THE SPECTROSCOPIC DIVERSITY OF TYPE Ia SUPERNOVAE

By S. Blondin, Thomas Matheson, R. Kirshner, Kaisey S. Mandel, P. Berlind, M. Calkins, P. Challis, P. Garnavich, S. Jha, Maryam Modjaz and 2 more. Astronomical Journal, 2000

162 citations recorded by the source corpus.

We present 2603 spectra of 462 nearby Type Ia supernovae (SNe Ia), including 2065 previously unpublished spectra, obtained during 1993–2008 through the Center for Astrophysics Supernova Program. There are on average eight spectra for each of the 313 SNe Ia with at least two spectra. Most of the spectra were obtained with the FAST spectrograph at the Fred Lawrence Whipple Observatory 1.5 m telescope and reduced in a consistent manner, making this data set well suited for studies of SN Ia spectroscopic diversity. Using additional data from the literature, we study the spectroscopic and photometric properties of SNe Ia as a function of spectroscopic class using the classification schemes of Branch et al. and Wang et al. The width–luminosity relation appears to be steeper for SNe Ia with broader lines, although the result is not statistically significant with the present sample. Based on the evolution of the characteristic Si ii λ6355 line, we propose improved methods for measuring velocity gradients, revealing a larger range than previously suspected, from ∼0 to ∼400  considering the instantaneous velocity decline rate at maximum light. We find a weaker and less significant correlation between Si ii velocity and intrinsic B − V color at maximum light than reported by Foley et al., owing to a more comprehensive treatment of uncertainties and host galaxy dust. We study the extent of nuclear burning and the presence of unburnt carbon in the outermost layers of the ejecta and report new detections of C ii λ6580 in 23 early-time SN Ia spectra. The frequency of C ii detections is not higher in SNe Ia with bluer colors or narrower light curves, in conflict with the recent results of Thomas et al. Based on nebular spectra of 27 SNe Ia, we find no relation between the FWHM of the iron emission feature at ∼4700 Å and Δm15(B) after removing the two low-luminosity SN 1986G and SN 1991bg, suggesting that the peak luminosity is not strongly dependent on the kinetic energy of the explosion for most SNe Ia. Finally, we confirm the correlation of velocity shifts in some nebular lines with the intrinsic B − V color of SNe Ia at maximum light, although several outliers suggest a possible non-monotonic behavior for the largest blueshifts.

Subfields: Astronomy and Astrophysics, Instrumentation, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/addc50b94267218d76f69151f1935225ea3945f1

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In Astronomy and Astrophysics

1. A. Filippenko
2. A. Riess
3. S. Jha
4. Weidong Li
5. Ryan Chornock
6. R. Kirshner
7. N. Smith
8. D. Maoz

In Instrumentation

1. A. Riess
2. A. Filippenko
3. J. Silverman
4. N. Smith
5. Weidong Li
6. Luis C. Ho
7. D. Leonard
8. Ryan Chornock

In Nuclear and High Energy Physics

1. D. Maoz
2. F. Mannucci
3. A. Filippenko
4. Weidong Li
5. Ryan Chornock
6. S. Jha
7. R. Kirshner
8. N. Smith

Citations in the corpus

• Berkeley Supernova Ia Program – I. Observations, data reduction and spectroscopic sample of 582 low-redshift Type Ia supernovae (2012, methodology): “The telescope scheduling and observing method are very different from those of Matheson et al. (2008) and (Blondin et al. 2012), who observed fewer SNe Ia but with a higher cadence for each object (see Section 6.1 for further comparisons of the two spectral datasets).”
• A Comprehensive Measurement of the Local Value of the Hubble Constant with 1 km s−1 Mpc−1 Uncertainty from the Hubble Space Telescope and the SH0ES Team (2021, methodology): “We obtain spectra directly from the Open Supernova Catalog25 (OSC; Guillochon et al. 2017), which aggregates data from numerous sources (including notable low-redshift SN Ia spectroscopy releases; e.g., Silverman et al. 2012; Blondin et al. 2012; Folatelli et al. 2013; Stahl et al. 2020b).”
• CfA4: LIGHT CURVES FOR 94 TYPE Ia SUPERNOVAE (2012, methodology): “This paper, with a sample of 94 new optical light curves, has substantial overlap with CfA NIR photometry (A. Friedman et al. 2012, in preparation) and optical spectra (Blondin et al. 2012) of the same objects.”
• Observational Clues to the Progenitors of Type Ia Supernovae (2013, background): “Blondin et al. (2012) and Silverman, Ganeshalingam & Filippenko (2013) have argued that the relation is driven only by very under-luminous events, and no correlation remains once they are excluded.”
• HEAD-ON COLLISIONS OF WHITE DWARFS IN TRIPLE SYSTEMS COULD EXPLAIN TYPE Ia SUPERNOVAE (2013, background): “…for several non- 8 Obtained from the Berkeley Supernova Ia Program (BSNIP; Silverman et al. 2013), the Center for Astrophysics Supernova Program (Blondin et al. 2012), and the compilation from various sources by the online Supernova Spectrum Archive (SUSPECT http://nhn.nhn.ou.edu/∼suspect/).”
• TYPE Iax SUPERNOVAE: A NEW CLASS OF STELLAR EXPLOSION (2012, methodology): “Blondin et al. (2012) presented several spectra of SN 2008A. 2.16.”
• OPTICAL SPECTRA OF 73 STRIPPED-ENVELOPE CORE-COLLAPSE SUPERNOVAE (2014, methodology): “…we downloaded the SN Ia data (A color version of this figure is available in the online journal.) from the CfA SN Archive (using spectra from Blondin et al. 2012 and photometry from Riess et al. 1999; Jha et al. 2006; Hicken et al. 2009) and re-analyzed them by applying the same procedure…”