Category Archives: Words from the Director

Welcome the new director!

After eight years of existence, the Oskar Klein Centre of cosmoparticle physics ranks among the most dynamic and successful European research centres in the field. We are proud for having hosted outstanding postdocs and recruited world leading researchers.
Today, a new chapter in the OKC success story is about to unfold: it is time for me to pass on the baton to Hiranya Peiris, as she starts her journey as the new director of the centre.

Foto credits Max Alexander
Foto credits Max Alexander

Hiranya Peiris is an internationally recognised cosmologist working in both theory and observation. She studied at Cambridge University and got her PhD from Princeton University in 2003. She was a Hubble Fellow at the University of Chicago from 2004–2007. She then moved back to Cambridge as a STFC Halliday Fellow, and began a faculty position at UCL in 2009, where she is now Professor of Astrophysics. Her research aims to test fundamental physics using large cosmological datasets, including the cosmic microwave background and galaxy surveys, using an interdisciplinary approach combining observations, theoretical physics, and advanced statistical methods. In addition to supporting the many existing strengths of the OKC in cosmoparticle physics, she hopes to create new initiatives in observational cosmology, transient and gravitational wave astronomy, and the interdisciplinary interface with data science.

On behalf of all of us at OKC and the Department of Physics at SU, I want to express Hiranya our best wishes for the future.

I hope she will enjoy the friendly and creative atmosphere in Stockholm. Hiranya is well suited for leading the centre to new scientific heights. Welcome!

– Ariel Goobar, outgoing director

As we turn the page to a new year

As we close the book on 2015 we can again look back at a year of exciting science and great accomplishments by members of the Oskar Klein Centre for Cosmoparticle Physics.

As in previous years, OKCers feature very prominently in the list of the most cited astrophysics and cosmology papers led by Swedish scientists published during the year. The list was compiled by Robert Cumming in populärastronomi and appears in today’s issue.

In fact, half of top-10 2015 publications originate in our centre, starting with a Fermi collaboration search for gamma-rays from dwarf galaxies, led by Brandon Anderson. Together with a similar study led by Christian Farnier based on observations from the H.E.S.S. array (place #4), gamma-rays are used as tracers for annihilation of dark matter particles. Unfortunately, the detection of dark matter particles remain elusive but the hunt goes on, now also directly using the Xenon 1T detector.
Addressing the challenges posed by the dark sector, including both dark matter and dark energy, has become a very active area of theoretical and phenomenological research at OKC. The cosmological implications of the bimetric Hassan-Rosen theory of gravity, an alternative to Einstein’s theory of gravity including a massive graviton, has been scrutinized in a paper led by Jonas Enander. This paper came in second in citations for 2015. The other OKC contributions to the top-10 list involve two studies of SN2014J, the nearest Type Ia supernova in many decades, and an essential laboratory for our understanding of the precision reach of the use of SNe Ia as distance indicators in cosmology in our quest to understand the nature of dark energy. In one of the studies that I led together with Markus Kromer, we explored the onset of the explosion with aunique data set allowing us to probe what powers the very first moments of the optical lightcurve. In another paper, led by Peter Lundqvist and Anders Nyholm, evidence showing that both SN2014J and SN2011fe are likely the result of a merger of two white dwarfs is presented. In a short time, there has been a paradigm shift in what we think is the most common channel triggering these powerful explosions used in cosmology. These are exciting times in the field!

Just before the end of 2015, we were also intrigued by the recent developments in particle physics. The two major LHC experiments, ATLAS (with OKC participation) and CMS, presented the results from the second run of 13 TeV proton-proton collisions. Although no signal reached the magical threshold of 5 standard deviations required to claim discovery, there is an intriguing accumulation of photon-pairs of what could be hinting at a decay of a 750 GeV scalar boson. If confirmed, this would be the sign of long awaited new physics!

Looking forward to a Great New Year at the Oskar Klein Centre!

Swedish Research Council grants 60 million for the recruitment of Frank Wilczek

Frank Wilczek 2007. Photo: Kenneth C. Zirkel
Frank Wilczek 2007. Photo: Kenneth C. Zirkel
The Swedish Research Council announced yesterday that a grant application to recruit the 2004 Nobel laureate Frank Wilczek to the Physics Department at Stockholm University was approved. This is extremely exciting news – also for the Oskar Klein Centre.

Frank Wilczek is one of the founders of the theory of strong interaction of particles and has proposed the existence of the axion, among the main particle candidates to explain the cosmic dark matter, and related physics of the early Universe. He is also an expert on physics tested with the Large Hadron Collider at CERN. Furthermore, he has made groundbreaking contributions to the theory of black holes. Clearly, Frank’s presence would contribute significantly to propel the Oskar Klein Centre to a world rank research environment.

Warm congratulations to Frank and every physicist in the Stockholm area. This could be the beginning of a new era for fundamental physics in Sweden, reminiscent of the golden days when Oskar Klein was a professor in town!

2014: another great year for the Oskar Klein Centre

After six very successful years of OKC leadership, Lars Bergström was asked to become the new Dean of the Mathematics and Physics Section of the Science Faculty of Stockholm University. As a consequence, he has stepped down as OKC director and  a new position at the Department of Physics at Stockholm University has been announced to find a replacement. In the mean time, I will serve as director of the centre. It is with a sense of great pride – and a fair bit of apprehension –  that I take on this challenge: it is no small task to keep up the high standards set by Lars!

top-ten-OKC Since its birth in 2008, the Oskar Klein Centre has become a national and international flagship in the field. OKC scientists have featured very prominently every year in the December summary of Populär Astronomi over the most cited papers in Astronomy with a first author currently working in Sweden.  2014 was not an exception, half of the top-ten papers were lead by OKC members. This is in fact, a low estimate, since some of the highly cited OKC-lead publications are by Fermi and IceCube collaborations, which uses alphabetical author lists. Best cited among the listed papers was Katie Freese’s March arXiv submission exploring the consistency between her model of Natural Inflation and the claimed results from BICEP2 on primordial gravitational waves.

We are extremely pleased to have Katie with us since last fall, as she shares her time between a position at the Physics Department and as the new director of Nordita. Sadly for cosmology and fundamental physics, disentangling the tiny first Big Bang traces from the signatures of more mundane astrophysical foregrounds may be more challenging than originally thought by the BICEP2 team. This is one of the big issues to be addressed during 2015, the year marking the 100:th anniversary of Einstein’s conception of General Relativity.

Other highlighted OKC results include two studies [Goobar et al; Amanullah et al] of supernova SN2014J, the closest Type Ia supernova in many decades. These are the kind of stellar explosions used as standard candles to study the accelerated expansion of the Universe. Understanding the nature of this phenomenon, dubbed ”dark energy”, remains a great challenge for fundamental physics, as does the ”dark matter” responsible for the observed structures.

Dark matter particles are searched for by OKC members using the Fermi gamma-ray satellite and the IceCube neutrino detector. IceCube also recently presented new evidence for high-energy neutrinos of astrophysical origin.

The  paper lead by OKC’s Stephan Rosswog at the Department of Astronomy  on the outcome of merger of the most compact objects in nature also made it to the top ranked research articles of 2014. Congratulations to all the successful researchers at the centre!

We look forward to many great scientific breakthroughs by OKC members in the New Year. The exploration of the extremes of nature continues, both in the skies and at the LHC accelerator at CERN. From this new platform, I will keep you posted of our progress!

– Ariel Goobar



New times for the Oskar Klein Centre

image003Dear all,

As you have noticed by following the OKC blog, our success is continuing. We had an international mid-term review in the beginning of the year, and we came through with flying colours. Just a couple of quotes from that report of the Swedish Research Council (VR):

”Research on some of the most profound mysteries of the universe, such as the nature of dark matter, is being conducted in OKC at the highest international levels…”

“The research is of excellent quality, as can be seen from publications and citations, but even more by looking at the published papers…”

“OKC is actively involved in several very high-profile international experiments or facilities… The most prominent is ATLAS, one of the two experiments which led to the discovery of the Higgs boson at the CERN LHC… “

“OKC has had hardware participation in, and is leading the search for, indirect detection of dark matter…”

“A 2011 OKC paper [by Fawad Hassan and OKC-Fellow Rachel Rosen] provided a consistent formulation of the “bimetric theory”, as an alternative to Einstein’s theory of gravitation…”

This was great words for us to read – and indeed they meant that we can continue in OKC with unchanged budget 5 more years.  This was soon followed by other positive news: Katie Freese was chosen new NORDITA Director, and also obtained a large VR 10-year excellence grant to perform her  research here at Stockholm University in the OKC environment. Then in October Jan Conrad received a substantial grant from the Wallenberg Foundation to enter the world-leading XENON experiment in Gran Sasso, and soon after that word came about OKC’s Ariel Goobar being honoured by the “Breakthrough Prize”  for his role in the Nobel Prize winning SCP project. Finally, a few weeks ago, OKC got one more Wallenberg Academy Fellow – congratulations to Matthew Hayes of the Astronomy Department!

As some of you know, I will now step down as Director for OKC, and will be Dean of the Mathematics and Physics Section of the Science Faculty of Stockholm University as from January 1st 2015. Ariel Goobar will take the responsibility to lead the OKC until a new Director arrives (there is still time to apply to the announced Chair at Stockholm University which has this as a first task).

I want to finish this blog by thanking all my colleagues and friends at the OKC who have helped making this such an enjoyable, exciting and successful 6 years. I am sure that the next leg of this wonderful OKC journey will be at least as exciting as the first part.

I wish you all Happy Holidays and a great New Year!



New Wallenberg grant to OKC’s Jan Conrad

Jan Conrad

The Knut & Alice Wallenberg Foundation released yesterday the list of this year’s recipients of funding for research projects with very high potential. We were very happy to see that on this list appears Jan Conrad with the project “Discovering Dark Matter Particles in the Laboratory”, with a grant of SEK 28 883 000 (around 3 MEUR) for five years.


Congratulations to Jan for this generous grant! Jan is a Member of the OKC Steering Group and has for long been one of the key researchers in the satellite experiment Fermi-LAT, and the ground-based HESS detector, searching for indirect detection signals of dark matter in gamma-rays. This is complementary to accelerator searches at CERN’s LHC in the ATLAS experiment, where we also have an important involvement from the OKC. Up until now, we have not had any activity concerning direct searches of scattering of dark matter in underground detectors, but thanks to the new grant, the OKC will through Jan Conrad have an important role to play also in this area, through the the world-leading XENON-1t experiment in the Gran Sasso tunnel.

Actually, the direct detection method was to a large extent developed in the 1980’s and onwards by Katie Freese and her colleagues. As Katie is now with us in Stockholm (she is a co-signer of the successful Wallenberg proposal, as is OKC’s Thomas Schwetz and Christian  Forssén of Chalmers, Gothenburg), we can expect this exciting new activity to flourish in Stockholm and at OKC.

Katie Freese receives big VR grant!

The members of the Oskar Klein Centre had just noticed with satisfaction that we could keep the VR Linnaeus grant at the same level (increased by 10% in 2010) the second half of the grant period (until 2018), when even more exciting news reached us. First, our valued member of the International Advisory Board, Katie Freese from Michigan University, was announced as the new Director of Nordita, which is located in the neighbouring building to OKC.

Katie Freese, New Director of Nordita and recipient of large VR grant.

Welcome to Stockholm, Katie!

The next positive surprise came yesterday, when the Swedish Research Council, VR, announced that Katie will receive a big excellence grant for astroparticle physics, namely 101 million Swedish Crowns (around 15 million US dollars) over 10 years. This grant was suggested to the VR by the Vice-Chancellor of Stockholm University, Astrid Söderbergh-Widding (see her blog about it).

Hooray, Katie!

The future of astroparticle physics in Sweden looks brighter than ever, I am sure that Katie will find the environment here excellent (as she has seen in her work in the OKC IAB), and now she can contribute to it in a substantial way. These are exciting times for all of us!

-Lars Bergström, OKC Project Leader

Sara Strandberg new member of the Swedish Young Academy

Congratulations to Sara Strandberg, member of the OKC Steering Group, who has just been elected into the Swedish Young Academy (SYA). SYA is a cross-disciplinary forum for young researchers. Although independent from the Royal Swedish Academy of Sciences, the creation of SYA has been encouraged by it. SYA has already made its voice heard in several important issues for young scientists, not the least concerning a sustainable academic career system.


Sara Strandberg

At the start of SYA in 2011, OKC:s Jan Conrad was one of the firstly elected members. I find it a great honour of OKC that we have contributed two members of this illustrious academic society, which can at most have 40 active members.

Another interesting and very successful year of the Oskar Klein Centre

Francois Englert just before Nobel lecture in Stockholm University’s Aula Magna. Photo: L. Bergström.

Hello and Happy Holidays to all friends of the OKC

As the year 2013 is now nearing its end, it is time to recapitulate the main events of the year from the OKC perspective. If I temporarily put on my Nobel hat (being the scientific secretary of the Nobel Committee for Physics) the main event from the Stockholm horizon is without doubt the Nobel Prize to Francois Englert and Peter Higgs for their almost 50-year old prediction from the early 1960’s that was so spectacularly confirmed by the ATLAS and CMS experiments at CERN’s LHC accelerator last year. Hats off for Englert and Higgs, and also for the many clever and hard-working experimentalists, in particular the ATLAS people of OKC such as Jonas Strandberg, who has been directly involved in the discovery of the Higgs particle in ATLAS. Of course we now look forward to the energy upgrade of LHC, which will increase the chances substantially to find the much awaited effects beyond the Standard Model that, hopefully, could give an indication of what the dark matter may consist of. At the Oskar Klein Centre we also have been searching in gamma-ray, positron and neutrino signals, without positive results (yet), but producing some of the best limits.

Peter Higgs signing the Nobel Poster (prepared with the help of OKC's Sara Strandberg and Oscar Stål). Photo: L. Bergström.

The OKC has now been in existence for 5 years, and we will soon encounter the international mid-review panel of the Science Council (VR) of Sweden. By September 1st we had to submit our self-assessment report, containing a detailed description This meant a lot of work for me and the OKC Steering Group: Christophe Clement, Jan Conrad, Claes Fransson, Ariel Goobar, Klas Hultquist, Garrelt Mellema, Mark Pearce, Sara Strandberg and Göran Östlin (and of course our great communications manager, Serena Nobili). We hope that we managed to convey our great enthusiasm for the scientific outcome of the OKC during its first 5 years, and that the evaluation committee will agree that it has been a great success. In fact, when we meet them January 30th, we will have quite a number of recent sucesses to report:

  • A generous grant of SEK 32 million from the K&A Wallenberg Foundation was given to groups in OKC (with J. Sollerman as PI) for contributing to the Zwicky Transient Facility (with S. Kulkarni of Caltech leading the team).
  • OKC Steering Group member Sara Strandberg has obtained both a young researcher’s grant from the VR and a Wallenberg Academy Fellow (WAF) grant – both in very strong competition.
  • Jan Conrad (also OKC Steering Group member) has in addition to his previous WAF grant also been given one of the new excellent junior investigator grants from VR. Congratulations to Sara and Jan!
  • The IceCube experiment has finally detected high-energy (PeV) cosmological neutrino events, with a surprising energy distribution.  This was declared the discovery of the year of the Physics World magazine. Congratulations to the OKC IceCube group (Chad Finley, P.O. Hulth, Klas Hultquist & al.) and the Uppsala group (with present IceCube spokesperson Olga Botner and her colleagues)!
  • The Fermi satellite project with large OKC contribution continues to make important discoveries. One concerns the discovery of a gamma-ray spectrum of two supernova remnants which clearly shows a hadronic origin (from decays of neutral pions), and thus is a proof that these sources accelerate protons, and are thus the long-sought-for sources of the Galactic cosmic rays. This was one of the runner-ups for the discovery of the year of Science magazine.

To conclude, with all the interesting science produced by OKC during its first half-life, one may only anticipate with great expectations what will come out of the second half!

Merry Holidays and a Happy New Year to all in the OKC research environment and all our followers!


A new interesting period for the OKC

Hello everybody in the OKC!
Welcome back after a well-deserved vacation for most of you. For OKC this is a rather hectic period, as we have our mid-term evaluation requested from Vetenskaprådet (VR)  just starting. The International Advisory Board (Katie Freese, Bengt Gustafsson, Wolfgang Hillebrandt, Hugh Montgomery, John Peacock and Larus Thorlacius) will visit us August 29 – 30, and you have been informed by Serena about some of the events taking place. 

The review process will take place during the autumn, with a face-to-face meeting during a site visit January 30, 2014. The IAB has promised to act as a “mock panel”, so that we get feedback before submitting our self-evaluation with deadline September 1. When the verdict of the review comes, sometime during spring, we will know whether our Linnaeus Centre OKC gets increased funding (by up to 20 %), decreased funding (by up to the same amount), or a constant budget. It is a zero-sum game between the 20 Linnaeus Centre that received grants in 2008, so if we win some others have to lose, and vice versa. Quite exciting, in other words! Continue reading A new interesting period for the OKC