J/ApJ/949/23ivo://CDS.VizieR/J/ApJ/949/23doi:10.26093/cds/vizier.19490023CDSZhu J.Jiang N.Dong S.Filippenko A.V.Rudy R.J.Pastorello A.,Ashall C.Bose S.Post R.S.Bersier D.Benetti S.Brink T.G.,Chen P.Dou L.Elias-Rosa N.Lundqvist P.Mattila S.Russell R.W.,Sitko M.L.Somero A.Stritzinger M.D.Wang T.Brown P.J.,Cappellaro E.Fraser M.Kankare E.Moran S.Prentice S.Pursimo T.,Reynolds T.M.Zheng W.2025-08-01T20:11:33Z2025-07-21T14:17:36ZCDS support team

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

cds-question@unistra.frsupernovaeultraviolet-photometryinfrared-photometryvisible-astronomybroad-band-photometryspectroscopyinfrared-astronomyx-ray-sourcesWhen discovered, SN 2017egm was the closest (redshift z=0.03) hydrogen-poor superluminous supernova (SLSN-I) and a rare case that exploded in a massive and metal-rich galaxy. Thus, it has since been extensively observed and studied. We report spectroscopic data showing strong emission at around HeI{lambda}10830 and four HeI absorption lines in the optical. Consequently, we classify SN 2017egm as a member of an emerging population of helium-rich SLSNe-I (i.e., SLSNe-Ib). We also present our late-time photometric observations. By combining them with archival data, we analyze high-cadence ultraviolet, optical, and near-infrared light curves spanning from early pre- peak (~-20days) to late phases (~+300 days). We obtain its most complete bolometric light curve, in which multiple bumps are identified. None of the previously proposed models can satisfactorily explain all main light-curve features, while multiple interactions between the ejecta and circumstellar material (CSM) may explain the undulating features. The prominent infrared excess with a blackbody luminosity of 10^7^-10^8^L_{sun}_ detected in SN 2017egm could originate from the emission of either an echo of a pre-existing dust shell or newly formed dust, offering an additional piece of evidence supporting the ejecta-CSM interaction model. Moreover, our analysis of deep Chandra observations yields the tightest-ever constraint on the X-ray emission of an SLSN-I, amounting to an X-ray-to-optical luminosity ratio <~10^-3^ at late phases (~100-200 days), which could help explore its close environment and central engine.2023ApJ...949...23Zhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/949/23CatalogResearchIsServedByTAP VizieR generic servicerelated-toB/chandra : The Chandra Archive Log (CXC, 1999-2014)B/swift : Swift Master Catalog (HEASARC, 2004-)J/ApJ/690/1358 : Spectra of unusual optical transient SCP 06F6 (Barbary+, 2009)J/ApJ/750/99 : The Pan-STARRS1 photometric system (Tonry+, 2012)J/ApJ/792/30 : NEOWISE magnitudes for near-Earth objects (Mainzer+, 2014)J/ApJ/852/81 : 17 PS1 superluminous SNe LCs + classif. sp. (Lunnan+, 2018)J/ApJ/864/45 : X-ray emission from superluminous SNe survey (Margutti+, 2018)J/ApJ/901/61 : LCs of 4 superluminous SNe from the ZTF survey (Lunnan+, 2020)J/ApJ/902/6 : UV to visible-light obs. of SN 2018fif (Soumagnac+, 2020)J/ApJ/902/L8 : Optical & NIR spectra of ZTF19aawfbtg (SN2019hge) (Yan+, 2020)J/ApJ/933/14 : LC analysis of type I superluminous SNe (Hosseinzadeh+, 2022)J/ApJ/943/42 : Hydrogen-poor superluminous SNe from ZTF P1. II. (Chen+, 2023)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/949/23https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/949/23http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/949/23https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/949/23https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/949/23http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/949/23GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tap3.830199579824256e-20 6.513807192489934e-20X-rayUVOpticalInfrareddefaultJ/ApJ/949/23/table1Photometry of SN 2017egmrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJD[57904.9/58293.2] Modified Julian Date (JD-2400000.5)dtime.epochdoubleTime[-20.3/356.5] Rest-frame time from g-band peak at JD=2457926.3dtime.intervalfloatFiltFiltermeta.id;instr.filtercharl_omag[> ] Limit flag on omagmeta.code.errorcharomag[14.4/21.8] Observed magnitude in Filter (1)magphot.magfloate_omag[0.01/1]? Uncertainty in omagmagstat.error;phot.magfloatnullableTelTelescope/Instrument used (2)meta.id;instr.telcharRefReference for photometry (3)meta.ref;pos.framecharJ/ApJ/949/23/table2Summary of late-time spectroscopic observations of SN 2017egmFileName1File identifier in the "sp" subdirectory (in MRT format); column added by CDSmeta.id;meta.filecharFileName2Name of a second file if any; column added by CDSmeta.id;meta.filecharDateUT date of observation'Y:M:D'time.epoch;obsnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJD[13/195.5] Julian Date; JD-2458000dtime.epochfloatTime[84/261.2] Rest-frame time from g-band peak at JD=2457926.3dtime.intervalfloatExpExposure timestime.duration;obs.exposurecharAirmass[1/2.9] Airmassobs.airMassfloatTelTelescope / InstrumentinstrcharJ/ApJ/949/23/table3Best-fit blackbody parametersrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTime[-19.1/249] Rest-frame time from g-band peak at JD=2457926.3dtime.intervalfloatTbb[4.78/17.4] black-body Temperature (1)1000Kphys.temperaturefloate_Tbb[0.05/1.5] Uncertainty in Tbb (1)1000Kstat.error;phys.temperaturefloatRbb[0.59/4] black-body radius (1)1e+15cmphys.size.radiusfloate_Rbb[0.01/0.6] Uncertainty in Rbb (1)1e+15cmstat.error;phys.size.radiusfloatlogLbb[41.8/44.3] log, black-body Luminosity (1)log(1e-07J)phys.luminosityfloate_logLbb[0.01/0.3] Uncertainty in logLbb (1)log(1e-07J)stat.error;phys.luminosityfloatJ/ApJ/949/23/fig5MIR light curves of SN 2017egme_W2mag[0.016/0.02]? Uncertainty in W2magmJystat.error;phot.mag;em.IR.4-8umfloatnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJD[57863.26/58797.5] Modified Julian Date of WISE datadtime.epochdoublel_W1magLimit flag on W1magmeta.code.error;phot.mag;em.IR.3-4umcharW1mag[0.028/0.08] WISE/NEOWISE 3.4um band fluxmJyphot.mag;em.IR.3-4umfloate_W1mag[0.014/0.015]? Uncertainty in W1magmJystat.error;phot.mag;em.IR.3-4umfloatnullablel_W2magLimit flag on W2magmeta.code.error;phot.mag;em.IR.4-8umcharW2mag[0.05/0.17] WISE/NEOWISE 4.6um band fluxmJyphot.mag;em.IR.4-8umfloat