J/ApJ/923/L8 Follow-up phot. & sp. of SNIa 2020hvf (Jiang+, 2021)
Discovery of the fastest early optical emission from overluminous SNIa 2020hvf:
a thermonuclear explosion within a dense circumstellar environment.
Jiang J.-A., Maeda K., Kawabata M., Doi M., Shigeyama T., Tanaka M.,
Tominaga N., Nomoto K., Niino Y., Sako S., Ohsawa R., Schramm M.,
Yamanaka M., Kobayashi N., Takahashi H., Nakaoka T., Kawabata K.S.,
Isogai K., Aoki T., Kondo S., Mori Y., Arimatsu K., Kasuga T.,
Okumura S.-I., Urakawa S., Reichart D.E., Taguchi K., Arima N.,
Beniyama J., Uno K., Hamada T.
<Astrophys. J. 923, L8 (2021)>
=2021ApJ...923L...8J 2021ApJ...923L...8J (SIMBAD/NED BibCode)
ADC_Keywords: Supernovae; Photometry, UBVRI; Ultraviolet; Spectra, optical
Keywords: Supernovae; Type Ia supernovae; Time domain astronomy
Transient sources; White dwarf stars
Abstract:
In this Letter we report a discovery of a prominent flash of a
peculiar overluminous Type Ia supernova, SN 2020hvf, in about 5hr of
the supernova explosion by the first wide-field mosaic CMOS sensor
imager, the Tomo-e Gozen Camera. The fast evolution of the early flash
was captured by intensive intranight observations via the Tomo-e Gozen
high-cadence survey. Numerical simulations show that such a prominent
and fast early emission is most likely generated from an interaction
between 0.01M☉ circumstellar material (CSM) extending to a
distance of ∼1013cm and supernova ejecta soon after the explosion,
indicating a confined dense CSM formation at the final evolution stage
of the progenitor of SN 2020hvf. Based on the CSM-ejecta
interaction-induced early flash, the overluminous light curve, and the
high ejecta velocity of SN 2020hvf, we suggest that the SN 2020hvf may
originate from a thermonuclear explosion of a super-Chandrasekhar-mass
white dwarf ("super-MCh WD"). Systematical investigations on
explosion mechanisms and hydrodynamic simulations of the super-MCh
WD explosion are required to further test the suggested scenario and
understand the progenitor of this peculiar supernova.
Description:
The Tomo-e Gozen camera (Tomo-e), is a wide-field mosaic CMOS sensor
imager mounted on the 1.05m Schmidt Telescope at the Kiso Observatory,
the University of Tokyo, Japan. The Tomo-e Gozen transient survey was
officially launched on 2019 October 1. See Section 2.
SN 2020hvf was discovered by the Asteroid Terrestrial-impact Last
Alert System (ATLAS) as a supernova candidate on UT 2020 April 21.38,
which was independently discovered by Tomo-e (internally designated as
Tomo-e202004aaelb) on UT 2020 April 20.5019 (MJD 58959.5019, ∼19.20d
before the polynomial-fitted B-band peak epoch). The Tomo-e
observation of the SN 2020hvf was continued for 10 days.
We carried out ground-based follow-up observations starting from
MJD58963.4, about 3.9d after the Tomo-e discovery with the Seimei 3.8m
telescope of Kyoto University and Kanata 1.5m telescope of Hiroshima
University.
In addition, multiband follow-up observations were performed using
several small robotic telescopes from 10 days after the Tomo-e
discovery. We used the 35cm telescope DSO-14 located at the Dark Sky
Observatory and the 60cm Rapid Response Robotic Telescope (RRRT)
located at the Fan Mountain Observatory. In addition we used two 70cm
telescopes located at the Sierra Remote Observatory and Spring Brook
Observatory which are operated as part of the Thai Robotic Telescope
(TRT) network.
The Ultraviolet Optical Telescope (UVOT) installed on the Neil Gehrels
Swift Observatory began observing SN 2020hvf on MJD 58961.10, about
1.60d after the Tomo-e discovery. The UVOT observation lasted for
about three months (from ~-18 to 60 days after the B-band peak).
SN 2020hvf was spectroscopically identified as an SN Ia by
Burke+ (2020TNSCR1105....1B 2020TNSCR1105....1B) who took a spectrum of SN 2020hvf by
FLOYDS-N installed on the Las Cumbres Observatory 2m telescopes on
Haleakala (FTN) on MJD 58961.25, about one day after the ATLAS
discovery.
In our follow-up observations, a series of spectra of SN 2020hvf have
been taken by the Kyoto Okayama Optical Low-dispersion Spectrograph
with an integral field unit (KOOLS-IFU; 4000-8900Å, R∼500) mounted
on the newly built Seimei 3.8m telescope and HOWPol from ~-16 to 208d
after the B-band peak.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
11 21 26.45 +03 00 52.8 SN 2020hvf = SN 2020hvf
----------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 115 109 Ground-based optical/NIR imaging observations
of SN 2020hvf
table2.dat 87 26 Swift/UVOT observations of SN 2020hvf
list.dat 59 4 List of spectra; table added by CDS
sp/* . 4 Spectra of SN 2020hvf at -16, -10, -3, and +10d
relative to the B-band peak epoch in ASCII format
(Data behind Figure 3)
--------------------------------------------------------------------------------
See also:
B/vsx : AAVSO International Variable Star Index VSX (Watson+, 2006-)
J/ApJ/607/810 : Companions to isolated elliptical galaxies (Madore+, 2004)
J/MNRAS/410/585 : SN 2009dc BVRI light curves (Silverman+, 2011)
J/ApJ/750/99 : The Pan-STARRS1 photometric system (Tonry+, 2012)
J/AJ/146/86 : Cosmicflows-2 catalog (CF2) (Tully+, 2013)
J/A+A/634/A37 : TURTLS Light curves of 56Ni distributions (Magee+, 2020)
J/A+A/675/A195 : ZTF DR11 classif. in ZTF/4MOST sky (Sanchez-Saez+, 2023)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 yr Obs.Y [2020] UT Observation date, year
6- 8 A3 "month" Obs.M UT Observation date, month
10- 16 F7.4 d Obs.D UT Observation date, fractional day in month
18- 25 F8.4 d Phase [-19.2/75.2] Phase,
relative to 2020-May-9.8047 (G1)
27 I1 --- Tel Telescope code (1)
29- 33 F5.2 mag Cmag [13.26/17.65]? Tomo-e non-filter "Clear" AB
magnitude (2)
35- 38 F4.2 mag e_Cmag [0.03/0.3]? Uncertainty in Cmag (3)
40- 44 F5.2 mag Bmag [12.6/16.4]? B-band Vega magnitude (2)
46- 49 F4.2 mag e_Bmag [0.02/0.2]? Uncertainty in Bmag
51- 55 F5.2 mag Vmag [12.6/16.2]? V-band Vega magnitude (2)
57- 60 F4.2 mag e_Vmag [0.02/0.1]? Uncertainty in Vmag
62- 66 F5.2 mag Rmag [12.6/16]? R-band Vega magnitude (2)
68- 71 F4.2 mag e_Rmag [0.03/0.07]? Uncertainty in Rmag
73- 77 F5.2 mag Imag [12.8/16]? I-band Vega magnitude (2)
79- 82 F4.2 mag e_Imag [0.04/0.08]? Uncertainty in Imag
84- 88 F5.2 mag Jmag [12.2/14.82]? J-band Vega magnitude (2)
90- 93 F4.2 mag e_Jmag [0.03/0.2]? Uncertainty in Jmag
95- 99 F5.2 mag Hmag [12.2/14.4]? H-band Vega magnitude (2)
101-104 F4.2 mag e_Hmag [0.03/0.3]? Uncertainty in Hmag
106-110 F5.2 mag Ksmag [11.8/14.7]? Ks-band Vega magnitude (2)
112-115 F4.2 mag e_Ksmag [0.02/0.4]? Uncertainty in Ksmag
--------------------------------------------------------------------------------
Note (1): Telescope code as follows:
1 = Kiso 1.05m Schmidt/Tomo-e Gozen (34 occurrences);
2 = Kanata 1.5m/Hiroshima One-shot Wide-field Polarimeter (HOWPol;
22 occurrences);
3 = Kanata 1.5m/Hiroshima Optical and Near-InfraRed camera (HONIR;
13 occurrences);
4 = 35cm telescope DSO-14, Dark Sky Observatory (16 occurrences);
5 = 60cm Rapid Response Robotic Telescope (RRRT; 15 occurrences);
6 = two 70cm telescopes located at the Sierra Remote Observatory and
Spring Brook Observatory, the Thai Robotic Telescope network
(TRT SRO/SBO; 9 occurrences).
Note (2): The Galactic extinction (E(B-V)MW=0.0356mag) has been corrected.
Note (3): The absolute flux calibration error is not included.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 yr Obs.Y [2020] UT Observation date, year
6- 8 A3 "month" Obs.M UT Observation date, month
10- 14 F5.2 d Obs.D UT Observation date, fractional day in month
16- 21 F6.2 d Phase [-17.6/66] Phase, relative to
2020-May-9.8047 (G1)
23- 27 F5.2 mag UVW2mag [13.6/17.7]? Swift/UVOT UVW2 Vega magnitude
29- 32 F4.2 mag e_UVW2mag [0.05/0.2]? Uncertainty in UVW2mag
34- 38 F5.2 mag UVM2mag [13.2/18]? Swift/UVOT UVM2 Vega magnitude
40- 43 F4.2 mag e_UVM2mag [0.06/0.2]? Uncertainty in UVM2mag
45- 49 F5.2 mag UVW1mag [12.5/17.2]? Swift/UVOT UVW1 Vega magnitude
51- 54 F4.2 mag e_UVW1mag [0.05/0.3]? Uncertainty in UVW1mag
56- 60 F5.2 mag Umag [11.9/16.6]? Swift/UVOT U-band Vega magnitude
62- 65 F4.2 mag e_Umag [0.04/0.1]? Uncertainty in Umag
67- 71 F5.2 mag Bmag [12.68/17.2]? Swift/UVOT B-band Vega magnitude
73- 76 F4.2 mag e_Bmag [0.04/0.2]? Uncertainty in Bmag
78- 82 F5.2 mag Vmag [12.6/16.8]? Swift/UVOT V-band Vega magnitude
84- 87 F4.2 mag e_Vmag [0.03/0.2]? Uncertainty in Vmag
--------------------------------------------------------------------------------
Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- Tel Telescope/Instrument
18- 21 I4 yr Obs.Y [2020] UT Observation date, year
23- 24 I2 "month" Obs.M UT Observation date, month
26- 27 I2 d Obs.D UT Observation date, fractional day in month
29- 31 I3 d Phase [-16/10] Phase, relative to 2020-May-9.8 (G1)
33- 59 A27 --- FileName Name of the ASCII file in subdirectory "sp"
--------------------------------------------------------------------------------
Byte-by-byte Description of file: sp/*
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 F16.11 0.1nm lambda [3650.3/9500] Wavelength, Angstroms
18- 30 E13.6 cW/m2/nm S [-3.6e-13/1.4e-13] Flux density,
erg/s/cm2/Angstrom (1)
--------------------------------------------------------------------------------
Note (1): Galactic extinction has not been corrected.
--------------------------------------------------------------------------------
Global notes:
Note (G1): Days (rest-frame) relative to the estimated date of the B-band
maximum, 2020 May 9.8047.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 07-Jun-2023