Super Topolini in the cosmos – Ultra-luminous X-ray sources

Ultraluminous X-ray sources (ULXs) have long been considered a unique field of study. Understanding the phenomena that produce their high luminosities has important implications not only for understanding the complicated interaction between radiation and matter during accretion, but also for understanding the maximum growth rates of black holes and populations of compact objects in galaxies around ours.
The long theoretical debate about these sources – large and therefore brighter black holes, or small black holes that exceed the traditional Eddington limit? – has recently become more complicated with the discovery that a significant fraction of them are… pulsars, neutron stars with a hypercaloric “diet” up to 1000 times the Eddington limit! These tiny, powerful stars have earned the nickname “Mighty Mice”, after the cartoon character.

In this Astro Chat, I will give a brief introduction to ULXs, explaining why it is important to understand them, and I will talk about some ongoing projects on the multi-frequency study of these objects. In particular, I will focus on the effort to find new pulsars in the archive data of various X-ray satellites and possibly in radio archives.

Today, Astro Chiacchiere! is an informal meeting between the staff of the Cagliari Astronomical Observatory (staff, postdocs and students), which aims to discuss topics of a mainly scientific, technological and informative nature concerning the activities of the Observatory. The meeting is usually held on Tuesdays at 11:30 a.m. in the Auditorium of the Cagliari Astronomical Observatory. For information and/or contributions, please contact vvacca@oa-cagliari.inaf.it and surcis@oa-cagliari.inaf.it