Gravitational Microlensing

• direct detection of a microlens; another detection
• Implications for dark matter: Circa 2001, 2003 plot, 2007 plot, 2011 plot
• Other applications of microlensing
  • looking through Baade's window to study the Galactic bulge
  • detection of extrasolar planets, e.g., lightcurve from Kains et al (2013)
  • identification of black holes
• the future: synoptic surveys open the time domain
  Pan-STARRS, LSST, WFIRST(?)

The Galactic Nucleus

• highly extincted optical view; annotated version
• Radio discovery G. Reber (1944)
• Galactic Center in infrared: 2MASS, Spitzer; multiwavelength
• journey to the center for a modern overview
• Sgr A west in molecules: circumnuclear ring
• X-ray: star clusters
• Sgr A*: in radio, with arc; X-ray
• mini-spiral of gas around Sgr A*
• cool animation of X-ray flare artist's conception

The Central Object

• The trouble with ground-based observations
  and the power of adaptive optics using laser guide stars
• Stellar orbits: Munich group, UCLA group; orbits in 3D!
• Implications
• Milky Way quiescence versus activity of, e.g., M87
• Ongoing: Galactic weather forecast: infall of gas clouds
• hypervelocity stars such as this one