J/ApJ/902/L8 Optical and NIR spectra of ZTF19aawfbtg (SN2019hge) (Yan+, 2020)
Helium-rich superluminous supernovae from the Zwicky Transient Facility.
Yan L., Perley D.A., Schulze S., Lunnan R., Sollerman J., De K., Chen Z.H.,
Fremling C., Gal-Yam A., Taggart K., Chen T.-W., Andreoni I., Bellm E.C.,
Cunningham V., Dekany R., Duev D.A., Fransson C., Laher R.R., Hankins M.,
Ho A.Y.Q., Jencson J.E., Kaye S., Kulkarni S.R., Kasliwal M.M.,
Golkhou V.Z., Graham M., Masci F.J., Miller A.A., Neill J.D., Ofek E.,
Porter M., Mroz P., Reiley D., Riddle R., Rigault M., Rusholme B.,
Shupe D.L., Soumagnac M.T., Smith R., Tartaglia L., Yao Y., Yaron O.
<Astrophys. J., 902, L8 (2020)>
=2020ApJ...902L...8Y 2020ApJ...902L...8Y
ADC_Keywords: Supernovae; Spectra, optical; Spectra, infrared
Keywords: Supernovae ; Type Ib supernovae
Abstract:
Helium is expected to be present in the massive ejecta of some
hydrogen-poor superluminous supernovae (SLSN-I). However, until now
only one event has been identified with He features in its
photospheric spectra (PTF10hgi). We present the discovery of a new
He-rich SLSN-I, ZTF19aawfbtg (SN2019hge), at z=0.0866. This event has
more than 10 optical spectra at phases from -41 to +103d relative to
the peak, most of which match well with that of PTF10hgi. Confirmation
comes from a near-IR spectrum taken at +34d, revealing HeI features
with P-Cygni profiles at 1.083 and 2.058µm. Using the optical
spectra of PTF10hgi and SN2019hge as templates, we examined 70 other
SLSNe-I discovered by Zwicky Transient Facility in the first two years
of operation and found five additional SLSNe-I with distinct
He-features. The excitation of HeI atoms in normal core-collapse
supernovae requires nonthermal radiation, as proposed by previous
studies. These He-rich events cannot be explained by the traditional
56Ni mixing model because of their blue spectra, high peak
luminosities, and long rise timescales. Magnetar models offer a
possible solution since pulsar winds naturally generate high-energy
particles, potential sources of nonthermal excitation. An alternative
model is the interaction between the ejecta and dense H-poor
circumstellar material, which may be supported by observed undulations
in the light curves. These six SLSNe-Ib have relatively low-peak
luminosities (rest frame Mg=-20.06±0.16).
Description:
Optical spectra of SN2019hge were obtained at -41 to +103d from the
g-band peak using the low-resolution (R∼100) Spectral Energy
Distribution Machine (SEDM) and the Double Beam Spectrograph (DBSP) on
the Palomar 60 inch and 200 inch telescopes, respectively, as well as
the Low Resolution Imaging Spectrometer (LRIS) on the Keck I
telescope. An observing log for all optical spectra of ZTF19aawfbtg
presented here is in Table 1.
SN2019hge was observed at +34d with the Near-Infrared Echellette
Spectrometer (NIRES), a prism cross-dispersed near-infrared
spectrograph mounted on the Keck II telescope. This spectrograph has a
resolution of ∼2700 and simultaneously covers the YJHK bands with a
wavelength range of 0.8-2.4um.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
22 24 21.20 +24 47 17.1 ZTF19aawfbtg = SN 2019hg
----------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 46 7 *Observing log of optical spectra for ZTF19aawfbtg
fig1.dat 66 31829 Spectra of SN2019hge (ZTF19aawfbtg) around
peak and at late phases, with PTF10hgi
(Quimby+ 2018ApJ...855....2Q 2018ApJ...855....2Q)
and SN 2005bf (Folatelli+ 2006ApJ...641.1039F 2006ApJ...641.1039F)
for comparison
fig2.dat 26 5517 The Near-IR spectrum of SN2008ax at -8 and +23d
from the B-band peak
(Taubenberger+ 2011MNRAS.413.2140T 2011MNRAS.413.2140T)
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Note on table1.dat: All spectral observations were taken using parallactic
angles.
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See also:
B/sn : Asiago Supernova Catalogue (Barbon et al., 1999-)
J/MNRAS/389/955 : u'BVg'r'i'z' light curves of SN 2008ax (Pastorello+, 2008)
J/other/PZ/29.2 : SN 2008ax UBVRI light curves (Tsvetkov+, 2009)
J/A+A/508/371 : UBVRIJHK observations of SN 2007gr (Hunter+, 2009)
J/AJ/147/99 : Spectroscopy of 73 stripped core-collapse SNe (Modjaz+, 2014)
J/ApJ/827/90 : Spectroscopy of SNe Ib, IIb and Ic (Liu+, 2016)
J/ApJ/830/13 : Host-galaxy NUV-NIR data of superluminous SNe (Perley+, 2016)
J/ApJ/860/100 : LCs of 26 hydrogen-poor superluminous SNe (De Cia+, 2018)
J/ApJ/864/45 : X-ray emission from superluminous SNe (Margutti+, 2018)
J/ApJ/886/152 : ZTF early observations of Type Ia SNe. I. LCs (Yao+, 2019)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 "Y/M/D" Date Observation date
12- 15 I4 d Phase [-26/103] Rest-frame days from the g-band peak
in the Julian date of 2458695.72
17- 25 A9 --- Tel Telescope/Instrument
27- 30 I4 s Exp [300/2250] Exposure time
32- 35 I4 0.1nm lam1 [3100/3900] Lower range of wavelength in Å
36 A1 --- --- [-]
37- 41 I5 0.1nm lam2 [9000/10000] Upper range of wavelength in Å
43- 46 I4 --- R [100/1000] Spectral resolution estimated
around 7000Å
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Byte-by-byte Description of file: fig1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- ID SN identifier
14- 23 A10 "Y/M/D" Date Observation date
25- 30 A6 --- Tel Facility (1)
32- 40 F9.3 0.1nm lambda [3056.9/24664.9] Wavelength; Angstroms
42- 53 E12.5 --- Flux [-0.023/2.8]? Flux density (2)
55- 66 E12.5 --- e_Flux [8.4e-37/0.05]? Uncertainty in Flux
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Note (1): Telescope as follows:
Keck1 = The Keck I telescope with the Low Resolution Imaging Spectrometer
(LRI; 12717 occurrences)
Keck2 = The Keck II telescope with the Near-Infrared Echellette Spectrometer
(NIRES; 6948 occurrences)
P200 = The Palomar 200inch telescope with the Double Beam Spectrograph
(DBSP; 8677 occurrences)
duPont = The Wide Field Reimaging CCD Camera (WFCCD) at the du Pont 2.5m
telescope (Folatelli+ 2006ApJ...641.1039F 2006ApJ...641.1039F ; 2845 occurrences)
P60 = The Palomar 60inch telescope with the Spectral Energy Distribution
Machine (SEDM; 642 occurrences)
Note (2): In units of erg/s/cm2/Å except for the 10hgi spectra which
are relative.
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Byte-by-byte Description of file: fig2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Phase [-8/23] Phase
5- 13 F9.3 0.1nm lambda [8700/24725.7] Wavelength; Angstroms
15- 26 E12.5 cW/m2/nm Flux [1.4e-16/7.3e-15] Flux density;
in erg/s/cm2/Å units
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 22-Apr-2022