ﻻ يوجد ملخص باللغة العربية
Using the Atacama Large Millimeter/submillimeter Array, we have made the first high spatial and spectral resolution observations of the molecular gas and dust in the prototypical blue compact dwarf galaxy II Zw 40. The CO(2-1) and CO(3-2) emission is clumpy and distributed throughout the central star-forming region. Only one of eight molecular clouds has associated star formation. The continuum spectral energy distribution is dominated by free-free and synchrotron: at 870$mu m$, only 50% of the emission is from dust. We derive a CO-to-H$_2$ conversion factor by several methods including a new method that uses simple photodissocation models and resolved CO line intensity measurements to derive a relationship that uniquely predicts $alpha_{CO}$ for a given metallicity. We find that the CO-to-H$_2$ conversion factor is 4 to 35 times that of the Milky Way (18.1 to 150.5 M$_odot$ / (K km/s pc$^2$)). The star formation efficiency of the molecular gas at least 10 times higher than that found in normal spiral galaxies, which is likely due to the burst-dominated star formation history of II Zw 40 rather than an intrinsically higher efficiency. The molecular clouds within II Zw 40 resemble those in other strongly interacting systems like the Antennae: overall they have high size-linewidth coefficients and molecular gas surface densities. These properties appear to be due to the high molecular gas surface densities produced in this merging system rather than to increased external pressure. Overall, these results paint a picture of II Zw 40 as a complex, rapidly evolving system whose molecular gas properties are dominated by the large-scale gas shocks from its on-going merger.
We present Atacama Large Millimeter/submillimeter Array observations of CO lines and dust continuum emission of the source RCSGA 032727--132609, a young $z=1.7$ low-metallicity starburst galaxy. The CO(3-2) and CO(6-5) lines, and continuum at rest-fr
Dense molecular gas and star formation are correlated in galaxies. The effect of low metallicity on this relationship is crucial for interpreting observations of high redshift galaxies, which have lower metallicities than galaxies today. However, it
Tracing the star formation history in circumnuclear regions (CNRs) is a key step towards understanding the starburst-AGN connection. However, bright nuclei outshining the entire host galaxy prevent the analysis of the stellar populations of CNRs arou
The effects of mergers in low mass galaxies are poorly understood. In this paper we analyze different observational evidences which support the view that mergers can trigger starbursts in dwarf galaxies. We discuss the relationships between blue comp
We analyse the 2-dimensional distribution and kinematics of the stars as well as molecular and ionised gas in the central few hundred parsecs of 5 active and 5 matched inactive galaxies. The equivalent widths of the Br-gamma line indicate there is no