http://arxiv.org/abs/1511.05668
Na I D absorbing systems towards Type Ia Supernovae (SNe Ia) have been intensively studied over the last decade with the aim of finding circumstellar material (CSM), which is an indirect probe of the progenitor system. However, it is difficult to deconvolve CSM components from non-variable, and often dominant, components created by interstellar material (ISM). We present a series of high resolution spectra of SN Ia 2014J from before maximum brightness to >~250 days after maximum brightness. The late-time spectrum provides unique information for determining the origin of the Na I D absorption systems. The deep late-time observation allows us to probe the environment around the SN at a large scale, extending to >~40 pc. We find that a spectrum of diffuse light in the vicinity, but not directly in the line-of-sight of the SN, has absorbing systems nearly identical to those obtained for the `pure’ SN line-of-sight. Therefore, basically all Na I D systems seen towards SN 2014J must originate from foreground material that extends to at least ~40 pc in projection and none at the CSM scale. A fluctuation in the column densities at a scale of ~20 pc is also identified. After subtracting the diffuse, “background” spectrum, the late-time SN line-of-sight Na I D profile is consistent with that of near-maximum brightness profiles. The lack of variability on a ~1 year timescale is consistent with the ISM interpretation for the gas.
K. Maeda, A. Tajitsu, K. Kawabata, et. al.
Thu, 19 Nov 15
69/73
Comments: 20 pages, 17 figures, 1 table. Accepted for publication in ApJ
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