Date:
Tue, 25/03/202512:30-13:30
Speaker: Dr. Sahar Shahaf (Department of particle physics and astrophysics, Weizmann Institute of Science)
Title: The Hunt for Invisible Stars
Abstract:
Most known stellar black holes are members of close binary systems, where accretion-fueled X-ray emission triggered their detection. However, if the separation between the two components is sufficiently large, the accretion rate drops, leaving the black hole in quiescence. Presumably, most compact objects in binaries reside in this dormant state, waiting to be discovered. The hunt for dormant black holes, neutron stars, and white dwarfs poses a long-standing challenge but holds key insights into the physical mechanisms governing stellar and binary evolution.
A unique opportunity to overcome these challenges was recently presented by Gaia, a space observatory monitoring over a billion stars; it has revolutionized astronomy by accurately measuring their positions, distances, motions, and colors. By identifying binary orbits, Gaia has enabled the detection of thousands of stars accompanied by white dwarfs, dozens accompanied by neutron stars, and three with an unambiguous black hole as their faint, massive companion. In this talk, I will describe the search methodologies used to detect these systems and the potential of empirical studies of their populations. I will highlight several unexpected implications of these samples for our understanding of white dwarf formation and binary evolution and outline promising directions for future research.
Zoom link:
https://huji.zoom.us/j/82055108525?pwd=HPTlylQcntkbO8npZpjhgpbEpGr9vD.1
Meeting ID: 820 5510 8525
Passcode: 874028
Contact: Dima Ofengeim
Title: The Hunt for Invisible Stars
Abstract:
Most known stellar black holes are members of close binary systems, where accretion-fueled X-ray emission triggered their detection. However, if the separation between the two components is sufficiently large, the accretion rate drops, leaving the black hole in quiescence. Presumably, most compact objects in binaries reside in this dormant state, waiting to be discovered. The hunt for dormant black holes, neutron stars, and white dwarfs poses a long-standing challenge but holds key insights into the physical mechanisms governing stellar and binary evolution.
A unique opportunity to overcome these challenges was recently presented by Gaia, a space observatory monitoring over a billion stars; it has revolutionized astronomy by accurately measuring their positions, distances, motions, and colors. By identifying binary orbits, Gaia has enabled the detection of thousands of stars accompanied by white dwarfs, dozens accompanied by neutron stars, and three with an unambiguous black hole as their faint, massive companion. In this talk, I will describe the search methodologies used to detect these systems and the potential of empirical studies of their populations. I will highlight several unexpected implications of these samples for our understanding of white dwarf formation and binary evolution and outline promising directions for future research.
Zoom link:
https://huji.zoom.us/j/82055108525?pwd=HPTlylQcntkbO8npZpjhgpbEpGr9vD.1
Meeting ID: 820 5510 8525
Passcode: 874028
Contact: Dima Ofengeim