The Lorimer burst (Lorimer et al., 2007)

Since the detection of the Lorimer burst in 2007, astronomers have learned that, on short time scales, our radio sky is far from static. With telescopes like CHIME, ASKAP and Westerbork, ultra-bright short-duration radio flashes are observed so frequently that they are estimated to occur more than one thousand times a day. Even so, we do not know what produces them.

A lot of time and effort is therefore spend on characterising these so called “Fast Radio Bursts” (FRBs). Learning more about their properties might give us a clue to their origin. However, so far, the phenomenon has only become more shrouded in mystery with our deepened knowledge about them.

For instance, from their “dispersion-sweep” it can be deduced that these bursts originate far outside our own galaxy. Such a sweep is evident in the image of the Lorimer burst as the burst’s higher frequencies arriving earlier than its lower frequencies. This, together with their short duration (the width of the Lorimer burst), reveals that whatever produces them must be rather energetic. At least, we do not know any source in our own galaxy that can produce such high energetic pulses in the radio domain.

As of 2018, astronomers have been able to pinpoint some FRBs to the galaxies from which they originated. One would hope to find similarities between these galaxies to narrow down the physical environments in which FRBs are produces. But, FRBs have now been seen to originate from almost every type of galaxy we distinguish.

FRB polarisation properties, the direction variabilities of the electromagnetic wave of light, are also all over the place. Something that does not aid the creation of a coherent picture about their emission mechanisms.

Another thing that does not help is the varying emission pattern between burst sources. Pleunis et al., 2021, showed that bursts can be classified into four categories based on their emission pattern (morphology). And to add to the overall mystery, that a burst’s emission pattern hints towards its source being either a repeating emitter of FRBs or that it emits just one.

Four categories of FRB emission patterns (Pleunis et al., 2021)

I.e. concerning FRBs, their are still a lot of open questions. Questions many astronomers try to find an answer to. Among them is Leon Houben, who co-created a VOEvent standard for the field. This standard eases the communication between telescopes, so observatories can follow-up new FRB detections swiftly and efficiently. The standard is adopted by several observatories around the world.

Through joint observations with the Effelsberg 100-m Radio Telescope and LOFAR, he put constraints on the low frequency spectrum of the first detected repeating FRB. During this venture, a new parameter was envisioned, the statistical spectral index, that gives an estimate on the detection probability of an FRB at one frequency given the detection rate of the FRB at another frequency.

Currently, he analyses a vast amount of archival data from Effelsberg. In this data he hopes to find pulsars, FRBs and potentially new types of single pulsed emission. To be able to analyse this data and increase his chances of finding interesting results, he developed new software published on his GitLab account. This software allows him, among other things, to rid the Effelsberg data from human interference and inject it with synthetic signals to quantify how well true signals can be discovered.