The neutral gas environment of the young supernova remnant SN 1006 (G327.6+14.6)

¹ Instituto de Astronomía y Física del Espacio, CC 67, Suc. 28, 1428, Buenos Aires, Argentina e-mail: gdubner, egiacani@iafe.uba.ar
² National Radio Astronomy Observatory, PO Box 0, Socorro, New Mexico 87801, USA e-mail: mgoss@aoc.nrao.edu
³ School of Physics, University of Sydney, NSW 2006, Australia e-mail: agreen@physics.usyd.edu.au
⁴ Onsala Space Observatory, Chalmers University of Technology, 439 92 Onsala, Sweden and European Southern Observatory, Casilla 19001, Santiago 19, Chile e-mail: lnyman@eso.org

Corresponding author: G. Dubner, gdubner@iafe.uba.ar

Received: 24 December 2001
Accepted: 8 March 2002

Abstract

Using the Australia Telescope Compact Array, we have carried out a survey of the H i emission in the direction of the bilateral supernova remnant (SNR) SN 1006 (G327.6+14.6). The angular resolution of the data is , and the rms noise ~39 mJy/beam (~ K). To recover structures at low spatial frequencies, single dish data have been added to the interferometric images. We have also studied the ¹²CO emission in the transitions –0 and –1, looking for very compact clumps of molecular gas as possible sites for the acceleration of electrons and nuclei to TeV energies associated with the γ-ray source detected on the NE limb of SN 1006. These molecular gas observations produced only marginal detections. From the present observations we conclude that the distribution of the surrounding neutral gas had no strong influence in shaping this SNR with a bilateral appearance. Intrinsic factors may have contributed to the present morphology. The remnant of SN 1006 appears to be evolving in a smooth environment with an atomic volume density  cm^-3. The existence of an H i concentration projected on the center of SN 1006 suggests an upper limit of ∼- km s on the systemic velocity of the SNR. This limit is compatible with a distance to the SNR of about 1.7 kpc, in good agreement with previous estimates. An extended H i cloud with volume density ~0.5 cm^-3 is detected towards the NW border of SN 1006. This concentration may be responsible for the formation of the bright Balmer filaments observed in SN 1006. The absorbing column density towards SN 1006 has been estimated to be N  h ~  cm^-2, in good agreement with previous suggestions based on X-ray results.