出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：Some of the most extreme ultra-luminous X-ray sources (ULX) are good candidates for the
long-sought missing link between stellar-mass and supermassive black holes. These hypothetic
intermediate-mass black holes (IMBH) may be revealed by very high angular resolution very long
baseline interferometry (VLBI) imaging. We show that these objects are naturally compact and
bright enough to be detected with present-day technology. We estimate the minimum mass of
black holes in nearby galaxies detectable by the European VLBI Network (EVN), and calculate
the expected radio flux densities for various X-ray luminosities. Using recent EVN observations
of M82 X-1, we derive an upper limit to the black hole mass of 500 M . We conclude that a
relativistic jet cannot be responsible for beaming the X rays in this ULX.
