DISCOVERY of BROAD MOLECULAR LINES and of SHOCKED MOLECULAR HYDROGEN from the SUPERNOVA REMNANT G357.7+0.3: HHSMT, APEX, SPITZER, and SOFIA OBSERVATIONS

J. Rho, J. W. Hewitt, John H Bieging, W. T. Reach, M. Andersen, R. Güsten

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Abstract

We report a discovery of shocked gas from the supernova remnant (SNR) G357.7+0.3. Our millimeter and submillimeter observations reveal broad molecular lines of CO(2-1), CO(3-2), CO(4-3), 13CO (2-1), and 13CO (3-2), HCO+, and HCN using the Heinrich Hertz Submillimeter Telescope, the Arizona 12 m Telescope, APEX, and the MOPRA Telescope. The widths of the broad lines are 15-30 km s-1, and the detection of such broad lines is unambiguous, dynamic evidence showing that the SNR G357.7+0.3 is interacting with molecular clouds. The broad lines appear in extended regions (>4.′5 × 5′). We also present the detection of shocked H2 emission in the mid-infrared but lacking ionic lines using Spitzer/IRS observations to map a few-arcminute area. The H2 excitation diagram shows a best fit with a two-temperature local thermal equilibrium model with the temperatures of ∼200 and 660 K. We observed [C ii] at 158 μm and high-J CO(11-10) with the German Receiver for Astronomy at Terahertz Frequencies (GREAT) on the Stratospheric Observatory for Infrared Astronomy. The GREAT spectrum of [C ii], a 3σ detection, shows a broad line profile with a width of 15.7 km-1 that is similar to those of broad CO molecular lines. The line width of [C ii] implies that ionic lines can come from a low-velocity C-shock. Comparison of H2 emission with shock models shows that a combination of two C-shock models is favored over a combination of C- and J-shocks or a single shock. We estimate the CO density, column density, and temperature using a RADEX model. The best-fit model with n(H2) = 1.7 ×104 cm-3, N(CO) = 5.6 ×1016 cm-2, and T = 75 K can reproduce the observed millimeter CO brightnesses.

Original languageEnglish (US)
Article number12
JournalAstrophysical Journal
Volume834
Issue number1
DOIs
Publication statusPublished - Jan 1 2017

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Keywords

  • infrared: ISM
  • ISM: individual objects (G357.7+0.3)
  • ISM: supernova remnants
  • radio lines: ISM

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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