J/ApJ/902/L8ivo://CDS.VizieR/J/ApJ/902/L8doi:10.26093/cds/vizier.19029008CDSYan 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.2022-06-13T11:40:47Z2022-05-13T09:11:12ZCDS support team

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

cds-question@unistra.frsupernovaevisible-astronomyspectroscopyinfrared-astronomyHelium 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 2.058{mu}m. 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 ^56^Ni 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).2020ApJ...902L...8Yhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/902/L8CatalogResearchIsServedByTAP VizieR generic servicerelated-toB/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)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/902/L8https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/902/L8http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/902/L8https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/902/L8https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/902/L8http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/902/L8GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticalInfrareddefaultJ/ApJ/902/L8/table1*Observing log of optical spectra for ZTF19aawfbtgrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDateObservation datetime.epoch;obsnullablePhase[-26/103] Rest-frame days from the g-band peak in the Julian date of 2458695.72dtime.intervalintTelTelescope/Instrumentmeta.notecharExp[300/2250] Exposure timestime.duration;obs.exposureintlam1[3100/3900] Lower range of wavelength in {AA}0.1nmem.wl;stat.minintlam2[9000/10000] Upper range of wavelength in {AA}0.1nmem.wl;stat.maxintR[100/1000] Spectral resolution estimated around 7000{AA}spect.resolutionintSpInteractive spectrum plotmeta.ref.urlcharJ/ApJ/902/L8/fig1Spectra of SN2019hge (ZTF19aawfbtg) around peak and at late phases, with PTF10hgi (Quimby+ 2018ApJ...855....2Q) and SN 2005bf (Folatelli+ 2006ApJ...641.1039F) for comparisonIDSN identifiermeta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDateObservation datetime.epoch;obsnullableindexedTelFacility (1)meta.notecharlambda[3056.9/24664.9] Wavelength; Angstroms0.1nmem.wldoubleFlux[-0.023/2.8]? Flux density (2)phot.fluxdoublenullablee_Flux[8.4e-37/0.05]? Uncertainty in Fluxstat.error;phot.fluxdoublenullableJ/ApJ/902/L8/fig2The Near-IR spectrum of SN2008ax at -8 and +23d from the B-band peak (Taubenberger+ 2011MNRAS.413.2140T)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintPhase[-8/23] Phasetime.intervalintlambda[8700/24725.7] Wavelength; Angstroms0.1nmem.wldoubleFlux[1.4e-16/7.3e-15] Flux density; in erg/s/cm^2^/{AA} unitscW.m**-2.nm**-1meta.unit;phot.fluxdouble