On the origin of a kiloparsec size superbubble in the JWST images of the "phantom galaxy" NGC628
Date & Time :
NGC628 is the first nearby galaxy for which JWST data became available to the public. The most striking characteristic of the publicly released MIRI image is the presence of a large number of "holes" in an otherwise bright mid-infrared (MIR) emitting disk. This porous structure has given it a popular nickname "phantom galaxy". The "holes" are most often expanding bubbles or superbubbles that are created by the mechanical power output by the massive stars in young star clusters. However, few cases exist where the stellar population that was responsible for the creation of the bubble was unambiguously identified. We here analyze the largest of the bubbles in the JWST/MIRI image of NGC628, measuring 1.3 kpc in diameter to understand the origin of such large bubbles. We combined the JWST NIRCam and MIRI dataset with archival images from the HST, ALMA, VLA and MUSE, to identify the resolved population that might be responsible for the creation of the bubble, and to map the multiphase morphology and kinematics of the gas in the shell surrounding the bubble. The bubble is dominated by the molecular gas and is expanding at 12 km/s velocity. We find conclusive evidence for the presence of a resolved stellar population of ages between 5 to 50 Myr inside the bubble, whose collective mechanical power output is sufficient to explain the presently observed radius, velocity and the shell mass. In the talk, I will discuss the star formation scenario inside the bubble and the conditions that favour the formation of large superbubbles.
About Speaker :
Prof. Divakara Mayya is a professor at INAOE, Mexico. He obtained his Ph.D. in 1993 from IISc, India. Between 1994-96, he was a Postdoctoral fellow at TIFR, Mumbai, India, and then between 1996-1997, he was a Guillermo Haro fellow at INAOE, Mexico. His main area of research is Extragalactic astronomy in the study of Star formation, the evolution of star clusters, and the evolution of galaxies.