Cores and filaments in the Central Molecular Zone are unlike those in the Galactic disk clouds
The central 500 pc of our Galaxy, known as the Central Molecular Zone (CMZ), contains a huge reservior of dense molecular gas. Due to the extreme physical conditions around the Galactic Center, star formation in the CMZ exhibits characteristics distinct from those in the solar neighborhood, such as a star formation efficiency approximately ten times lower, and a potentially top-heavy initial mass function (IMF). To explore the origins of these peculiar star formation activities, we have initiated an ALMA observational campaign, termed CONCERT, which peers into molecular clouds, dense cores, and accretion disks in the CMZ. In this talk, I will highlight recent findings from our studies of 0.01-pc dense cores and pc-scale filaments within molecular clouds in the CMZ. Key results include: i) The cores are primarily bound by external pressure, contrasting with their counterparts in Galactic disk clouds, which are predominatly bound by self gravity. ii) Spectral indices derived from 1.3 mm and 3 mm continuum emission of the cores are intriguingly low, a feature not observed in Galactic disk clouds (e.g., those studied in the ALMA-IMF project), suggesting beam-diluted optically thick substructures or the presence of large dust grains. iii) A unique class of slim filaments seen in several shock tracers and complex organic molecules but not in dust continuum are found to be in dynamically inequilibrium and could dissipate soon, which may be related to the widespread emission of SiO and complex organic molecules in the CMZ. iv) Intriguing absorption filaments, which are discovered by Bally et al. (2014) using two molecular lines in one cloud, are revealed in more molecules and toward more clouds, whose nature is still uncertain.
