Institut für Astronomie & Astrophysik

In search of the extreme with MeerKAT: a wealth of exotic pulsars and binary systems found in globular clusters

Alessandro Ridolfi, INAF, Osservatorio Astronomicodi Cagliari, Italy - Dec 12, 2022

Pulsars are very fast-spinning, magnetized neutron stars (NS) that result from the supernova explosion of massive stars. Thanks to their exceptional rotational stability, in combination with the emission of coherent pulsed radiation, pulsars behave as super-precise cosmic "clocks", which can be exploited to perform exciting astrophysics and fundamental physics experiments.

The most extreme pulsars are often found in globular clusters (GCs). These are spherical, self-gravitating collections of stars that orbit our Milky Way. They are amongst the oldest stellar systems in the Universe and, as such, they host a large number of compact objects. The latter, because of the extreme stellar densities found in the core of GCs, can interact with other stars and produce dynamically formed binaries, which can in turn spin up NSs and, hence, form millisecond pulsars. The high interaction rates in GCs can also alter the typical evolution of binary systems, resulting in the formation of exotic binaries, with extreme or unconventional properties.  All of this makes GCs outstanding laboratories and their pulsars can be exploited for a large variety of scientific applications.

In the last few years, the total known population of GC pulsars has increased dramatically, jumping from about 150 objects known in 2018, to more than 270 known today. The MeerKAT radio telescope, located in South Africa, has been having a leading role in the recent surge in new discoveries and the consequent "renaissance" of the field.

In this talk, I will report on the main scientific results obtained in the science of pulsars in GCs with MeerKAT, in the context of the TRAPUM and MeerTIME experiments. After discussing the challenges that GC observations pose, I will present some major breakthroughs so far obtained, with particular emphasis on the case of a few extreme binary millisecond pulsars and other peculiar objects. I will conclude discussing about the prospects of GC pulsar science with MeerKAT over the next few years, in view of the future expansions planned for the telescope, which is a core part of the newly born SKA Observatory.