Letters of Intent received in 2017

LoI 2019-2017
New Horizons in Galactic Center Astronomy and Beyond

Date: 21 October 2019 to 25 October 2019
Category: Non-GA Symposium
Location: Yokohama, Japan
Contact: Tomoharu OKA (tomo@phys.keio.ac.jp)
Coordinating division: Division J Galaxies and Cosmology
Other divisions: Division D High Energy Phenomena and Fundamental Physics
Division G Stars and Stellar Physics
Division H Interstellar Matter and Local Universe
Co-Chairs of SOC: Takeshi Go Tsuru (Kyoto University)
Tomoharu Oka (Keio University)
Geoffrey Bower (ASIAA)
Cornelia C. Lang (University of Iowa)
Chair of LOC: ()



1) Structure and evolution of the Central Molecular Zone
Large-scale structure and gas kinematics; physical conditions and chemical compositions; magnetic field configuration and strength; cloud formation and disruption; cloud collisions and their outcomes; interstellar shocks and their origin; the origin and evolution of the CMZ; comparison with CMZs in nearby galaxies
2) Star formation and stellar popution in the CMZ
Properties of molecular clouds; star formation inhibition; dissipation of supersonic turbulence; massive star forming regions; young massive stellar clusters; nuclear star cluster; initial mass function; metallicity; star formation history; microbursts of star formation; interstellar dust in the CMZ; interstellar extinction; pulsars and magnetars; late-type stars; the Galactic bars
3) Past and current activity of the Galactic center
Time variation of Sgr A*; flares and flashes; changes in the spectral energy distribution and polarization; high-energy events; PeVatron; annihilating dark matter; signatures of past activities; accretion disk models; gas feeding toward the nucleus; dusty objects orbiting Sgr A*; the circumnuclear disk; giant molecular clouds near the center; supernova; supernova remnants
4) Unveiling black holes and neutron stars near the Galactic nucleus
Imaging Sgr A* at high angular resolution; formation and evolution of the central supermassive black hole; stellar dynamics around supermassive black holes; missing pulsars near Sgr A*; intermediate-mass black holes; missing (stray) black holes; black hole physics; tests for general relativity



The central region of the Milky Way Galaxy is characterized by the presence of the nearest supermassive black hole, a strong concentration of stars and interstellar matter, all of which have been object of intesive study for the last several decades. Many surveys as well as pointed observations so far have revealed a wide variety of astrophysical phenomena, the understanding of which remain elusive: including, the three-dimensional configuration of gas distribution, suppressed star formation despite the abundance of dense molecular gas, a currently inactive supermassive black hole, rich signatures of past central activities, and the unexpected discovery of a magnetar bound to the supermassive black hole. These unsolved issues span wide ranges of spatial scale, time scale, and energy scale, likely being related each other. The unprecedented capabilities of the Atacama Large Millimeter/submillimeter Array are now unveiling the nature of this most fascinating part of the Milky Way. The ambitious millimeter-wave VLBI project is about to image the event horizon of the Galactic supermassive black hole, Sgr A*. High resolution infrared instruments such as GRAVITY on the VLT are transforming our view of the stellar population and Sgr A*. Gamma-ray/neutrino telescopes are currently stacking evidence for high-energy processes possibly occurring in the vicinity of Sgr A*. Under these circumstances, it will be fruitful to hold an international symposium of Galactic center astronomy. The goal of this symposium is to bring together researchers with broad expertise, to share the latest research, to encourage active discussion and collaboration, and thereby to explore the new horizon of the Galactic center astronomy and beyond.