分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: We present a large-scale survey of the central molecular zone (CMZ) of our Galaxy, as well as a monitoring program of Sgr A*, with the AzTEC/Large Millimeter Telescope (LMT) in the 1.1 mm continuum. Our 1.1 mm map covers the main body of the CMZ over a field of $1.6 \times 1.1$ deg$^2$ with an angular resolution of $10.5''$ and a depth of 15 mJy/beam. To account for the intensity loss due to the background removal process, we combine this map with lower resolution CSO/Bolocam and \textit{Planck}/HFI data to produce an effective full intensity 1.1 mm continuum map. With this map and existing \textit{Herschel} surveys, we have carried out a comprehensive analysis of the spectral energy distribution (SED) of dust in the CMZ. A key component of this analysis is the implementation of a model-based deconvolution approach, incorporating the Point Spread Functions (PSFs) of the different instruments, and hence recovering a significant amount of spatial information on angular scales larger than $10.5''$. The monitoring of Sgr A* was carried out as part of a worldwide, multi-wavelength campaign when the so-called G2 object was undergoing the pericenter passage around the massive black hole (MBH). Our preliminary results include 1) high-resolution maps of column density, temperature and dust spectral index across the CMZ; 2) a 1.1~mm light curve of Sgr A* showing an outburst of $140\%$ maximum amplitude on 9th May, 2014 but otherwise only stochastic variations of $10\%$ and no systematic long-term change, consistent with other observations.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: We present an overview and data release of the spectral line component of the SMA Large Program, \textit{CMZoom}. \textit{CMZoom} observed $^{12}$CO(2-1), $^{13}$CO(2-1) and C$^{18}$O(2-1), three transitions of H$_{2}$CO, several transitions of CH$_{3}$OH, two transitions of OCS and single transitions of SiO and SO, within gas above a column density of N(H$_2$)$\ge 10^{23}$\,cm$^{-2}$ in the Central Molecular Zone (CMZ; inner few hundred pc of the Galaxy). We extract spectra from all compact 1.3\,mm \emph{CMZoom} continuum sources and fit line profiles to the spectra. We use the fit results from the H$_{2}$CO 3(0,3)-2(0,2) transition to determine the source kinematic properties. We find $\sim 90$\% of the total mass of \emph{CMZoom} sources have reliable kinematics. Only four compact continuum sources are formally self-gravitating. The remainder are consistent with being in hydrostatic equilibrium assuming that they are confined by the high external pressure in the CMZ. Based on the mass and density of virially bound sources, and assuming star formation occurs within one free-fall time with a star formation efficiency of $10\% - 75\%$, we place a lower limit on the future embedded star-formation rate of $0.008 - 0.06$\,M$_{\odot}$\,yr$^{-1}$. We find only two convincing proto-stellar outflows, ruling out a previously undetected population of very massive, actively accreting YSOs with strong outflows. Finally, despite having sufficient sensitivity and resolution to detect high-velocity compact clouds (HVCCs), which have been claimed as evidence for intermediate mass black holes interacting with molecular gas clouds, we find no such objects across the large survey area.