Cosmo-torun

cosmo-torun@cosmo.torun.pl

328 discussions

CAMK workshop this week: 12-17 lipca 2011: Cosmic web morphology and topology
by Boud Roukema 11 Jul '11

11 Jul '11

hi cosmo-torun, There's a CAMK workshop *this* week: 12-17 July 2011: Cosmic web morphology and topology http://users.camk.edu.pl/pchela/workshop/ Here, "topology" means 2D topology of constant density surfaces embeded in 3D space, not 3D topology of 3D spaces. This is about the cosmic web, meaning the filaments and knots of mostly dark matter and some baryonic matter on scales of about 10-100 Mpc. Most of you have seen the animation of a simulation of this that i show fairly often. Observations of the cosmic web include clusters at the "knots" of the web (e.g. observed by OCRA through the SZ effect) and the Lyman-alpha forest - clouds of neutral hydrogen that absorb background quasars. i don't expect any problem with informal participation, but send an email to Wojtek Hellwing (see the website) to briefly introduce yourself. You can make a day trip to Warsaw - leave early morning and return e.g. with the 18.45+(n>1 * 10 minutes) train - or stay overnight at a friend's place and see several days of talks. The talks look mostly (but not only) theoretical to me, and based on the FLRW model + perturbations, not the inhomogeneous approach. This is an easy opportunity to meet some international extragalacticians/cosmologists. pozdr boud

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n-body review 1106.1082v1, correction by Adrian Melott 1105.1774
by Boud Roukema 11 May '11

11 May '11

hi cosmo-torun, These two articles may be useful especially for Zbyszek and Bartek: * n-body review http://arxiv.org/abs/1106.1082v1 Dehnen and Read * correction by Adrian Melott http://arxiv.org/abs/1105.1774 i'm not sure if there's anything especially new in 1106.1082, but figs 5 and 6 look nice, and reading a review paper you can often find something you didn't know before. pozdr boud

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kpc-scale triple AGN: arXiv:1104.3391 Liu, Shen, Strauss
by Boud Roukema 22 Apr '11

22 Apr '11

witam cosmo-torun This should be interesting especially for AGN people: http://arxiv.org/abs/1104.3391 Cosmic Train Wreck by Massive Black Holes: Discovery of a kpc-Scale Triple Active Galactic Nucleus Authors: Xin Liu, Yue Shen, Michael A. Strauss pozdr boud

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fitting LT models to data: new Bolejko et al paper arXiv:1102.3370
by Boud Roukema 22 Feb '11

22 Feb '11

hi cosmo-torun http://arxiv.org/abs/1102.3370 The Metric of the Cosmos from Luminosity and Age Data Krzysztof Bolejko, Charles Hellaby, Alnadhief H. A. Alfedeel This is an algorithm for using LT models to construct a metric from apparent magnitude and maximum stellar age data (as an alternative to forcing an FLRW model onto the data). Graphs of estimates of Omega_m(r) and t_Bang(r) are in Figs 7 and 8. pozdr boud

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Bolejko arxiv:1101.3338
by Boud Roukema 19 Jan '11

19 Jan '11

hi everyone, A different problem in using a more accurate metric than the FLRW metric is how we interpret the CMB. The following seems to be the first paper on this. Since "real" calculations are difficult, the approach seems to be to test various toy model calculations that at least show how much things could change compared to FLRW + Concordance parameter values. The answer in this case is not Omega_Lambda = 0, but since these are toy models, i don't think this is a claim that Omega_Lambda != 0. What Krzysztof does argue is that \Delta \Omega_\Lambda_{\mathrm{sys}} \gg 0.01. The effect of inhomogeneities on the distance to the last scattering surface and the accuracy of the CMB analysis - Krzysztof Bolejko http://arxiv.org/abs/1101.3338 pozdr boud

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the Universe is old and old age caught up with Allan Sandage :(
by Boud Roukema 19 Nov '10

19 Nov '10

hi everyone, I think I heard at least one conference talk by Sandage. Some of the more senior people here may have known him better. I'll just quote the Wikipedia summary for the younger people among us: Allan Rex Sandage (born June 18, 1926 in Iowa City, Iowa, died November 13, 2010) was an American astronomer. He was Staff Member Emeritus with the Carnegie Observatories in Pasadena, California. He is best known for determining the first reasonably accurate value for the Hubble constant and the age of the universe. http://en.wikipedia.org/wiki/Allan_Sandage pozdr boud

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a fourth neutrino (sterile neutrino)?
by Boud Roukema 05 Nov '10

05 Nov '10

hi everyone, Even if the electron, tau and muon neutrinos are usually considered to be of too low mass to be relevant for non-baryonic dark matter, it looks like there are several hints that a fourth, "sterile" neutrino exists: http://cosmocoffee.info/viewtopic.php?p=4864 It's not clear to me what this could/would imply for the sterile neutrino's mass... pozdr boud

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highest spectroscopically confirmed redshift: z = 8.6 Lehnert et al. 1010.4312
by Boud Roukema 25 Oct '10

25 Oct '10

hi everyone, We're still a long way from galaxy/qso redshifts of 20 to 30, but we're getting towards 10: Spectroscopic confirmation of a galaxy at redshift z=8.6 Lehnert et al. http://arxiv.org/abs/1010.4312 By comparing to other high z galaxies, the stellar age is suggested to be in the range 0.01 to 0.1 Gyr. pozdr boud

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arXiv:1010.1634 neural-network removal of WMAP foregrounds
by Boud Roukema 11 Oct '10

11 Oct '10

hi cosmo-torun, Foreground removal from WMAP 5yr temperature maps using an MLP neural network Authors: H. U. Norgaard - Nielsen http://arxiv.org/abs/1010.1634 This looks cool! i've just read it very briefly... My initial understanding is that it's like an ILC map but without the arbitrary definition of "regions". pozdr boud

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14.00 Fri 8.10.10 cosmo group web pages workshop
by Boud Roukema 06 Oct '10

06 Oct '10

hi everyone, Cosmo workshop! This Friday: When, where: 14.00 Fri 8.10.2010, @KRA. Topic: cosmology group web pages. i'll try to set up a switch so that people with laptops can edit simultaneously, but anybody is still welcome to participate without a laptop. Just by seeing people edit "live" may help you get the basic idea. At 15.00, following the wiki workshop and a short break, there'll be a cosmic topology workshop. pozdr boud

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