Current research interests
Tracking the Yeti in the snow — Looking for metal-poor massive stars
Massive stars with a metallicity below 0.1 Z☉ are like the Yeti.
People talk about their possible existence, create hypotheses about
them, use them to explain otherwise unsolvable phenomena... But no one
ever seen one directly.
Currently, I am conducting two
campaigns to spot the Yeti in the snow.
One involves fast-rotating, hot massive stars ("TWUIN stars" as we
call them) that our theory predicts to exist in dwarf galaxies around
the Milky Way. If they indeed exist, we should know how they look like
in order to spot them. Therefore, we organized the
TWUIN-collaboration, and created simulations of these stars'
spectra—in hope of better understanding what we should search for in
the dwarf galaxy observations.
Another collaboration is built on finding footsteps of the Yeti in the
snow. Ancient starclusters in the Milky Way, the so-called globular
clusters may have harboured metal-poor massive stars in the past. We
simulated the hydrodynamic evolution of these clusters, and found that
if the Yeti was big and strong enough, its footsteps should be
observable today... That is, if there was a sufficiently massive
population of metal-poor stars in the early globular clusters, this
explains these clusters' observed structure today.
Both of these research projects are currently undergoing. Stay tuned!
Some related publications and preliminary results may be found in my PUBLICATION LIST. Also check out my Jan Frič Prize Talk here, telling the whole story of the Yeti.
PhD
The evolution of low metallicity massive stars
Supervisor: Norbert Langer (AIfA, Bonn)
Online version of my thesis /
Defence-Presentation
Massive star evolution taking place in astrophysical environments consisting almost entirely of hydrogen and helium – in other words, low-metallicity environments – is responsible for some of the most intriguing and energetic cosmic phenomena, including supernovae, gamma-ray bursts and gravitational waves. This thesis aims to investigate the life and death of metal-poor massive stars, using theoretical simulations of the stellar structure and evolution.
Master Thesis
Direction Dependent Background Fitting Method for analysing the Fermi Gamma-ray Space Telescope's Data (in Hungarian)
Supervisor: Bagoly, Zsolt (Eötvös University, Budapest)
Preprint /
Master-Thesis-Online /
Presentation
While analysing the Fermi data (see Bachelor Thesis), it became clear that old techniques are rather inefficient, since developments like proper motion of the satellite were implemented. However, there were no computational tools available at this point to filter the additional noise in the data. For this reason, I started to understand and handle motion effects, and finally developed a new method called the direction dependent background fitting.
With this new method, we were able to filter the noise in a more effective and a physically reasonable way. After I had written and defended my master thesis, I spent two months as a research assistant at the Konkoly Observatory, completing the project and writing a paper about our results. This paper of which I am the first author is now accepted and published in the journal Astronomy and Astrophysics (A&A 557, A8 (2013)).
Bachelor Thesis
Study of the Gamma-ray Bursts' Temporal Properties with the Fermi Satellite (in Hungarian)
Supervisor: Bagoly, Zsolt (Eötvös University, Budapest)
Preprint /
Bachelor-Thesis-Online /
Presentation
I started to work on gamma-ray bursts (GRBs) in 2008, after the first year of my bachelor programme. My first project was to compute duration of GRBs observed by the just-launched Fermi satellite with a technique developed and used for the data set of a former satellite BATSE. My bachelor thesis was based on this research project.
List of publications