Abstract

Oral Abstract

Oral Contribution (O0.4) Jakob van den Eijnden ()

A new radio census of accreting neutron stars

X-ray binaries are close binary systems hosting a compact object and a donor star, where mass istranferred onto the compact object and possibly launched into the surrounding medium via winds andjets. These systems come in a plethora of classes and categories, based on the properties of thecompact object and donor, the on type of and mass tranfer: neutron stars versus black holes, low-massversus high-mass donors, Roche-lobe overflow versus wind capture. Observations in differentwavebands probe different components of the system: for instance, X-rays are emitted by the infallingmatter, while radio emission has so far typically been attributed to relativistic jets launched from the inneraccretion flow. Despite decades of searches, a subclass that makes up a remarkable fraction of X-raybinaries remained systematically undetected in the radio band: neutron stars accreting from high-massdonors, which form roughly half of the known X-ray binary population. Making use of the improvedsensitivity of the upgraded jVLA and ATCA radio observatories, we have observed a sample of thirty-sixaccreting neutron stars of various X-ray binary types, thereby more than doubling the number ofaccreting neutron stars observed at current day radio sensitivities. We detect radio emission fromthirteen systems, showing that all types of neutron star X-ray binaries emit in the radio band, regardlessof neutron star, donor, or mass tranfer properties. In this talk, I will present an overview of the observedradio properties, before discussing whether the radio emission originates from jets or other components,such as ionized stellar winds. Finally, I will discuss the implications of our results on (neutron star) jetphysics, focussing on the effects of the neutron star's magnetic field and spin.