J/ApJ/910/151 KMTNet BVi photometry of SNIa KSP-OT-201509b (Moon+, 2021)
Rapidly declining hostless type Ia supernova KSP-OT-201509b from the KMTNet
Supernova Program: transitional nature and constraint on 56Ni distribution and
progenitor type.
Moon D.-S., Ni Y.Qi, Drout M.R., Gonzalez-Gaitan S., Afsariardchi N.,
Park H.S., Lee Y., Kim S.C., Antoniadis J., Kim D.-J., Lee Y.
<Astrophys. J., 910, 151 (2021)>
=2021ApJ...910..151M 2021ApJ...910..151M
ADC_Keywords: Supernovae; Photometry, UBVRI
Keywords: Type Ia supernovae ; Supernovae
Abstract:
We report the early discovery and multicolor (BVI) high-cadence
light-curve analyses of the rapidly declining sub-Chandrasekhar Type
Ia supernova KSP-OT-201509b (= AT 2015cx) from the KMTNet Supernova
Program. The Phillips and color stretch parameters of KSP-OT-201509b
are ΔMB,15∼1.62mag and sBV∼0.54, respectively, at an
inferred redshift of 0.072. These, together with other measured
parameters (such as the strength of the secondary I-band peak, colors,
and luminosity), identify the source to be a rapidly declining Type Ia
of a transitional nature that is closer to Branch-normal than
91bg-like. Its early light-curve evolution and bolometric luminosity
are consistent with those of homologously expanding ejecta powered by
radioactive decay and a Type Ia SN explosion with 0.32±0.01M☉
of synthesized 56Ni mass, 0.84±0.12M☉ of ejecta mass, and
(0.61±0.14)x1051erg of ejecta kinetic energy. While its B-V and
V-I colors evolve largely synchronously with the changes in the I-band
light curve, as found in other supernovae, we also find the presence
of an early redward evolution in V-I prior to -10 days since peak. The
bolometric light curve of the source is compatible with a stratified
56Ni distribution extended to shallow layers of the exploding
progenitor. Comparisons between the observed light curves and those
predicted from ejecta-companion interactions clearly disfavor Roche
lobe-filling companion stars at large separation distances, thus
supporting a double-degenerate scenario for its origin. The lack of
any apparent host galaxy in our deep stack images reaching a
sensitivity limit of ∼28mag/arcsec2 makes KSP-OT-201509b a hostless
Type Ia supernova and offers new insights into supernova host galaxy
environments.
Description:
We conducted high-cadence, multicolor (BVI) monitoring observations of
a 2°x2° field containing the galaxy NGC 300 in the direction
of the south Galactic pole using the Korea Microlensing Telescope
Network (KMTNet) as part of its KMTNet Supernova Program (KSP;
Moon+ 2016SPIE.9906E..4IM and Afsariardchi+ 2019, J/ApJ/881/22). The
initial phase of the monitoring started in 2015 July during the
commissioning test period of the KMTNet and continued until
2017 August 9. The KMTNet operates three wide-field 1.6m telescopes
located at the Cerro Tololo Inter-American Observatory (CTIO; Chile),
the South African Astronomical Observatory (SAAO), and the Siding
Spring Observatory (SSO; Australia). We obtained about 2460 images of
the field with 60s exposure time for each of the Johnson-Cousins BVI
bands, and the mean cadence of our observations within the monitoring
period was approximately 3.5hr for each band.
The BV-band magnitudes of KSP-OT-201509b presented in this paper are
in the Vega magnitude system, while its I-band magnitudes are in the
AB system. See Section 2.
Objects:
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RA (ICRS) DE Designation(s)
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00 57 03.19 -37 02 23.6 KSP-OT-201509b = AT 2015cx
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 26 1575 Observed KMTNet BVi magnitudes of KSP-OT-201509b
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See also:
J/MNRAS/383/1485 : BVRI light curves of SN 2003jd (Valenti+, 2008)
J/AJ/139/519 : Carnegie supernova project. SNe Ia (Contreras+, 2010)
J/MNRAS/412/1441 : SNe luminosity functions (Li+, 2011)
J/MNRAS/448/1345 : YJK for Type Ia supernovae (Dhawan+, 2015)
J/A+A/578/A9 : Optical and NIR spectra of SN iPTF13ebh (Hsiao+, 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/836/60 : Bgri light curves of PTF11kmb and PTF12bho (Lunnan+, 2017)
J/ApJ/869/56 : Updated calibration of CSP-I SNe Ia sample (Burns+, 2018)
J/ApJ/881/22 : BVI phot. of TypeII SN KSP-SN-2016kf (Afsariardchi+, 2019)
J/ApJ/870/L1 : K2 obs. of type Ia supernova SN 2018oh (Dimitriadis+, 2019)
J/A+A/627/A174 : Early light curve of SN 2013gy (Holmbo+, 2019)
J/MNRAS/483/628 : SN Ia properties using bolometric LCs (Scalzo+, 2019)
J/ApJ/870/13 : K2 LC alternative analysis of ASASSN-18bt (Shappee+, 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/908/51 : TESS early LCs of type Ia Supernovae (Fausnaugh+, 2021)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 11 F11.5 d MJD [57289.89/57359.48] Time, Modified Julian Date
(JD-2400000.5)
13- 18 F6.3 mag omag [18.37/22.18] Observed magnitude in Filt (1)
20- 24 F5.3 mag e_omag [0.016/0.5] Uncertainty in omag
26- 26 A1 --- Filt [BVi] Band
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Note (1): The B- and V-band magnitudes are in the Vega system, while the
i-band magnitudes are in the AB system (see text).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 21-Sep-2022