SHAO Astrophysics Colloquium

Title : Co-evolution of the first supermassive black holes and their host galaxies

Speaker: Ran Wang (Peking University)
Time: 3 pm, June 06(Thursday)
Location: Lecture Hall, 3rd floor

Abstract :

Quasars discovered at the highest redshift probe the early evolution of the first supermassive black holes (SMBHs) and their host galaxies at the epoch of cosmic reionization. The dust and gas in the host galaxies of these earliest quasars have been studied at submillimeter and millimeter wavelengths using thermal continuum emission, molecular (mostly CO), and fine structure lines, such as the [C II] 158um emission line . The observations reveal active star formation at rates of hundreds to thousands Msun/yr. The source size measurements with ALMA suggest that the star formation regions are compact, over scales of a few kpcs. The most far-infrared (FIR) luminose objects show peak surface brightnesses comparable to that found in the submillimeter galaxies, indicating a similar high surface density of star formation in the nuclear region of the quasar hosts. The kinematics of the star forming interstellar medium traced by the [C II] and CO lines appear to be very turbulent, and show features of tidal perturbation from companion interaction and/or outflows from AGN and star formation feedback. The young quasars at the earliest epoch are unique laboratories with rich physics of the interstellar medium (ISM) in extreme AGN-starburst environments. In this talk, I will present recent observations of the atomic and molecular gas content, and discuss our current knowledge on the evolutionary properties of the young quasar host galaxies at z>=6.

Seminar talk

Title: GRAVITY science highlights and technical challenge/advance in near-infrared interferometry

Speaker: Feng Gao (MPE, Germany)

Time: 3 pm, June 4 (Tuesday)

Location: Middle Conference room, 3rd floor

Abstract:

GRAVITY is a 2nd generation beam combiner instrument for the Very Large Telescope Interferometer at ESO's Paranal Observatory in Northern Chile. Commissioned in early 2017, it coherently combines beams from 4 telescopes at near-infrared K band (2 micron) to form a telescope with equivalent diameter of 130 meters and collecting area of up to 200m^2. In this talk, I will briefly introduce the GRAVITY working principles, then focusing on the science highlights achieved with GRAVITY observations on the Galactic Center, AGN and exo-planets in the past 2 years. For the rest of the talk, I will focusing on the technical challenges encountered in the GRAVITY project in the past and how they have been overcome/mitigated. I will end with future perspective for GRAVITY and also share the lessons I've learned in my transition from an outsider to an insider in the project.