Evidence for Black Holes

• X-ray binaries: Cygnus X-1
• Milky Way center:
  • Radio overview
  • The power of adaptive optics
  • Stellar orbits: Munich group, and UCLA group here, here, and here
  • The 2020 Nobel Prize in Physics
  • possibly related: gamma-ray bubbles
  • coming soon(?): Event Horizon Telescope image of a black hole, perhaps like this
• other galaxies
  • active galaxies: M87; AGN gallery
  • gravitationally lensed quasar: the Einstein cross
  • quasar and host galaxies
  • supermassive black holes
  • black holes and galaxies somehow know about each other
  • important clues: a binary supermassive black hole pairs and even triples! optical detection by our own Prof. Xin Liu, X-ray

Imaging a Black Hole: M87^*

• Virgo cluster of galaxies
• M87 at center
• M87 jet: our closest AGN!
• Event Horizon Telescope: array
• expectations: black hole ray tracing, simulations
• EHT image of M87^*! paper: EHT Collaboration (2019)
• putting it all together

Black Holes and Gravitational Radiation

• Theory: ripples in spacetime
• Indirect evidence: Hulse & Taylor's award-winning binary pulsar
• Direct detection: gravity-wave observatories
  • Advanced LIGO: detectors in Hanford and Livingston
  • VIRGO: detector near Pisa, Italy
  • the future: LIGO India, KAGRA, Japan, LISA
• Welcome to the era of gravity wave astronomy!
  • merging black holes scientific summary paper: Abbott et al 2016
  • merging neutron stars
  • astrophysics: sky localization, observed stellar graveyard masses
  • Nobel Prize 2017: Rainer Weiss, Barry Barish, Kip Thorne
• LIGO/Virgo catalog from Nov 2021, masses plotted here and here, orbits visualized