2024/04/18 by Sofue, Yoshiaki
#Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2404.11892
We performed a 12CO and 13CO-line study of the "Brick" (G0.253+0.016) in the Galactic Centre (GC) by analyzing archival data obtained with the Nobeyama 45-m telescope. We present kinematics and molecular gas distributions in the longitude-velocity diagram, and suggest that the Brick is located along the GC Arm I in the central molecular zone (CMZ), which yields a distance from the Sun of 8 kpc and galacto-centric distance of 0.2 kpc. The major and minor-axis diameters of the Brick are Dx× Dy=8.4 \rm pc × 4.1 \rm epc at position angle of 40° and 130°, respectively, and the scale radius is r\rm brick=√(Dx Dy)=2.96 pc. The molecular mass inferred from the 12CO-line integrated intensity is M\rm bri,xco∼ 5.1× 104 M_\odot for a conversion factor X\rm CO=1.0× 1020 H2 cm-2 [K km/s]-1. On the other hand, the dynamical (Virial) mass for the measured velocity dispersion of σv=10.0 km/s is calculated to be M\rm bri,vir∼ 6.8 × 104M_\odot, which yields a new conversion factor of X\rm CO =1.3× 1020 H2 cm-2 [K km/s]-1. The Brick's center has a cavity surrounded by a spherical molecular bubble of radius r\rm bub=1.85 pc and mass ∼ 1.7× 104M_\odot expanding at v\rm exp≃ 10 km/s with kinetic energy of E0∼ 1.7× 1049 erg. If the bubble is approximated by an adiabatic spherical shock wave, the age is estimated to be t∼ 2/5 r\rm bub/v\rm exp∼ 7.2× 104 y. Neither non-thermal radio structures nor thermal radio emission indicative of HII region are found in the archival data from the MeerKAT. We suggest that the molecular bubble will be a dark supernova remnant buried in the Brick, which, therefore, has experienced in the past (∼ 0.1 Myr ago) massive-star formation with a supernova explosion.