Category Archives: Events

2015 Oskar Klein Medal to be awarded to Rashid Sunyaev

The 2015 Oskar Klein Memorial Lecture will be given by Professor Rashid Sunyaev of the Max Planck Institute for Astrophysics, Garching, who is also the recipient of the Oskar Klein Medal for 2015.

Rashid Sunyaev. Photo credit: Juan Diego Soler
Rashid Sunyaev. Photo credit: Juan Diego Soler
Professor Sunyaev has made groundbreaking contributions to theoretical astrophysics in the areas of cosmology, high-energy astrophysics and X-ray astronomy through his studies of some of the most extreme physical processes in the universe. His theory of the evolution of density fluctuations in the early universe (developed with Zel’dovich) predicted the acoustic peaks that are observed in the cosmic background radiation. He has also made key contributions to the theoretical description of matter accreting onto black holes, predicting a signature for the resulting X-ray emission.

Rashid Alievich Sunyaev received his PhD in astrophysics from Moscow University in 1968 and became a Professor at the Moscow Institute of Physics and Technology in 1974. He is a Director of the Max Planck Institute for Astrophysics in Garching, Germany and has been chief scientist at the Space Research Institute of the Russian Academy of Sciences since 1992.

The Oskar Klein Memorial lecture will take place at 3:15 PM on Thursday, February 4,
in the Oskar Klein Auditorium at the AlbaNova University Centre in Stockholm.

Title: “Unavoidable distortions in the spectrum of CMB and the Blackbody Photosphere
of our Universe”

Abstract: Spectral features in the CMB spectrum contain a wealth of information about physical processes in the early Universe at redshifts z < 2 10^6, i.e. when Universe was older than 2 months. The Cosmic Microwave Background Radiation (CMB) spectral distortions are complementary to other probes of cosmology. In fact, most of the information contained in the CMB spectrum is inaccessible by any other means. This talk outlines the main physics behind the spectral features in the CMB produced throughout the history of the Universe. I will concentrate on the distortions which are inevitable and must be present at the level observable by the next generation of CMB experiments. The spectral distortions considered here include spectral features from cosmological recombination of hydrogen and helium, resonant scattering of CMB by metals during reionization which allows us to measure their abundances, y-type spectral distortions produced during and after reionization and μ - type distortions created at redshifts z > 10^5 due to any significant energy release (for example: due to decay or annihilation of the dark matter particles or due to viscous decay of the primordial sound waves).

Special attention will be given to existence of the Blackbody Photosphere of our Universe at redshift z ~ 2 10^6, behind which Comptonization, double Compton and Bremsstrahlung are able to wash out any spectral distortions arising due to arbitrary strong energy release.

CMB spectral distortions detected on the sky by Planck spacecraft, South Pole Telescope and Atacama Cosmology Telescope permitted us to discover more than thousand unknown before clusters of galaxies (most massive gravitationally bound objects in the Universe, containing thousands of galaxies, hot (kTe > 1 KeV) intracluster gas, gravitational lenses and huge amount of dark matter). These clusters of galaxies are serving today as probes for modern cosmology tracing the growth of the Large Scale Structure with time and containing strong gravitational lenses.

If you want to know more, check also the official webpage for the Oskar Klein Memorial Lectures

Passerby become Supernova hunters in Kungsträdgården

Fysik i Kungsträdgården is one of the major outreach events in Stockholm where scientists have the chance to show their research (read more about the whole event in Fysikum blog). This year the supernova group at the OKC invited the public to look for supernovae with us using the intermediate Palomar (Transient) Factory (iPTF) collaboration telescope in Palomar, California, U.S.A (read more about the iPTF). Due to the time difference between Stockholm and California, we were able to look at live images as they were taken from the telescope, to search for new transient objects such as supernovae. The event was successful, bringing a lot of people from the park in central Stockholm to come and search with us. During this search, we found two supernovae of type Ia with the help of these volunteers, who shared their thoughts with us:

Passerby supernova hunter Manoj Bartakke (in the middle) with Emir (left) and Anders (right)
Passerby supernova hunter Manoj Bartakke (in the middle) with Emir (left) and Anders (right)

“Ahoy! In the midst of bachelor studies, it can sometimes be easy to forget what you are actually studying for, therefore I can only describe my experience of that day as awesome and invaluable. Everyone were very helpful and pedagogical in their explanations of how it all worked. I would rate my experience a 12/10 and I would love to have the chance of doing it again some time.” – Patrik Tegner

Supernova discovery Kungsträdgården
Passerby supernova hunter Patrik Tegner (in the middle) and the supernova group from left to right Tanja, Semeli, Raphael, Anders and Emir

“I was in the Kungsträdgården with my office colleague on 5th September, surfing through stalls from a science exhibition. I came across this ‘supernova’ stall. The two guys there (Emir Karamehmetoglu and Anders Nyholm) , gave us good information of universe and supernova. They also introduced with their research on supernova. It was really interesting and informative. For that duration, I was like in another world. In a practical conducted by them, I was also able to discover one of the new supernova, which they named as ‘iPTF15cpp’ . ( I felt very proud in my internal universe ☺ ). So it was a different and good experience for me.” – Manoj Bartakke

Tanja, Semeli and Emir

The 13th Marcel Grossmann Meeting at AlbaNova

Einstein with his friend and mathematical collaborator Marcel Grossmann.
This week Stockholm University and AlbaNova are hosting the 13th Marcel Grossmann Meeting. The triennial Grossmann meetings are organized by the ICRANet research institute, this year with Stockholm University and KTH as local partners.

The general theme of the Grossmann meetings is applications and theory relating to Einstein’s general relativity.

The meeting has a broad spectrum with 20 parallel sessions devoted to theory and experiments/observations including quantum aspects of gravity, precision tests of general relativity, relativistic astrophysics, cosmology and astroparticle physics.

There will also be two special lectures on Saturday about the latest discovery of the Higgs(-like) particle by Chiara Mariotti from CMS and Domizia Orestano from ATLAS.
Continue reading The 13th Marcel Grossmann Meeting at AlbaNova

Grids, Clouds and the Big (CHEP) Apple

Stephan Zimmer is a PhD students in the OKC. This is his report from the CHEP conference last week.

Alvarez illustrating our fights when trying to connect to a video conference and what we always think but never dare to say
Do you care about computing? Probably not, probably you are happy just knowing that all your stuff just works. But what “Does work” actually means? Let me try to give you a few reasons why you should actually care… and why it matters.

Last week I was at the CHEP conference where the latest and greatest news of computing in high energy nuclear and particle physics were discussed. CHEP is an international conference with about 500 scientists, computing experts and business professionals, reviewing the current set of Clouds, Grids and technologies for the upcoming challenges, first and foremost those posed by the LHC experiments. I believe most sessions were actually recorded, so have a look and see if there’s anything that fancies your interest.

It was quite an exciting conference for me, given that we (physicists) usually don’t attend this kind of conference.

During the plenary talk we were shown some of the greatest highlights of all LHC experiments, along with the latest developments. The bottom line (but of course the ATLAS folks at OKC know that already) is that by the end of this year, we’ll probably have either killed or confirmed the intriguing hint of a signal in both CMS and ATLAS at roughly 125 GeV.

All of us who work in HEP know of the pain with C++ and ROOT and all the other goodies we (have to) use in the community. Those of us that DON’T use ROOT, please skip this paragraph.
We were promised by Fons Rademakers, the new Mr. ROOT, after Rene Brun (you all know him! By the way: he gave a nice talk covering computing in HEP since the 1970s and was honored by standing ovations during the closing session of CHEP) to see ROOT v6 by November and from my little experience of C++ this will bring quite some interesting changes, among others a giant boost of performance (and lots of more support for iOS on various levels). Axel Nauman from CERN detailed Cling and Clang in a blog post on the ROOT website (http://tinyurl.com/75wsfm9). Continue reading Grids, Clouds and the Big (CHEP) Apple

Workshop: clusters of galaxies as cosmic laboratories

Galaxy clusters occupy a central role in the ongoing efforts to understand some of the greatest questions in particle astrophysics and cosmology: the nature of Dark Matter and Dark Energy. Moreover, these huge mass concentrations serve as Nature’s own telescopes, capable of amplifying faint high-redshift sources that would otherwise be beyond our reach. At the same time, the use of galaxy clusters as probes for fundamental physics requires a good understanding of the state of the intra-cluster medium.

No wonder that the Oskar Klein Centre got involved in the organization of a workshop in Stockholm, 12-14 September. Ariel Goobar, professor at the Oskar Klein Centre, explains that there is a large effort by the community to collect multi-wavelength galaxy cluster data, which present a great opportunity to make significant progress over a broad range of topics: Continue reading Workshop: clusters of galaxies as cosmic laboratories

The 7th TeV Particle Astrophysics conference in Stockholm

The Oskar Klein Centre will host the 7th TeV Particle Astrophysics conference at the Albanova Centre in Stockholm August 1-5, 2011.

The fields of high energy astrophysics, particle astrophysics and particle physics at colliders are dealing with some of the most pressing subjects in modern physics, in trying to understand the nature of dark matter and the origin of cosmic rays.

The scientific program includes gamma rays, neutrinos, charged cosmic rays, cosmic rays above the knee, direct dark-matter searches, distribution of dark matter, and particle physics.

Invited speakers will present and discuss the status of different experiments Continue reading The 7th TeV Particle Astrophysics conference in Stockholm

H.M. The King’s Medal to Lars Bergström

We are honored to announce that today, June 14 Lars Bergström, director of the Oskar Klein Centre, will receive H.M. The King’s Medal for significant contributions to Swedish research, including his work as secretary of the Academy of Sciences Nobel Committee for Physics. The ceremony will happen at the Royal Palace at 15:00.
From the Royal official website we learn that H.M. The King’s Medal (1850s) is presented to Swedish and foreign citizens for special merit and to officials of the Royal Court for long and faithful service.
This medal is combined with chain or ribbon and there are both gold and silver versions in various sizes.

Here you can read the complete list of people that will receive the medal today.
Congratulations Lars!

The Fermi symposium 2011: AGNs, pulsars and gamma ray bursts

The results presented at the III Fermi symposium in Rome reflected, in particular, what a magnificent instrument the Fermi LAT is for observing active galactic nuclei and pulsars. The 2 source catalogue 2FGL was presented and will soon be released with 1888 sources. Much attention was given to the blazar 3C454.3 which has been monitored since the launch and has undergone a series of very bright outbursts. The multiwavelength analysis by Stefan Larsson revealed a far more complex behaviour than expected in the simple picture we had of AGN jets before the launch of Fermi. The discovery of spectral breaks at GeV energies was nicely interpreted by the former Stockholm astronomer Juri Poutanen and collaborators as a result of gamma-ray absorption via photon-photon pair production on He II Lyman recombination continuum and lines within the broad-line region.

The Aula Magna at La Sapienza, Rome

It was also made clear that all models we have for description of the high energy emission around pulsars are, more or less, wrong. Fermi has told us for certain that the emission is from high altitudes in the outer magnetosphere; Fermi has killed the polar cap model and the classical TPC, while the other models are in need of modifications. Continue reading The Fermi symposium 2011: AGNs, pulsars and gamma ray bursts

The Fermi Symposium 2011: a dark matter perspective

The Fermi Symposium of 2011 in Rome has now reached its last day and we have heard many interesting talks, ranging all the way from dark matter to various astrophysical sources and observations. The OKC has been very well represented with participants both from the Department of Physics and the Department of Astronomy at Stockholm University and by the KTH group.

Maja Llena Garde presents the Fermi-LAT results on dark matter searches from a stacked dwarf analysis.
Maja Llena Garde presents the Fermi-LAT results on dark matter searches from a stacked dwarf analysis at the 2011 Fermi Symposium.

Science-wise, and from my personal dark matter oriented perspective, I think one of the most interesting talks was Maja Llena Garde’s talk on placing limits on dark matter models from dwarf galaxies using Fermi data in a stacked likelihood analysis. The limits are really approaching the vanilla WIMP expectations.   Continue reading The Fermi Symposium 2011: a dark matter perspective

The Return of de Sitter

The return of De Sitter During the last three weeks, we were visited by an impressive list of cosmologists trying to make sense of what is driving the present accelerated expansion of the Universe. The return of De Sitter, this is the name of the NORDITA workshop organized by OKC members Fawad Hassan and Ariel Goobar, together with Stefan Hofmann from LMU in Munich.
I asked Ariel Goobar, professor at OKC, and Stefan Sjörs, a PhD student in the Cosmology, Astroparticle Physics and String Theory group, to tell us about the conference.

Continue reading The Return of de Sitter