gazeta Wyborcza o odkryciu Tegmarka
by Andrzej Marecki 18 Mar '03

18 Mar '03

Artykuł o odkryciu ("odkryciu" ?) Tegmarka: http://www.gazeta.pl/nauka/1,34148,1376101.html Krytyka Marka Demiańskiego: http://www.gazeta.pl/nauka/1,34148,1376526.html -- Andrzej

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Re: map data
by szajtan odwieczny 18 Mar '03

18 Mar '03

I know this looks bad ;) and ... discouraging. But non of is comes from my code. I just ploted the data from internet - from lambda. They get a nice spectra because they bin it every 25 multipoles (on average), and as Boud noticed with some weight, which I have to chack. In this way we get that few point like in the first picture I sent but the errors become smaller. They also drop all data above l approx 600. Well there is no easy way out, and much to do. Now I'm also thinking about calculating the power spectra directly from the map from MAP. Any ideas with aid of what to do it ? (witting a new code I give up - from time reasons ) bart. oh btw. that "vast f90" you mentioned is also commercial now. On Mon, 17 Mar 2003, Michal Frackowiak wrote: > you must have missed something important.... it's more than a game of > "show the diffrences in 2 pictures". it's a game of "check your code and > do it again..." ;-) > > szajtan odwieczny wrote: > > >well this is the thing I've been talking about on last thursday. > >Look at these two pictures. ;) > >Maeybe this kind of analysion is useless but surely it shows what problem > >we are dealing with here. > >On my plot (green dots) I chop off all negative values, all the values > >above 10000 for > >multipoles greater that 300 (which isn't a big crime), and throw out all > >points of which "errorbars" were bigger that the values itself. > >The red dots are raw data as it goes from LAMBDA. > > > >Well perhaps (I hope ;) somewhere among green dots are those we see at the > >picture from NASA. > > > > > >bartek > > > > > > > > ------------------------------------------------------------------------ > > > >------------------------------------------------------------------------ > > > >LISTNAME: shape-univ > >HELP: send an email to sympa(a)astro.uni.torun.pl with "help" > >WEB ARCHIVE: http://www.astro.uni.torun.pl/sympa/shape-univ/ > >UNSUBSCRIBE: email to sympa(a)astro.uni.torun.pl with "unsubscribe shape-univ" > > > > > > > > >

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Re: new cmb code... (fwd)
by szajtan 17 Mar '03

17 Mar '03

ok. ciakawa koncepcja ale nie do konca rozumiem jak to dziala. masz obliczona i zparametryzowana (parametrami) w jakis sposob siatke modeli (o roznych parametrach kosmologicznych). tak ze na podstawie zadanych wartosci parametrow (nie kosmolog.) mozna szybko odtworzyc widmo. poszukiwane widmo w n wymiarowej przestrzeni parametrow jest otoczone przez 2^n modeli bazowych (o znanych zestawach wartosci parametrow kosmologicznych, i tych z parametryzacji). Mozna tez obliczyc jak daleko w przestrzeni parametrow kosmologicznych lezy poszukiwany model od modelow budujacych wezly siatki (tylko jak z tego skorzystac). Wiemy rowniez o ile roznia sie miedzy soba zestawy wartosci parametrow przypisanych do wezlow sieci. Ale nie chwytam kewstii obliczenia poszukiwanych wartosci parametrow na podstawie ktorych mozna odtworzyc widmo. Czyli innymi slowy jak to interpolowac skoro wiemy tylko ze poszukiwany zestaw parametrow lezy gdzies w oczku siatki parametrow.? > I have the code - not publicly available yet, but soon > it works as follows: > > 1. grid is produced and in nodes exact (well... cmbfast) cl spectrum is > calculated > 2. for every node some parametrisation of the spectrum is done (scaling, > chebyshev coeficients etc.) > 3. for given cosmo parms those parameters are interpolated and the > spectrum is reconstructed. > > quite simple. but faster than other interpolation methods (for gridded > models). > that is the main idea... > > polarisation also possible, but not yet implemented. > I can send you the code with the spectrum database if you wish. > > Bartosz Lew wrote: > > >ok, what's the catch ? > >and where is the code ? > > > >and btw. how this works ? > > > >On Mon, 17 Feb 2003, Michal Frackowiak wrote: > > > > > > > >>well, not completed, not even documented, but if anyone of you would > >>like to use it to reconstruct cmb spectrum REALLY FAST (within > >>miliseconds) - please try. > >>http://coyote.ncac.torun.pl/~michalf/cmbrecon/cmbrecon.php > >> > >>well - you can treat it as a preview of what is really about to happen. > >>a fast cmb-spectrum reconstruction code. with quintessence (or whatever) > >>included (soon also other scalar-tensor things). for generating grid: > >>server-client architecture, quite smart reconstruction algorithms.... > >>in case of interest/doubts/will to use - feel free to contact me. code > >>is quite complete and usable. > >> > >>michal frackowiak > >> > >> > >> > >> > >> > > > > > > > >------------------------------------------------------------------------ > > > >LISTNAME: shape-univ > >HELP: send an email to sympa(a)astro.uni.torun.pl with "help" > >WEB ARCHIVE: http://www.astro.uni.torun.pl/sympa/shape-univ/ > >UNSUBSCRIBE: email to sympa(a)astro.uni.torun.pl with "unsubscribe shape-univ" > > > > > > > > > > > > ---------------------------------------------------------------------------- ---- LISTNAME: shape-univ HELP: send an email to sympa(a)astro.uni.torun.pl with "help" WEB ARCHIVE: http://www.astro.uni.torun.pl/sympa/shape-univ/ UNSUBSCRIBE: email to sympa(a)astro.uni.torun.pl with "unsubscribe shape-univ" --------------r-e-k-l-a-m-a----------------- Tanie bilety lotnicze! http://samoloty.onet.pl

5 11

map data
by szajtan odwieczny 15 Mar '03

15 Mar '03

well this is the thing I've been talking about on last thursday. Look at these two pictures. ;) Maeybe this kind of analysion is useless but surely it shows what problem we are dealing with here. On my plot (green dots) I chop off all negative values, all the values above 10000 for multipoles greater that 300 (which isn't a big crime), and throw out all points of which "errorbars" were bigger that the values itself. The red dots are raw data as it goes from LAMBDA. Well perhaps (I hope ;) somewhere among green dots are those we see at the picture from NASA. bartek

2 1

about the variability
by Bartosz Lew 20 Feb '03

20 Feb '03

I was inspired by Magda's seminar this monday about the variability of css, gps or whatever. She said that variability is something like a hundret years. And then I thought: shouldn't it (the period) be corrected for the expansion of the universe since these objects happend to be so strongly redshifted ? Or maeybe this effect is negligible. bartek

3 4

Fwd: The Oldest Light in the Universe
by Tomasz Laczkowski 12 Feb '03

12 Feb '03

NASA Science News for February 11, 2003 A NASA satellite has taken a picture of the Big Bang's ancient afterglow. Scientists have analyzed the data and learned that the universe is 13.7 billon years old (plus or minus 1 percent)and that the first stars appeared only 200 million years after the Big Bang. These results are a milestone in cosmology, says the NASA director of astronomy and physics. FULL STORY at http://science.nasa.gov/headlines/y2003/11feb_map.htm?list129344 <czosnek> \|/ (|||) " -

1 0

all those constraints
by szajtan 15 Jan '03

15 Jan '03

Boud, I got your point about those constraints ;) (Maeybe there arose a little confiusion because I treat everything from the CMB point of view (CMB & rest of the world) as everything else (other methods) were just a kind of supplementary thing, some aid of narrowing our choices in space of parameters.) When we have a theory describing sth. with some free parameters, it doesnt give any constraints on unknown values until we know the values of those parameters. In that moment measurments enter the scene as some kind of calibration. Then we have a model and can derive whatever we want quantitatively. (e.g. LSS constraint - from assumption on model + "calibration" measurments ) But what if we had such a good theory that it doesnt need any additional measurmenst (except some well known physical constants) (nb measurments that introduce additional uncertanities) to predict the thing we're looking for. That would be a constraint of purely theoretical nature. (e.g. BBN constraint - only from physics of high energy particles - which happens to be more less consistent with constraints from observations of Ly_\alpha forest) Do you agree with this approach to the word "constraint" in astronomy ? Bartek ps. mentioned constraints include h uncertanity (which should be constrained externaly (eg. by SNIa constraint :)) (hmm but in this case I treat SNIa constraint supplementary not equivalently which at the beginning wasn't my intent) Maeybe this is just a nomenclature problem. We cannot deal with all methods of estimating parameters simultanously, so we pick one to ESTIMATE (DERIVE) parameters and then as an additional help treat all other estimations (comming from other methods) as CONSTRAINTS. I think thats it ! ***************r-e-k-l-a-m-a************** Chcesz oszczedzic na kosztach obslugi bankowej ? mBIZNES - konto dla firm http://epieniadze.onet.pl/mbiznes

3 5

P(k)
by Bartosz Lew 07 Jan '03

07 Jan '03

what is the true meaning of P(k) ??? bartek

2 2

Re: military masking net
by szajtan odwieczny 16 Dec '02

16 Dec '02

> As Michaウ said, it's true that the deviations from homogeneity are > small on scales anything much bigger than the Schwarzschild horizon of > a SMBH http://adjani.astro.uni.torun.pl:9673/zwicky/SuperMBH > > Another problem is that in the 2D balloon, the positive fluctuations > (the net) are connected in a continuous network, while the negative > fluctuations (lowest density) are unconnected, separated from one > another. Why do you consider that as a problem. That's just what we observe, isn't it. Those great cosmic scale filaments extending for hundredths of Mpcs. > > In the standard (3D) model, at early times the + and - fluctuations > are typically of the same typical sizes (e.g. from the hypothesis of > "gaussian fluctuations"), and the 2D topology of contours of constant > density ("genus analysis") is connected both for + and - fluctns. agreed but in time the curvature evolves, like everything else in this Universe. In time, because of gravity, matter tends to gather in a strings or clumps of higher density, and thus the curvature changes. > > If you consider all matter more dense than some value, > - a low density value gives a "gruyere (ser) topology" > - a critical density values gives a "sponge topology" what is the difference between these two ? is it only about the thickness of strings ? > - a high density gives a "meatball topology" > > This is impossible to do with a balloon, which is 2D, since the > topology of constant density "1-surfaces" is 1D. Let's consider a cross section of a large part of the universe with a plain. Then we take a pencil and draw all the contours of a constant matter density (= constant curvature) on that plane. We make a little step back to see the picture. We will see some distinctive pattern similar to the one observed for clusters of galaxies. This is the analogy to that net on the balloon. But strings of the net are not 1D but 2D (they have width) and in reality 3D, so for the fishing net we should sometimes even fill up some gaps not allowing the balloon the out stand. This I should call now a military masking net. The constraint of 2D balloon is as you mentioned that - fluctuations are separated. That's right but this is only because that on 2d surface a circle splits it into two regions. So in general this is not a good model. In 3D we can easily jump from one loop into another, unless there are walls (also those from that masking net :) but in 3D) - like The Great Wall. na razie bartek. --------------r-e-k-l-a-m-a----------------- Masz dosc placenia prowizji bankowi ? mBank - zaloz konto http://epieniadze.onet.pl/mbank

2 1

fishing net
by szajtan odwieczny 13 Dec '02

13 Dec '02

hello everybody. Got an idea to share. Once upon a time I thought about such a thing. What was observed are the great voids (of size about 100 Mly in diameter or even bigger) separated by some cosmic great scale structures so it altogether looks like a soap foam. Assuming that the voids are empty, than the curvature of out local part of the Universe would look like - example in 2d: as we were pumping the balloon but confined by a fishing net which doesn't allow the surface of the balloon for free expansion, and in the end the balloon is quizzed by the strings of the net but it out stands in the holes of the net between the strings. In 3d this would be little more complicated to imagine but what do you thing about this ? with best holiday greetings Bartek --------------r-e-k-l-a-m-a----------------- Masz dość płacenia prowizji bankowi ? mBank - załóż konto http://epieniadze.onet.pl/mbank

3 2

andrzej: wyklad jest 12:40-14:40 poniedz.
by Boud Roukema 11 Dec '02

11 Dec '02

Cze�� Andzrej, This semester it's a bit late anyway, but you can see the correct time of the wyk�ad monographiczny here: http://www.astro.uni.torun.pl/sympa/shape-univ/ Sorry about the misunderstanding. pozdrawiam boud

1 0

zwicky pages (so far)
by Boud Roukema 02 Dec '02

02 Dec '02

Cześć wszystkim, (1) How to write in latin-2 on emacs: (1a) With a fairly new emacs (e.g. 20.7 or later): - M-x set-language-environment latin-2 - M-x set-input-method latin-2-prefix (also C-x <ret> C-\) - then can toggle input method with: C-\ Examples: `a`e`l's'c'o`z'z'n ąęłśćóżźń to stop ' being used, use, e.g., a space: ' a -> 'a (1b) You can put the following in your ~/.emacs file (custom-set-variables ;; custom-set-variables was added by Custom -- don't edit or cut/paste it! ;; Your init file should contain only one such instance. '(case-fold-search t) '(current-language-environment "latin-2") '(default-input-method "latin-2-prefix")) (2) The zwicky pages at the moment have a verrrrrrrrrry long URL: http://adjani.astro.uni.torun.pl:9673/zwicky/ Please see Tomek (czosnek) or me to create an account. pozd boud

4 5

expected fluctuations in xi(r)
by Gary Mamon 25 Nov '02

25 Nov '02

Dear Boud and other very large scale structure enthusiasts. I've come back to the issue of what amplitude fluctuations in the 2 point correlation function of quasars or galaxies or whatever should we expect given an assumed non-smooth P(k). The enclosed figure shows xi(r)s for 4 choices of P(k), smoothed with a gaussian of sigma=15 h-1 Mpc. The black curves are the CMBFAST prediction for Omega_m = 0.3 Omega_lambda = 0.7 Omega_b = 0.1 h = 0.6 sigma_8 = 0.6 Note that I prefer the CMBFAST predictions of P(k) to the analytical approximations by Bardeen et al. (1989, BBKS) and others, because the approximations cannot reproduce the wiggles in P(k) that generate power in xi(r). The cosmological parameters above were chosen to fit well the P(k) that Hoyle et al. (2002, MNRAS 329, 336) measured from the 2dF-10k release of quasars. Here P(k)s are defined as (2*pi)^3 times the Peebles definition (as was done by Hoyle et al.). I assume (Peebles 1993, eq. [21.40]) xi(r) = 4pi/(2pi)^3 int_0^infty k^2 dk P(k) sin(kr)/(kr) which I compute with Simpson integration as xi(r) = 4pi/(2pi)^3 ln(10) int_{-5}^5 k^3 P(k) sin(kr)/(kr) d log k with a step in log k of 0.01. The red curves use a spline fit to the Hoyle et al. measurements of P(k) within the interval of wavenumbers where they have measurements, and the CMBFAST prediction outside. The green curves use the CMBFAST P(k) everywhere, except that the point at log k/h = -1.162 is multiplied by 3. The blue curves multiply the point at log k/h = -1.162 by 10 instead. The resulting xi(r) curves show very oscillations of much weaker amplitude than found by Roukema, Mamon & Bajtlik (2002, A&A 382, 397), who smoothed their xi(r)'s with the same 15/h Mpc gaussian. Indeed, RMB found oscillations in xi(r) of amplitude 0.05 for Omega_m=0.3,Omega_lambda=0.7, whereas the oscillations predicted here are at best of 0.002 at separations of around 200/h Mpc, hence 25x smaller. Even if the RMB xi(r)s are affected by their incorporation of selection effects in the z-direction, this should affect the normalization of xi, but presumably not the amplitude of the oscillations. Moreover, the Hoyle at al. P(k) produces a minimum of xi(r) at r = 245/h Mpc, whereas RMB predict a maximum at that separation. This makes me worry that the RMB result is caused by noise... Please convince me that I am wrong! I need to think again about the (2pi)^3 factor... cheers Gary

1 0

Re: what's with that transparency
by szajtan odwieczny 15 Nov '02

15 Nov '02

ok....at first thanks - you gave me quite homework to do, it will take a few days until I manage to read that book but I just can't sit like that after what you wrote. firstly I want to remark that I don't know what that damn word manifold mean - I cant find it anywhere - I can just suppose. But this isn't at most important right now. Boud, I have a few remarks to what wrote. Let me quote: > > possible, so we came to the conclusion that the 2-torus in three > > dimensional Euclidean space is not an good example of two > > dimensional closed space of zero curvature. But if we introduced > Agreed. Unless we redefine the metric. For example: > Let's put the 2-torus in the X-Y plane, centred on (0,0,0), with > radius R. > > Then the metric of E^3 (Euclidean 3-space, i.e. R^3 with flat metric) > is > > ds^2 = dx^2 + dy^2 + dz^2 > = (dr^2 + r^2 d\theta^2) + dz^2 where r=\sqrt{x^2+y+2} > >Under this metric, the 2-torus does not, in general, have zero >curvature, and it is inhomogeneous (curvature different on different >points). I assume that theta is an angle between x and y axies and (r^2 = x^2+y^2), right ? If so then this is just an infinitesimal length in E^3 space in cylindrical coordinates. ok, I understand this point. (btw. but even here I have an uncertainty, look at the end, because it's a little different topic) > >So let's just make a new metric on the 2-torus: > >ds^2 = (dr^2 + R^2 d\theta^2) + dz^2 where r=\sqrt{x^2+y+2} > >only difference: "r^2" -> "R^2". ( but I think dr should be = 0 in this metric ) > >(Exercise: Is this a metric on R^3?) as you wrote this is a metric on flat torus. but in fact it's not true. if we use cylindrical sthight-linear coordinates than the equation r=R is an equation of tube, thus this is a metric on a surface of tube not torus. If we go to the coordinates like: r' = r \phi' = \phi z' = \rho arcsin(z/\rho) where \rho is an radius of torus (the one from it's center) then the same equation r' = R describes torus. For the first equation r=R I checked Pythagoras's theorem integrating for each side of chosen triangle, and finally came to the conclusion that 1=1 as expected (meaning it's true). now I wanted to do the same thing with an equation r'=R which would be for torus. In fact in that prime coordinates, tube becomes torus so I thought since ds is invariant, all that should be showed is to check if that transformation is an isometry. Well it is, under condition that \rho = infinity or z=0. And this is good for nothing. I'm still gonna spend some time trying to find such function of the complementary - third side of an triangle on a surface of torus so after integrating along that side and putting it into the Pythagoras's theorem I will find equality. but I am sceptic because... > > >> > the fourth spital dimension than it becomes possible. Like for > >possible: yes; necessary: no. > > > > But the problem now is how to put this idea into the real > > world. All these considerations about the topology of space were > > made from "the higher ground" - I mean from the point of view of a > > space with at lest two dimensions more that the space (earlier a > > transparency or just a piece of paper) we were thinking of. The > > problem appears if we talk about the topology of the Universe > > where there are only three spital dimensions. To make it close > > like 3-torus it is essential to introduce 3 more dimensions (it's > > six) to make it possible. Then I say that, that all topoloy thing > Only if you *assume* that the only spaces which are physically > possible are n-dimensional Euclidean spaces. ... that's just the point - as a basis the first thing was that we were looking among spaces of zero curvature which are Euclidean spaces, so I do assume only Euclidean spaces. The metric tensor g in cylindrical coordinates of torus is (I guess) | R^2 0 | g= | | | 0 1/[1-(z-\rho)^2] | ( and for tube is with g_22 = 1.) It depends on point, and in general det(g) might be negative so it can't be an Euclidean space. Can it ? (and now I am not in some 3-dimensional space but just two). So I bring back my implication about topology science and 3+n - dimensional space. Despite of all what was said, don't we assume k almost zero these days ? ------------------- this is bizzare: Let's imagine tube. From mathematical point of view we can define it's curvature in each of it's points along two perpendicular directions (along the axis of symmetry and the other one). the first radius of curvature will be infinity, while the other one will be R (radius of the tube). Living on a surface of tube I could also measure is's curvature by measuring it's circumference and dividing by 2pi. Now I can imagine a 2-space of shape of this tube. Although I computed the Pythagoras's theorem is satisfied (so the curvature must be zero) how can I deal with the fact, that it is flat in the circumstances I mentioned above. thanks for references. when I finally get satisfied with this problems because if this going to be like this (I working on it for at least week) I won't start with my master thesis - this is quite off my topic ;) nevertheless very interesting, although maybe for you - boring. pozdrawiam, bartek

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Re: what's with that transparency
by szajtan odwieczny 15 Nov '02

15 Nov '02

sorry in that g_22 should be / instead - ;) czyli like this 1/[1-(z/\rho)^2] bart

1 0

Re: what's with that transparency
by Boud Roukema 13 Nov '02

13 Nov '02

Cześć Bartek, Michał, everyone, I'm happy to see this discussion starting up! :) On 12 Nov 2002, Michal Frackowiak wrote: > On Sun, 2002-11-10 at 17:12, szajtan odwieczny wrote: > > questions: > > ---------- > > 1) does the cosmological principle introduce any restrictions on the topology of the universe. This is a *big* question ;). Firstly, it depends what you mean by "cosmological principle" If you mean local homogeneity and local isotropy, which is (more or less) consistent with observations, then it allows all constant curvature 3-manifolds. If you mean global homogeneity and global isotropy, which is not (yet or maybe never?) measured, then many multiply connected 3-manifolds are inconsistent with this strict definition, since some points in space or directions can be "favoured". See http://de.arxiv.org/abs/astro-ph/0101191 > > 2) does the topology science relies on some multidimentional theory - like string theory The physics explaining topology *might* be related to higher dimensional theories, but the mathematics does not require it, and the physics certainly does not *require* a higher dimensional theory. > > now look here, > > > > the problem: > > ------------ > > > > I finally figured it out. It is about that transparency > > problem. The problem was how it is possible to roll up the > > transparency into a torus not stretching it so it's curvature > > remained the same. I was stubborn to say that this was not > > possible, so we came to the conclusion that the 2-torus in three > > dimenitonal eucliean space is not an good example of two > > dimentional closed space of zero curvature. But if we introduced Agreed. Unless we redefine the metric. For example: Let's put the 2-torus in the X-Y plane, centred on (0,0,0), with radius R. Then the metric of E^3 (euclidean 3-space, i.e. R^3 with flat metric) is ds^2 = dx^2 + dy^2 + dz^2 = (dr^2 + r^2 d\theta^2) + dz^2 where r=\sqrt{x^2+y+2} Under this metric, the 2-torus does not, in general, have zero curvature, and it is inhomogeneous (curvature different on different points). So let's just make a new metric on the 2-torus: ds^2 = (dr^2 + R^2 d\theta^2) + dz^2 where r=\sqrt{x^2+y+2} only difference: "r^2" -> "R^2". (Exercise: Is this a metric on R^3?) > > the fourth spital dimention than it becomes possible. Like for possible: yes; necessary: no. > > But the problem now is how to put this idea into the real > > world. All these considerations about the topology of space were > > made from "the higer groud" - I mean from the point of view of a > > spce with at lest two dimentions more that the space (earlier a > > transparency or just a piece of paper) we were thinking of. The > > problem appeares if we talk about the topology of the Universe > > where there are only three spital dimentions. To make it close > > like 3-torus it is essential to introduce 3 more dimentions (it's > > six) to make it possible. Then I say that, that all topoloy thing Only if you *assume* that the only spaces which are physically possible are n-dimensional Euclidean spaces. > > implies that out phisical space is in fact more than three > > dimentional, otherwise we would stand before question: what is > > that thing that out space (universe) lies in. Since this question > > is considered to be sensless, or at least redundant, the only > > solution is to assume the first option. > > It leads to the link with the science of the nature of the space > > itself - like in the string theory, which assumes that our > > spacetime is 10-dimentional - time plus three known spital > > dimentions and 6 other which were reduced to the lenght of Planck > > during the very early stages of evolution of the universe. In that > > case that bending our unverse into a 3-torus around those > > additional axies could be easily (al least theoreticaly) done but > > the "radius" of that bend would be very small. But whatever. > > Is this way of thinking of topology ok ? I think there's still some work to do on your intuition, sorry... > the main problem is that real-world intuition is EXTREMALLY ILLUSIONARY > AND DECEIVING when dealing with spacetime and its curvature. > If you would think in terms of manifolds with given metric (riemann > manifolds) there is ABSOLUTELY NO PROBLEM with 2-torus, 3-torus and so > on. they do not even have to be embedded in other spaces. I would say that ordinary intuition can be used as *one* possible framework for building intuition of other possibilities. But you have to accept that part of your intuition consists of arbitrary assumptions, and consider using other ways of thinking about the space or spacetime which interests you which avoid making these assumptions. > so i strongly recommend http://arxiv.org/abs/gr-qc/9712019 with an > excelent introduction to modern general realtivity Nice :) I added it here: http://www.wikipedia.org/wiki/General_relativity > ps. you will see that you do not have to stretch a transparency to > create a 2-torus, which is a perfect example of a zero-corvature > manifold (PROVIDED that you imply a proper METRIC). > thats the METRIC that is responsible for the curvature, not the SHAPE!!! > Bartek, please read: http://www.wikipedia.org/wiki/Shape_of_the_universe and maybe if you write: http://pl.wikipedia.com/wiki.cgi?action=edit&id=Forma_Wszech%B6wiata in po polsku, then this would help you clarify the question. You could try translating the English version, but rewriting it in the way you understand it and want to explain it. If Michał or I disagree with you, don't worry, we'll correct it sooner or later ;). na razie boud

1 0

what's with that transparency
by szajtan odwieczny 10 Nov '02

10 Nov '02

questions: ---------- 1) does the cosmological principle introduce any restrictions on the topology of the universe. 2) does the topology science relies on some multidimentional theory - like string theory now look here, the problem: ------------ I finally figured it out. It is about that transparency problem. The problem was how it is possible to roll up the transparency into a torus not stretching it so it's curvature remained the same. I was stubborn to say that this was not possible, so we came to the conclusion that the 2-torus in three dimenitonal eucliean space is not an good example of two dimentional closed space of zero curvature. But if we introduced the fourth spital dimention than it becomes possible. Like for example we imagine a string which has one pair of zero dimentional ends, we need at least one more dimentional space (it's two) to make it closed (to joing the ends), so in case of a flat plane (or paper) which has two pairs of one dimentional ends which we have to join, then we need two more dimentions to do that. That would be 4 dimentions. Thus in four dimenitons matematically we can do with the topology of the space whatever we want and it's curvature will still be the same. But the problem now is how to put this idea into the real world. All these considerations about the topology of space were made from "the higer groud" - I mean from the point of view of a spce with at lest two dimentions more that the space (earlier a transparency or just a piece of paper) we were thinking of. The problem appeares if we talk about the topology of the Universe where there are only three spital dimentions. To make it close like 3-torus it is essential to introduce 3 more dimentions (it's six) to make it possible. Then I say that, that all topoloy thing implies that out phisical space is in fact more than three dimentional, otherwise we would stand before question: what is that thing that out space (universe) lies in. Since this question is considered to be sensless, or at least redundant, the only solution is to assume the first option. It leads to the link with the science of the nature of the space itself - like in the string theory, which assumes that our spacetime is 10-dimentional - time plus three known spital dimentions and 6 other which were reduced to the lenght of Planck during the very early stages of evolution of the universe. In that case that bending our unverse into a 3-torus around those additional axies could be easily (al least theoreticaly) done but the "radius" of that bend would be very small. But whatever. Is this way of thinking of topology ok ? further questions: ------------------ For the curvature matter, there is general theory of relativity which connects the energy density with curvature. What about the topology ? What is that force that shapes the topology of space, and can the topology change in time ? pozdrawiam Bartek

1 0

Workshop on Particle Physics...
by Bartosz Lew 03 Nov '02

03 Nov '02

I found some stuff from International Workshop on Particle Physics and the Early Universe (Chicago, Illinois, USA September 18-21, 2002) page with variety of topics concerning cosmology - but there is only the stuff presented on that workshop (no papers). http://pancake.uchicago.edu/~cosmo02/sched/parallel.html ******************************************************************************* Bartosz Lew e-mail: szajtan(a)astri.uni.torun.pl szajtan(a)phys.uni.torun.pl Centrum Astronomii UMK szajtan(a)poczta.onet.pl TORUN, POLAND www: http://www.phys.uni.torun.pl/~szajtan *******************************************************************************

1 0

references on alternatives to Big Bang model
by Boud Roukema 30 Oct '02

30 Oct '02

Cześć Magda, wszystkim, Tu szybko tłumaczenie i referaty (w po angielsku, niestety) o temat modele alternatywne (lub extrapolające) od model standardowy FLRW: http://www.wikipedia.org/wiki/Beyond_the_standard_Big_Bang_model pozdrawiam boud

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lecture time: 12:40-14:40 each Monday
by Boud Roukema 14 Oct '02

14 Oct '02

The lecture time is now set at 12:40-14:40 on Mondays. Please check the mailing list archive: http://www.astro.uni.torun.pl/sympa/shape-univ and/or subscribe to the list and feel free to make useful comments or even ask "stupid" questions - sometimes the "stupid" questions are the best ones... One student wishes to take this course as an examined course. I proposed that contributions to the Wikipedia - on the theme of the shape of the universe, or cosmology generally, - could count as an "essay-type" exam. Here is the first page to write: http://pl.wikipedia.com/wiki.cgi?action=edit&id=Forma_Wszech%B6wiata Anyone wishing to do this and have this count as an exam should "log in" to the wikipedia so that his/her work is "signed" (otherwise noone will know who did it!) Any objections to this sort of exam? Some of my contributions (with the help of others!) are: http://pl.wikipedia.com/wiki.cgi?action=history&id=Kosmologia_obserwacyjna http://www.wikipedia.org/wiki/Shape_of_the_universe But everyone should feel free to write their "lecture notes" here, in the style of an encyclopedia, of course. Jeśli robisz w po polsku w http://pl.wikipedia.com , twója praca będzie użyteczna dla całe inne studenci, teraz i w przyśłości, ale też dla siebie... na poniedziałku boud

1 0

cosmo books
by Boud Roukema 14 Oct '02

14 Oct '02

message with some discussion of cosmo textbooks: http://www.astro.uni.torun.pl/sympa/shape-univ/2002-05/msg00014.html Since then, some more books have been bought for TCfA and have arrived. To start from the beginning, if you can't find this in the library you can probably just buy it - 7 funt (UK) -> roughly 40 zloty Liddle in po polsku! pozdrawiam boud

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wikipedia & twin paradox
by Boud Roukema 07 Oct '02

07 Oct '02

Cze�� wszystkim, I've put a rough draft of the first lecture here: http://www.wikipedia.org/w/wiki.phtml?title=Shape_of_the_universe but I have to catch the bus now.. Staszek: you'll see the answer to the Twin Paradox stuff in the arXiv reference at the bottom of the page. Please write a wikipedia entry (Polish or English) so that non-specialists can follow this too.... pozd boud

1 1

day/date??
by Boud Roukema 03 Oct '02

03 Oct '02

Hi everyone, I've had two responses so far for choice of afternoon (Monday vs Thursday vs Friday): 1 person in favour of Friday and 1/week - > I think, that friday afternoon, will be just fine, and frequency of a > 1/week will be good ,too. I'm the second/third year student:) 1 person strongly against Friday, but Thursday OK. Since lectures are supposed to start this week, we need to make a quick decision. Is there anyone who wants to attend the course and *cannot* attend Thursday 14h-16h? pozd boud

1 3

day and frequency of shape-univ monog course?
by Boud Roukema 25 Sep '02

25 Sep '02

Cze�� wszystkim, Could students (np IV, V or III rok) interested in the "Shape of the Universe" monograph course this semester please send an email with their preferred day and frequency for the course to: cosmo-spotka(a)astro.uni.torun.pl day: At the moment, Monday, Thursday and Friday afternoons seem to be free. (but III r students are *not* free Thurs afternoon - they have "lektoraty") freqency: 1/week or 1/fortnight? A general description of the course is here: http://www.astro.uni.torun.pl/sympa/shape-univ/ but the details, whether it's introductory or more detailed, etc., will depend on who is interested. Remember that there is a page to help communication among students, and between students and faculty, on cosmology-related courses, here: http://www.astro.uni.torun.pl/sympa/cosmo-intro/index.html pozdrawiam boud

1 0

urlop 29/07 - 02/08
by Boud Roukema 27 Jul '02

27 Jul '02

Cze�� wszystkim, B�dzi� w urlopu 29/07 - 02/08, w Hajn�wce przez �ubr�w... Na ra�e Boud

1 0

xi(r) from Hoyle's P(k)
by Gary Mamon 01 Jul '02

01 Jul '02

Dear all, I finally computed the correlation function extpected from Hoyle etal.'s P(k) obtained from their analysis of the 2QZ-10k quasar sample. I used the final part of eq. (21.40) of Peebles (1993) book to convert P(k) to xi(r). I now understand that last equation as resulting from the integral over angles of the previsou integral (which is in fact triple: dk dtheta dphi). I extended the P(k) beyond the values of Hoyle et al in two ways: 1) I used the theoretical BBKS (Bardeen et al. 84, appendix) P(k) (black & white plot). Notice that Hoyle's points are about a factor of 10000 too high so the P(k) is highly discontinuous. 2) I moved up the BBKS P(k) on each side of the Hoyle range so as to make the whole P(k) continuous. 3) Same as 2) with a step in log k decreased from 0.075 (Hoyle et al.'s step) to 0.01. (see 4th attached file). The three xi(r) plots are attached. The calculation were done with Omega = 0.3, h = 0.7, Omegab = 0.04. Even though Hoyle's peak is at 2 pi h / 89 Mpc, the 1st plot shows xi(r) with peaks at 67, 127 and 255 h-1 Mpc, close to what we (Boud really) gave in RMB02. This gives us some confidence that Boud's calculations are not completely wrong :-) and that there is no simple relation such as peak in xi at 2 pi / k_peak, where k_peak is the peak in P(k). However, in the 2nd plot, the peaks are very narrow and marginally significant at 90.6, 107.6, 109.3, 127.8, 180.6 and 255.0 h-1 Mpc. Finally, in the 3rd plot, it is hard to distinguish anything! However, with some imagination, one can guess excess broad power around 140 h-1 Mpc and a finer excess around 255 h-1 Mpc... Let me know what you think. all the best Gary

3 2

smoothed xi(r)
by Gary Mamon 30 Jun '02

30 Jun '02

Hi again, Attached you will find the same xi(r) as case 3 of the previous e-mail with, in red, it's smoothing by a 15 h-1 Mpc gaussian. I must admit that I worked avery quickly and there may be errors... cheers Gary

1 0

xi(r) from P(k)
by Gary Mamon 13 Jun '02

13 Jun '02

Hi everyone, For my talk at the IAP colloquium on July 2, it would be nice if I could show the xi(r) expected from the 2dFGRS and 2QZ P(k)'s (that are quite similar). I want to see how strong and where will the wiggles be in the xi(r) derived from the P(k). Does anyone have time to do this? By the way, I don't understand the formulation given in Peebles's book (1993, PoPC), eq. 21-40 (p. 509). If P(k) = <|delta(k)|^2>, then shouldn't the right-hand-side of the 2nd line in eq. 21-40 be sin(kr) instead of sin(kr/(kr)? cheers Gary P.S. I agree with Boud that doing ML estimation or chi2 estimation on xi(r)s is dangerous because the separation bins are not truly independent.

1 0

seminar at Mt Stromlo
by Gary Mamon 04 Jun '02

04 Jun '02

Dear all, My talk at Mt Stromlo went very well. Brian Schmidt of supernovae fame made a good remark. Instead of looking for peaks, which could simply require that the xi(r)'s in different z bins are similar (he thought of using a maximum likelihood technique). He was referring to Alcock & Paczynski... Matthew Colless mentioned that both 2dF galaxies (2dFGRS) and quasars (2QZ) show a feature in P(k) at 2pi/89 h Mpc-1. Matthew's postdoc, Roberto de Propris, showed me a plot of the correlation function of the superposition of many pencil beams drawn through the 2dFGRS. He has access to the full 250k sample, and avoided computing a complete xi(r) using all 30 billion separations. There is a feature around 250 Mpc, but there are also stronger features elsewhere, but not at 130 h-1 Mpc. It thus appears that Broadhurst et al. were lucky back in 1990. cheers Gary

3 4

comments from Brian Boyle
by Gary Mamon 03 Jun '02

03 Jun '02

Dear all, Brian Boyle (PI of 2dF quasar survey) came to my talk at Macquarie University. He seemed to like our analysis. His main comment was: "Have you tried repeating your correlation function analysis by replacing the scambled redshifts with a smoothed redshift distribution?" This is what I gathered you (Boud) have done these last few days (extrapolating from Boud's often cryptic messages). I answered that we are in the process of doing just that, and our *** preliminary *** result is that the 125 h-1 Mpc feature comes out strongly in the 1st z-bin, but that we did not have yet any conclusion on Omega,Lambda. cheers Gary

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