Abstract
Abstract The inner ∼200 pc region of the Galaxy contains a 4 million M⊙ supermassive black hole (SMBH), significant quantities of molecular gas, and star formation and cosmic-ray energy densities that are roughly two orders of magnitude higher than the corresponding levels in the Galactic disk. At a distance of only 8.2 kpc, the region presents astronomers with a unique opportunity to study a diverse range of energetic astrophysical phenomena, from stellar objects in extreme environments, to the SMBH and star-formation-driven feedback processes that are known to influence the evolution of galaxies as a whole. We present a new survey of the Galactic center conducted with the South African MeerKAT radio telescope. Radio imaging offers a view that is unaffected by the large quantities of dust that obscure the region at other wavelengths, and a scene of striking complexity is revealed. We produce total-intensity and spectral-index mosaics of the region from 20 pointings (144 hr on-target in total), covering 6.5 square degrees with an angular resolution of 4″ at a central frequency of 1.28 GHz. Many new features are revealed for the first time due to a combination of MeerKAT’s high sensitivity, exceptional u, v-plane coverage, and geographical vantage point. We highlight some initial survey results, including new supernova remnant candidates, many new nonthermal filament complexes, and enhanced views of the Radio Arc bubble, Sagittarius A, and Sagittarius B regions. This project is a South African Radio Astronomy Observatory public legacy survey, and the image products are made available with this article.
Highlights
Jansky’s discovery that some of his instrumental noise was moving according to sidereal time marked the birth of radio astronomy as a science (Jansky 1933)
Surrounding Sagittarius A (Sgr A)∗ out to radii of ∼100–200 pc is a twisted toruslike structure detected at far-infrared wavelengths (Molinari et al 2011), rich in molecular gas and dust known as the Central Molecular Zone (CMZ; Mills 2017), thought to be driven and sustained by the innermost region of the Galaxy’s barred potential (Nayakshin & Cuadra 2005; Wardle & Yusef-Zadeh 2008; Krumholz & Kruijssen 2015; Tress et al 2020)
In this article we present a new survey of the Galactic center conducted with the South African MeerKAT1 radio telescope (Jonas & MeerKAT Team 2016) at a frequency of 1.28 GHz
Summary
Jansky’s discovery that some of his instrumental noise was moving according to sidereal time marked the birth of radio astronomy as a science (Jansky 1933). On a larger than kpc scale, anomalous-velocity neutral hydrogen (Hi) clouds seen to trace a conical outflow out to Galactic latitudes of |b|∼10◦ (Di Teodoro et al 2018) offer strong evidence that these outflows are entraining enriched material (Di Teodoro et al 2020) These features bridge the gap between the Galactic center and the Fermi bubbles (Su, Slatyer, & Finkbeiner 2010), gamma-ray emitting structures with approximately coincident polarized synchrotron emission (Carretti et al 2013) that extend to |b|∼50◦, thought to be caused by previous energetic outflows from the GC.
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