Poster Abstract
I work for the MeerTRAP project that uses the MeerKAT radio telescope in a South African desert to search for enigmatic bursts of radio emission of roughly millisecond duration that are known as Fast Radio Bursts (FRBs). FRBs, their origins and how those extragalactic phenomena can be used to study the Universe are currently one of the hottest topics in Astronomy. There is recent evidence that at least some FRBs are emitted by intensely magnetised neutron stars, the so-called magnetars, but explosive (i.e. cataclysmic) events cannot be ruled out so far. Our understanding of how those bursts are created is, therefore, a matter of cutting-edge research. The MeerKAT telescope is one of the largest radio telescopes in the world and was only recently inaugurated. In my poster, I will outline how our international team searches for the mysterious radio bursts and how we try to localise them to high precision to allow their host environments (galaxies from which they originate) to be studied. I will give a quick summary of the current status of our search for FRBs and other radio sources, such as pulsars. Our work touches on many parts of Astrophysics, as well as computer and Data Science through our instrument development efforts.
Plain text summary
In my presentation, I discuss our searches for Fast Radio Bursts (FRBs) with the MeerKAT telescopes. In particular, I describe first what we know about FRBs so far and why they are such exciting phenomena. Then I explain how we search for FRBs with the MeerKAT telescopes in South Africa. Finally, I give a quick overview of the current status of our search for FRBs. FRBs are enigmatic radio bursts of roughly millisecond duration that come from extragalactic and cosmological distances of up to 10^9 light years. About 130 FRBs have been published since 2007, of which about 20 sources repeat. The burst profiles are mostly single-peaked, but more complicated morphologies have been observed at higher time resolutions. We known the distances of FRBs from their dispersion measures, the frequency-dependent delay of the bursts, that corresponds to the total free electron density that an FRBs has passed through. Alternatively, a few FRBs have been localised to their host galaxies, in which they originated. Given their large distances, FRBs must be created in energetic events. One of the most intriguing questions is about the origin of FRBs. We currently do not know how they are created. Competing theories are that they come from explosive events in which the progenitor vanished on the one hand and that they are from repeating sources on the other hand. The discovery of repeating FRBs has given credibility to the second set of theories. The large distances that FRBs travel through makes them ideal probes to study the Universe and especially its Cosmology. They are an additional tool to more classical cosmological techniques. A magnetar, an intensely magnetised neutron star, was recently seen to emit an FRB-like burst at the same time as an X-ray/gamma-ray burst. This is exciting, as it suggests that magnetars could produce at least some of the FRBs. We use the MeerKAT telescope, that is a 64 dish array. The voltages are combined in phase to create a telescope equivalent in size to a ~112 m dish. A supercomputer form about 800 narrow tied-array beams on the sky inside the field-of-view of the telescope by shifting the signals from the individual dishes with respect to each other. The narrow tied-array beams allow for initial localisation of FRBs via a technique roughly similar to triangulation. Our single-pulse pipeline searches the output data streams of those beams for FRB-like signals. It performs a computationally-intensive brute force search in multiple parameters. We installed the supercomputer, developed and commissioned the software for the MeerTRAP project. Since September 2019 the instrument takes part in science observations. Earlier in 2020, we discovered our first FRB and got extremely excited about it. It is interesting because it is currently the second most distant FRB at about 19 x 10^9 light years. It is also among the most energetic ones. Details about the discoveries and the search project will be published soon. Additionally, we discovered several previously unknown Galactic neutron stars by their single-pulses. The discoveries already contribute significantly to the field because they have well-determined positions, which allows them to be followed up. Our future work concerns a machine-learning software to classify FRB candidates in real-time so that we can retain higher time-resolution data. This will allow up to study their burst morphologies, which will, in turn, help constrain possible FRBs emission mechanisms. The high-resolution data will also let us make radio images of the fields around the FRBs to localise them to arcsecond precision. This is essential in the hunt for FRB host galaxies.
Poster Title
Searches for Fast Radio Bursts with the MeerKAT telescopes
