J/A+A/694/A12 ZTF SN Ia DR2. Secondary maximum in Type Ia SN (Deckers+, 2025)
ZTF SN Ia DR2: Secondary maximum in Type Ia supernovae.
Deckers M., Maguire K., Shingles L., Dimitriadis G., Rigault M., Smith M.,
Goobar A., Nordin J., Johansson J., Amenouche M., Burgaz U., Dhawan S.,
Ginolin M., Harvey L., Kenworthy W.D., Kim Y.-L., Laher R.R., Luo N.,
Kulkarni S.R., Masci F.J., Galbany L., Mueller-Bravo T.E., Nugent P.E.,
Pletskova N., Purdum J., Racine B., Sollerman J., Terwel J.H.
<Astron. Astrophys. 694, A12 (2025)>
=2025A&A...694A..12D 2025A&A...694A..12D (SIMBAD/NED BibCode)
ADC_Keywords: Supernovae ; Photometry ; Optical
Keywords: surveys - supernovae: general
Abstract:
Type Ia supernova (SN Ia) light curves have a secondary maximum that
exists in the r, i, and near-infrared filters. The secondary maximum
is relatively weak in the r band, but holds the advantage that it is
accessible, even at high redshift. We used Gaussian Process fitting to
parameterise the light curves of 893 SNe Ia from the Zwicky Transient
Facility's (ZTF) second data release (DR2), and we were able to
extract information about the timing and strength of the secondary
maximum. We found >5σ correlations between the light curve decline
rate ({DELTA}m15(g)) and the timing and strength of the secondary maximum
in the r band. Whilst the timing of the secondary maximum in the i
band also correlates with {DELTA}m15(g), the strength of the secondary
maximum in the i band shows significant scatter as a function of
{DELTA}m15(g). We found that the transparency timescales of 97 per cent of
our sample are consistent with double detonation models, and that SNe
Ia with small transparency timescales (<32d) reside predominantly in
locally red environments. We measured the total ejected mass for the
normal SNe Ia in our sample using two methods, and both were
consistent with medians of 1.3±0.3 and 1.2±0.2 solar masses. We
find that the strength of the secondary maximum is a better
standardisation parameter than the SALT light curve stretch (x1).
Finally, we identified a spectral feature in the r band as FeII,
which strengthens during the onset of the secondary maximum. The same
feature begins to strengthen at <3d post maximum light in 91bg-like
SNe. Finally, the correlation between x1 and the strength of the
secondary maximum was best fit with a broken line, with a split at
x01=-0.5±0.2, suggestive of the existence of two populations of
SNe Ia.
Description:
Summary of timing of secondary maximum in the r and i bands (t2_r,
t2_i) and the integrated flux under the secondary maximum in the r and
i bands (f2_r, f2_i) all with associated errors.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
2ndmax2.dat 162 893 Properties of the secondary maximum derived from
the Gaussian process fits
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See also:
J/A+A/694/A9 : Spectral Measurements of ZTF SN Ia DR2 (Burgaz+, 2025)
J/A+A/694/A10 : ZTF SN Ia DR2 (Dimitriadis+, 2025)
J/A+A/694/A11 : SN 2020alm spectrum (Terwel+, 2025)
Byte-by-byte Description of file: 2ndmax2.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name ZTF name (ZTFNNaaaaaaa)
14- 19 F6.3 d t2r ? Timing of secondary maximum in the r band
21- 38 F18.16 d e_t2r ? Timing of secondary maximum in the r band error
40- 45 F6.3 d t2i ? Timing of secondary maximum in the i band
47- 64 F18.16 d e_t2i ? Timing of secondary maximum in the i band error
66- 83 F18.16 --- F2r ? Integrated flux under the secondary maximum
in the r band (1)
85-102 F18.16 --- e_F2r ? Integrated flux under the secondary maximum
in the r band error
104-121 F18.16 --- F2i ? Integrated flux under the secondary maximum
in the r band (1)
123-140 F18.16 --- e_F2i ? Integrated flux under the secondary maximum
in the r band error
142-151 F10.6 deg RAdeg Right ascension (J2000)
153-162 F10.6 deg DEdeg Declination (J2000)
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Note (1): normalised to peak flux and divided by the number of days of the
integration interval.
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Acknowledgements:
Maxime Deckers, deckersm(at)tcd.ie
(End) Patricia Vannier [CDS] 28-Jun-2024