Galactic Center Shells and a Recurrent Starburst Model

Abstract

By applying filtering techniques to remove straight filaments in the 20-cm VLA radio image of the Galactic Center Arc region, we have shown that numerous concentric radio shells of radii 5 to 20 pc are surrounding the Pistol and Sickle region, which we call Galactic Center Shells (GCS). Each shell has thermal energy of the order of $10^{49-50}$ erg. Several CO-line shells are associated, whose kinetic energies are of the order of $10^{49-50}$ erg. Summing up the energies of recognized GCSs, the total energy amounts to $\sim 10^{51}$ erg. The GCSs show an excellent correlation with the FIR shells observed at 16--26 microns with the MSX. We propose a model in which GCSs were produced by recurrent and/or intermittent starbursts in the Pistol area during the last million yr. The most recent burst occurred some $10^5$ years ago, producing an inner round-shaped shell (GCS I); earlier ones a million years ago produced outer shells (GCS II and III), which are more deformed by interactions with the surrounding ISM and Sgr A halo. We argue that recurrent starbursts had also occurred in the past, which produced larger scale hyper shell structures as well. A burst some million years ago produced the Galactic Center Lobe, and a much stronger one 15 million years ago produced the North Polar Spur.

To appear in PASJ, Latex 8 pages, 5 figures, See http://www.ioa.s.u-tokyo.ac.jp/~sofue/htdocs/2003gcs/ for original figures

References in corpus (5)

• Starburst-driven galactic winds: I. Energetics and intrinsic X-ray emission
• Bipolar-Hyper-Shell Galactic Center Statrburst Model: Further Evidence from ROSAT Data and New Radio and X-ray Simulations
• High Resolution Infrared Imaging and Spectroscopy of the Pistol Nebula: Evidence for Ejection
• Radio Detections of Stellar Winds from the Pistol Star and Other Stars in the Galactic Center Quintuplet Cluster
• Bipolar hypershell models of the extended hot interstellar medium in spiral galaxies

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• Suzaku observations of the diffuse x-ray emission across the fermi bubbles' edges
• GBT Multiwavelength Survey of the Galactic Center Region
• X-ray and Gamma-ray Observations of the Fermi Bubbles and NPS/Loop I Structures
• The Galactic center chimneys: The base of the multiphase outflow of the Milky Way
• Suzaku Observations of the North Polar Spur: Evidence for Nitrogen Enhancement
• Possible connection between the asymmetry of North Polar Spur and Loop I with Fermi Bubbles
• The Fossil Nuclear Outflow in the Central 30 pc of the Galactic Center
• Feedback between Sgr A and B : AGN-Starburst Connection in the Galactic Centre