The Department of Radioastronomy and Cosmic Physics is a unit within the Astronomical Observatory of the Jagiellonian University which coordinates research and teaching duties of its members.
Research focuses on:
- Investigation of gas and magnetic fields in galaxies, galaxy clusters, and intergalactic medium, studies of cosmic ray transport in galaxies
- Radio polarimetric observations of galaxies and active galactic nuclei
- Numerical modelling of evolution of cosmic magnetic fields and gravitational interactions of galaxies
- Studies of interstellar medium with pulsars
- Investigations of primordial magnetic fields and fields on the largest cosmic scales
- Research on dynamic scenarios of evolution of the Universe motivated by fundamental physics
Observational investigations are based on projects performed with the largest radioastronomy instruments in the world (JVLA (photo, credit NRAO), LOFAR, GMRT, WSRT, 100-m telescope in Effelsberg) and space observatories (XMM-Newton, Herschel).
LOFAR (LOw Frequency ARray) is a unique radio interferometer observing in the very low frequency range (10-240 MHz). It is currently the largest instrument, operating at the lowest frequencies that can be observed from Earth. The radio astronomers from OAUJ initiated the erection of three LOFAR stations in Poland which entered the Polish Roadmap for Research Infrastructures. We currently maintain the LOFAR station in Łazy, near Bochnia.
- LOFAR observations of galaxies
LOFAR's Multifrequency Snapshot Sky Survey (MSSS) has resulted in extensive studies of a large sample of nearby star-forming galaxies. Using the measured 150MHz flux densities from the survey and flux densities at various frequencies from the literature we have obtained integrated radio spectra for 106 galaxies. This image illustrates examples of such spectra showing that they are generally flatter at lower compared to higher frequencies. The interpretation of the observed spectra was performed with a three-dimensional numerical model of galaxy radio emission, and radiation transfer dependent on the galaxy viewing angle and absorption processes. Our modelling suggests that the weak spectral flattening observed in the nearby galaxies results principally from synchrotron spectral curvature due to cosmic ray energy losses and propagation effects. We predict much stronger effects of thermal absorption in more distant galaxies with high star formation rates.
Chyży, K. T.; Jurusik, W.; Piotrowska, J.; Nikiel-Wroczyński, B et al. LOFAR MSSS: Flattening low-frequency radio continuum spectra of nearby galaxies
- Combining X-rays and radio observations
The physical parameters of galactic hot gas, such as the temperature, electron density or thermal energy, when combined with the properties of the magnetic fields, can improve our understanding of the evolution of spiral galaxies, as well as galaxy groups or clusters. A very efficient way of tracing the interactions between galaxies was obtained by a comparison of the morphology of magnetic fields with the temperature of the hot gas observed in X-rays with the XMM-Newton satellite. It allowed to distinguish between tidal interactions between galaxies and the influence exerted upon them by the surrounding cluster environment, that is, the hot and dilute intracluster medium.
X-rays and radio emission can also be used in search for signatures of heating of the interstellar medium by the effect of reconnection of the magnetic fields. If the energy of the magnetic field is converted into the thermal energy of the hot gas, the energy per particle should be higher in the areas of higher ordering of the magnetic field. That we found in two galaxies so far: NGC6946 and M83.
Weżgowiec, M.; Bomans, D. J.; Ehle, M.; Chyży, K. T.; Urbanik, M.; Braine, J.; Soida, M. Tidal interaction vs. ram pressure stripping effects as seen in X-rays. Hot gas in group and cluster galaxies
Weżgowiec, M.; Ehle, M.; Soida, M.; Dettmar, R. -J.; Beck, R.; Urbanik, M. Hot gas heating via magnetic arms in spiral galaxies. The case of M 83
- Tracing galaxy collisions
Galaxies seem to have a lot in common with ponies – and that’s a fact (although not a commonly recognised one). They prefer to live in herds, they tend to interact with each other a lot. One certain thing that differs those two are the collisions. Ponies certainly collide, but while a pony collision is a rather disturbing and definitely not a nice-to-watch event, a galactic collision is undoubtedly one of the most picturesque phenomena in the Universe. Two (or more!) giant clouds of stars, gas, dust, and (as we suppose) dark matter find themselves on a collision course, and – if only they are unlucky enough in terms of trajectory and velocity – start a dance of death, before finally merging together to form a larger body, with just a few remnants of their past appearance. Such events seem to be a bread and butter in Space, as isolated galaxies constitute a mere exception.
Interestingly, there is one certain collision-related event that seems to be very similar in case of both ponies and galaxies. If you put two ponies of appropriate types in their mutual proximity, it might eventually lead to a birth of a new, smaller pony – literally made from the parts of their parents, and having a lot of traits inherited from them. And galaxies seem to be doing the same thing (well, the process is a tiny bit different, but let us spare the details...): if two galaxies are too close to each other, the tidal forces might lead to a birth of a small, self-gravitating entity. We call those galaxies Tidal Dwarf Galaxies (TDG), because they are dwarf galaxies born as a result of the tidal interactions (this making them one of the best defined types in the galaxy classification scheme). Not much is known much about them, especially if someone asks about their magnetic fields. And this is exactly what we are trying to do: find out if they are generally magnetised (or not), if these magnetic fields are strong (or not), and if there is any real preference for a specific environment for them to be born (or not…). And we don’t forget about the fate of the magnetic field in their parent objects, too!
Nikiel-Wroczyński, Błażej; Soida, Marian; Heald, George; Urbanik, Marek A large-scale, regular intergalactic magnetic field associated with Stephan's Quintet?
- Other activities
Every few years we organise in Kraków international scientific conferences on magnetic fields, galaxies and LOFAR studies:
- 2020: "LOFAR Survey Key Science Project meeting" - online mini-symposia
- 2018: "Magnetism Key Science Project"
- 2016: "LOFAR - Wszechświat na niskich częstotliwościach radiowych"
- 2014: "Cosmic magnetic fields: current knowledge and the future idea"
- 2011: "Magnetic fields in the Universe III: From Laboratory and Stars to Primorsial Structures"
We are also passionates in teaching end education. Various radioastronomy projects for amateurs, teachers and their pupils are undertaken (EUHOU).