Kristoffer Nielsen

Kristoffer Nielsen    (Denmark)

nielsen @

The search for stellar mass black holes

Black holes are rare and notoriously difficult to observed. As of March 2020 only a few dozen stellar mass black holes have been found. The majority of these are x-ray binaries, i.e., black holes with a luminous accretion disk. The accretion disk is the product of a close in binary configuration which allows a significant mass flow from the companion star.

Predictions state that many black holes should exist in slightly wider binary systems and thus remain undetected. The advent of the large astronomic surveys such as Gaia, TESS, and LAMOST marks a turning point in the search for stellar mass black holes. The vast size of the datasets promises new detections, however the number of predicted systems varies by more than a factor of a thousand. These difference reflects the uncertainty related to the exact formation processes of stellar mass black holes, e.g., the size of the natal kick of the black hole.

The aim of my PhD project it to discover new stellar mass black holes using a number of different methods; Detecting large radial velocity variations in spectroscopic data (LAMOST), observing periodic lightcurve variations caused by the strong gravity of a close companion (TESS), and witnessing the astrometric wobble in projected motion of the companion star (Gaia).
In the end a statistical analysis comparing the observations with model populations will allow better constrains for the formation process of the black holes.

Supervisor:    Hans-Walter Rix   (MPIA)

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