Evidence for activity at the Galactic center based on low frequency radio continuum observations

Abstract

Aperture synthesis observations of the galactic center region at 123.0 and 110.6 MHz reveal striking asymmetric steep spectrum (α≤−0.8) radio lobes. The northern galactic lobe (NGL) appears to be a unique galactic source and cannot be easily classified as an SNR, extragalactic source, or a foreground object. The southern ‘‘lobe’’ appears directly linked to the galactic center and has been identified by Yusef‐Zadeh et al. as a low energy jet emanating from Sgr‐A. We present here new 80 MHz observations of an expanded region around the galactic center obtained one year after the initial set of observations. Excellent morphological agreement between these separate sets of observations confirm the persistence of the NGL as the dominant emission feature in the entire region at these frequencies. The similarities of this source with the jet feature suggest a common origin. Together with the compact nonthermal source located at the galactic center, the properties and geometry of these sources resemble the radio ...