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Pavel Kroupa on “The vast polar structures around the Milky Way and Andromeda “

Posted 22 November 2013 by Marcel S. Pawlowski

In case you, like me, have missed Pavel Kroups's recent talk at the Joint Astronomical Colloquium in Heidelberg, you now have the opportunity to watch a movie of the event and download the slides. The movie is quite long (more than an hour), but it is worth watching it to the end. While the talk is titled "The vast polar structures around the Milky Way and Andromeda", Pavel talks about much more, starting with tidal dwarf galaxies and ending with... Read more

LUX: Results from another direct (non-)detection experiment for Dark Matter

Posted 1 November 2013 by Marcel S. Pawlowski

WIMP Dark Matter cross section

On Wednesday, the Large Underground Xenon Detector (LUX), a direct detection experiment for Dark Matter, has announced its first results. Before the announcement there was the usual excitement, with Nature News titling “Final Word is near on dark-matter signal”. So, has Dark Matter finally been detected? Some previous experiments had reported possible detections already. For example, the Cryogenic Dark Matter Search (CDMS) recently presented an impressive number of 3 possible dark matter events (compared to 0.7 they estimated to be... Read more

The Planck Results on the Cosmic Microwave Background

Posted 22 April 2013 by Pavel Kroupa

Guest contribution by Behnam Javanmardi Prologue by Pavel Kroupa: The much awaited Planck results on the CMB have been published recently. The results are consistent with those arrived at by using Wilkinson Microwave Anisotropy Probe (WMAP) measurements. This agreement is excellent news, because it means that the two missions are consistent and thus the Planck data enhance our confidence in what we know about the CMB. But, what do the results mean in terms of our physical understanding of the... Read more

Scott Dodelson on dark matter and modified gravity (guest post)

Posted 9 March 2013 by Marcel S. Pawlowski

Following the recent incident, we and the SciLogs team decided to invite a renown colleague to write a guest blog post. Thinking about possible guest bloggers who are experts in the field of cosmology and approach theories such as MOND with the necessary scientific skepticism, we arrived at Scott Dodelson as one candidate. Scott is a very well-respected cosmologist. He is a scientist at Fermilab and  a professor in the Department of Astronomy and Astrophysics and the Kavli Institute for... Read more

The Dark Matter Crisis continues: on the difficulties of communicating controversial science

Posted 8 March 2013 by Marcel S. Pawlowski

(Continuation of the series A-E) There has been an unsuccessful attempt to close down The Dark Matter Crisis. Here is the story (and an email by Jim Peebles): UPDATE: The guest post is now online. As regular readers of our blog know, and first-time readers may be able to guess from this blog name, Pavel and I mostly write about the problems and shortcomings of the dark matter hypothesis. One aspect of our research is to test dark matter models... Read more

Are there two types of dwarf galaxies in the universe?

Posted 7 March 2013 by Marcel S. Pawlowski

Dwarf galaxies, that is galaxies less massive than a few billion solar masses, are expected to be formed through two processes. They might either be the luminous components of small dark matter halos, formed early in the universe when gas fell into the potential well of those halos. These dwarf galaxies are called primordial dwarf galaxies (PDGs) and are expected to be dominated by their dark matter content. The other formation mechanism is a process observed even in the present-day... Read more

This blog moves to SciLogs.com

Posted 8 January 2013 by Marcel S. Pawlowski

Pavel and I have been too busy to blog for a while (my excuse being that I am in the final stages of my PhD studies). This is also why we did not announce this sooner: Our blog has moved from SciLogs.eu to SciLogs.com. The new site provides an improved blogging system and maybe more international visibility, as well as a pleasant neighborhood of science bloggers. The new URL for "The Dark Matter Crisis" is http://www.scilogs.com/the-dark-matter-crisis/. All future articles will... Read more

Andromeda’s satellites behave as expected … if they are tidal dwarf galaxies

Posted 3 January 2013 by Marcel S. Pawlowski

Today's issue of Nature contains a very exciting study by Rodrigo Ibata et al. which might be a game-changer in the research areas of galaxy formation and near-field cosmology. It is titled “A vast, thin plane of corotating dwarf galaxies orbiting the Andromeda galaxy” and already now should be seen as a candidate for the most-exciting paper of 2013. UPDATE Jan. 4th: The article is now also available on the arXiv. Pavel Kroupa and I have been waiting for this... Read more

A filament of dark matter between two clusters of galaxies: dark matter detected

Posted 5 July 2012 by Pavel Kroupa

We briefly comment on the paper by Dietrich, Werner, Clowe et al. on "A filament of dark matter between two clusters of galaxies " which is now in press with Nature.  The media have it that this may be a direct detection of dark matter.  The abstract of this paper reads "It is a firm prediction of the concordance Cold Dark Matter (CDM) cosmological model that galaxy clusters live at the intersection of large-scale structure filaments. The thread-like structure of... Read more

13th Marcel Grossmann Meeting

Posted 2 July 2012 by Marcel S. Pawlowski

We are now on our way to the 13th Marcel Grossmann Meeting in Stockholm. The meeting of physicists and astronomers covers General Relativity, Gravity and relativistic field theories and is held every three years (since 1975) in different cities. It is named after Marcel Grossmann, who was a Swiss mathematician and a collaborator of Einstein in his work on general relativity. Following his recent review paper “The dark matter crisis: falsification of the current standard model of cosmology”, Pavel has... Read more