Broad emission lines from the opaque electron‐scattering environment of SN 1998S

By N. Chugai. 2001

165 citations recorded by the source corpus.

I propose that broad narrow-topped emission lines with full width at zero intensity >20 000 km s−1 revealed by early-time spectra of SN 1998S originate from a dense circumstellar shell (CS) with an outer radius R≈1015 cm. The tremendous line width is the result of multiple scattering of the photons of the narrow line by the thermal electrons of the opaque CS gas. The Hα line on 1998 March 6 is reproduced by Monte Carlo simulations, provided that the Thomson optical depth of the CS shell is 3–4 at this epoch. The high density of the CS shell implies that a cool dense shell (CDS), which forms at the ejecta–wind interface, is opaque in the Paschen continuum for about 40–50 d after the explosion. This explains why strong lines from the supernova ejecta were not seen during an initial period of about 40 d after the discovery of this object. The Thomson optical depth recovered from the electron-scattering wings is consistent with observational constraints imposed by the bolometric luminosity, photospheric radius and expansion velocity of the CDS.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/1d649349b51cf15e0feb5300d84bdb1c00d2fc72

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In Astronomy and Astrophysics

1. N. Smith
2. S. Smartt
3. A. Filippenko
4. E. Berger
5. Ryan Chornock
6. A. Riess
7. Weidong Li
8. R. Kirshner

Citations in the corpus

• CALTECH CORE-COLLAPSE PROJECT (CCCP) OBSERVATIONS OF TYPE IIn SUPERNOVAE: TYPICAL PROPERTIES AND IMPLICATIONS FOR THEIR PROGENITOR STARS (2010, methodology): “…previous studies. vshock is extracted from the intermediate component in the Hα feature (following the interpretation presented in section § 1; but see Chugai 2001; Dessart et al. 2009) and vwind is extracted from the narrow component and/or the blue edge of the narrow P-Cygni profile (see…”
• HIGH-DENSITY CIRCUMSTELLAR INTERACTION IN THE LUMINOUS TYPE IIn SN 2010jl: THE FIRST 1100 DAYS (2013, methodology): “This is done by a Monte Carlo code developed for this purpose, which is similar to that developed by Auer & van Blerkom (1972) and Chugai (2001).”
• Spectropolarimetry of Supernovae (2008, background): “Soc., 345, 111 Chornock et al.(2006)Chornock, R., Filippenko, A. V., Branch, D., Foley, R. J., Jha, S., & Li, W. 2006, PASP, 118, 722 Chugai(2001)Chugai, N. N. 2001, Mon.”
• SPECTRAL EVOLUTION OF THE EXTRAORDINARY TYPE IIn SUPERNOVA 2006gy (2009, background): “In this interpretation, the net +150 km s−1 redshift of the Lorentzian centroid corresponds to the expansion speed of the CSM at these inner radii (see Chugai 2001).”
• Light-curve modelling of superluminous supernova 2006gy: collision between supernova ejecta and a dense circumstellar medium (2012, methodology): “As is shown in the previous works (e.g. Chevalier & Fransson 1994; Chugai 2001; Chugai et al. 2004) and as will be shown in the following sections, the interaction of SN ejecta and a dense CSM results in a dense cool shell between the SN ejecta and the dense CSM.”
• A PANCHROMATIC VIEW OF THE RESTLESS SN 2009ip REVEALS THE EXPLOSIVE EJECTION OF A MASSIVE STAR ENVELOPE (2013, background): “Interpreting the broad wings as a result of multiple Thomson scattering in the circumstellar shell of the narrow-line radiation (Chugai 2001) suggests that the optical depth of the unaccelerated circumstellar shell envelope to Thomson scattering is τ ∼ 3.”
• SN 2008S: An electron-capture SN from a super-AGB progenitor? (2009, background): “Alternatively it might be IR radiation from shock-heated newly-formed CDS dust or pre-existing circumstellar grains.”
• SHOCK BREAKOUT IN DENSE MASS LOSS: LUMINOUS SUPERNOVAE (2011, background): “Outside of the shell is an electron scattering region of moderate optical depth (between c/vsh and 1) where the peaked Hα profile with a broad base can be formed (Chugai 2001; Smith et al. 2010); the broadening is due to scattering in the thermal gas as opposed to the Doppler effect.”
• Luminous blue variable eruptions and related transients: diversity of progenitors and outburst properties (2010, background): “…Lorentzian profile with a small contribution from very narrow emission closely resembles that of the Type IIn SNe 1998S and 2006gy at early times (Chugai 2001; Smith et al. 2010b), which was thought to be indicative of diffusion of radiation through an opaque circumstellar envelope or slow wind.”
• The Type IIn supernova 1994W: evidence for the explosive ejection of a circumstellar envelope (2004, methodology): “In many respects our approach repeats the analysis of SN 1998S by Chugai (2001), which involved calculations of the CDS dynamics and Monte Carlo computations of the emergent lines formed outside the CDS.”
• Carnegie Supernova Project: Observations of Type IIn supernovae ⋆ (2013, background): “Within this general picture, the broad-line component is typically associated with SN emission, although one cannot rule out thermal broadening of the narrow core for an optically thick wind (Chugai 2001).”
• Nearby Supernova Factory Observations of SN 2005gj: Another Type Ia Supernova in a Massive Circumstellar Envelope (2006, background): “However, Thomson scattering of the lines also must be considered (Chugai 2001;Wang et al. 2004).”
• DUST AND THE TYPE II-PLATEAU SUPERNOVA 2004dj (2009, background): “…the bulk motion of the ejecta however, some of the width of the Hα and Paβ lines may also have been produced by scattering from thermal electrons as in the cases of SN 1998S (Chugai 2001) and SN 2006gy (Smith et al. 2010), but this effect is unlikely to have a significant influence at later epochs.”
• THE ULTRAVIOLET-BRIGHT, SLOWLY DECLINING TRANSIENT PS1-11af AS A PARTIAL TIDAL DISRUPTION EVENT (2013, background): “The same CSM that provides the ongoing interaction luminosity in SNe IIn is ionized by the SN shock prior to the interaction and produces strong Balmer line emission (Chugai 2001), but such lines are not present in PS1-11af at any time.”