Seminar “History of couples and fusional relations. Formation, evolution and fusion of stellar binaries.”

As part of the Planetology and Space Sciences Seminars, Sylvain Chaty (AIM/Université Paris Diderot/CEA) will speak on the theme “History of couples and fusional relations. Formation, evolution and fusion of stellar binaries.”

The seminar will take place on Wednesday 30 May 2018 at 11h00 – 522, bât Lamarck – Campus Paris-Rive-Gauche

Summary :

The discovery, by the LIGO-Virgo collaboration on 14 September 2015, of gravitational waves resulting from the fusion of two stellar mass black holes was unexpected: two such massive stellar black holes (~ 30 solar masses) had never been detected before, although they probably constitute the tip of the iceberg. From this detection, several questions immediately emerged: how can such black holes form, and how many exist in our local Universe, and beyond?

The second surprise came with the detection of a kilonova associated with a fusion of two neutron stars on August 17, 2017. Other questions then emerged, such as the nature of the result of such a merger. More generally, one of the most fundamental questions, in terms of astrophysics and physics, concerns the nature of the progenitors that eventually merge.

Massive star pairs containing compact objects (such as neutron stars and black holes) are the main candidates for progenitors. These systems evolve until finally merging into binary black holes, neutron stars or neutron stars/black holes, and emitting gravitational waves. The evolution of such stellar pairs is subject to numerous uncertainties of certain parameters of their evolution, such as: the natal kick received during the supernova, the stellar winds and their dependence on metallicity, the common envelope phase conditioning the survival of the stellar couple, the spin of each component, the dynamic capture, etc.

During this seminar, we will detail the evolution of these stellar pairs, from their formation to their ultimate fusion, in the context of gravitational wave detection.

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