A Short History of the Discovery of Black Holes

The concept of black holes or completely collapsed gravitational objects as they were originally called has fascinated the scientific community and writers of science fiction for centuries. The mathematical proof of the existence of black holes came from the collation of multiple lines of evidence, some of which were highly debated and was derived from both indirect and direct sources. The measurement of gravitational waves and the observation of a black hole represent one of the most astounding achievements in astrophysics which will open up new areas of investigation for the role that black holes play in the formation, maintenance and evolution of galactic structure.

Symmetry of Galactic Structure

It is hypothesized that due to mass-energy equivalence there exist transverse fields caused 7 by energy flows that are analogous to gravitomagnetic fields generated by mass flows. 8 Relativistically correct equations describing energy flow are derived by using the action integral of 9 a Lagrangian and assuming that the properties of energy, when described four-dimensionally with 10 time, are independent of the material system which supports them. The equations allow the 11 electromagnetic and gravitational energy flows to be compared revealing an underlying symmetry 12 of galactic structure.

VVV WIN 1733−3349: a low extinction window to probe the far side of the Milky Way bulge

ABSTRACT Windows of low extinction in the Milky Way (MW) have been used along the past decades for the study of the Galactic structure and the stellar population across the inner bulge and disc. Here, we report the analysis of another low extinction near-IR window discovered by the VISTA Variables in the Vía Láctea Survey (VVV). VVV WIN 1733−3349 is about half a degree in size and is conveniently located right in the MW plane, at Galactic coordinates (l, b) = (−5.2, −0.3). The mean extinction of VVV WIN 1733−3349 is $A_{K_{\mathrm{ s}}}$ = 0.61 ± 0.08 mag, which is much smaller than the extinction in the surrounding area. The excess in the star counts is consistent with the reduced extinction and complemented by studying the distribution of red clump (RC) stars. Thanks to the strategic low-latitude location of VVV WIN 1733−3349, we are able to interpret their RC density fluctuations with the expected overdensities due to the presence of the spiral arms beyond the bulge. In addition, we find a clear excess in the number of microlensing events within the window, which corroborates our interpretation that VVV WIN 1733−3349 is revealing the far side of the MW bulge.