3. Fundamental Physics in Radio Astronomy Group

PhD projects

of the Fundamental Physics in Radio Astronomy Group

Director: Prof. M. Kramer                                                                                           

Group website

Code: MK01

Pulsars as tools for fundamental physics

The Fundamental Physics in Radio Astronomy group of the MPIfR led by Prof. Michael Kramer concentrates on various aspects of fundamental physics, namely the Galactic population of neutron stars, their use for precision tests of general relativity and alternative theories of gravity, the detection of low-frequency gravitational waves and the structure and properties of super-dense matter. We are seeking a student for one of the following research areas:

a) Searching for pulsars and transient radio sources 

The discovery of new pulsars frequently leads to new scientific results depending on the pulsar's properties. With recent advancements in receivers and computing we are able to probe deeper into the Galaxy than ever before. Radio astronomy also offers a unique chance to explore the dynamic sky as many energetic process are expected to be visible in this part of the electromagnetic spectrum.

b) Pulsars as probes of gravity 

Pulsars are very compact objects, exhibiting the strongest gravitational fields next to black holes. Acting as cosmic lighthouses and precise cosmic clocks, pulsars can be used to probe gravitational physics under strong-field conditions. High precision timing of pulsars provided the first, evidence for the existence of gravitational waves as predicted by Einstein's theory of gravity (Nobel Prize 1993), and leads to some of the best constraints on alternative gravity theories. Our research in that field of experimental gravity is driven by improvements in instrumentation, new pulsar discoveries, and ongoing theoretical work.

c) Pulsar as detectors for low frequency gravitational waves 

The direct detection of gravitational waves from merging black holes with LIGO has opened up a completely new window to the Universe: the gravitational wave sky. Using a Pulsar Timing Array a number of high-precision millisecond pulsars are timed to detect low frequency gravitational waves,  and complement the observations of ground-based gravitational wave detectors like LIGO and VIRGO. To make such a detection a European collaboration, the European Pulsar Timing Array, uses the largest radio telescopes in Europe, including the 100-m radio telescope in Effelsberg.

d) Pulsars as probes of super-dense matter and stellar evolution 

Neutron stars represent the most extreme state of matter in the observable Universe. We can study the properties of this super-dense matter when we observe neutron stars in the form of radio pulsars, e.g. mass measurements in binary pulsars offer some of the best constraints for the "equation-of-state". These mass measurements also offer clues for understanding the birth mass distribution of neutron stars and for the evolution of different types of binary pulsars. 

The applicant's research proposal should be related to the above research themes.

Contact: Prof. Dr. Michael Kramer (mkramer@mpifr.de), Dr. David Champion (champion@mpifr-bonn.mpg.de), Dr. Paulo Freire (pfreire@mpifr-bonn.mpg.de), Dr. Norbert Wex (wex@mpifr-bonn.mpg.de),

Site: Bonn, Max-Planck-Institut für Radioastronomie, Fundamental Physics in Radio Astronomy Group

Code: MK02

Advanced interferometry techniques

Radio interferometers are the instruments that provide the highest resolution for astronomical observations. For given baselines, higher frequencies correspond to higher resolutions. Under certain conditions, however, lower frequencies can be advantageous. The interstellar medium can deflect and scatter radiation and sometimes (particularly at low frequencies) produce multiple signal paths that interfer with each other. These paths can be used as huge interstellar interferometric baselines with extreme resolution.

Using this effect requires a good understanding on many levels: low-frequency interferometry on long baselines (e.g. with LOFAR), details of the scattering properties of the interstellar medium and sophisticated analysis techniques

The successful applicant will have the opportunity to work on these challenging topics and advance the field with own developments.

Contact: Dr. Olaf Wucknitz (wucknitz@mpifr-bonn.mpg.de), Prof. Dr. Michael Kramer (mkramer@mpifr.de)

Site: Bonn, Max-Planck-Institut für Radioastronomie, Fundamental Physics in Radio Astronomy Group

Code MK03

Targeted searches for pulsars

The study of neutron stars is motivated by fundamental open questions in physics, such as the properties of dense nuclear matter, and the behaviour of gravity under extreme conditions (see MK01). Searches for new radio pulsars play a crucial role in advancing the field: new pulsars improve our overall knowledge of neutron star properties while, in rare ocassions, the discovery of extreme objects leads to a paradigm shifts.  
Most modern pulsar surveys are optimized to cover wide areas of the sky in as little time as possible. While this approach has multiple benefits, it often comes at the expense of sensitivity which depends strongly on integration time. 
Targeted surveys provide a solution to this problem by focusing on specific sky positions that have a higher-than-average probability of coinciding with a pulsar. Those searches allow for much longer integration times and therefore improved sensitivity, accelerating the discovery rate and often leading to the discovery of exotic systems.
The advent of multi-wavelength sky surveys (such as Fermi and GAIA) and sensitive telescopes (MeerKAT, SKA, LSST) that are currently coming online, make targeted surveys more timely and urgent than ever. 

The successful applicant will investigate target selection and survey optimization strategies using a number of theoretical and observational tools. 
In particular, the PhD project will focus on: 
  • constraining the dynamical and observational properties of binary pulsars using state-of-the-art stellar evolution and population synthesis techniques. 
  • comparing the outcome of those simulations to real datasets from GAIA and Fermi to optimize target-selection strategies  
  • leveraging those results to search, discover and follow-up pulsars using the Effelsberg, Arecibo and MeerKAT telescopes. 
Contact: Dr. John Antoniadis (janton@mpifr.de), Prof. Dr. Michael Kramer (mkramer@mpifr.de
Site: Bonn, Max-Planck-Institut für Radioastronomie, Fundamental Physics in Radio Astronomy Group.


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