Galactic Center

We are members of the Galactic Center Group at UCLA. In the muLab, we focus on the following Galactic Center science cases and methodologies:

• Dynamics and Initial Mass Function (IMF) of Young Nuclear Cluster

• Improved astrometry for stellar orbits and binary searches

• Gravitational lensing by stellar mass black holes and the supermassive black hole

A complete list of papers for the Galactic Center Group, including muLab members, can be found here. Those listed below had major involvement or were led by muLab members.

Dynamics and Initial Mass Function (IMF) of the Young Nuclear Cluster:

Our Galactic Center hosts a supermassive black hole, around which a nuclear star cluster (NSC) resides. There are early (young) and late-type (old) stars within central parsecs of Galactic Center. The young nuclear cluster is particularly interesting as it indicates that star formation can occur in this region, despite the harsh conditions and strong tidal forces. However, the star formation process is likely very unusual.

We measure the IMF as a probe for how the star formation process changes in this environment.

Current Members at Berkeley: Jessica Lu, Ruoyi Yin, Ningyuan Xu

• Stellar Populations in the Central 0.5 pc of Our Galaxy III: The Dynamical Sub-structures (Jia, Xu et al. 2023)

• Properties of the Remnant Clockwise Disk of Young Stars in the Galactic Center (Yelda et al. 2014)

• Stellar Populations in the Central 0.5 pc of the Galaxy. II. The Initial Mass Function (Lu et al. 2013)

• Stellar Populations in the Central 0.5 pc of the Galaxy. I. A New Method for Constructing Luminosity Functions and Surface-density Profiles (Do et al. 2013)

• A Disk of Young Stars at the Galactic Center as Determined by Individual Stellar Orbits (Lu et al. 2009)

Improved astrometry for stellar orbit in the Galactic Center:

The accurate and precise astrometric measurements for stellar populations in Galatic Center is important for solving puzzles such as missing cusp problem, dynamical properties and IMF of stars within central parsec, characterizing more accurate 3D orbits of stars, binary-star candidates and General Relativity from supermassive black hole.

Improved astrometry can be achieved from transforming astrometric and photometric data of stars into a common coordinate system, deriving better measurements for positionsm, proper motions, accelerations and thus orbits.

Current Members at Berkeley: Jessica Lu, Sean Terry

• The Galactic Center: Improved Relative Astrometry for Velocities, Accelerations, and Orbits near the Supermassive Black Hole (Jia et al. 2019)

• The Galactic Center: An Improved Astrometric Reference Frame for Stellar Orbits around the Supermassive Black Hole (Sakai et al. 2019)