Interview with Timur Delahaye

Timur Delahaye is one of the OKC fellows working at the Cosmology, Particle astrophysics and String theory group (CoPS) since this summer. let’s get to know him better.

Where have you studied or did research before coming to the OKC?
I did my undergraduate studies at École Polytechnique near Paris. I then completed my Mas ter degree at the theoretical physics department of École Normale Supérieure in Lyon and did my Ph.D. with the IDAPP (International Doctorate on AstroParticle Physics) program both in Annecy and Turin under the supervision of Pierre Salati and Nicolao Fornengo. Autumn 2010, I moved to Madrid to do my first post-doc at the Instituto de Física Teórica (IFT) of the Universidad Autónoma where I stayed for two years. Last year I worked at the Laboratoire d’Annecy-le-Vieux de Physique Théorique (LAPTh) and the Institut d’Astrophysique de Paris (IAP).

What is your field of research?
I work in modelling the propagation of Galactic Cosmic Rays and Dark Matter indirect detection. Cosmic rays are high energy particle that are accelerated by exploding stars, by high magnetised stars called pulsars, and maybe by the annihilation or decay of Dark Matter particles. Even though cosmic rays have been discovered more than 100 years ago we still do not understand precisely where they come from nor how they propagate in the interstellar medium. In spite of being a rather young science, cosmic ray physics are is a wonderful way to look at things in the sky that do not emit light and cannot be probed by usual astronomy.

What I really enjoy in this field is that it is at the intersection of cosmology, astrophysics and particle physics and allows to interact with many people from very different fields.

What interest you most of cosmology?
The research of Dark Matter is a very exciting subject right now. From many observations that span over very different scales, from the whole Universe to the galaxies, we are quite convinced that a large fraction of the Universe is made of a matter that does not interact much with light and the usual matter we know. The problem is that we have no idea what this matter is, so we call it Dark. The idea of Dark Matter is around since ~1933 but it is only today that we have the technology that could detect it. Indeed, if Dark Matter particle do interact a little with our matter then the Large Hadron Collider (LHC) at CERN, Geneva may be abble to produce and detect it, or maybe we can see it when a particle bounces off a single atom of a 1 ton detector like the Xenon experiment, or, dark matter in the Galaxy could annihilate and produce an extra cosmic ray population. Detecting these phenomenon was impossible a few years ago.
The particle detector that is now on board the International Space Station, AMS-02, has recently started to publish their first measurements of cosmic ray fluxes. In the next few years we should expect big changes in our understanding of how these cosmic rays are accelerated and how they propagate in the turbulent interstellar medium.

If dark matter is indeed detected through cosmic rays then we will have a wonderful probe to its properties that, together with data from the LHC and direct detection experiments, will open a brand new window on physics beyond the standard model of particle physics.

Why did you chose to join the OKC? Did you know it before coming?
I attended two conferences at the OKC in the past and I had been very much impressed by the centre but also by the city of Stockholm. My first visit was in January, the second in August, so I saw the city in two very different periods of the year, and I really enjoyed both. Knowing very well how life in large cities can sometimes be extremely stressful or even oppressive, I really care about enjoying a good quality of life. Also the Swedish social system is highly praised in the rest of Europe so I was very curious to discover it with my own experience.

From the scientific point of view, I was very much attracted by the idea of working in the only institute I know in the world that is 100% dedicated to astroparticles. Last year I was actually lucky enough to be able to chose between two different and very interesting job offers. But the choice was not very difficult because I have known the work of many OKC researchers for a very long time and I was confident that working at the OKC would be very interesting. I am really excited to finally be able to start working here.

How is it going so far? What are your impressions?
Sweden is the fifth country I am living in (I am both French and Turkish, I studied in Italy and worked in Spain). Changing country always takes some time because you need to adapt to a new culture, a new language, a new food, a new weather, and what is probably more difficult, a new bureaucracy. So of course after only one month of being here I would not say that I feel at home yet, but everything is getting very smoothly and I am confident I will enjoy my stay here.

Giving the limited experience you have so far, would you suggest your fellow postdocs looking for a position to apply for joining the OKC?
I already have ! And am pretty sure that many of colleagues will apply. In many countries, institutes are dedicated either to astrophysics or to particle physics so for astroparticle physicists it is a wonderful opportunity to come at the OKC which combines both.

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