J/ApJ/902/47 ZTF early obs. of type Ia SNe. II. Rise time (Miller+, 2020)
ZTF early observations of Type Ia supernovae.
II. First light, the initial rise, and time to reach maximum brightness.
Miller A.A., Yao Y., Bulla M., Pankow C., Bellm E.C., Cenko S.B.,
Dekany R., Fremling C., Graham M.J., Kupfer T., Laher R.R., Mahabal A.A.,
Masci F.J., Nugent P.E., Riddle R., Rusholme B., Smith R.M., Shupe D.L.,
van Roestel J., Kulkarni S.R.
<Astrophys. J., 902, 47 (2020)>
=2020ApJ...902...47M 2020ApJ...902...47M
ADC_Keywords: Supernovae; Surveys; Redshifts
Keywords: Type Ia supernovae ; Surveys ; Catalogs ;
Observational astronomy ; Supernovae
Abstract:
While it is clear that Type Ia supernovae (SNe) are the result of
thermonuclear explosions in C/O white dwarfs (WDs), a great deal
remains uncertain about the binary companion that facilitates the
explosive disruption of the WD. Here, we present a comprehensive
analysis of a large, unique data set of 127 SNe Ia with exquisite
coverage by the Zwicky Transient Facility (ZTF). High-cadence (six
observations per night) ZTF observations allow us to measure the SN
rise time and examine its initial evolution. We develop a Bayesian
framework to model the early rise as a power law in time, which
enables the inclusion of priors in our model. For a volume-limited
subset of normal SNe Ia, we find that the mean power-law index is
consistent with 2 in the rZTF-band (αr=2.01±0.02), as
expected in the expanding fireball model. There are, however,
individual SNe that are clearly inconsistent with αr=2. We
estimate a mean rise time of 18.9 days (with a range extending from
∼15 to 22d), though this is subject to the adopted prior. We identify
an important, previously unknown, bias whereby the rise times for
higher-redshift SNe within a flux-limited survey are systematically
underestimated. This effect can be partially alleviated if the
power-law index is fixed to α=2, in which case we estimate a
mean rise time of 21.7 days (with a range from ∼18 to 23d). The sample
includes a handful of rare and peculiar SNe Ia. Finally, we conclude
with a discussion of lessons learned from the ZTF sample that can
eventually be applied to observations from the Vera C. Rubin Observatory.
Description:
In this paper, we have presented an analysis of the initial evolution
and rise times of 127 ZTF-discovered SNe Ia with early observations;
see Paper I (Yao+ 2019, J/ApJ/886/152) for details on how the sample
was selected. These SNe were observed as part of the ZTF high-cadence
extragalactic experiment, which obtained three gZTF and three rZTF
observations every night the telescope was open.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 101 127 90% credible regions for marginalized model
parameters (uninformative prior)
table5.dat 43 127 90% credible region for trise (α=2 prior)
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See also:
J/ApJ/716/712 : HST light curves of six SNe and Union2 (Amanullah+, 2010)
J/MNRAS/410/585 : SN 2009dc BVRI light curves (Silverman+, 2011)
J/MNRAS/446/3895 : The rising light curves of Type Ia supernovae (Firth+, 2015)
J/ApJ/826/56 : HST/WFC3 obs. of Cepheids in SN Ia host gal. (Riess+, 2016)
J/ApJ/826/144 : Follow-up observations of SNIa ASASSN-14lp (Shappee+, 2016)
J/ApJ/859/101 : The supernovae Ia Pantheon sample (Scolnic+, 2018)
J/ApJ/870/L1 : K2 obs. of type Ia supernova SN 2018oh (Dimitriadis+, 2019)
J/ApJ/870/13 : K2 LC alternative analysis of ASASSN-18bt (Shappee+, 2019)
J/ApJ/886/152 : ZTF early observations of Type Ia SNe. I. LCs (Yao+, 2019)
J/A+A/634/A37 : TURTLS Light curves of 56Ni distributions (Magee+, 2020)
J/ApJ/898/56 : UVOT, ZTF gri LCs & sp. of the SN Ia 2019yvq (Miller+, 2020)
J/ApJ/902/48 : ZTF early obs. of type Ia supernovae. III. (Bulla+, 2020)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- ZTF ZTF identifier
14- 23 A10 --- Name TNS identifier
25- 30 F6.4 --- z [0.018/0.17] Spectroscopic redshift
31 A1 --- n_z Flag on z (1)
33- 37 F5.2 d trise5 [9.68/21.15] The 5th percentile rise time (3)(2)
39- 43 F5.2 d trise50 [10/23.3] The 50th percentile rise time (2)(3)
45- 49 F5.2 d trise95 [10.4/24.9] The 95th percentile rise time (3)(2)
51- 54 F4.2 --- alphag5 [0.02/3.15] The 5th percentile power-law index of
g-band rise (2)(4)
56- 59 F4.2 --- alphag50 [0.26/4.4] The 50th percentile power-law index of
g-band rise (2)(4)
61- 64 F4.2 --- alphag95 [1/6.5] The 95th percentile power-law index of
g-band rise (2)(4)
66- 69 F4.2 --- alphar5 [0.02/3] The 5th percentile power-law index of
r-band rise (2)(4)
71- 74 F4.2 --- alphar50 [0.2/5.3] The 50th percentile power-law index of
r-band rise (2)(4)
76- 79 F4.2 --- alphar95 [0.84/6.9] The 95th percentile power-law index of
r-band rise (2)(4)
81- 85 F5.2 --- ar-ag5 [-3.3/0.7] The 5th percentile power-law index of
g-r color evolution (2)(4)
87- 91 F5.2 --- ar-ag50 [-2.9/2.6] The 50th percentile power-law index of
g-r color evolution (2)(4)
93- 97 F5.2 --- ar-ag95 [-1.5/3.9] The 95th percentile power-law index of
g-r color evolution (2)(4)
99 A1 --- Rel Reliable model parameters flag;
see Appendix B (y=reliable group; 51 occurrences)
101 A1 --- Norm Normal SNe Ia flag;
see Appendix C (n=peculiar; 7 occurrences)
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Note (1): Flag as follows:
h = Redshifts are reported to 4 decimal places as the SN host galaxy
redshift (zhost) is known.
u = the SN redshift (zSN) has 3 significant decimals
See Yao+ 2019, J/ApJ/886/152 for further details.
Note (2): The 90% credible regions are obtained by subtracting the
5th percentile from the 95th percentile.
Note (3): Estimates for trise come from tfl while accounting for the
uncertainties on tB,max.
Note (4): Estimates for the α parameters have been corrected to a flat
prior (see text for further details).
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- ZTF ZTF identifier
14- 23 A10 --- Name TNS identifier
25- 29 F5.2 d trise5 [12.78/26.94] The 5th percentile rise time (1)
31- 35 F5.2 d trise50 [13.16/28.56] The 50th percentile rise time (1)
37- 41 F5.2 d trise95 [13.55/29.78] The 95th percentile rise time (1)
43 A1 --- Rel Reliable model parameters flag
(y: 122 occurrences) (2)
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Note (1): After adopting the α=2 prior (see text for further details).
Note (2): Note that the α=2 prior definition of reliable differs
from that in Appendix B (see text).
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History:
From electronic version of the journal
References:
Yao et al. Paper I. 2019ApJ...886..152Y 2019ApJ...886..152Y Cat. J/ApJ/886/152
Yao et al. Paper II. 2020ApJ...902...47M 2020ApJ...902...47M This catalog
Bulla et al. Paper III. 2020ApJ...902...48B 2020ApJ...902...48B Cat. J/ApJ/902/48
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 11-Apr-2022