Type Iax Supernovae

Saurabh W. Jha with Curtis McCully (LCOGT/UCSB), Ryan Foley (UC Santa Cruz), Max Stritzinger (Aarhus), et al. Supernovae Through the Ages Rapa Nui August 12, 2016 78 GARNAVICH ET AL. Vol. 509

H with a Gaussian prior based on our own Type Ia SNs this result beyond a cosmological-constant model because 0 result including our estimate of the systematic error from of the possible time dependence ofax. But for an equation the Cepheid distance scale, H \ 65 ^ 7 km s~1 Mpc~1 of state Ðxed after recombination, the combined constraints (R98a). It is important to note0 that the Type Ia SNs con- continue to be consistent with a Ñat geometry as long as straints on()m, ) ) are independent of the distance scale ax [ [0.6. With better estimates of the systematic errors in but that the CMB" constraints are not. We then combine the Type Ia SN data and new measurements of the CMB marginalized likelihood functions of the CMB and Type Ia anisotropy, these preliminary indications should quickly SNs data. The result is shown inFigure 3. Again, we must turn into very strong constraints(Tegmark et al. 1998). caution that systematic errors in either the Type Ia SNs CONCLUSIONS data(R98a) or the CMB could a†ect this result. 6. Nevertheless, it is heartening to see that the combined The current results from the High-z Supernova Search constraint favors a location in this parameter space that has Team suggest that there is an additional energy component not been ruled out by other observations, though there may sharing the universe with gravitating matter. For a Ñat be mild conÑict with constraints on) from gravitational geometry, the ratio of the pressure of the unknown energy " lensing(Falco et al. 1998). In fact, the region selected by the to its density is probably more negative than [0.6. This Type Ia SN and CMB observations is in concordance with e†ectively rules out topological defects such as strings and inÑation, large-scale structure measurements, and the ages textures as the additional component, and it disfavors of stars(Ostriker & Steinhardt 1995; Krauss & Turner domain walls as that component. Open models are less con- 1995). The combined constraint removes much of the high- strained but favor ax \ [0.5. Although there are many ) , high-) region that was not ruled out by the Type Ia intriguing candidates for the x-component, the current m " SN data alone, as well as much of the high-)m, low-) Type Ia SN observations imply that a vacuum energy or a region allowed by the CMB data alone. The combined con-" scalar Ðeld that resembles the cosmological constant is the straint is consistent with a Ñat universe, as ) \ )m most likely culprit. THE ASTRONOMICAL JOURNAL, 116:1009È1038, 1998 September 0.94 0.26 for MLCS and 1.00 0.22 for totm (B) Combining the Type Ia SNs probability distribution with ( 1998. The American Astronomical Society. All rights reserved. Printed in U.S.A. ] ) \ ^ ^ * (1 p "errors). The enormous redshift di†erence between15 the constraints of today from the position of the Ðrst acoustic historicalCMB and the Type Ia SNs prelude makes it dangerous to generalize peak in the CMB power spectrum provides a simultaneous OBSERVATIONAL EVIDENCE FROM SUPERNOVAE FOR AN ACCELERATING UNIVERSE Garnavich, Jha, + High-Z Team (1998) AND A COSMOLOGICAL CONSTANT

ADAM G.RIESS,1 ALEXEI V. FILIPPENKO,1 PETER CHALLIS,2 ALEJANDRO CLOCCHIATTI,3 ALAN DIERCKS,4 PETER M. GARNAVICH,2 RON L. GILLILAND,5 CRAIG J.HOGAN,4 SAURABH JHA,2 ROBERT P. KIRSHNER,2 B. LEIBUNDGUT, M. M. PHILLIPS, DAVID REISS, BRIAN P. SCHMIDT, ROBERT A. SCHOMMER, HE STROPHYSICAL OURNAL 6 7 4 8,9 7 T A J , 509:74È79, 1998R. C DecemberHRIS SMITH 10 , J. SPYROMILIO, CHRISTOPHER STUBBS, ( 1998. The American Astronomical Society. All rights reserved. Printed in U.S.A. 7,10 6 4 NICHOLAS B. SUNTZEFF,7 AND JOHN TONRY11 Received 1998 March 13; revised 1998 May 6

SUPERNOVA LIMITS ON THE COSMIC EQUATION OF STATE ABSTRACT PETER M. GARNAVICH,1 SAURABH JHA,1 PETER CHALLIS,1 ALEJANDRO CLOCCHIATTI,2 ALAN DIERCKS,3 High-Z Team SN Ia + We presentLEXEI spectralILIPPENKO and photometricON observationsILLILAND ofRAIG 10 TypeOGAN Ia supernovaeOBERT (SNeIRSHNER Ia) in the redshift range 0.16A z V.0.62.F The luminosity,4 R L. distancesG of these,5 C objectsJ.H are determined,3 R byP. methodsK that,1 employ π πRUNO EIBUNDGUT HILLIPS AVID EISS DAM IESS relations betweenB SNL Ia luminosity,6 M. and M. lightP curve,7 shape.D CombinedR ,3 A withG. previousR ,4 data from our ground-based CMB (1st peak) High-z Supernova SearchBRIAN TeamP. SCHMIDT and recent,8 ROBERT resultsA. bySCHOMMER Riess et, al.,7 R. this CHRIS expandedSMITH, set9 of 16 high-redshift ASON PYROMILIO HRIS TUBBS ICHOLAS UNTZEFF supernovaePublications of andthe Astronomical a setJ of Society 34S nearby of the Pacific supernovae,6, C119: 360–387,S are 2007 used April,3 N to place constraintsB. S on,7 the following cosmo- ᭧ 2007. The Astronomical Society of the Pacific.JOHN All rightsTONRY reserved.,10 Printed AND in U.S.A.SEAN M. CARROLL11 logical parameters: the Hubble constant(H ), the mass density()M), the cosmological constant (i.e., the vacuum energy density,) ), the decelerationReceived 19980 May parameter 28; accepted(q ), 1998 and July the 10 dynamical age of the universe (t ). The distances of the high-redshift" SNe Ia are, on average, 10%0 È15% farther than expected in a low mass0 ABSTRACT density ()M \ 0.2) universe without a cosmological constant. Di†erent light curve Ðtting methods, SN Ia Wesubsamples,The use Type Peculiar and Ia supernovae prior SN 2005hk: constraints studied Do unanimously Some by the Type High- favor Iaz Supernova Supernovae eternally expandingSearch Explode Team models as to Deflagrations? constrain with positive the1,2,3 properties cosmo- oflogical an energy constant component (i.e.,) that[ 0) may and have a current contributed acceleration to accelerating of the expansion the cosmic (i.e., expansion.q \ 0). With We noÐnd prior that 4 " 5 6,7,8 9,10 11 0 11 12 forconstraint aM. Ñat M. geometry Phillips, on massWeidong the density equation-of-state Li, Joshua other A. than Frieman, parameter) º 0,S. the I. forBlinnikov, spectroscopically the unknownDarren component, DePoy, conÐrmedJose´ SNe L.a Prieto, IaP / areoP., Milne,statisticallymust be less Carlos Contreras,4 Gastoń Folatelli,4 NidiaM Morrell,4 Mario Hamuy,13 Nicholas B. Suntzeff,x \14 Miguelx x Roth,4 thanconsistent0.55 with (95%q con\ 0Ð4 dence) at the 2.8 forp anyand4 3.9valuep con ofÐdence, and levels,5 it is and further with) limited[15 0 at to the 3.0 p 5and0.60 4.0(95%p [ Sergio Gonza0´lez, Wojtek Krzeminski, Alexei V. Filippenko,)m Wendy L. Freedman," Ryan Chornock,ax \ [ conÐdence levels,5,16 for two di†erent15,17Ðtting methods,15 respectively. Fixing15 a ““ minimal ÏÏ15 mass density, 15) \ conÐdence)Saurabh if Jha,)m isBarry assumed F. Madore, to beS. greater E. Persson, thanChristopher 0.1. These R. values Burns, arePamela inconsistent Wyatt, David with Murphy, the unknownM 0.2, results in the weakest5 detection,) [5 0 at the 3.0 p conÐ5dence level from18 one of the two19,20 methods. componentRyan being J. Foley, topologicalMohan Ganeshalingam, defects such" asFranklin domain J. D. walls, Serduke, strings,Kevin or Krisciunas, textures. TheBruce supernova Bassett, (SN) data For a Ñat universe21 prior () ]7,22) \ 1), the11 spectroscopically con18 Ðrmed SNe23 Ia require) [7,240 at 7 p are consistentAndrew Becker, with a cosmologicalBen Dilday,M J." constant Eastman, (Peterax \[ M.1) Garnavich,or a scalarJon Holtzman,Ðeld that hasRichard had, Kessler, on" average, an equation-of-stateand 9 p formalHubertparameter statistical Lampeitl,25 signiJohn similarÐ Marriner,cance to forthe8 S. the cosmological Frank, two11 di†erentJ. L. Marshall, constantÐtting11 methods.Gajus value Miknaitis, of A universe1 over8 Masao the closed Sako, redshift26 by ordinary range of 27 19 [ 28 z matter1 to (i.e.,the present.)M \ 1) is SNDonald formally and P. cosmicSchneider, ruled out microwaveKurt at the van 7 derp backgroundto Heyden, 8 p conandÐ observationsdence Naoki level Yasuda for give the complementary two di†erent Ðtting con- B Received 2006 July 1; accepted 2007 March 22; published 2007 April 24 straintsmethods. on the We densities estimate the of matter dynamical and age the of unknown the universe component. to be 14.2 If^ only1.7 Gyr matter including and vacuum systematic energy uncer- are tainties in the current Cepheid distance scale. We estimate the likely e†ect of several sources of system- considered,ABSTRACT. then the currentWe present combined extensive ugriBVRIYJHK data′′′′ sets provides photometry direct and evidence optical spectroscopy for a spatially of the ÑatType universe Ia with atic error, including progenitor and metallicity evolution, extinction, sample selection bias, local ) \ ) ]supernova) \ (SN)0.94 2005hk.^ 0.26 These(1 p data). reveal that SN 2005hk was nearly identical in its observed properties to SN totperturbationsm 2002cx," in which the has expansion been called rate, “the most gravitational peculiar known lensing, Type Ia and supernova.” sample Both contamination. supernovae exhibited Presently, high- none of Subjectthese headings: e†ectsionization appearcosmology: SN 1991T–like to reconcile observations premaximum the data spectra, with È cosmology: yet) low\ 0 peak and luminosities theoryq º 0. È like supernovae: that of SN 1991bg. general The spectra " 0 Key words:revealcosmology: that SN 2005hk, observations like SN 2002cx, È exhibited supernovae: expansion general velocities that were roughly half those of typical Type1. INTRODUCTION Ia supernovae. The R and I light curves of both supernovaecannot were accelerate also peculiar the expansion; in not displaying therefore, the if taken at face secondary maximum observed for normal Type Ia supernovae.value Our theYJH observationsphotometry of SN demand 2005hk reveals an additional the energy com- Matter that clusterssame peculiarity on the in scale the near-infrared. of galaxies By or combining galaxy our opticalponent and near-infrared for the universe. photometry Whileof SN 2005hk the vigorous with pursuit of pos- clusters is insufficientpublished to close ultraviolet the light universe, curves obtained with conven- with the Swift satellite, we are able to construct a bolometric light ÈÈÈÈÈÈÈÈÈÈÈÈÈÈÈcurve from 15 days before to 60 days after B maximum.sible The shape systematic and unusually e†ects low peak (see, luminosity e.g.,Ho of Ñich, Wheeler, & tional values near ) \ ∼0.2 ^ 0.1 (Gott∼ et al. 1974; 1. INTRODUCTION 1 Department ofthis Astronomy, lightm curve, University plus the low of expansion California velocities at Berkeley, and absenceThielemann of a secondary1998) maximum will at be red important and near-infrared in understanding these CarlbergBerkeley,et CA al. 94720-3411. 1996;wavelengths, Lin et al. are 1996; all in reasonable Bahcall, agreementFan, & with Cen model calculationsobservations,This paper of a three-dimensional reportsit is instructive observations deflagration to see of whatthat 10 new they high-redshift imply about 1997).2 Harvard-SmithsonianObservations of Centerdistant for supernovae Astrophysics,56 (SNs)60 Garden provide Street, produces 0.2 M, of Ni. theType energy IaF supernovaeIG content. 3.ÈCombined of (SNe the universe. Ia) constraints and the values from of Type the Ia cosmo- SNs and the position of the Ðrst Doppler peak of the CMB angular power spectrum. The equation-of-state credibleCambridge, evidence MA 02138. that the∼ deceleration rate of the universal Departamento de Astronom• a y Astrof• sica, PontiÐcia Universidad logicalTheparameter cosmological parameters for derived the constant unknown from was them. component revived Together to isÐ like withll the that the gap for a cosmological constant,a \[1. The contours mark the 68%, 95.4%, and 99.7% enclosed 3 Online material: color figures x expansionCato lica, Casilla is small, 104, Santiago which 22, implies Chile. that the total matter betweenfourprobability high-redshift the observed regions. supernovae mass density previously and the reported theoretical by our pref- density,4 Department clustered of or Astronomy, smooth, University is insufficient of Washington, to create Box a351580, Ñat erenceHigh-z forSupernova a Ñat universe Search(Turner, Team Steigman,(Schmidt &et Krauss al. 1998;1984; Seattle, WA 98195. geometry (Garnavichet al.1. 1998; INTRODUCTION Perlmutteret al. 1998). degeneratePeeblesGarnavich star. 1984), Overet al.as the 1998a) well intervening as and to alleviate years, two others progress the(Riess has embarrassment been et al. 1998b), of a Either5 Space the universe Telescope Science has an Institute, open 3700 geometry San Martin or, Drive, if Ñat, Baltimore, other MD 21218. More than 45 years ago, Hoyle & Fowler (1960) first rec- slowyoungthe in sample identifying universe of the 16 progenitorwith is now older systems large stars enough of these(Carroll, objects to yield Press, and interesting & Turner forms6 ofEuropean energyognized Southernare that more Type Observatory, important Ia supernovae than Karl-Schwarzschild-Strasse (SNe matter. Ia; for a review of su- 2, understanding1992).cosmologicalThe the cosmological details results of the of explosion high constant statistical mechanism. is a signi At negative pre-Ðcance. pressure Con- LargeD-85748 samples Garchingpernova of bei classification, SNs Mu nchen, analyzed Germany. see Filippenko by the High- 1997)z wereSupernova the obser- sent,componentÐdence the most in popular these arising model results from for the nonzero depends progenitors vacuum not of typical on energy SNe increasing (Weinberg the Search7 Cerro collaborationvational Tololo signature Inter-American(Riess ofet al. the 1998a, Observatory, thermonuclear hereafter National disruption R98a) Optical ofand a sample size but on improving our understanding of system- Astronomy Observatories, Casilla 603, La Serena, Chile. NOAO is oper- 1989). It would be extraordinarily difficult to detect on a the Supernova Cosmology Project (Kim 1998) now suggest 7atic uncertainties. ated by the Association of Universities for Research in Astronomy, Inc., smallKavli Institute scale, for but Cosmological) \ Physics,1 [ University)m could of Chicago, make Chicago, up the di†erence thatunder the cooperative universe agreement may well with be theNational accelerating. Science Foundation. Matter alone IL;between [email protected],The time the evolution matter [email protected]." density of the cosmic and scale a factor Ñat geometry depends on and 1 8 )m 8 Mount StromloBased in part and on Siding observations Spring taken Observatories, at the Cerro Tololo Private Inter-American Bag, mighttheFermi composition National be detected Accelerator of Laboratory, mass-energy by measurements Batavia, inIL; [email protected], the universe. on a cosmological While the Weston Creek,Observatory, ACT 2611, National Australia. Optical Astronomy Observatory, which is operated by [email protected],universe [email protected]. is known to contain a signiÐcant amount of ordi- the Association of Universities for Research in Astronomy, Inc., (AURA) under 9 Institute for Theoretical and Experimental Physics, Moscow, Russia; 9 Visiting Astronomer, Cerro Tololo Inter-American Observatory. scale. There are few independent observational constraints 1 Harvard-Smithsoniancooperative agreement Center with for the National Astrophysics, Science Foundation. 60 Garden Street, [email protected] matter,)M, which decelerates the expansion, its Department2 of Astronomy, University of Michigan, 834 Dennison on10 the cosmological constant, butFalco, Kochanek, & Cambridge,10 MA 02138.Based in part on observations obtained with the Apache Point Observatory dynamicsMax-Planck-Institut may fu¨r also Astrophysik, be signi Garching,Ðcantly Germany. a†ected by more exotic Building, Ann Arbor, MI 48109. 11 Departmento3.5 m de telescope, Astronomi which a is ownedy Astrophisica, and operated by Ponti the AstrophysicalÐcia Universidad Research MunDepartment8 oz(1998) of Astronomy, estimated Ohio State that University,) \ Columbus,0.7 (95% OH; conÐdence) 2 11 Institute for Astronomy, University of Hawaii, 2680 Woodlawn forms of energy. Preeminent among" these is a possible Cato lica, CasillaConsortium. 104, Santiago 22, Chile. [email protected],from the current statistics [email protected], of strong gravitational frank@ lenses. If Drive, Honolulu,3 Partly HI based 96822. on observations collected at the European Southern Obser- astronomy.ohio-state.edu,energy of the vacuum [email protected].() ), EinsteinÏs ““ cosmological con- Department of Astronomy, University of Washington, Seattle, WA 3 vatory, Chile, in the course of program 076.A-0156. the12 Steward matter Observatory, density Tucson, is AZ; less [email protected]. than" )m D 0.3, this limit is close to 98195. 4 Las Campanas Observatory, Carnegie Observatories, La Serena, Chile; 1009preventing13 Universidad de the Chile, cosmological Departamento de Astronomı constantá, Santiago, from Chile; making a Ñat 4 [email protected], of Astronomy, [email protected], University [email protected], of California, [email protected], Berkeley, miguel@ CA [email protected]. Further, a cosmological constant that just 94720-3411. lco.cl, [email protected], [email protected]. 14 Texas A&M University Physics Department, College Station, TX; 5 Space Telescope5 Department Science of Institute, Astronomy, 3700 University San Martin of California, Drive, Berkeley, Baltimore, CA; [email protected] to be of the same order as the matter content at the MD 21218. [email protected], [email protected], chornock@astro. present15 Observatories epoch of the Carnegie raises Institution the issue of Washington, of ““ Ð Pasadena,ne tuning CA; ÏÏ(Coles & 6 Europeanberkeley.edu, Southern Observatory, [email protected], Karl-Schwarzschild-Strasse [email protected], 2, Frank@ Gar- [email protected]). [email protected], A number of [email protected], exotic forms [email protected], of matter that might ching, Germany.Serduke.com. [email protected], [email protected]. 6 Department of Astronomy and Astrophysics, University of Chicago, Chi- contribute16 Kavli Institute for to Particle cosmic Astrophysics acceleration and Cosmology, are Stanford physically Linear possible 7 Cerro Tololocago,Inter-American IL. Observatory, Casilla 603, La Serena, Accelerator Center, Menlo Park, CA; [email protected]. Chile. and viable alternatives to the cosmological constant Mount Stromlo and Siding Spring Observatory, Private Bag, Weston (Frieman& Waga 1998; Caldwell, Dave, & Steinhardt 8 360 Creek P.O., Australia. 1998). The range of possibilities can be narrowed by using 9 University of Michigan, Department of Astronomy, 834 Dennison, SNs because the luminosity distance not only depends on Ann Arbor, MI 48109. the present densities of the various energy components but 10 Institute for Astronomy, University of Hawaii, Manoa, HI 96822. 11 Institute for Theoretical Physics, University of California, Santa also depends on their equations of state while the photons Barbara, CA 93106. we see were in Ñight. Here, with some simplifying assump- 74 “Someone smart and young will sweep away these silly subclasses…” −N.B. Suntzeff, 2016-08-09

Dec 2011 thanks a lot, Nick and Mark! The Astrophysical Journal,767:57(28pp),2013April10 Foley et al. SN 2011ay SN 2012Z

5 −2.0 1.9 3 −13.7

−12.7 4.8 4 10.8 1.1 2 + Constant 26.4 λ 4.1 3

+ Constant 6.1 λ 36.2 Relative f 1 6.2

Relative f 2 49.9 7.1 29.0

62.7 0 1 4000 5000 6000 7000 8000 9000 10000 Rest Wavelength (Å) Figure 14. Optical spectra of SN 2012Z. Rest-frame phases relative to V 175.6 maximum are listed to the right of each spectrum.

0 Type Iax Supernovae SN 2002cx (Li et al. 2003) 4000 5000 6000 7000 8000 9000 10000 >50 members in the class Rest Wavelength (Å) the “most peculiar” SN Ia Figure 13. Optical spectra of SN 2011ay. Rest-frame phases relative to V maximum are listed to the right of each spectrum. −18 02cx-like subclass of SN Ia to SN 2008ge, which might be >20 days) is also larger than for (Jha et al. 2006) that of SNe Ia (Ganeshalingam et al. 2011); based on current −17 e.g., SN 2002cx ↔ SN 2005hk data, it appears that the average SN Iax has a shorter rise time than the average SN Ia, but few SNe have light curves sufﬁcient (Phillips et al. 2007) for this measurement. Despite their rough similarity in light- curve shape, SNe Iax have consistently lower luminosity (even −16 if that criterion is relaxed from our classiﬁcation scheme) than SN Iax (Foley et al. 2013) SNe Ia. Stritzinger et al.: The bright and energetic Type Iax SN 2012Z. For SNe Iax, there are several clear trends in the derived −15 photometric parameters. Peak brightness and decline rates are highly correlated for a given object in all bands. In other words, an SN that is bright and declines slowly in B is also bright and 11ay −14 12Z declines slowly in R. 08A

Absolute V Magnitude 05hk Performing a Bayesian Monte-Carlo linear regression on the 08ge data (Kelly 2007), we determine correlations between different −13 08ae parameters in different bands. The linear relationships and their 02cx 13dh 03gq McCully et al. correlation coefﬁcients are presented in Table 6,wherethe 05cc in prep equations are all of the form Foley et al. (2013) 09J −12 08ha p2 αp1 + β, (1) Stritzinger et al. (2015) = 0 20 40 60 where p1 and p2 are the two parameters, α is the slope, and β is Rest−Frame Days Relative to V Maximum the offset. Figure 15. Absolute V-band light curves for a subset of SNe Iax. Each SN isFigure 6: MB plotted vs. ∆m15(B) for a sample of CSP SNe Ia (black dots), a handful of SNe Iax (blue squares) that span their Using the equations in Table 6,onecaneffectivelytrans- plotted with a different color. full range in luminosity, and SN 2012Z (red star). Note the error bars associated with SN 2012Z are smaller than its symbol size. form observations in one band into measurements in another. (A color version of this ﬁgure is available in the online journal.) The comparison SNe Iax plotted are SN 2002cx (Li et al. 2003; Phillips et al. 2007), SN 2003gq (see Foley et al. 2013, and references therein), SN 2005hk (Phillips et al. 2007), SN 2007qd 15 (McClelland et al. 2010), SN 2008A (see Foley et al. 2013, and references therein), SN 2008ge (Foley et al. 2013), SN 2008ha (Stritzinger et al. 2014), SN 2010ae (Stritzinger et al. 2014), and SN 2011ay (Brown, private communication).

19 these are white dwarf supernovae SN 2005hk Jha et al. (2006), Phillips et al. (2007), McCully et al. (2014)

S II

Stritzinger et al.: The bright and energetic Type Iax SN 2012Z. SN 2002cx 455

TABLE 1 Photometry of Comparison Stars

ID V BϪV VϪR VϪI Ncalib 1 ...... 15.467(06) 0.635(30) 0.410(08) 0.807(30) 2 2 ...... 17.254(26) 0.608(33) 0.374(30) 0.744(36) 3 3 ...... 16.332(23) 0.523(40) 0.338(20) 0.663(12) 2 4 ...... 16.503(15) 0.509(40) 0.376(07) 0.734(08) 2 5 ...... 16.788(34) 0.586(20) 0.362(17) 0.755(37) 6 6 ...... 17.026(40) 0.796(21) 0.499(09) 0.967(35) 6 7 ...... 17.109(36) 0.658(13) 0.407(18) 0.819(45) 6 8 ...... 17.901(39) 1.166(62) 0.831(17) 1.528(55) 6

velocities half Note.—All quantities are magnitudes. Uncertainties in the last two of normal SNe Ia digits are indicated in parentheses. SN 2002cx

Fig. 1.—V-band KAIT image of the ﬁeld ofSNSNSN 2002cx, 2008A 2008Ataken on 2002 1 arcmin May 18. The ﬁeld of view is 6Ј.7 # 6Ј.7. The eight local standard stars are marked (1–8).

(Stetson 1987) and then employed to determine transformation coefficients to the standard Johnson-Cousins BVRI system. The derived transformation coefficients and color terms were then used to calibrate the sequence of eight local standard stars in the SN 2002cx field. The magnitudes of these eight stars and the associated uncertainties derived by averaging over the photometric nights are listed in Table 1. Notice that the local standard stars have different numbers of calibrations (last column in Table 1) because the two telescopes have different total fields of view. Stritzinger et al. (2015) We tried the point-spread function (PSF) fitting method (Stet- Figure16: Comparison of NIR-wavelength spectra of SN 2012Z – 50 – at phases of 0d (top) and +22d (bottom), to similar epoch spectra son 1987) to perform differential photometry of SN 2002cx of SN 2005hk (Kromer et al. 2013). Prevalent features attributed relative to the comparison stars, but the results are less than – 56 – to ions of Fe ii, Si iii,andCo ii are indicated with labels. satisfactory. As can be seen in Figure 1, SN 2002cx is con- taminated by its host galaxy (especially in the R and I bands), and the relatively poor resolution of KAIT images together -20 mag 0.2–0.1ע with seeing variationsLickyield 40”fluctuations V-bandat the -19 B level in the final lightJancuruarves y(lower 12,panel 2008in Fig. 2). The PSF- NGC 634 DSS fitting method also overestimates the brightness of SN 2002cx, -18 2005hk Figureas a negative 1: Imageresidual can of SNbe seen 2008Aat the position from theof the LickSN on Observatory-17 1 m Nickel telescope (left) compared to the processed images with SN 2002cx and the comparison stars thesubtracted. pre-explosion DSS image (right). -20 V – 50 – The solution for getting precise photometry of SN 2002cx -19 is to obtain BVRI template images after the SN fades and apply Fig. 2.—Preliminar-18 y B, V, R, and I light– 56cur–ves of SN 2002cx. The open galaxy subtraction to remove the galaxy contamination. We circles are the KAIT measurements, and the filled circles are the Nickel data. -17 have attempted to get these template images with both KAIT For most of the points, the statistical uncertainties are smaller than the plotted symbols. The upper panel shows the results from the adopted galaxy-subtrac- and the Nickel telescope (which has better resolution than the tion technique-20discussed in the text, while the lower panel shows a comparison KAIT data) when SN 2002cx was 7 months old, but unfor- B between the-19galaxy-subtraction photometry (solid lines) and the PSF-fittingI

tunately, owing to its slow late-time decline (see below for photometrmax y (open and ﬁlled circles). -18 29 M 2005hk 2003 PASP, 115:453–473 -17 -20 1.0 VJ -19 -18 ) + constant ! -17

SN 2002cx (+25 days) -20

Log (f I SN 2005hk (+24 days) -19 H 0.1 SN 2008A (+28 days) max -18 M -18 SN 2008A -17 4000 5000 6000 7000 8000 9000 -20 0.8 1 1.2 1.4 1.6 1.8 2 Rest Wavelength (Å) m (B) J -19 ! 15 -18 Figure 2: February 12, 2008 Keck spectrum ofFig SN. 14.— 2008AThe abs comparedolute magnitude tos of analoguesSNe Ia at maxim SNum 2002cxlight in the andBV IJH bands -17 SN 2005hk at similar epochs showing strikingpl homogeneityotted versus the dec (left);line rate p andarame absoluteter ∆m15(B). opticalThe black magnitudestriangles arFeigS.N8e.—in Cthoemparison of spectra of SN 2005hk at phases of -5, +13, +24, and +55 days with redshift range 0.01 < z < 0.1 whose distances were calculated from their host galaxy radial similar epoch spectra of SN 2002cx from LFC. The spectra are plotted on a logarithmic ﬂux of SN 2008A and SN 2005hk showing these areveloc outliersities in the-20co comparedsmic microwave toback agro sampleund frame a ofssum normaling a Hubb SNele const Iaant of H = 72 scale an0d shifted by an arbitrary constant. The wavelengths of the spectra were shifted to km s−1 Mpc−1. The red circle in each panel corresponds to SN 2005hk.H (right; panel adapted from Phillips et al. 2007). -19 the SN rest frame using the heliocentric velocities of the host galaxies given in NED. -18 -17 0.8 1 1.2 1.4 1.6 1.8 2 !m (B) 4 15 Fig. 14.— The absolute magnitudes of SNe Ia at maximum light in the BV IJH bands plotted versus the decline rate parameter ∆m15(B). The black triangles arFeigS.N8e.—in Cthoemparison of spectra of SN 2005hk at phases of -5, +13, +24, and +55 days with redshift range 0.01 < z < 0.1 whose distances were calculated from their host galaxy radial similar epoch spectra of SN 2002cx from LFC. The spectra are plotted on a logarithmic ﬂux velocities in the cosmic microwave background frame assuming a Hubble constant of H = 72 scale an0d shifted by an arbitrary constant. The wavelengths of the spectra were shifted to km s−1 Mpc−1. The red circle in each panel corresponds to SN 2005hk. the SN rest frame using the heliocentric velocities of the host galaxies given in NED. Iax environments

host-galaxy distribution similar to SN IIP, but also 91T-like SN Ia (Perets et al. 2009; Foley et al. 2009; Lyman et al. 2013; SN 2008ge SN 2008ha White et al. 2015) SN 2010ae SN 2010el 1 Perets et al. (2009) 0.9 0.8 91bg 0.7

0.6 05E 0.5 Ia 91bg 0.4 Ia 91T Ib 0.3 Ic II 0.2 02cx II Cumulative Fraction 02cx 0.1 05E 0 all late-type hosts (except 08ge) E S0 Sa−Sab Sb Sbc Sc Scd−Sm Irr Galaxy Type FigureFigure 4: 3 Host:ThecumulativedistributionofhostgalaxiesofSNefromtheKAITSN galaxy distributions for di↵erent classes of supernovae. Note that the 02cx-like survey.SNe We are found corrected preferentially the classification in late-type galaxies, of a fewsimilar SN to Ib/c core-collapse hosts SNe usin (II,g higher-quality Ib, Ic) and obser- di↵erent from the bulk of the SN Ia population. However, the 02cx-like objects are also vationsdistributed from the similarly Palomar to SN 60-inch1991T-like telescope SNe Ia, thought (SN to 2005ar, be thermonuclear. 2006ab, aThisnd figure2006lc is were found to be hostedadapted by from spiral Perets galaxies et al. (2009). rather than elliptical galaxies). After correcting the classification we find that all SNe Ib/c found in early-type galaxies are faint Ca-rich SNe similar to SN 2005E. Note that the SN 2005E-like SN host distribution is very dierent from that of otherDescription SNe Ib/c, of as the well Observations as that of SNe II (known to have young massive progenitors) and that of SN 2002cx-like SNe Ia, with half of the SN 2005E-like group(fouroutof We propose to obtain late-time optical WFC3/UVIS VrI photometry of SN 2012Z in NGC eight)1309 observed in two epochs, in early-type once during (elliptical Cycle 20 (sometime or S0) galaxies. approximately The progen 400 to 600itors days of after SN SN 2005E and the othermaximum members light), and of its again group during are Cycle therefore 21 (sometime likely approximately to belong to 750 an to o 950ld, days low-mass past stellar population.maximum). The The total few extant numbersHST ofobservations host galaxies of SNe included Ia at these in late this times figure haveare often 244, been 25, 8, 257, 30, 63,taken 14, in and just 8 one for or SNe two ofoptical types filters; Ia, 91bg, this makes 91T, it II, di⌅ Ib,cult Ic, to 02cxget solid,and05E,respectively. physical insight. For this important object, we will observe in V (F555W), r (F625W), and I (F814W). We need two epochs to trace the development of any excess r-band flux (signifying the emergence of strong [O I] 6300) and importantly, to ensure that we don’t miss the strong color evolution predicted by models of the IR catastrophe. The V observations will connect SN 2012Z to other SNe Ia observed at late epochs (Figure 3), and both the V and I observations will tie into the exquisite extant HST data set on NGC 1309 (Figure 1). Because we expect the SED to have strong features, it is imperative that we have our two epochs observed with the same instruments and filters; we cannot aord the imprecision in compar- ing ground-based and HST broad-band magnitudes to make the measurement! We choose

6 LETTER RESEARCH

The Astrophysical Journal,790:3(9pp),2014July20 Kelly et al. a b c

SN 2014J Star 1 SN 2011fe Star 2 Li et al. (2011) Li et al. Kelly et al. (2014) et al. Kelly ] III

Figure 1. Coadded Keck-II K-band NIRC2 AO (left) and HST pre-explosion F160W (right) exposures of the location of SN 2014J. We use only the central 16 16 of

′′ ′′ upper Figure 1 |The site of SN 2011fe in galaxy M101 as imaged by the Hubble is marked by two circles. The× smaller circle has a radius of our 1s astrometric

the distortion-corrected AO image to perform astrometric registration. The 68 sources used for registration are identiﬁed with white circles, while the position of SN , an order and [O

σ 2014J is markedSpace by a black Telescope/Advanced circle with radius corresponding Camera to for the uncertaintySurveys. in a, that A full-view position estimate. colour picture uncertaintyCrB T (21 mas), and the bigger circle has a radius of nine times that. No −1 α

of the face-on spiral galaxy M101 (189 3 189 field of view) constructed from the object is detected at the nominal supernova location, or within the 8s error , as well as the Table 1 images of SN M5 three-colour HubbleHST Data Space Sets Telescope/Advanced and Upper Absolute Magnitude Camera Limits for on Point-sourceSurveys images Flux at Explosionradius. Site Two nearby red sources are labelled ‘Star 1’ and ‘Star 2’; they are ⊙

taken at multiple mosaic pointings. North is up and east to the left. M101 displaced from our nominal supernova location by about 9s, and hence are erg s Instrument Aperture Filter UT Date Obs. Exp. Time (s) Prop. No. Visual Limit 3σ Background Limit

displays several well-defined spiral arms. With a diameter of 170,000 light formally excluded as viable candidate objects involved in the progenitor system 33 WFC3 UVIS F225W 2010-01-01 1665.0 11360 26.50 26.80 years, M101 is nearly twice the size of our Milky Way Galaxy, and is estimated of SN 2011fe. Credit for the colour pictureU Sco in a (from http://hubblesite.org): 10 WFC3 UVIS F336W 2010-01-01 1620.0 11360 26.71 27.23 Type Ia Supernova Progenitors 123 9 3 9

to contain at least one trillion stars. b, A cutout section (3 3 )ofa, centred on NASA, ESA, K. Kuntz (JHU), F. Bresolin (University of Hawaii), J. Trauger (Jet • ACS WFC F435W 2006-09-29 1800.0 10766 26.30 27.05 5,000 3,000 × RS Oph WFC3 the supernovaUVIS location. F487N SN 2011fe 2009-11-17 is spatially projected 2455.0 on a prominent11360 spiral Propulsion26.01 Lab), J. Mould25.94 (NOAO), Y.-H. Chu (University of Illinois, Urbana) 2 WFC3 UVIS F502N 2009-11-17 2465.0 11360 25.93 26.28 arm. c, A cutout section (20 3 20)ofb centred on the supernova location, which and STScl. emission is concentrated on

WFPC2 WF F502N 1998-08-28 3600.0 6826 21.76 22.70 ≈ II WFC3 UVIS F547M 2010-01-01 1070.0 11360 D26.14 6 25.94 WFPC2 archivalWF Chandra F547M X-ray observations 1998-08-28 of M101100.0 taken in 20046826 (see ( 21.63t < 10 years) of22.12 steady nuclear burning during the mass-transfer Hubble Space Telescope HeII ACS SupplementaryWFC Information), F555WA5 G0 2006-03-29 and derived upper 1360.0 limits for the10766 X-ray process.26.42 Such systems26.52 should appear as luminous X-ray sources: L WFPC2 luminosityWF at the location F631N of SN 1998-08-28 2011fe in the range 1200.0 (4–25)3 10366826erg s21 1021.4336–1038 erg s21 (kT22.17< 100 eV). Indeed, nearly a hundred of these

ACS WFC F658N 2004-02-09 700.0 9788 limit SN 2011fe 24.63 24.76

(depending on the details of the assumed spectrum). Single-degenerate ‘supersoft’ sources have been identified so far in the Milky Way10,000 and ACS WFC Iax & SN F658N 2006-03-29 4440.0 10766 25.06 25.17 20,21 WFPC2 progenitorWF systems F658N are thought 1997-03-16 to undergo 1200.0 a prolonged6826 period other21.31 nearby galaxies,21.86 including M101 itself . Double-degenerate (2011) Li et al. WFC3 UVIS F673N 2009-11-15 2760.0 11360 24.53 25.62 www.annualreviews.org ACS WFC F814W 2006-03-29 700.0 10766 24.83 25.09

WFC3 IR F110WB5 2010-01-01 1195.39 11360 23.54 23.51 Figure 2 |Progenitor system constraints in a Hertzsprung–Russell WFC3 IR F128NO5 2009-11-17B5 1197.69 A5 G011360 M5 22.90 22.85 WFC3 –6 IR F160W 2010-01-01 2395.39 11360 diagram.22.43 The thick yellow22.48 line is the 2s limit in MV against effective WFC3 IR F164N 2009-11-17 2397.7 11360 temperature21.98 at the supernova22.17 location (see text) from a combination of the four

SN 2006dd limit (K) Temperature

Hubble Space Telescope filters, weighted using synthetic colours of redshifted20,000 Notes. Limiting magnitudes in the Vega system for point sources near the explosion coordinates in the HST images.stellar Visual limiting spectra magnitudes at solar are metallicity estimated for that temperature and luminosity class. A by injecting a point source of increasing brightness in close proximity to the AO explosion coordinates, and identifyingmore when conservative a source is clearly limit dete comescted. The from taking the single filter that most constrains 3σ background detections are computed using the rms of the background measured in a region without point sources or pronounced background gradients. line luminosity is only –4 the stellar type and luminosity class; shown is the 2s limit assuming the adopted magnitude versus effective temperature) showing the 2 II

distance modulus27,28 of 29.05 mag (middle grey curve at the bottom of the V of all pre-explosion HST exposures, and the F435W (Johnson analyzed by Tendulkar etyellow al. (2014 shading);0′′.36), with our a restriction total uncertainty of of 0.23 mag (top/bottom grey curve at B), F814W (Wide I), and F160W (H) HST coadded images. cross-matched sources to those inside of the central 16 16

the bottom of the yellow shading).′′ × ′′ We also show the theoretical estimates (He-

The Tendulkar et al. (2014)positionwasreportedrelativetotheO5 He-star channel regionHe-star RS of Oph the 40′′ 40′′ wide-ﬁeld NIRC213,14 camera to minimize 17 16

V445 Pup star channel ) and observed candidate systems (V445 Pup , RS Oph , He-star channel × WCS of the HLA F814W image, and we use our astrometric the effects of residual distortion, the numbers of matched & Nelemans (2014) Mannucci, via Maoz, USco18,29 and T CrB16). The grey-shaded rectangle shows the location of V445 registration of–2 the images to determine the location of the sources (68 and 8, respectively) incorporated into the astrometric

Pup. Also plotted are the theoretical evolutionary tracks (from 1 Myr to 13 Gyr) ,butitsHe Tendulkar et al. (2014)positioninourreferenceF160Wimage. ﬁt by the two analyses, and our matching of sources in the 50,000

of isolated stars for a range of masses for solar metallicity; note that the limits on −1

The SN 2014J position that we measure is offset by 0′′.08 from K-band NIRC2 image against the near-IR HST F160W image V445 Pup V445 the progenitor mass of SN 2011fe under the supersolar metallicity assumption

the coordinates we calculate6.7 ≳ − for the Tendulkar et al. (2014) as opposed to the I-band F814W image to be able to minimize

F814W position in the F160WV image. SN 2011fesource limit confusion and the effectsare similar of differential to those representedreddening. here. The grey curve at top is the limit inferred erg s T CrB The angularv distance between the position we estimate and the from Hubble Space Telescope analysis of SN 2006dd, representative of the other 0 SN 2006dd limit M ∼1 pc. The reasons for the discrepancy between the observed supersoft ionization M preliminary coordinates reported by Tendulkar et al. (2014)may 4.1. Uppernearby Flux type Limits Ia supernova progenitor limits (see Supplementary Information). 37 0 2 4 6 –6 –4 –2 arise from several differences between our AO coadded images As may be seen in the representativeFor the helium-star images inchannel, Figure bolometric2,the luminosity corrections to the V band 10 and astrometric ﬁtting. These include the substantially improved v 30 local environment of SN 2014Jare adopted exhibits on strong the basis surface of effective bright- temperature . For an effective temperature × resolution of our NIRC2 AO exposures (0′′.1) compared to those M ness variations from both resolvedof 3,000–4,000 and unresolved K, as expected sources, for as the red-giant-branch stars, the MV limit 3 excludes progenitors brighter than an absolute I-band magnitude of M 22. 2 I < = 3 28

This limit is 2 mag fainter than the observed tip of the red-giant branch in x However, there is only one known case, CAL 83, of a supersoft X-ray source that has a detected M101 and places an upper bound to the radius of R=60R8 for an effective L limits (thick yellow) line on the presence of progenitors in pre-explosion of magnitude below model expectations (Gruyters et al. 2012). Contrary to the H 2011fe in M101, from Lirange et of al. masses, (2011a). theoretical Also location shownrecurrent of are novae. a theoretical The SD evolution data He-star tracks rule donor, of out and isolated red location stars giants, on with and the a any diagram evolved of star several more known massive than 3.5M Figure 1 Hertzsprung-Russell diagram (absolute ionization nebula, whereas nine othershave that yielded have only been searched upperCAL for limits, 83 such at (Remillard, extended luminosity Rappaport line & emission is levels Macri an 1995). order Furthermore, of the magnitude X-ray lower luminosity of than CAL that 83 of recurrent nova systems above thefor limit. the Gray more curve distant is SN the 2006dd. corresponding Reproduced limit by by permission Maoz of & Nature Mannucci publishing (2008) group. emission, which is roughly symmetrical around the source, the He temperature of 3,500 K on any red-giant branch progenitor. In a progenitor one side within

SN 2014J U Sco model that requires RLOF, this limit then demands an orbital period smaller SN 2011fe (Li et al. 2011) (Li et al. SN 2006dd than 260 to 130 days in a binary system with a 1:3M8 white dwarf (where the

4 1.0M 6.0M

(Kelly et al. 2014) et al. (Kelly ! ! ≈ −3.5 range of orbital period accommodates the 0:5M8{2:5M8 range allowed for a V only. use personal For 09/16/14. on Libraries University Rutgers by

2.2M 9.0M red-giant-branch star). The foreground Galactic and M101 extinction due to ! ! 7 www.annualreviews.org from Downloaded 2014.52:107-170. Astrophys. Astro. Rev. Annu. dust is negligible and is taken to be AV 5 0 mag here. Had a source at the 2.0s AA52CH03-Maoz ARI 28 July 2014 7:58 3.5M! 12.0M! photometric level been detected in the Hubble Space Telescope images at the (Foley et al. 2010) et al. (Foley

(Maoz & Mannucci 2008) (Maoz & Mannucci precise location of the supernova, we would have been able to rule out the null 6 SN Iax 2012Z SN Iax 2008ge SN Iax hypothesis of no significant progenitor with 95% confidence. We therefore use

50,000 20,000 10,000 5,000 3,000 the 2s photometric uncertainties in quoting the brightness limits on the

Temperature (K) progenitor system. SN 2012Z pre-

white-dwarf SN

pre-explosion limits for normal SN Ia SN normal for limits pre-explosion explosion data are

15 DECEMBER 2011 | VOL 480 any deepest for 3rd | NATURE | 349

A luminous, blue progenitor system for the type Iax supernova 2012Z

Curtis McCully1, Saurabh W. Jha1, Ryan J. Foley2,3, Lars Bildsten4,5, Wen-fai Fong6, Robert P. Kirshner6, G. H. Marion6,7, Adam G. Riess8,9 & Maximilian D. Stritzinger10

Type Iax supernovae are stellar explosions that are spectroscopicallyHST ACSSN 2005/2006 2012Zwas discovered16 inthe Lick Observatory Supernova Search similar to some type Ia supernovae at the time of maximum light on 2012 January 29.15 UT. It had an optical spectrum similar to the type emission, except with lower ejecta velocities1,2. They are also dis- Iax (previously called SN 2002cx-like) SN 2005hk3–5 (see Extended Data tinguished by lower luminosities. At late times, their spectroscopic Fig. 1). The similarities between type Iax and normal type Ia supernovae properties diverge from those of other supernovae3–6, but their com- make understandingthe progenitors ofthe former important, especially position (dominated by iron-group and intermediate-mass elements1,7) because no progenitor of the latter has been identified. Like core-collapse suggests a physical connection to normal type Ia supernovae. Super- supernovae (but also slowly declining, luminous type Ia supernovae), novae of type Iax are not rare; they occur at a rate between 5 and 30 type Iax supernovae are found preferentially in young,S1 star-forming per cent of the normal type Ia rate1. The leading models for type Iax galaxies17,18. A single type Iax supernova, SN 2008ge, was in a relatively supernovae are thermonuclear explosions of accreting carbon–oxygen old (S0) galaxy with no indication of current star formation to deep 8–10 19 white dwarfsthat do not completely unbindthe star ,implyingthatHST WFC3limits . Non-detection2013 of the progenitor of SN 2008ge in Hubble Space they are ‘less successful’ versions of normal typeIa supernovae, where Telescope (HST) pre-explosion imaging restricts its initial mass to complete stellar disruption is observed. Here we report the detection = 12 M8(where M[ is the solar mass), and combined with the lack of the luminous, blue progenitor system of the type Iax SN 2012Z in ofhydrogen or helium inthe SN 2008gespectrum, favoursa white dwarf deeppre-explosion imaging. Theprogenitor system’s luminosity, col- progenitor19. ours, environmentN and similarity to the progenitor of the Galactic Deep observations of NGC 1309, the host galaxy of SN 2012Z, were helium nova V445 Puppis11–13 suggest that SN 2012Z was the explo- obtainedN with HST in 2005–06 and 2010, serendipitously including the sion of a white20″ dwarf =" accreting material from a helium-star compan- location of the supernova before its explosion. To pinpoint the position 3.2 kpc 5″ =" SN 2012Z ion. Observations over the next few years, after SN 2012Z has faded, of800 SN 2012Z pc with high precision, we0.5 obtained″ = follow-up HST data in Ewill either confirm this hypothesisMcCully or perhaps et al. show (2014 that this) super-E 2013. Colour-composite images made80 pc from these observations before nova was actually the explosive death of a massive star14,15. and after the supernova are shown in Fig. 1, and photometry of stellar

abHST ACS 2005/2006 c

deHST WFC3 2013

N N 20 = 3.2 kpc 5 = SN 2012Z 800 pc 0.5 = E E 80 pc

Figure 1 | HST colour images before and after supernova 2012Z. a, Hubble d, e, Shallower post-explosion images of SN 2012Z on the same scale as b and Heritage image of NGC 1309 (http://heritage.stsci.edu/2006/07); panels b and c, respectively. The source data for these images are available as Supplementary c zoom in on the progenitor system S1 in the deep, pre-explosion data. Information.

1Department of Physics and Astronomy, Rutgers, the State University of New Jersey, 136 Frelinghuysen Road, Piscataway, New Jersey 08854, USA. 2Astronomy Department, University of Illinois at Urbana- Champaign, 1002 West Green Street, Urbana, Illinois 61801, USA. 3Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801, USA. 4Department of Physics, University of California, Santa Barbara, California 93106, USA. 5Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106, USA. 6Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, USA. 7Department of Astronomy, University of Texas at Austin, Austin, Texas 78712, USA. 8Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, USA. 9Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, Maryland 21218, USA. 10Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark.

McCully et al. (2014) a b −6 SSS 12Z−S1

−5 He star 12Z−S1

(mag) SSS −4 V445 Pup F555W

M WR He star WR −3 11 M A 11 M A 10 M V = 0.5 mag 10 M V = 0.5 mag 9 M 9 M 7 M 7 M −2 8 M 8 M −0.3 −0.2 −0.1 0.0 0.1 0.2 0.3 −0.2 0.0 0.2 0.4 F435W − F555W (mag) F555W − F814W (mag) C/O white dwarf + helium star model • already suggested by Foley et al. (2013) to explain SN Iax properties, environments • e.g., binary evolution model of Liu et al. (2010) 7 MSun + 4 MSun close binary → 1 MSun C/O WD + 2 MSun He star

Postnov & Yungelson (2006)

• speculation & comparison to V445 Pup:

high accretion rate → stable He burning → C/O WD grows to MCh → deﬂagration

low accretion rate → He nova artist’s conception by Christine Pulliam (CfA) Stritzinger et al.: The bright and energetic Type Iax SN 2012Z.

SN Iax late-time (not nebular) spectroscopy

Jha et al. (2006) McCully et al. (2014) Yamanaka et al. (2015) Stritzinger et al.: The bright and energetic Type Iax SN 2012Z. Stritzinger et al. (2015)

Figure11: Comparison of late phase visual-wavelength spectra of a number of SNe Iax and other SN types. The first 5 spectra, low line-widths ~500 km/s → barely unboundsorted from faintestmaterial to brightest (top to bottom),→ aresome the Type Iax fallback? SNe 2010ae (Stritzinger et al. 2014), 2008ge (Foley et al. 2010), 2002cx (Jha et al. 2006), 2005hk (Sahu et al. 2008), and 2012Z. Also shown are similar epoch spectra of the normal Type Ia significant variation → varying explosionSN 1998bu, (Silverman, Ganeshalingam energies? & Filippenko 2013), the Type Ib SN 2007Y (Stritzinger et al. 2009), and the sublu- minous Type IIP SN 2008bk (Stritzinger et al. 2014). Note in SN 2008bk Balmer lines are associated with emission from the SN ejecta, rather than with the narrower lines associated with pulsating delayed detonation model (PDD;host nebular lines, asHoeflich is the case for SNe 2002cx et and 2010ae.al. 1995;

Quimby et al. 2007; Dessart et al. 2014;24 Stritzinger et al. 2015)?

Figure11: Comparison of late phase visual-wavelength spectra of a number of SNe Iax and other SN types. The ﬁrst 5 spectra, sorted from faintest to brightest (top to bottom), are the Type Iax SNe 2010ae (Stritzinger et al. 2014), 2008ge (Foley et al. 2010), 2002cx (Jha et al. 2006), 2005hk (Sahu et al. 2008), and 2012Z. Also shown are similar epoch spectra of the normal Type Ia SN 1998bu, (Silverman, Ganeshalingam & Filippenko 2013), the Type Ib SN 2007Y (Stritzinger et al. 2009), and the sublu- minous Type IIP SN 2008bk (Stritzinger et al. 2014). Note in SN 2008bk Balmer lines are associated with emission from the SN ejecta, rather than with the narrower lines associated with host nebular lines, as is the case for SNe 2002cx and 2010ae.

24 calcium-line density diagnostics

forbidden + permitted lines with similar velocity structure → densities remain high to very late times bound remnant driving an optically thick wind?

see also Barna et al. poster and Kawabata et al. poster on SN 2014dt

McCully et al. (2014) 2002cx-like SNe from 3D deﬂagrations 2289

Figure 2. Snapshots of the hydrodynamic evolution of our model N5def. Shown are volume renderings of the mean atomic number calculated from the reduced set of species in the hydrodynamic simulation (see the colour bar). To allow a view to the central part of the ejecta, a wedge was carved out from the front of the ejecta. (i) At 0.75 s a one-sided deﬂagration plume rises towards the WD surface and fragments due to Rayleigh–Taylor and Kelvin–Helmholtz instabilities. (ii) At 1.5 s the expansion of the WD quenches the burning and the explosion ashes wrap around the unburned core. (iii) Finally, at 100 s the unburned core is completely engulfed by the explosion ashes which are ejected into space. The small triads at the bottom-right corner of each panel indicate the scaling at the origin of each plot: from left to right the legs of the triads represent 1000, 4000 and 500 000 km, respectively.

100 s after ignition when the ejecta reach homologous expansion. To Since only a moderate fraction of the core of the WD is burned, 50 this end we used the LEAFS code, a three-dimensional finite-volume the nuclear energy release in our simulation (E 4.9 10 erg) nuc = × discretization of the reactive Euler equations which is based on the is less than the binding energy of the initial WD (Ebind 5.2 50 = × PROMETHEUS2288 implementationM. Kromer (Fryxell, et al. Muller¨ & Arnett 1989) of 10 erg). Nevertheless, about 0.37 M of the WD is accelerated to the ‘piecewise parabolic method’ by Colella & Woodward (1984). escape velocity and ejected into the ambient⊙ medium with a kinetic 50 Deflagration frontsturbulent are deflagrations modelled inas WDs discontinuities (Gamezo, Khokhlov between & Oran CO 2004; energy of 1.34 10 erg. The remainder of the mass of the initial × fuel and nuclearRopke¨ ash, & and Hillebrandt their propagation 2005). The lowis tracked expansion with velocities a level- are also WD is left behind and forms a bound remnant.Similarfindings set scheme (Smiljanovski,insuccessful good agreement Moser with & the Klein small 1997; amountfailures: Osher of kinetic & energy Sethian released were already reported in 2D (e.g. Livne, Asida & Hoflich¨ 2005) and 1988; Reineckein et deflagration al. 1999). models. All material Such considerations crossed by led these Branch fronts et al. (2004) recently in the context of a failed gravitationally confined detonation and Jha et al. (2006) to conclude that SN 2002cx-like objects might is converted3d pure tobe nuclear related ash todeflagration pure with deflagrations a composition of Chandrasekhar-mass and energy models release WDs. This (Jordan et al. 2012b). dependingJordan onet fuelal.interpretation (2012), density. Composition wasKromer supported et by and al. Phillips energy(2013), et release al. Fink (2007), are et who in-al. com-(2013)To obtain detailed nucleosynthesis yields of the explosion, we terpolated frompared tables the which broad-band have light been curves calibrated of SN 2005hk using (a our well-sampled full performed a post-processing calculation with a 384-isotope network 384-isotope network.prototypical After 02cx-like a very event) short to phase synthetic of light laminar curves burning of a 3D defla- for 106 Lagrangian tracer particles which were passively advected followingmatch ignition,gration theearly model propagation of Blinnikovlight of deflagrations et curves al. (2006) and is found dominated& spectra good agreement by during the hydrodynamic simulation to record thermodynamic tra- buoyancy-inducedbetween and the shear-induced data and the model. instabilities and interactions jectories of mass elements (Travaglio et al. 2004; Seitenzahl et al. energetics,The models presentedejecta, by Blinnikov bound et al. (2006),remnant however, do with a complexnot turbulent allow for flow a detailed field. comparison The unresolved to the observed acceleration spectral time 2010). A compilation of the masses of important species is given ofhot/inflated the flame duesequence to turbulence since ex-WD the multigroup is accounted with approximation for bystrong a employed sub-grid- inwind? their in Table 2. To determine the mass that stays bound in the remnant scale model (Schmidt,radiative-transfer Niemeyer simulations & Hillebrandt is too coarse. 2006a; Moreover, Schmidt their under- and that of the unbound ejecta, we calculated the asymptotic spe- et al. 2006b).lying Self-gravity hydrodynamic is dealt explosion with models by a monopole are restricted gravity to one spatial cific kinetic energy ϵkin, a ϵkin, f ϵgrav, f for all tracer particles. octant of the progenitor WD, introducing artificial symmetries to the 2 = + solver. Here, ϵkin,fKromervf /2and etϵ al.grav, (2013) f are the specific kinetic and gravita- The hydrodynamicflame evolution. evolution Here, of we our report model on a 3Dis shown full-star in deflagration Fig. 2. sim- tional binding= energies at t 100 s, i.e. at the end of our simulation, ulation through to the homologous expansion phase. We perform = Since a deflagrationdetailed flame radiative-transfer cannot burn calculations against with the thedensity time-dependent gradi- 3D Figure 1. Ignition setup of the N5def model. Shown is a volume rendering ent, our asymmetricradiative-transfer ignition configuration code ARTIS (Sim 2007; leads Kromer to the & formation Sim 2009) from of theTable WD in 2. mintYields green of colour. select As species discussed for model in Section N5def. 2, the ignition of a one-sided deflagrationwhich we obtain plume a time that series fragments of synthetic due spectra to Rayleigh– that we compare kernels were randomly placed within a radius of 150 km around the centre Taylor and Kelvin–Helmholtzto the observed spectra instabilities. of SN 2005hk. Once the deflagration of the WD, as illustrated byBound the bluish remnant sphere. The exact configurationEjecta of the ignition kernels is shown in the enlarged inlay (see also Table 1). front reaches theThe outer paper layers is organized of the as WD, follows. the In burning Section 2quenches we give a brief (M )(M) description of our explosion simulation and present the resulting ⊙ ⊙ due to the expansion of the WD and the ashes wrap around the Table 1. Position of the ignition kernels of model N5def. ejecta structure. In Section 3 we present synthetic observables for Total 1.028 0.372 still unburned core until they finally engulf it completely. A similar Given are the x, y and z coordinates of the centre of the this explosion model and compare them to the observed light curves C0individual ignition kernels.42 and20 their distance d to the.043 evolution of theand deflagration spectra of SN flame 2005hk. was Finally, already we described discuss our for results single- and give O0centre of the WD. .4840.060 spot off-centreconclusions ignitions by in e.g.Sections Plewa, 4 and Calder 5, respectively. & Lamb (2004) and Ne 0.054 0.005 Ropke,¨ Woosley & Hillebrandt (2007). While Plewa et al. (2004) Mg# xyzd0.004 0.013 found an ensuing detonation to be triggered when the ashes collide Si 0.015(in km) 0.025 on the far side of the star (see also Seitenzahl et al. 2009a), we – sim- S0165.5 15.5.0040 24.0 71.5.009 − McCully2EXPLOSIONSIMULATION et al. (2014) Ca 238.60.000322.7 67.3 80.90.001 ilarly to Ropke¨ et al. (2007) and Jordan et al. (2012b) – do not find − Fe 3 13.00.004 8.2 15.1 21.60.031 high enough densitiesA Chandrasekhar-mass and temperatures WD is for believed such a to detonation undergo about to oc- a century Ni 4 5.0 0.02551.3 2.6 51.70.187 cur due to a significantof convective expansion carbon of burning the WD in the during centre the before deflagration a thermonuclear − − − 56Ni55.62.90.66.30.022 0.158 phase. runaway finally sets in. Since this so-called simmering phase is characterized by highly turbulent flows, it cannot be fully accounted 1 for by present-day numerical simulations (but see e.g. Hoflich¨ & sition of carbon and oxygen in equal parts by mass. To account for Stein 2002; Kuhlen, Woosley & Glatzmaier 2006; Zingale et al. an assumed solar metallicity of the zero-age main-sequence pro- 2009; Nonaka et al. 2012). Thus, the actual ignition configuration genitor, we start with a Ye of 0.498 86, corresponding to 2.5 per cent 22 of Chandrasekhar-mass WDs is not well constrained. Given this of Ne in the initial composition. The WD was then discretized on 3 ignorance, one may use the ignition geometry as a free parame- a three-dimensional Cartesian moving grid (Ropke¨ 2005) with 512 ter and explore a larger set of explosion simulations with various cells consisting of two nested parts (central resolution of 1.9 km) ignition setups. Thereby one has to account for both different ig- and ignited in five spherical ignition kernels that were placed ran- nition strengths and ignition positions. A good way to achieve the domly in a Gaussian distribution within a radius of 150 km from the former is to use a multispot ignition scheme which seeds unstable WD’s centre. By chance, for model N5def this algorithm produced burning modes in a robust and numerically well-controlled way. a fairly one-sided ignition configuration with all kernels lying in Recently, we have performed such a systematic study for differ- a relatively small solid angle. Thus, this configuration is represen- ent ignition setups of 3D full-star pure deflagration simulations tative for a slightly off-centred single-spot ignition with a larger (Fink et al., in preparation) yielding 56Ni masses between 0.035 and number of initially excited burning modes. The actual configuration is shown in Fig. 1. All kernels have a radius of r 10 km 0.38 M . ka = Here,⊙ we focus on a detailed comparison to SN 2005hk. For that and are at distances d between 6.3 and 80.9 km from the origin (see purpose we select one of the models of the series by Fink et al. that Table 1). produces a 56Ni mass of the order of the observationally derived Neglecting any possible deflagration-to-detonation transition [see value of SN 2005hk. Applying Arnett’s law (Arnett 1982) to the Seitenzahl et al. (2012) for an alternative evolution of this model in a observed bolometric light curve, Phillips et al. (2007) report a 56Ni delayed-detonation scenario] we followed the flame evolution up to mass of 0.2 M for this SN. With a 56Ni mass of 0.18 M ,model ∼ ⊙ ⊙ N5def of the Fink et al. series comes close to that value. 1 Although the detailed flame evolution depends on the exact value of the In the N5def simulation, an isothermal (T 5 105 K) = × central density (which is not well constrained for Chandrasekhar-mass WDs; Chandrasekhar-mass WD was set up in hydrostatic equilibrium with e.g. Seitenzahl, Ciaraldi-Schoolmann & Ropke¨ 2011), it is not expected to 9 3 acentraldensityof2.9 10 gcm− and a homogeneous compo- have a qualitative impact on the outcome of the explosion. × SN 2012Z +4 years • detected in January 2016 deep HST imaging

• extrapolation of earlier decline: “supernova” (ejecta) ﬂux should not be signiﬁcant now

• not fainter than pre-explosion, still consistent with S1 being the companion star

• source of excess ﬂux? • impacted companion? • wind photosphere? • bound remnant? • other energy source in SN ejecta??? The Astrophysical Journal Letters,794:L28(5pp),2014October20 Wang et al.

Evolution of SN Ia progenitors 1279

hybrid CONe white6.0 dwarfs 6.0

Denissenkov et al. (2013), Chen et al. (2014), 1 5.0 5.0 CO WD+He star (Ch-mass) Figure 4. Distribution of properties of the donors inMeng the plane of (log& TPodsiadlowskieff ,logL) (2014), Wang et al. (2014),

when the WDs grow to 1.378 M . Here, we set α λ 1.5(set3).Thedashed )

ce )

⊙ = ⊙ ⊙ − 0

line denotes the ﬁnal region obtained from the binary calculations in Figure 1. L SN 2012Z S1

Figure 2. Distribution of the initial CONe WD masses that can ultimately KromerL et al. (2015), Liu et al. (2015) / 4.0 CO The error bars present the location of the possible companion in the SN 2012Z 4.0 L produce SNe Ia with different values of αceλ. L / ( progenitor system, the luminosity and temperature of which are based on a ( 10 (A color version of this figure is available in the online journal.) 10 blackbody approximation of the measurements of McCully et al. (2014). log (A color versionsignatures of this figure is available in the online in journal.) explosion → spectra? log -1 3.0 3.0 i strongly dependent on the choice of the initial conditions; they MWD = 0.865, 0.9, 1.0, 1.1M⊙ addition, the SN Ia birthrates decrease with the CBR factor; a are sensitive to the choice of the CE ejection parameter, CBR, high CBR factor will result in a small upper mass limit for the BPS IMF, and initial mass ratio distribution, etc. Notably, if we adopt carbon flame quenching can 2.0leadSTARS to hybrid WDs 2.0 -2 CONe WDs, and consequently a low birthrate. an extreme mass-ratio distribution with uncorrelated component 5.5 5.0 4.5 4.0 3.5 3.0 5.5 5.0 4.5 4.0 3.5 3.0 In Figure 3, we also present the delay time distributions masses (set 8), the SN Ia birthrate will decrease significantly. ofwith SNe Ia obtained central from a singlecarbon starburst (seeeven the right up to 1.3 M log10 (Teff/K) log10 (Teff/K) Downloaded from This is because most of the donors in this scenario are not ☉ panel). From this panel, we see that SN Ia explosions occur 6.0 6.0 massive, the result of which is that WDs cannot accrete enough between 28 Myr and 178 Myr after the starburst, which mass to grow to the Chandrasekhar mass. may contribute∼ to the population∼ of young SNe Ia in late-type 1 In Figure 3,wecomparetheevolutionofSNIabirthratesfor higher initial mass stars can still lead to WDs 5.0 1 galaxies. Wang et al. (2009b)foundthattheminimumdelay 5.0 CO WD+He star (Ch-mass) a constant SFR (3.5 M yr− ;leftpanel)andasinglestarburst ⊙ time from the CO WD + He star scenario is 45 Myr, which

(right panel). According to our standard model (set 2), the SN Ia ) ) ∼ http://mnras.oxfordjournals.org/ ⊙

3 1 is longercapable than the results of obtainedthermonuclear in this work. It seems that explosion⊙ − 0

L SN 2012Z S1 birthrates are 0.298 0− yr− ,whichisroughlyone-tenthof L SNe Ia from the CONe WD + He star scenario are the youngest / 4.0 ∼ × 3 1 4.0 L L / the observed birthrate ( 3 10 yr ;Cappellaro&Turatto ( ∼ × − − of all current progenitor models. ( 10 1997). Even the largest birthrate in our BPS model (set 7) is only + less accretion to trigger carbon10 runaway log afactoroftwogreater.ThisindicatesthattheCONeWD+He 3.3. Surviving Companions of SNe Ia log -1 star scenario can only be responsible for part of the total SN Ia 3.0 3.0 i birthrate (for other SN Ia formation scenarios, see Wang & Han The donor star in the CONe→ WDshorter + He star scenario delay would sur- times MWD = 0.865, 0.9, 1.0, 1.1, 1.2M⊙ 2012). We note that SN Ia birthrates will become lower with vive and potentially be identifiable if the WD was completely CONe BPS the decrease in αceλ (see the left panel). This is because more disrupted at the moment of the SN explosion (e.g., Wang & 2.0 STARS 2.0 -2 binaries after the CE ejection may merge with a low α λ.In Han 2009;Panetal.2010;Liuetal.2013). By interpolating in ce CONe WD + He star: shortest5.5 time5.0 to4.5 MCh4.0 WD3.5 SN 3.0 5.5 5.0 4.5 4.0 3.5 3.0 log10 (Teff/K) log10 (Teff/K) at Rutgers University on August 2, 2015 6.0 6.0 1

5.0 5.0 Hybrid CO-Ne WD+He star (Ch-mass) 0 ) ) ⊙

⊙ −

L SN 2012Z S1 L / 4.0 4.0 L L / ( ( 10 10 -1 log log 3.0 3.0 i MWD = 1.1, 1.2, 1.3M⊙

BPS 2.0 STARS 2.0 -2 5.5 5.0 4.5 4.0 3.5 3.0 5.5 ONe5.0 4.5 4.0 3.5 3.0

log10 (Teﬀ/K) log10 (Teﬀ/K)

Figure 3. Left panel: the evolution of SN Ia birthrates for a constant SFR with different BPS simulation sets. Right panel: similar to the left panel, but for a singleFigure 2. Left column: similar to panel (b) of Fig.1,butonlyfortheHe-stardonorCh-massscenario.Rightcolumn: the distributions starburst. (inFigure logarithmic 4. Similar scale) to Fig. of companion1; all three cases stars have in an the initial the mass plane of of 6.5(log M 10andTeff convective,log10 L), boundary which mixingare obtained for C-shell from burning. BPS Shown calculations are three assuming runs with a CBR factors of 1, 10, and 100 from top to bottom.−1 These stellar models⊙ with the same initial mass illustrate the three different types of cores that can be (A color version of this figure is available in the online journal.) constant star formation rate of 3.5M⊙ yr .Here,theC/OWD+Hestar(top+middlerow)andhybridC/O/NeWD+He star (bottom row)produced Ch-mass depending channel on the are CBR. considered, The shown respectively. models lie on theTo black better dashed compare line seen with in Fig. the5 observation. of the SN 2012Z-S1 (the error in red, see McCully et al. 2014), we show the results from the C/O WD+He star channel by including (middle row) or excluding (top row) the 3 calculations with an initial WD mass of 1.2M⊙. model would imply that the initial mass for the formation of CO Ne WDs can ignite a thermonuclear runaway, the mass range of WDs is slightly increased and CO core masses could be up to SN Ia progenitor WDs could increase significantly. Hybrid WDs of1.1 SN M 2012Z-S1. The more is onlyinteresting consistent implication with however the predicted is the possibility com- thanthat could their form pure if the C/O reduced counterparts hindrance CBR (Denissenkov is appropriate could et al. panionof unknown⊙ locations resonances from that the would hybrid increase WD+He the CBR star and scenario may lead 2015be as), large which as 1.3 probably M .SuchalargeWDmasswouldmakereach- lead to different observational andto thea decrease C/O WD+Heof the maximum star scenario initial mass with to form an initial CO WDs C/O and characteristicsing the Chandrasekhar≈ from⊙ limit those much of easier, the Ch-mass since only C/O a small WDs amount af- WDlimit mass the maximum of 1.2M⊙ CO. Taking WD core the mass problem to 0.93 of M the. origin of terof mass the has SN to explosions be accreted. and In addition, thus being the maximum distinguished initial mass by veryFor massive the case C/O in which WDs a into small account, amount≈ of our convective detailed⊙ boundary binary spectroscopyin this case could observations. be just in excess Recently, of 8 M an. This off-centre would imply defla- evolutionmixing leads calculations to the formation seem to of disfavor hybrid C–O–Ne that SN WDs, 2012Z-S1 the im- grationa significantly in a near shorter Ch-mass SN Ia delay hybrid time C/O/Ne compared⊙ toWD the has standard been isplications a non-degenerate of the CBR companion uncertainties star are more to a significant. C/O WD, If C–O– it is simulatedcase. by Kromer et al. (2015). This showed that de- more likely to be a He star with a hybrid C/O/Ne WD. flagrations in near Ch-mass hybrid C/O/Ne WDs can ex- Because the hybrid WDs have much lower C to O abun- plain the faint SN Iax SN 2008ha (Kromer et al. 2015). dance ratios at the moment of the explosive C ignition However, only a simple nearMNRAS Ch-mass440, 1274–1280 hybrid C/O/Ne (2014) conclusions

• white dwarf supernovae encompasshttp://www.latimes.com/science/sciencenow/la-sci-sn-nasa-hubble-zombie-star-20140806-story.html more than just normal SN Ia http://www.latimes.com/science/sciencenow/la-sci-sn-nasa-hubble-zombie-star-20140806-story.html • SN 2012Z: detection of a progenitor system for a thermonuclear, white dwarf supernova in pre-explosion data

a single degenerate system that exploded! • 2005-2006 2013 • late-time HST observations are still consistent with this picture • a model for SN Iax: a CO (or hybrid CONe) WD accretes He from a He star companion pure deﬂagration explosion near MCh without complete disruption SN ejecta + bound remnant driving an optically thick wind diversity from deﬂagration strength & how much mass is ejected/bound • SN Iax model much more constrained than models for normal SN Ia! Supernovae Through the Ages Rapa Nui August 12, 2016