Local Group L-Band Survey

A Karl G. Jansky Very Large Array "extra large" survey of 21-cm , continuum, and OH emission from the Local Group of Galaxies

The Local Group L-Band Survey (LGLBS) is an ongoing "Extra Large" survey using the Karl G. Jansky Very Large Array.

The Survey: The LGLBS will use approximately 1800 hours of "L band" (1-2 GHz) observations in all VLA configurations obtain the deepest and highest spatial and velocity resolution imaging imaging to date of 21-cm line and L-band continuum emission over the full area of the six actively star-forming Local Group galaxies visible to the VLA - M31 (Andromeda), M33 (Triangulum), NGC 6822, IC 10, IC 1613, and WLM. The 21-cm line traces the atomic hydrogen that make up the diffuse interstellar medium (ISM) in these targets while the 1-2 GHz radio continuum reflects a mixture of free-free emission and synchrotron, and so traces star-forming regions, supernova remnants, and background galaxies and quasars.

The Science: Our observations will address many of the most important open questions about the "baryon cycle," the interplay of diffuse interstellar matter, star formation, and stellar feedback, including:

  • What is the physical state of the atomic gas that fills the space between stars and how does this change across galaxies?

  • How is interstellar turbulence driven and how does it shape the structure of the gas in galaxies?

  • How do stellar photoionization and supernovae feedback couple to the the interstellar medium?

  • Where have massive stars exploded as supernovae in the relatively recent past?

  • How do cold, dense, gravitationally bound clouds that will make stars form out of diffuse interstellar gas?

Our data can also be used to address many other science goals, including searches for gas in galaxy halos, tracing the abundance of dust grains, searching for black holes, hunting for masers, tracing the strength and orientation of magnetic fields.

Why These Targets? These are the six closest VLA-accessible targets that rich ISMs and active star formation. They all lie between 500 kpc and 1 Mpc from the Milky Way. This proximity enables VLA 21-cm and continuum observations to achieve the best possible physical resolution: our data products will have resolutions from <10 to 100 pc, enough to resolve individual supernova remnants, HII regions, or atomic gas clouds, something that has not been easy to do before now. The proximity also enables excellent sensitivity to individual regions or gas clouds, which in turn will allow us to characterize the physical properties of each individual region in each galaxy in great detail. More, these galaxies have legacy observations from essentially all major telescopes, from Chandra to Hubble to ALMA to Spitzer to Herschel (and soon JWST and the Roman Space Telescope). This extensive coverage across the electromagnetic spectrum plays a key role in enabling our science program.


Contact leroy.42 at osu dot edu for more information on the project.