J/ApJ/921/L6ivo://CDS.VizieR/J/ApJ/921/L6doi:10.26093/cds/vizier.19219006CDSKarambelkar V.R.Kasliwal M.M.Maguire K.Anand S.G.Andreoni I.,De K.Drake A.Duev D.A.Graham M.J.Kool E.C.Laher R.R.,Magee M.R.Mahabal A.A.Medford M.S.Perley D.Rigault M.,Rusholme B.Schulze S.Sharma Y.Sollerman J.Tzanidakis A.,Walters R.Yao Y.2023-07-03T14:29:06Z2023-04-05T09:42:59ZCDS support team

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

cds-question@unistra.frsupernovaephotometryvisible-astronomyspectroscopyWe present the discovery of ZTF 21aaoryiz/SN 2021fcg-an extremely low luminosity Type Iax supernova. SN 2021fcg was discovered by the Zwicky Transient Facility in the star-forming galaxy IC0512 at a distance of ~27Mpc. It reached a peak absolute magnitude of M_r_=-12.66+/-0.20mag, making it the least luminous thermonuclear supernova discovered to date. The E(B-V) contribution from the underlying host galaxy is unconstrained. However, even if it were as large as 0.5mag, the peak absolute magnitude would be M_r_=-13.78+/-0.20mag-still consistent with being the lowest-luminosity SN. Optical spectra of SN 2021fcg taken at 37 and 65 days post-maximum show strong [CaII], CaII, and NaID emission and several weak [FeII] emission lines. The [CaII] emission in the two spectra has extremely low velocities of ~1300 and 1000km/s, respectively. The spectra very closely resemble those of the very low luminosity Type Iax supernovae SN2008ha, SN2010ae, and SN2019gsc taken at similar phases. The peak bolometric luminosity of SN2021fcg is ~2.5_-0.3_^+1.5^x10^40^erg/s, which is a factor of 3 lower than that for SN2008ha. The bolometric lightcurve of SN2021fcg is consistent with a very low ejected nickel mass (M_Ni_~0.8_-0.5_^+0.4^x10^-3^M_{sun}_). The low luminosity and nickel mass of SN2021fcg pose a challenge to the picture that low-luminosity SNe Iax originate from deflagrations of near-Mch hybrid carbon-oxygen-neon white dwarfs. Instead, the merger of a carbon-oxygen and oxygen-neon white dwarf is a promising model to explain SN2021fcg.2021ApJ...921L...6Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/921/L6CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/A+A/465/71 : 21cm observations of 452 galaxies (Theureau+, 2007)J/MNRAS/383/1485 : BVRI light curves of SN 2003jd (Valenti+, 2008)J/A+A/561/A146 : SN 2010ae optical spectra (Stritzinger+, 2014)J/A+A/573/A2 : SN 2012Z spectra (Stritzinger+, 2015)J/ApJ/843/16 : Galaxy groups within 3500km/s (Kourkchi+, 2017)J/ApJ/867/105 : ATLAS all-sky stellar ref. cat., ATLAS-REFCAT2 (Tonry+, 2018)J/ApJ/886/152 : ZTF early observations of Type Ia SNe. I. LCs (Yao+, 2019)J/ApJ/905/58 : Local universe with ZTF. I. Ca-rich gap transients (De+, 2020)http://fallingstar.com/ : ATLAS home pagehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/921/L6https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/921/L6http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/921/L6https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/921/L6https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/921/L6http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/921/L6GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/ApJ/921/L6/fig2The g, r, i, o and c band light curve of SN 2021fcgrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJD[59252.2/59366.9] Modified Julian Date of observationdtime.epochdoublemag[19.6/22.9]? Apparent magnitude of 3-sigma detections in Filtermagphot.magfloatnullablee_mag[0.08/0.4]? Uncertainty in magmagstat.error;phot.magfloatnullableLimmag[/21]? The 5-sigma limiting magnitude in Filtermagphot.mag;stat.maxfloatnullableFilterFilter of observationobs.param;obscharJ/ApJ/921/L6/fig4Late-time optical spectra of SN 2021fcgrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintPhase[37/63] Days since r-band peak (MJD59284.0)dtime.intervalintlamAir[3101/10301.5] Air Wavelength in Angstroms0.1nmem.wldoubleFlux[-9.2e-17/3.3e-16] Flux in erg/s/cm^2^/HzmW.m**-2.Hz**-1phot.fluxdouble