High luminosity, slow ejecta and persistent carbon lines: SN 2009dc challenges thermonuclear explosion scenarios★

Taubenberger, S.; Benetti, S.; Childress, M.; Pakmor, Rüdiger; Hachinger, Stephan; Mazzali, P. A.; Stanishev, V.; Elias‐Rosa, N.; Agnoletto, I.; Bufano, F.; Ergon, M.; Harutyunyan, A.; Inserra, C.; Kankare, E.; Kromer, M.; Navasardyan, H.; Nicolas, J.; Pastorello, A.; Prosperi, E.; Salgado, Francisco; Sollerman, J.; Stritzinger, M. D.; Turatto, M.; Valenti, S.; Hillebrandt, W.

doi:10.1111/j.1365-2966.2010.18107.x

Cited by 203 publications

(320 citation statements)

References 119 publications

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“…In addition, the so-called super-Chandrasekhar mass SNe Ia are thought to contain >1.4 M of SN ejecta and thus are likely formed from the DD scenario (e.g., Howell et al 2006;Yamanaka et al 2009;Scalzo et al 2010;Silverman et al 2011;Taubenberger et al 2011). However, there are a few SNe Ia that show strong evidence for the SD channel, possibly with a red giant (RG) companion.…”

Section: Introductionmentioning

confidence: 99%

Type Ia Supernovae Strongly Interacting with Their Circumstellar Medium

Silverman¹,

Nugent

Gal‐Yam

et al. 2015

Proc. IAU

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Owing to their utility for measurements of cosmic acceleration, Type Ia supernovae (SNe Ia) are perhaps the beststudied class of SNe, yet the progenitor systems of these explosions largely remain a mystery. A rare subclass of SNe Ia shows evidence of strong interaction with their circumstellar medium (CSM), and in particular, a hydrogenrich CSM; we refer to them as SNe Ia-CSM. In the first systematic search for such systems, we have identified 16 SNe Ia-CSM, and here we present new spectra of 13 of them. Six SNe Ia-CSM have been well studied previously, three were previously known but are analyzed in depth for the first time here, and seven are new discoveries from the Palomar Transient Factory. The spectra of all SNe Ia-CSM are dominated by Hα emission (with widths of ∼2000 km s −1 ) and exhibit large Hα/Hβ intensity ratios (perhaps due to collisional excitation of hydrogen via the SN ejecta overtaking slower-moving CSM shells); moreover, they have an almost complete lack of He i emission. They also show possible evidence of dust formation through a decrease in the red wing of Hα 75-100 days past maximum brightness, and nearly all SNe Ia-CSM exhibit strong Na i D absorption from the host galaxy. The absolute magnitudes (uncorrected for host-galaxy extinction) of SNe Ia-CSM are found to be −21.3 mag M R −19 mag, and they also seem to show ultraviolet emission at early times and strong infrared emission at late times (but no detected radio or X-ray emission). Finally, the host galaxies of SNe Ia-CSM are all late-type spirals similar to the Milky Way, or dwarf irregulars like the Large Magellanic Cloud, which implies that these objects come from a relatively young stellar population. This work represents the most detailed analysis of the SN Ia-CSM class to date.

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Section: Introductionmentioning

confidence: 99%

Type Ia Supernovae Strongly Interacting with Their Circumstellar Medium

Silverman¹,

Nugent

Gal‐Yam

et al. 2015

Proc. IAU

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“…One reason a model SNIa might not match near the emission component of the Si II is when the model does not center C IIλ6580 at similar projected Doppler velocities as Si II during the first month after the explosion (Taubenberger et al 2011;Pereira et al 2013). Other lines that impact this region for SNIa include S IIλ6305 and lines of Fe II near maximum light and thereafter.…”

Section: Thermonuclear Sn Iamentioning

confidence: 99%

LINE IDENTIFICATIONS OF TYPE I SUPERNOVAE: ON THE DETECTION OF Si II FOR THESE HYDROGEN-POOR EVENTS

Parrent

Milisavljević

Söderberg

et al. 2016

ApJ

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Here we revisit line identifications of type I supernovae (SNe I) and highlight trace amounts of unburned hydrogen as an important free parameter for the composition of the progenitor. Most one-dimensional stripped-envelope models of supernovae indicate that observed features near 6000-6400 Å in typeI spectra are due to more than Si IIλ6355. However, while an interpretation of conspicuous Si IIλ6355 can approximate 6150 Å absorption features for all SNe Ia during the first month of free expansion, similar identifications applied to 6250 Å features of SNe Ib and Ic have not been as successful. When the corresponding synthetic spectra are compared with highquality timeseries observations, the computed spectra are frequently too blue in wavelength. Some improvement can be achieved with Fe II lines that contribute redward of 6150 Å; however, the computed spectra either remain too blue or the spectrum only reaches a fair agreement when the rise-time to peak brightness of the model conflicts with observations by a factor of two. This degree of disagreement brings into question the proposed explosion scenario. Similarly, a detection of strong Si IIλ6355 in the spectra of broadlined Ic and super-luminous events of type I/R is less convincing despite numerous model spectra used to show otherwise. Alternatively, we suggest 6000-6400 Å features are possibly influenced by either trace amounts of hydrogen or blueshifted absorption and emission in Hα, the latter being an effect which is frequently observed in the spectra of hydrogen-rich, SNe II.

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“…At least three events are currently known: SN 2003fg (Howell et al 2006), SN 2007if (Scalzo et al 2010;Yuan et al 2010) and SN 2009dc (Yamanaka et al 2009;Tanaka et al 2010;Silverman et al 2011;Taubenberger et al 2011). A fourth event, SN 2006gz (Hicken et al 2007), is usually classed with these three, although its maximum-light luminosity depends on an uncertain extinction correction from dust in its host galaxy.…”

Section: Introductionmentioning

confidence: 99%

Early ultraviolet emission in the Type Ia supernova LSQ12gdj: No evidence for ongoing shock interaction

Scalzo¹,

Childress²,

Tucker³

et al. 2014

Monthly Notices of the Royal Astronomical Society

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We present photospheric-phase observations of LSQ12gdj, a slowly-declining, UV-bright Type Ia supernova. Classified well before maximum light, LSQ12gdj has extinction-corrected absolute magnitude M B = −19.8, and pre-maximum spectroscopic evolution similar to SN 1991T and the super-Chandrasekhar-mass SN 2007if. We use ultraviolet photometry from Swift, ground-based optical photometry, and corrections from a near-infrared photometric template to construct the bolometric (1600-23800 Å) light curve out to 45 days past B-band maximum light. We estimate that LSQ12gdj produced 0.96 ± 0.07 M ⊙ of 56 Ni, with an ejected mass near or slightly above the Chandrasekhar mass. As much as 27% of the flux at the earliest observed phases, and 17% at maximum light, is emitted bluewards of 3300 Å. The absence of excess luminosity at late times, the cutoff of the spectral energy distribution bluewards of 3000 Å, and the absence of narrow line emission and strong Na I D absorption all argue against a significant contribution from ongoing shock interaction. However, ∼ 10% of LSQ12gdj's luminosity near maximum light could be produced by the release of trapped radiation, including kinetic energy thermalized during a brief interaction with a compact, hydrogen-poor envelope (radius < 10 13 cm) shortly after explosion; such an envelope arises generically in double-degenerate merger scenarios.

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High luminosity, slow ejecta and persistent carbon lines: SN 2009dc challenges thermonuclear explosion scenarios★

Cited by 203 publications

References 119 publications

Type Ia Supernovae Strongly Interacting with Their Circumstellar Medium

Type Ia Supernovae Strongly Interacting with Their Circumstellar Medium

LINE IDENTIFICATIONS OF TYPE I SUPERNOVAE: ON THE DETECTION OF Si II FOR THESE HYDROGEN-POOR EVENTS

Early ultraviolet emission in the Type Ia supernova LSQ12gdj: No evidence for ongoing shock interaction

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