A Low Frequency Survey of the Galactic Plane Near l=11 degrees: Discovery of Three New Supernova Remnants

Abstract

We have imaged a 1 deg^2 field centered on the known Galactic supernova remnant (SNR) G11.2-0.3 at 74, 330, and 1465 MHz with the Very Large Array radio telescope (VLA) and 235 MHz with the Giant Metrewave Radio Telescope (GMRT). The 235, 330, and 1465 MHz data have a resolution of 25 arcsec, while the 74 MHz data have a resolution of 100 arcsec. The addition of this low frequency data has allowed us to confirm the previously reported low frequency turnover in the radio continuum spectra of the two known SNRs in the field: G11.2-0.3 and G11.4-0.1 with unprecedented precision. Such low frequency turnovers are believed to arise from free-free absorption in ionized thermal gas along the lines of site to the SNRs. Our data suggest that the 74 MHz optical depths of the absorbing gas is 0.56 and 1.1 for G11.2-0.3 and G11.4-0.1, respectively. In addition to adding much needed low frequency integrated flux measurements for two known SNRs, we have also detected three new SNRs: G11.15-0.71, G11.03-0.05, and G11.18+0.11. These new SNRs have integrated spectral indices between -0.44 and -0.80. Because of confusion with thermal sources, the high resolution (compared to previous Galactic radio frequency surveys) and surface brightness sensitivity of our observations have been essential to the identification of these new SNRs. With this study we have more than doubled the number of SNRs within just a 1 deg^2 field of view in the inner Galactic plane. This result suggests that future low frequency observations of the Galactic plane of similar quality may go a long way toward alleviating the long recognized incompleteness of Galactic SNR catalogs.

arXiv comment31 pages, 9 figures. Figure 7 is in color. Accepted to AJ

References in corpus (14)

• The Velocity Distribution of Isolated Radio Pulsars
• A New $\Sigma -D$ Relation and Its Application to the Galactic Supernova Remnant Distribution
• The Parkes Multibeam Pulsar Survey -- II. Discovery and Timing of 120 Pulsars
• Proper motion, age and initial spin period of PSR J0538+2817 in S147
• Chandra Observations of G11.2-0.3: Implications for Pulsar Ages
• The ASCA Catalog of Potential X-Ray Counterparts of GeV Sources
• Excitation and Disruption of a Giant Molecular Cloud by the Supernova Remnant 3C391
• Diffuse Hard X-ray Sources Discovered with the ASCA Galactic Plane Survey
• The Pulsar Wind Nebula in G11.2-0.3
• Radio Emission from a Young Supernova Remnant Interacting with an Interstellar Cloud: MHD Simulation with Relativistic Electrons
• Molecular and Ionic shocks in the Supernova Remnant 3C391
• Spatially-resolved Thermal Continuum Absorption against the Supernova Remnant W49B
• Spectral Components of the Radio Composite Supernova Remnant G11.2-0.3
• A high frequency radio study of G11.2-0.3, a historical supernova remnant with a flat spectrum core

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