J/A+A/694/A292 SN 2020xga and SN 2022xgc light curves (Gkini+, 2025)
Eruptive mass-loss less than a year before the explosion of superluminous
supernova. I. The cases of SN 2020xga and SN 2022xgc.
Gkini A., Fransson C., Lunnan R., Schulze S., Poidevin F., Sarin N.,
Konyves-Toth R., Sollerman J., Omand C.M.B., Brennan S.J., Hinds K.R.,
Anderson J.P., Bronikowski M., Chen T.-W., Dekany R., Fraser M.,
Fremling C., Galbany L., Gal-Yam A., Gangopadhyay A., Geier S.,
Gonzalez E.P., Gromadzki M., Groom S.L., Gutierrez C.P., Hiramatsu D.,
Howell D.A., Hu Y., Inserra C., Kopsacheili M., Lacroix L., Masci F.J.,
Matilainen K., McCully C., Moore T., Muller-Bravo T.E., Nicholl M.,
Pellegrino C., Perez-Fournon I., Perley D.A., Pessi P.J., Petrushevska T.,
Pignata G., Ragosta F., Sahu A., Singh A., Srivastav S., Wise J.L., Yan L.,
Young D.R.
<Astron. Astrophys. 694, A292 (2025)>
=2025A&A...694A.292G 2025A&A...694A.292G (SIMBAD/NED BibCode)
ADC_Keywords: Supernovae ; Photometry ; Optical
Keywords: supernovae: general - supernovae: individual: SN 2020xga -
supernovae: individual: SN 2022xgc
Abstract:
We present photometric and spectroscopic observations of SN 2020xga
and SN 2022xgc, two hydrogen-poor superluminous supernovae (SLSNe-I)
at z=0.4296 and z=0.3103 respectively, that show an additional set of
broad Mgii absorption lines, blueshifted by a few thousands km s∼1
with respect to the host galaxy absorption system. Previous work
interpreted this as due to resonance line scattering of the SLSN
continuum by rapidly expanding CSM expelled shortly before the
explosion. The peak rest-frame g-band magnitude of SN 2020xga is
∼22.30±0.04mag and of SN 2022xgc is ∼21.97±0.05mag, placing them
among the brightest SLSNe-I. We use high-quality spectra from
ultraviolet to near-infrared wavelengths to model the Mgii line
profiles and infer the properties of the CSM shells. We find that the
CSM shell of SN 2020xga resides at ∼1.3x1016cm moving with a
maximum velocity of 4275 km s∼1, and the shell of SN 2022xgc is
located at ∼0.8x1016cm reaching up to 4400km/s. These shells were
expelled ∼11 and ∼5 months before explosion for SN 2020xga and
SN 2022xgc respectively, possibly as a result of Luminous Blue
Variable-like eruptions or pulsational pair instability (PPI) mass
loss. We also analyze optical photometric data and model the light
curves considering powering from the magnetar spin-down mechanism. The
results support very energetic magnetars, approaching the
masss-hedding limit, powering these SNe with ejecta masses of
∼7-9M☉. The ejecta masses inferred from the magnetar modeling
are not consistent with the PPI scenario pointing towards stars
>50M☉ He-core, hence alternative scenarios such as fallback
accretion are discussed. Modeling the spectral energy distribution of
the host galaxy of SN 2020xga reveals a host mass of 107.8M☉,
a star formation rate of 0.96+0.47-0.26M☉/yr, and a
metallicity of ∼0.2Z☉.
Description:
The data files include the photometric data of the objects discussed
in the paper. Each file includes five columns which describes the MJD,
the phase relative to the g-band peak magnitude, the filter, the
apparent magnitude with the 1sigma uncertainty and the instrument that
the data was collected.
Objects:
----------------------------------------------------
RA (2000) DE Designation(s)
----------------------------------------------------
03 46 39.36 -11 14 33.8 SN2020xga = ATLAS 20beys
07 12 41.81 +07 18 59.9 SN2022xgc = ATLAS 22bjqu
----------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
2020xga.dat 32 155 Photometric data of SN 2020xga
2022xgc.dat 32 186 Photometric data of SN 2022xgc
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Byte-by-byte Description of file: 2020xga.dat 2022xgc.dat
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Bytes Format Units Label Explanations
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1- 7 F7.1 d MJD Modified Julian date
9- 13 F5.1 d Phase Phase
15 A1 --- Filter [grizco] Filter
17- 21 F5.2 mag mag Magnitude in Filter (AB) (1)
23- 26 F4.2 mag e_mag Magnitude in Filter (AB) error
28- 32 A5 --- Inst Instrument
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Note (1): The photometry is reported on the AB system and is not corrected for
reddening. Multiple exposures on any given night are averaged to give the
values presented here.
Rest-frame relative to the g-band maximum (MJD 59172.5) for SN 2020xga
and (MJD 59901.9) for SN 2022xgc.
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Acknowledgements:
Anamaria Gkini, anamaria.gkini(at)astro.su.se
(End) Patricia Vannier [CDS] 31-Dec-2024