Correlation Study between Infrared Dust Bubbles and CO Molecular Gas in the Milky Way

Abstract

The study systematically analyzes the correlation between infrared dust bubbles and CO molecular gas in the Galactic region where 10${}^{\circ }$ $\le l\le$ 20${}^{\circ }$ and $\left|b\right|\le$ 5${}^{\circ }$, based on infrared survey data from WISE (Wide-Field Infrared Survey Explorer), GLIMPSE (Galactic Legacy Infrared Mid-Plane Survey Extraordinaire), and MIPSGAL (Multiband Imaging Photometer for Spitzer Galactic), combined with CO molecular gas survey data from the Milky Way Imaging Scroll Painting. A data analysis method based on Gaussian process regression was designed for the study. Among the 143 published infrared dust bubble samples, 44 bubbles were found to correlate with CO molecular gas, accounting for 30.8% of the total sample size. The study estimates the physical parameters such as CO molecular optical depth, H${}_2$ column density, and mass associated with bubbles, and conducts statistical analysis. The average column density of the 44 bubbles is calculated to be approximately 10${}^{22}$ cm${}^{-2}$, with most bubble masses not exceeding 10${}^5$ $M_{\odot }$. The H${}_2$ column density of the molecular gas associated with the infrared dust bubbles generally reached the conditions for dense clumps that could potentially form stars. There are 26 bubbles that may be expanding, with an average expansion velocity of 2.75 km$·s^{-1}$. The research results provide samples for understanding infrared dust bubbles and star formation studies.