Institute of Astronomy

Getting close to the brightest black holes with NICER

SpeakerTalk DateTalk Series
Phil Uttley (Amsterdam)25 April 2019Institute of Astronomy Colloquia


The brightest black hole systems we can study are outbursting X-ray binaries in our galaxy. At the peaks of their outbursts, these systems show an array of phenomena that are linked to strong X-ray spectral evolution in the innermost accretion flow, such as mysterious X-ray quasi-periodic oscillations, which may be signatures of relativistic frame-dragging of material close to the black hole. X-ray observations are key to understanding these phenomena, but for many years these studies have been limited by the technical challenge of observing X-ray sources at high count rates, which can overwhelm detectors and significantly degrade the time and spectral-resolution of our instruments. The Neutron star Interior Composition ExploreR (NICER), installed on the International Space Station in 2017, is a new type of X-ray observatory which is capable of observing very bright X-ray sources with high time resolution and good spectral resolution, to provide a remarkable new view of the brightest black holes. I will present some of the key results on black hole X-ray binaries obtained by NICER so far and show how they can transform our view of the structure and evolution of accretion flows close to black holes.