J/A+A/678/A170 Effective collision strengths for Ni III (Blondin+, 2023)
Nebular spectra from Type Ia supernova explosion models compared to JWST
observations of SN 2021aefx.
Blondin S., Dessart L., Hillier D.J., Ramsbottom C.A., Storey P.J.
<Astron. Astrophys. 678, A170 (2023)>
=2023A&A...678A.170B 2023A&A...678A.170B (SIMBAD/NED BibCode)
ADC_Keywords: Atomic physics ; Excitation rates ; Models, atmosphere
Keywords: supernovae: general - radiative transfer - atomic data -
line: identification - supernovae: individual: SN 2021aefx
Abstract:
Recent JWST observations of the Type Ia supernova (SN Ia) 2021aefx in
the nebular phase have paved the way for late-time studies covering
the full optical to mid-infrared (MIR) wavelength range, and with it
the hope to better constrain SN Ia explosion mechanisms.
We investigate whether public SN Ia models covering a broad range of
progenitor scenarios and explosion mechanisms (Chandrasekhar-mass, or
MCh, delayed detonations, pulsationally assisted
gravitationally-confined detonations, sub-MCh double detonations, and
violent mergers) can reproduce the full optical-MIR spectrum of SN
2021aefx at ∼270 days post explosion. Methods. We consider
spherically-averaged 3D models available from the Heidelberg Supernova
Model Archive with a 56Ni yield in the range 0.5-0.8M☉. We
perform 1D steady-state non-local thermodynamic equilibrium
simulations with the radiative-transfer code CMFGEN, and compare the
predicted spectra to SN 2021aefx.
The models can explain the main features of SN 2021aefx over the full
wavelength range. However, no single model, or mechanism, emerges as a
preferred match, and the predicted spectra are similar to one another
despite the very different explosion mechanisms. We discuss possible
causes for the mismatch of the models, including ejecta asymmetries
and ionisation effects. Our new calculations of the collisional
strengths for NiIII have a major impact on the two prominent lines at
7.35um and 11.00um, and highlight the need for more accurate
collisional data for forbidden transitions. Using updated atomic data,
we identify a strong feature due to [CaIV] 3.21um, attributed to
[NiI] in previous studies. We also provide a tentative identification
of a forbidden line due to [NeII] 12.81um, whose peaked profile
suggests that neon is mixed inwards during the explosion, as predicted
for instance in violent merger models. Contrary to previous claims, we
show that the [ArIII] 8.99um line can be broader in sub-MCh models
compared to near-MCh models. Last, the total flux in lines of Ni is
found to correlate strongly with the stable nickel yield, although
ionisation effects can bias the inferred abundance.
Our models suggest that key physical ingredients are missing from
either the explosion models, or the radiative-transfer
post-processing, or both. Nonetheless, they also show the potential of
the near- and mid-infrared to uncover new spectroscopic diagnostics of
SN Ia explosion mechanisms.
Description:
We carried out calculations of collisional cross-sections for
electron-impact excitation of NiIII. We report transition
probabilities (Aul) and effective collision strengths (Υlu)
in the temperature range 1000-100000K. Entries for transitions among
the lowest eight levels for temperatures ≤40000K were computed
following the methods outlined in Storey et al. (2016MNRAS.456.1974S 2016MNRAS.456.1974S,
Cat. VI/148). All other entries are based on Ramsbottom et al.
(2007A&A...475..765R 2007A&A...475..765R, Cat. J/A+A/475/765); in this latter approach,
transition probabilities less than 10-10s-1 are deemed too small to
be significant and we set these to an arbitrarily small value
10-30s-1.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablef1.dat 20 43 Level indexing for NiIII used in tablef2.dat
tablef2.dat 185 903 Transition probabilities and collision strengths
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See also:
VI/148 : Collision Strengths for [Co II] Forbidden Lines - SS4
(Storey+, 2016)
J/A+A/475/765 : Fine structure forbidden lines in FeII (Ramsbottom+, 2007)
Byte-by-byte Description of file: tablef1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Index [1/43] Level index
4- 20 A17 --- Level Level name
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Byte-by-byte Description of file: tablef2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- l [1/42] Lower level index
4- 5 I2 --- u [2/43] Upper level index
7- 14 E8.3 s-1 Aul Transition probability (Einstein A value)
16- 23 E8.3 --- ups1.0e3 Effective collision strength at T=1.0e+3K
25- 32 E8.3 --- ups1.5e3 Effective collision strength at T=1.5e+3K
34- 41 E8.3 --- ups1.8e3 Effective collision strength at T=1.8e+3K
43- 50 E8.3 --- ups2.0e3 Effective collision strength at T=2.0e+3K
52- 59 E8.3 --- ups2.5e3 Effective collision strength at T=2.5e+3K
61- 68 E8.3 --- ups5.0e3 Effective collision strength at T=5.0e+3K
70- 77 E8.3 --- ups7.5e3 Effective collision strength at T=7.5e+3K
79- 86 E8.3 --- ups1.0e4 Effective collision strength at T=1.0e+4K
88- 95 E8.3 --- ups1.5e4 Effective collision strength at T=1.5e+4K
97-104 E8.3 --- ups1.8e4 Effective collision strength at T=1.8e+4K
106-113 E8.3 --- ups2.0e4 Effective collision strength at T=2.0e+4K
115-122 E8.3 --- ups3.0e4 Effective collision strength at T=3.0e+4K
124-131 E8.3 --- ups4.0e4 Effective collision strength at T=4.0e+4K
133-140 E8.3 --- ups5.0e4 Effective collision strength at T=5.0e+4K
142-149 E8.3 --- ups6.0e4 Effective collision strength at T=6.0e+4K
151-158 E8.3 --- ups7.0e4 Effective collision strength at T=7.0e+4K
160-167 E8.3 --- ups8.0e4 Effective collision strength at T=8.0e+4K
169-176 E8.3 --- ups9.0e4 Effective collision strength at T=9.0e+4K
178-185 E8.3 --- ups1.0e5 Effective collision strength at T=1.0e+5K
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Acknowledgements:
Stephane Blondim, stephane.blondin(at)lam.fr
(End) Patricia Vannier [CDS] 29-Aug-2023