J/A+A/655/A90ivo://CDS.VizieR/J/A+A/655/A90doi:10.26093/cds/vizier.36550090CDSYang S.Sollerman J.Strotjohann N.L.Schulze S.Lunnan R.Kool E.,Fremling C.Perley D.Ofek E.Schweyer T.Bellm E.C.Kasliwal M.M.,Masci F.J.Rigault M.Yang Y.2021-12-03T13:25:55Z2021-11-26T12:18:30ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frsupernovaeinfrared-photometryvisible-astronomybroad-band-photometryspectroscopyWe present observations and analysis of SN 2020cxd, a low-luminosity (LL), long-lived Type IIP supernova (SN). This object was a clear outlier in the magnitude-limited SN sample recently presented by the Zwicky Transient Facility (ZTF) Bright Transient Survey. We demonstrate that SN 2020cxd is an additional member of the group of LL SNe, and discuss the rarity of LL SNe in the context of the ZTF survey, and how further studies of these faintest members of the core-collapse (CC) SN family might help understand the underlying initial mass function for stars that explode. We present optical light curves (LCs) from the ZTF in the $gri$ bands and several epochs of ultra-violet data from the Neil Gehrels Swift Observatory as well as a sequence of optical spectra. We construct colour curves, a bolometric LC, compare ejecta-velocity and black-body temperature evolutions for LL SNe, as well as for typical Type II SNe. Furthermore, we adopt a Monte Carlo code that fits semi-analytic models to the LC of SN 2020cxd, which allows the estimation of physical parameters. Using our late-time nebular spectra, we also compare against SN II spectral synthesis models from the literature to constrain the progenitor properties of SN 2020cxd. The LCs of SN 2020cxd show great similarity with those of LL SNe IIP, in luminosity, timescale and colours. Also the spectral evolution of SN 2020cxd is that of a Type IIP SN. The spectra show prominent and narrow P-Cygni lines, indicating low expansion velocities. This is one of the faintest LL SNe observed, with an absolute plateau magnitude of M_r_=-14.5mag, and also one with the longest plateau lengths, with a duration of 118 days. Finally, the velocities measured from the nebular emission lines are among the lowest ever seen in a SN, with intrinsic Full Width at Half Maximum of 478km/s. The underluminous late-time exponential LC tail indicates that the mass of ^56^Ni ejected during the explosion is much smaller than the average of normal SNe IIP, we estimate M_^56^Ni_=0.003M+{sun+_. The Monte Carlo fitting of the bolometric LC suggests that the progenitor of SN 2020cxd had a radius of R_0_=1.3x10^13^cm, kinetic energy of E_kin_=4.3x10^50^erg, and ejecta mass M_ej_=9.5M_{sun}_. From the bolometric LC, we estimate the total radiated energy E_rad_=1.52x10^48^erg. Using our late-time nebular spectra, we compare against SN II spectral synthesis models to constrain the progenitor Zero-age Main-sequence mass and found it likely to be <~15M_{sun}+. SN 2020cxd is a LL Type IIP SN. The inferred progenitor parameters and the features observed in the nebular spectrum favour a low-energy, Ni-poor, iron CC SN from a low mass ~12M_{sun}_ red supergiant.2021A&A...655A..90Yhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/655/A90CatalogResearchIsServedByTAP VizieR generic servicerelated-tohttp://www.wiserep.org/object/14204 : WISeREPhttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/655/A90https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/655/A90http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/655/A90https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/655/A90https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/655/A90http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/655/A90GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tap3.322582951404819e-19 6.118840631666147e-19OpticalInfrareddefaultJ/A+A/655/A90/groundPhotometry of P48 P60 LT and NOTrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJD[2458896.0/2459131.37] Julian Datedtime.epochdoublePhase[-1.52/232.94] Rest Frame Phasedtime.intervalfloatInstInstrument Namemeta.id;instrcharl_umagUpper limit flag on umagmeta.code.errorcharumag? u band magnitude (1)magphot.mag;em.opt.Ufloatnullablee_umag? Error of u band magnitudemagstat.error;phot.magfloatnullablel_gmagUpper limit flag on gmagmeta.code.errorchargmag? g band magnitude (1)magphot.mag;em.opt.Bfloatnullablee_gmag? Error of g band magnitudemagstat.error;phot.magfloatnullablel_rmagUpper limit flag on rmagmeta.code.errorcharrmag? r band magnitude (1)magphot.mag;em.opt.Rfloatnullablee_rmag? Error of r band magnitudemagstat.error;phot.magfloatnullablel_imagUpper limit flag on imagmeta.code.errorcharimag? i band magnitude (1)magphot.mag;em.opt.Ifloatnullablee_imag? Error of i band magnitudemagstat.error;phot.magfloatnullablezmag? z band magnitudemagphot.mag;em.opt.Ifloatnullablee_zmag? Error of z band magnitudemagstat.error;phot.magfloatnullableJ/A+A/655/A90/swiftPhotometry of Swift UVOTUVW2? UVW2 band magnitude (1)magphot.mag;em.UVfloatnullablee_UVW2? Error of UVW2 band magnitudemagstat.errorfloatnullablel_UVM2Upper limit flag on UVM2 (1)meta.code.errorcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJD[2458899.87/2459003.04] Julian Datedtime.epochdoublePhase[2.33/105.1] Rest Frame Phasedtime.intervalfloatl_VmagUpper limit flag on Vmagmeta.code.errorcharVmagV band magnitude (1)magphot.mag;em.opt.Vfloate_Vmag? Error of V band magnitudemagstat.error;phot.magfloatnullableBmagB band magnitudemagphot.mag;em.opt.Bfloate_BmagError of B band magnitudemagstat.error;phot.magfloatl_UmagUpper limit flag on Umagmeta.code.errorcharUmagU band magnitude (1)magphot.mag;em.opt.Ufloate_Umag? Error of U band magnitudemagstat.error;phot.magfloatnullablel_UVW1Upper limit flag on UVW1meta.code.errorcharUVW1? UVW1 band magnitude (1)magphot.mag;em.UVfloatnullablee_UVW1? Error of UVW1 band magnitudemagstat.errorfloatnullablel_UVW2Upper limit flag on UVW2meta.code.errorcharUVM2? UVM2 band magnitudemagphot.mag;em.UVfloatnullablee_UVM2? Error of UVM2 band magnitudemagstat.errorfloatnullableJ/A+A/655/A90/lt-0220Calibrated Spectrum of LT on 2020/02/20recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength0.1nmem.wlfloatFlux? Flux (erg/cm^2^/s/{AA})10mW.m**-2.nm**-1phot.fluxdoublenullableJ/A+A/655/A90/p60-0220Calibrated Spectrum of P60 on 2020/02/20recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength0.1nmem.wlfloatFlux? Flux (erg/cm^2^/s/{AA})10mW.m**-2.nm**-1phot.fluxdoublenullableJ/A+A/655/A90/p60-0225Calibrated Spectrum of P60 on 2020/02/25recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength0.1nmem.wlfloatFlux? Flux (erg/cm^2^/s/{AA})10mW.m**-2.nm**-1phot.fluxdoublenullableJ/A+A/655/A90/p60-0522Calibrated Spectrum of P60 on 2020/05/22recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength0.1nmem.wlfloatFlux? Flux (erg/cm^2^/s/{AA})10mW.m**-2.nm**-1phot.fluxdoublenullableJ/A+A/655/A90/lt-0625Calibrated Spectrum of LT on 2020/06/25lambdaWavelength0.1nmem.wlfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFlux? Flux (erg/cm^2^/s/{AA})10mW.m**-2.nm**-1phot.fluxdoublenullableJ/A+A/655/A90/p60-0626Calibrated Spectrum of P60 on 2020/06/26recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength0.1nmem.wlfloatFlux? Flux (erg/cm^2^/s/{AA})10mW.m**-2.nm**-1phot.fluxdoublenullableJ/A+A/655/A90/not-0701Calibrated Spectrum of NOT on 2020/07/01recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength0.1nmem.wlfloatFlux? Flux (erg/cm^2^/s/{AA})10mW.m**-2.nm**-1phot.fluxdoublenullableJ/A+A/655/A90/geminiCalibrated Spectrum of Gemini on 2020/07/28recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength0.1nmem.wlfloatFlux? Flux (erg/cm^2^/s/{AA})10mW.m**-2.nm**-1phot.fluxdoublenullableJ/A+A/655/A90/keck1Calibrated Spectrum of Keck1 on 2020/10/19recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength0.1nmem.wlfloatFlux? Flux (erg/cm^2^/s/{AA})10mW.m**-2.nm**-1phot.fluxdoublenullable