(The Progenitors of ) Type Iax Supernovae

The Progenitors of Type Ia Supernovae Lijiang, China August 5, 2019

Saurabh W. Jha with Yssavo Camacho-Neves (Rutgers), Curtis McCully (LCOGT), and Ryan Foley (UC Santa Cruz)

see review in Handbook of Supernovae

arXiv:1707.01110

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DispatchDate: 16.07.2019 · ProofNo: 858, p.1

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REVIEW ARTICLEhttps://doi.org/10.1038/s41550-019-0858-0

1Department of Physics and Astronomy, Rutgers, The State University of New Jersey, Piscataway, NJ, USA. 2Center for Computational Astrophysics, Flatiron Institute, New York, NY, USA. 3Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, Belfast, UK. 4School of Physics, Trinity College Dublin, Dublin, Ireland. 5School of Physics and Astronomy, University of Southampton, Southampton, UK. *e-mail: saurabh@physics.rutgers.edu

The modern classification scheme for supernovae traces back to Minkowski1 who in 1941 split ‘type I’ from ‘type II’ super-novae based on optical spectra. Further subdivision of these

basic classes has continued on an empirical basis2,3, and in this Review Article we describe the observational properties of what are now called SNe Ia, along with other similar objects. The obser-vational classification effort arises from a desire for the physical understanding of these objects, explaining our use of the term ther-monuclear supernovae in the title. That categorization is based on the explosion mechanism: objects where the energy released in the explosion is primarily the result of thermonuclear fusion. Given our current state of knowledge, we could equally well call this a review of the observational properties of white dwarf supernovae, a catego-rization based on the kind of object that explodes. This is contrasted with core-collapse or massive star supernovae, respectively, in the explosion mechanism or exploding object categorizations. Unlike those objects, where clear observational evidence exists for mas-sive star progenitors and core-collapse (from both neutrino emis-sion and remnant pulsars), the direct evidence for thermonuclear supernova explosions of white dwarfs is limited4,5 and not neces-sarily simply interpretable6,7. Nevertheless, the indirect evidence is strong, though many open questions about the progenitor systems and explosion mechanisms remain..

m

.

m

.

m

.

m

SNe Ia are important both to the evolution of the Universe and to our understanding of it. As standardizable candles whose distance can be observationally inferred8, SNe Ia have a starring role in the discovery of the accelerating expansion of the Universe9,10 and in the measurement of its current expansion rate11. SNe Ia are also major contributors to the chemical enrichment of the Universe, producing most of its iron12 and elements nearby in the periodic table. Because of the stellar evolutionary timescales involved, the enrichment of these elements occurs differently from other elements whose main origin is in massive star supernovae.

In this Review Article we review the observational properties of thermonuclear supernovae, including both normal SNe Ia and

Q2 Q3 Q4 Q5

related objects. We describe the photometric and spectroscopic properties of SNe Ia in the first section, and their environments and rates in the second section. Evidence has been growing that not all thermonuclear explosions of white dwarfs result in ‘normal’ SNe Ia; we discuss related supernovae in the third section. We pro-vide a broad overview supplemented by further discussion of the newest developments. Our reference list is limited and thus neces-sarily incomplete. We have chosen to highlight illustrative, recent works with a strong bias towards observations rather than theory or models. These deficiencies are rectified in recent reviews that cover many of these topics in more detail13–15. Parallel reviews on core-collapse and extreme supernovae can be found elsewhere in this issue16,17.

Type-Ia supernovaeBelow we describe.

m the photometric and spectroscopic properties of

SNe Ia, along with the applications and implications knowledge of these properties brings.

Energetics and lightcurve properties. The runaway thermonuclear explosion of a carbon–oxygen.

m white dwarf, producing iron-group

elements, releases on the order of 1051 erg as kinetic energy that unbinds the star. The expanding ejecta travel at ~10,000 km s–1 and cool rapidly. The luminosity of SNe Ia is subsequently powered by the decay of radioactive elements that were synthesized in the explosion18,19. The primary power source is the isotope nickel-56, which decays to cobalt-56 with a half-life of 6.1 days, and which in turn decays with a half-life of 77.3 days to stable iron-56. The peak SN Ia bolometric luminosity is typically of the order of 1043 erg s–1, with 0.3–0.8 M⊙ of iron-56 ultimately produced in each event. The majority (~85%) of the luminosity of a SN Ia emerges at optical wavelengths and this is where they have been best studied to date. Arnett’s rule20 says the peak luminosity of the SN is proportional to the mass of nickel-56 produced in the explosion, though in general this is only approximately true21,22.

Q6

Q7

Observational properties of thermonuclear supernovaeSaurabh W. Jha! !1,2*, Kate Maguire! !3,4 and Mark Sullivan! !5

The explosive death of a star as a supernova is one of the most dramatic events in the Universe. Supernovae have an outsized impact on many areas of astrophysics: they are major contributors to the chemical enrichment of the cosmos and significantly influence the formation of subsequent generations of stars and the evolution of galaxies. Here we review the observational properties of thermonuclea.

mr supernovae—exploding white dwarf stars resulting from the stellar evolution of low-mass stars in

close binary systems. The best known objects in this class are type-Ia supernovae (SNe Ia), astrophysically important in their application as standardizable candles to measure cosmological distances and the primary source of iron group elements in the Universe. Surprisingly, given their prominent role, SNe Ia progenitor systems and explosion mechanisms are not fully under-stood; the observations we describe here provide constraints on models, not always in consistent ways. Recent advances in supernova discovery and follow-up have shown that the class of thermonuclear supernovae includes more than just SNe Ia, and we characterize that diversity in this review.

Q1

NATURE ASTRONOMY | www.nature.com/natureastronomy

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DispatchDate: 16.07.2019 · ProofNo: 858, p.1

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263

REVIEW ARTICLEhttps://doi.org/10.1038/s41550-019-0858-0

1Department of Physics and Astronomy, Rutgers, The State University of New Jersey, Piscataway, NJ, USA. 2Center for Computational Astrophysics, Flatiron Institute, New York, NY, USA. 3Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, Belfast, UK. 4School of Physics, Trinity College Dublin, Dublin, Ireland. 5School of Physics and Astronomy, University of Southampton, Southampton, UK. *e-mail: saurabh@physics.rutgers.edu

The modern classification scheme for supernovae traces back to Minkowski1 who in 1941 split ‘type I’ from ‘type II’ super-novae based on optical spectra. Further subdivision of these

basic classes has continued on an empirical basis2,3, and in this Review Article we describe the observational properties of what are now called SNe Ia, along with other similar objects. The obser-vational classification effort arises from a desire for the physical understanding of these objects, explaining our use of the term ther-monuclear supernovae in the title. That categorization is based on the explosion mechanism: objects where the energy released in the explosion is primarily the result of thermonuclear fusion. Given our current state of knowledge, we could equally well call this a review of the observational properties of white dwarf supernovae, a catego-rization based on the kind of object that explodes. This is contrasted with core-collapse or massive star supernovae, respectively, in the explosion mechanism or exploding object categorizations. Unlike those objects, where clear observational evidence exists for mas-sive star progenitors and core-collapse (from both neutrino emis-sion and remnant pulsars), the direct evidence for thermonuclear supernova explosions of white dwarfs is limited4,5 and not neces-sarily simply interpretable6,7. Nevertheless, the indirect evidence is strong, though many open questions about the progenitor systems and explosion mechanisms remain..

m

.

m

.

m

.

m

SNe Ia are important both to the evolution of the Universe and to our understanding of it. As standardizable candles whose distance can be observationally inferred8, SNe Ia have a starring role in the discovery of the accelerating expansion of the Universe9,10 and in the measurement of its current expansion rate11. SNe Ia are also major contributors to the chemical enrichment of the Universe, producing most of its iron12 and elements nearby in the periodic table. Because of the stellar evolutionary timescales involved, the enrichment of these elements occurs differently from other elements whose main origin is in massive star supernovae.

In this Review Article we review the observational properties of thermonuclear supernovae, including both normal SNe Ia and

Q2 Q3 Q4 Q5

related objects. We describe the photometric and spectroscopic properties of SNe Ia in the first section, and their environments and rates in the second section. Evidence has been growing that not all thermonuclear explosions of white dwarfs result in ‘normal’ SNe Ia; we discuss related supernovae in the third section. We pro-vide a broad overview supplemented by further discussion of the newest developments. Our reference list is limited and thus neces-sarily incomplete. We have chosen to highlight illustrative, recent works with a strong bias towards observations rather than theory or models. These deficiencies are rectified in recent reviews that cover many of these topics in more detail13–15. Parallel reviews on core-collapse and extreme supernovae can be found elsewhere in this issue16,17.

Type-Ia supernovaeBelow we describe.

m the photometric and spectroscopic properties of

SNe Ia, along with the applications and implications knowledge of these properties brings.

Energetics and lightcurve properties. The runaway thermonuclear explosion of a carbon–oxygen.

m white dwarf, producing iron-group

elements, releases on the order of 1051 erg as kinetic energy that unbinds the star. The expanding ejecta travel at ~10,000 km s–1 and cool rapidly. The luminosity of SNe Ia is subsequently powered by the decay of radioactive elements that were synthesized in the explosion18,19. The primary power source is the isotope nickel-56, which decays to cobalt-56 with a half-life of 6.1 days, and which in turn decays with a half-life of 77.3 days to stable iron-56. The peak SN Ia bolometric luminosity is typically of the order of 1043 erg s–1, with 0.3–0.8 M⊙ of iron-56 ultimately produced in each event. The majority (~85%) of the luminosity of a SN Ia emerges at optical wavelengths and this is where they have been best studied to date. Arnett’s rule20 says the peak luminosity of the SN is proportional to the mass of nickel-56 produced in the explosion, though in general this is only approximately true21,22.

Q6

Q7

Observational properties of thermonuclear supernovaeSaurabh W. Jha! !1,2*, Kate Maguire! !3,4 and Mark Sullivan! !5

The explosive death of a star as a supernova is one of the most dramatic events in the Universe. Supernovae have an outsized impact on many areas of astrophysics: they are major contributors to the chemical enrichment of the cosmos and significantly influence the formation of subsequent generations of stars and the evolution of galaxies. Here we review the observational properties of thermonuclea.

mr supernovae—exploding white dwarf stars resulting from the stellar evolution of low-mass stars in

close binary systems. The best known objects in this class are type-Ia supernovae (SNe Ia), astrophysically important in their application as standardizable candles to measure cosmological distances and the primary source of iron group elements in the Universe. Surprisingly, given their prominent role, SNe Ia progenitor systems and explosion mechanisms are not fully under-stood; the observations we describe here provide constraints on models, not always in consistent ways. Recent advances in supernova discovery and follow-up have shown that the class of thermonuclear supernovae includes more than just SNe Ia, and we characterize that diversity in this review.

Q1

NATURE ASTRONOMY | www.nature.com/natureastronomy

A B

DispatchDate: 16.07.2019 · ProofNo: 858, p.1

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263

REVIEW ARTICLEhttps://doi.org/10.1038/s41550-019-0858-0

1Department of Physics and Astronomy, Rutgers, The State University of New Jersey, Piscataway, NJ, USA. 2Center for Computational Astrophysics, Flatiron Institute, New York, NY, USA. 3Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, Belfast, UK. 4School of Physics, Trinity College Dublin, Dublin, Ireland. 5School of Physics and Astronomy, University of Southampton, Southampton, UK. *e-mail: saurabh@physics.rutgers.edu

The modern classification scheme for supernovae traces back to Minkowski1 who in 1941 split ‘type I’ from ‘type II’ super-novae based on optical spectra. Further subdivision of these

basic classes has continued on an empirical basis2,3, and in this Review Article we describe the observational properties of what are now called SNe Ia, along with other similar objects. The obser-vational classification effort arises from a desire for the physical understanding of these objects, explaining our use of the term ther-monuclear supernovae in the title. That categorization is based on the explosion mechanism: objects where the energy released in the explosion is primarily the result of thermonuclear fusion. Given our current state of knowledge, we could equally well call this a review of the observational properties of white dwarf supernovae, a catego-rization based on the kind of object that explodes. This is contrasted with core-collapse or massive star supernovae, respectively, in the explosion mechanism or exploding object categorizations. Unlike those objects, where clear observational evidence exists for mas-sive star progenitors and core-collapse (from both neutrino emis-sion and remnant pulsars), the direct evidence for thermonuclear supernova explosions of white dwarfs is limited4,5 and not neces-sarily simply interpretable6,7. Nevertheless, the indirect evidence is strong, though many open questions about the progenitor systems and explosion mechanisms remain..

m

.

m

.

m

.

m

SNe Ia are important both to the evolution of the Universe and to our understanding of it. As standardizable candles whose distance can be observationally inferred8, SNe Ia have a starring role in the discovery of the accelerating expansion of the Universe9,10 and in the measurement of its current expansion rate11. SNe Ia are also major contributors to the chemical enrichment of the Universe, producing most of its iron12 and elements nearby in the periodic table. Because of the stellar evolutionary timescales involved, the enrichment of these elements occurs differently from other elements whose main origin is in massive star supernovae.

In this Review Article we review the observational properties of thermonuclear supernovae, including both normal SNe Ia and

Q2 Q3 Q4 Q5

related objects. We describe the photometric and spectroscopic properties of SNe Ia in the first section, and their environments and rates in the second section. Evidence has been growing that not all thermonuclear explosions of white dwarfs result in ‘normal’ SNe Ia; we discuss related supernovae in the third section. We pro-vide a broad overview supplemented by further discussion of the newest developments. Our reference list is limited and thus neces-sarily incomplete. We have chosen to highlight illustrative, recent works with a strong bias towards observations rather than theory or models. These deficiencies are rectified in recent reviews that cover many of these topics in more detail13–15. Parallel reviews on core-collapse and extreme supernovae can be found elsewhere in this issue16,17.

Type-Ia supernovaeBelow we describe.

m the photometric and spectroscopic properties of

SNe Ia, along with the applications and implications knowledge of these properties brings.

Energetics and lightcurve properties. The runaway thermonuclear explosion of a carbon–oxygen.

m white dwarf, producing iron-group

elements, releases on the order of 1051 erg as kinetic energy that unbinds the star. The expanding ejecta travel at ~10,000 km s–1 and cool rapidly. The luminosity of SNe Ia is subsequently powered by the decay of radioactive elements that were synthesized in the explosion18,19. The primary power source is the isotope nickel-56, which decays to cobalt-56 with a half-life of 6.1 days, and which in turn decays with a half-life of 77.3 days to stable iron-56. The peak SN Ia bolometric luminosity is typically of the order of 1043 erg s–1, with 0.3–0.8 M⊙ of iron-56 ultimately produced in each event. The majority (~85%) of the luminosity of a SN Ia emerges at optical wavelengths and this is where they have been best studied to date. Arnett’s rule20 says the peak luminosity of the SN is proportional to the mass of nickel-56 produced in the explosion, though in general this is only approximately true21,22.

Q6

Q7

Observational properties of thermonuclear supernovaeSaurabh W. Jha! !1,2*, Kate Maguire! !3,4 and Mark Sullivan! !5

The explosive death of a star as a supernova is one of the most dramatic events in the Universe. Supernovae have an outsized impact on many areas of astrophysics: they are major contributors to the chemical enrichment of the cosmos and significantly influence the formation of subsequent generations of stars and the evolution of galaxies. Here we review the observational properties of thermonuclea.

mr supernovae—exploding white dwarf stars resulting from the stellar evolution of low-mass stars in

close binary systems. The best known objects in this class are type-Ia supernovae (SNe Ia), astrophysically important in their application as standardizable candles to measure cosmological distances and the primary source of iron group elements in the Universe. Surprisingly, given their prominent role, SNe Ia progenitor systems and explosion mechanisms are not fully under-stood; the observations we describe here provide constraints on models, not always in consistent ways. Recent advances in supernova discovery and follow-up have shown that the class of thermonuclear supernovae includes more than just SNe Ia, and we characterize that diversity in this review.

Q1

NATURE ASTRONOMY | www.nature.com/natureastronomy

Observational Properties ofThermonuclear SupernovaeSaurabh W. Jha1,2, Kate Maguire3,4, Mark Sullivan5

July 29, 2019

1Department of Physics and Astronomy, Rutgers, the State University

of New Jersey, Piscataway NJ, USA2Center for Computational As-

trophysics, Flatiron Institute, New York, NY, USA3Astrophysics Re-

search Centre, School of Mathematics and Physics, Queen’s Uni-

versity Belfast, UK4School of Physics, Trinity College Dublin, Ire-

land5School of Physics and Astronomy, University of Southampton,

Southampton, SO17 1BJ, UK

The explosive death of a star as a supernova is one of the

most dramatic events in the Universe. Supernovae have an

outsized impact on many areas of astrophysics: they are

major contributors to the chemical enrichment of the cos-

mos and significantly influence the formation of subsequent

generations of stars and the evolution of galaxies. Here we

review the observational properties of thermonuclear super-

novae, exploding white dwarf stars resulting from the stellar

evolution of low-mass stars in close binary systems. The best

known objects in this class are type Ia supernovae (SN Ia),

astrophysically important in their application as standardis-

able candles to measure cosmological distances and the pri-

mary source of iron group elements in the Universe. Surpris-

ingly, given their prominent role, SN Ia progenitor systems

and explosion mechanisms are not fully understood; the ob-

servations we describe here provide constraints on models,

not always in consistent ways. Recent advances in super-

nova discovery and follow-up have shown that the class of

thermonuclear supernovae includes more than just SN Ia,

and we characterise that diversity in this review.

The modern classification scheme for supernovae tracesback to Minkowski1 who in 1941 split “Type I” from “TypeII” supernovae based on optical spectra. Further subdivision ofthese basic classes has continued on an empirical basis2, 3, and inour review we describe the observational properties of what arenow called SN Ia, along with other similar objects. The obser-vational classification effort arises from a desire for physical un-derstanding of these objects, explaining our use of the term ther-

monuclear supernovae in the title. That categorisation is basedon the explosion mechanism: objects where the energy releasedin the explosion is primarily the result of thermonuclear fusion.Given our current state of knowledge, we could equally well callthis a review of the observational properties of white dwarf su-pernovae, a categorisation based on the kind of object that ex-plodes. This is contrasted with core-collapse or massive star su-

pernovae, respectively, in the explosion mechanism or explodingobject categorisations. Unlike those objects, where clear obser-vational evidence exists for massive star progenitors and core-collapse (from both neutrino emission and remnant pulsars), thedirect evidence for thermonuclear supernova explosions of whitedwarfs is limited4, 5 and not necessarily simply interpretable6, 7.Nevertheless, the indirect evidence is strong, though many openquestions about the progenitor systems and explosion mecha-nisms remain.

SN Ia are important both to the evolution of the Universe andto our understanding of it. As standardisable candles whose dis-tance can be observationally inferred8, SN Ia have a starring rolein the discovery of the accelerating expansion of the Universe9, 10

and in measurement of its current expansion rate11. SN Ia arealso major contributors to the chemical enrichment of the Uni-verse, producing most of its iron12 and elements nearby in theperiodic table. Because of the stellar evolutionary timescales in-volved, the enrichment of these elements occurs differently fromother elements whose main origin is in massive star supernovae.

Here we review the observational properties of thermonu-clear supernovae, including both normal SN Ia and related ob-jects. We describe the photometric and spectroscopic propertiesof SN Ia in section 1, and their environments and rates in sec-tion 2. Evidence has been growing that not all thermonuclearexplosions of white dwarfs result in “normal” SN Ia; we dis-cuss related supernovae in section 3. In this review article weprovide a broad overview supplemented by further discussion ofthe newest developments. Our reference list is limited and thusnecessarily incomplete. We have chosen to highlight illustra-tive, recent works with a strong bias towards observations ratherthan theory or models. These deficiencies are rectified in recentreviews that cover many of these topics in more detail13–15.

1 Type Ia SupernovaeEnergetics and light curve properties: The runaway ther-monuclear explosion of a carbon-oxygen white dwarf to iron-group elements releases on the order of 1051 erg as kineticenergy that unbinds the star. The expanding ejecta travel at⇠10,000 km s�1 and cool rapidly. The luminosity of SN Iais subsequently powered by the decay of radioactive elementsthat were synthesised in the explosion16, 17. The primary power

1

-20 -10 0 10Rest frame days from R maximum light

0.0

0.2

0.4

0.6

0.8

1.0

No

rma

lize

d f

lux

KSN 2011bKSN 2011bKSN 2011bKSN 2011bKSN 2011bKSN 2011bKSN 2011bSN 2018oh/ASASSN-18btSN 2018oh/ASASSN-18btSN 2018oh/ASASSN-18btSN 2018oh/ASASSN-18bt

SN 2017cbv/DLT17u rSN 2017cbv/DLT17u rSN 2017cbv/DLT17u rSN 2017cbv/DLT17u rSN 2017cbv/DLT17u USN 2017cbv/DLT17u USN 2017cbv/DLT17u USN 2017cbv/DLT17u U

-20 -18 -16 -14 -12

0.00

0.05

0.10

0.15

0.20

Taubenberger (2017)

Decline rate Δm15(B) (mag)

Peak

abs

olut

e B

mag

nitu

de (m

ag)

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

–21

–11

–12

–13

–14

–15

–16

–17

–20

–19

–18

coming soon… (this week!)

Type Iax Supernovae>60 members in the class (Jha 2017)

rate: ~30% of SN Ia rate (all) ~few% of SN Ia rate (bright)

The Astrophysical Journal, 767:57 (28pp), 2013 April 10 Foley et al.

4000 5000 6000 7000 8000 9000 10000Rest Wavelength (Å)

0

1

2

3

4

5R

elat

ive

f λ +

Con

stan

t

SN 2011ay−2.0

1.9

4.8

10.8

26.4

36.2

49.9

62.7

175.6

Figure 13. Optical spectra of SN 2011ay. Rest-frame phases relative to Vmaximum are listed to the right of each spectrum.

to SN 2008ge, which might be > 20 days) is also larger than forthat of SNe Ia (Ganeshalingam et al. 2011); based on currentdata, it appears that the average SN Iax has a shorter rise timethan the average SN Ia, but few SNe have light curves sufficientfor this measurement. Despite their rough similarity in light-curve shape, SNe Iax have consistently lower luminosity (evenif that criterion is relaxed from our classification scheme) thanSNe Ia.

For SNe Iax, there are several clear trends in the derivedphotometric parameters. Peak brightness and decline rates arehighly correlated for a given object in all bands. In other words,an SN that is bright and declines slowly in B is also bright anddeclines slowly in R.

Performing a Bayesian Monte-Carlo linear regression on thedata (Kelly 2007), we determine correlations between differentparameters in different bands. The linear relationships and theircorrelation coefficients are presented in Table 6, where theequations are all of the form

p2 = αp1 + β, (1)

where p1 and p2 are the two parameters, α is the slope, and β isthe offset.

Using the equations in Table 6, one can effectively trans-form observations in one band into measurements in another.

4000 5000 6000 7000 8000 9000 10000Rest Wavelength (Å)

0

1

2

3

Rel

ativ

e f λ

+ C

onst

ant

SN 2012Z

−13.7

−12.7

1.1

4.1

6.1

6.2

7.1

29.0

Figure 14. Optical spectra of SN 2012Z. Rest-frame phases relative to Vmaximum are listed to the right of each spectrum.

0 20 40 60Rest−Frame Days Relative to V Maximum

−12

−13

−14

−15

−16

−17

−18

Abs

olut

e V

Mag

nitu

de

08ha09J05cc03gq02cx08ae08ge05hk08A12Z11ay

Figure 15. Absolute V-band light curves for a subset of SNe Iax. Each SN isplotted with a different color.(A color version of this figure is available in the online journal.)

15

Foley et al. (2013)

17 Type Iax Supernovae 381

Fig. 2 Absolute magnitude vs. decline rate relation for SN Iax (colored) compared to normalSN Ia (black) showing the Phillips (1993) relation, in B-band (above) and R (or r)-band below(These plots are adapted from Stritzinger et al. 2015 and Magee et al. 2016)

permitted lines of predominantly Fe II, often with low velocities < 2000 km s!1,plus Na I D and the Ca II IR triplet. Forbidden lines of [Fe II], [Ni II], and[Ca II] are also usually present and, in some cases, with narrow widths down to< 500 km s!1 (McCully et al. 2014b; Stritzinger et al. 2015). The linewidths and

SN 2002cx (Li et al. 2003) “most peculiar” SN Ia

02cx-like subclass of SN Ia (Jha et al. 2006)

SN Iax (Foley et al. 2013)Foley et al. (2013)Miller et al. (2017)

Stritzinger et al. (2015)

Magee et al. (2016)

these are white dwarf supernovaeJha et al. (2006), Phillips et al. (2007), McCully et al. (2014)

velocities half of normal SN Ia

S IIStritzinger et al.: The bright and energetic Type Iax SN 2012Z.

Figure 16: Comparison of NIR-wavelength spectra of SN 2012Zat phases of 0d (top) and+22d (bottom), to similar epoch spectraof SN 2005hk (Kromer et al. 2013). Prevalent features attributedto ions of Fe ii, Si iii, and Co ii are indicated with labels.

29

Stritzinger et al. (2015)

Magee et al. (2016, 2017) Barna et al. (2017, 2018)

rest λ:

archivalC

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ofM

101taken

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entaryInform

ation),andderived

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therange(4–25)310

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).Single-degenerateprogenitor

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106years)

ofsteady

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duringthe

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Indeed,nearly

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Double-degenerate

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Figure1

|The

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imaged

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elescope/Advanced

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Surveys.a,A

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M101

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ubbleSpace

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dvancedC

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osaicpointings.N

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cutoutsection(393

39)ofa,centredon

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isspatially

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ism

arkedby

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oobjectis

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areform

allyexcluded

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objectsinvolvedin

theprogenitorsystem

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reditforthe

colourpicture

ina

(fromhttp://hubblesite.org):

NA

SA,ESA

,K.K

untz(JH

U),F.Bresolin

(University

ofHaw

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PropulsionLab),J.M

ould(N

OA

O),Y

.-H.C

hu(U

niversityofIllinois,U

rbana)and

STScl.

O5

–6–4–20

V445 Pup

He-star channel

SN

2006dd limit

24650,000

Mv

1.0M!

2.2M!

3.5M!

6.0M!

9.0M!

12.0M!

B5

A5

G0

M5

20,000

Temperature (K

)

10,0003,000

5,000

U S

co

RS

Oph

T CrB

SN

2011fe limit

Figure2

|Progenitor

systemconstraints

ina

Hertzsprung–R

usselldiagram

.T

hethick

yellowline

isthe

2slim

itinM

Vagainsteffective

temperatureatthesupernova

location(see

text)froma

combination

ofthefour

Hubble

SpaceT

elescopefilters,w

eightedusing

syntheticcolours

ofredshiftedstellar

spectraatsolar

metallicity

forthattem

peratureand

luminosity

class.Am

oreconservativelim

itcomesfrom

takingthesingle

filterthatmostconstrains

thestellartypeandlum

inosityclass;show

nisthe2s

limitassum

ingtheadopted

distancem

odulus27,28of29.05

mag

(middle

greycurve

atthebottom

oftheyellow

shading)with

atotaluncertainty

of0.23m

ag(top/bottom

greycurve

atthe

bottomofthe

yellowshading).W

ealso

showthe

theoreticalestimates(H

e-star

channel 13,14)and

observedcandidate

systems

(V445

Pup17,R

SO

ph16,

USco

18,29andT

CrB

16).The

grey-shadedrectangle

shows

thelocation

ofV445

Pup.Also

plottedarethetheoreticalevolutionary

tracks(from1

Myrto

13G

yr)ofisolated

starsforarangeofm

assesforsolarmetallicity;notethatthelim

itsonthe

progenitormass

ofSN2011fe

underthe

supersolarm

etallicityassum

ptionare

similarto

thoserepresented

here.The

greycurve

attopisthe

limitinferred

fromH

ubbleSpaceTelescopeanalysisofSN

2006dd,representativeoftheothernearby

typeIa

supernovaprogenitor

limits

(seeSupplem

entaryInform

ation).For

thehelium

-starchannel,bolom

etriclum

inositycorrections

tothe

Vband

areadopted

onthe

basisofeffectivetem

perature30.Foran

effectivetem

peratureof3,000–4,000

K,as

expectedfor

thered-giant-branch

stars,theM

Vlim

itexcludesprogenitors

brighterthanan

absoluteI-band

magnitude

ofMI <

22.

This

limitis

2m

agfainter

thanthe

observed28tip

ofthered-giantbranch

inM

101and

placesan

upperbound

tothe

radiusofR=

60R8

foran

effectivetem

peratureof3,500

Kon

anyred-giantbranch

progenitor.Ina

progenitorm

odelthatrequiresR

LOF,this

limitthen

demands

anorbitalperiod

smaller

than260

to130

daysin

abinary

systemw

itha

1:3M8

white

dwarf(w

herethe

rangeoforbitalperiod

accomm

odatesthe0:5M

8{

2:5M8

rangeallow

edfora

red-giant-branchstar).T

heforeground

Galactic

andM

101extinction

dueto

dustisnegligible7and

istakento

beA

V5

0m

aghere.H

ada

sourceatthe

2.0sphotom

etriclevelbeen

detectedin

theH

ubbleSpace

Telescope

images

attheprecise

locationofthe

supernova,we

would

havebeen

ableto

ruleoutthe

nullhypothesisofno

significantprogenitorwith

95%confidence.W

etherefore

usethe

2sphotom

etricuncertainties

inquoting

thebrightness

limits

onthe

progenitorsystem

.

LETTERRESEARCH

15

DE

CE

MB

ER

20

11

|V

OL

48

0|

NA

TU

RE

|3

49

Macm

illan Publishers Limited. A

ll rights reserved©2011

AA52CH03-Maoz ARI 28 July 2014 7:58

–6

–4

–2

0

2

4

650,000 20,000

O5

SN 2006dd limit

SN 2011fe limit

V445

Pup

T Cr

B

RS Oph

U Sco

He-st

ar ch

anne

l

B5 A5 G0 M5

10,000

Temperature (K)

Mv

5,000 3,000

Figure 1Hertzsprung-Russell diagram (absolute V magnitude versus effective temperature) showing the 2σ upperlimits (thick yellow line) on the presence of progenitors in pre-explosion Hubble Space Telescope images of SN2011fe in M101, from Li et al. (2011a). Also shown are theoretical evolution tracks of isolated stars with arange of masses, theoretical location of a SD He-star donor, and location on the diagram of several knownrecurrent novae. The data rule out red giants, and any evolved star more massive than 3.5 M⊙, as well as therecurrent nova systems above the limit. Gray curve is the corresponding limit by Maoz & Mannucci (2008)for the more distant SN 2006dd. Reproduced by permission of Nature publishing group.

However, there is only one known case, CAL 83, of a supersoft X-ray source that has a detectedionization nebula, whereas nine others that have been searched for such extended line emissionhave yielded only upper limits, at luminosity levels an order of magnitude lower than that ofCAL 83 (Remillard, Rappaport & Macri 1995). Furthermore, the X-ray luminosity of CAL 83is Lx = 3 × 1037 erg s−1, but its HeII line luminosity is only LHeII ≈ 2 × 1033 erg s−1, an orderof magnitude below model expectations (Gruyters et al. 2012). Contrary to the Hα and [OIII]emission, which is roughly symmetrical around the source, the HeII emission is concentrated onone side within ∼1 pc. The reasons for the discrepancy between the observed supersoft ionization

www.annualreviews.org • Type Ia Supernova Progenitors 123

Ann

u. R

ev. A

stro

. Ast

roph

ys. 2

014.

52:1

07-1

70. D

ownl

oade

d fr

om w

ww

.ann

ualre

view

s.org

by R

utge

rs U

nive

rsity

Lib

rarie

s on

09/1

6/14

. For

per

sona

l use

onl

y.

pre-explosion limits for normal SN Ia

SN 2006dd(Maoz & Mannucci 2008)

SN 2014J(Kelly et al. 2014)

SN 2011fe(Li et al. 2011)

SN 2012Z pre-explosion data are3rd deepest for any

white-dwarf SN SN 2011feLi et al. (2011)

Th

eA

strophysical

Journ

al,790:3(9pp),2014

July20

Kelly

etal.

Figure

1.Coadded

Keck-IIK

-bandN

IRC

2A

O(left)and

HST

pre-explosionF160W

(right)exposuresofthe

locationofSN

2014J.We

useonly

thecentral16 ′′×

16 ′′ofthe

distortion-correctedA

Oim

ageto

performastrom

etricregistration.T

he68

sourcesused

forregistration

areidentified

with

white

circles,while

theposition

ofSN

2014Jis

marked

bya

blackcircle

with

radiuscorresponding

tothe

uncertaintyin

thatpositionestim

ate.

Table1

HST

Data

Setsand

UpperA

bsoluteM

agnitudeL

imits

onPoint-source

FluxatE

xplosionSite

Instrument

Aperture

FilterU

TD

ateO

bs.E

xp.Time

(s)Prop.N

o.V

isualLim

it3σ

Background

Lim

it

WFC

3U

VIS

F225W2010-01-01

1665.011360

26.5026.80

WFC

3U

VIS

F336W2010-01-01

1620.011360

26.7127.23

AC

SW

FCF435W

2006-09-291800.0

1076626.30

27.05W

FC3

UV

ISF487N

2009-11-172455.0

1136026.01

25.94W

FC3

UV

ISF502N

2009-11-172465.0

1136025.93

26.28W

FPC2

WF

F502N1998-08-28

3600.06826

21.7622.70

WFC

3U

VIS

F547M2010-01-01

1070.011360

26.1425.94

WFPC

2W

FF547M

1998-08-28100.0

682621.63

22.12A

CS

WFC

F555W2006-03-29

1360.010766

26.4226.52

WFPC

2W

FF631N

1998-08-281200.0

682621.43

22.17A

CS

WFC

F658N2004-02-09

700.09788

24.6324.76

AC

SW

FCF658N

2006-03-294440.0

1076625.06

25.17W

FPC2

WF

F658N1997-03-16

1200.06826

21.3121.86

WFC

3U

VIS

F673N2009-11-15

2760.011360

24.5325.62

AC

SW

FCF814W

2006-03-29700.0

1076624.83

25.09W

FC3

IRF110W

2010-01-011195.39

1136023.54

23.51W

FC3

IRF128N

2009-11-171197.69

1136022.90

22.85W

FC3

IRF160W

2010-01-012395.39

1136022.43

22.48W

FC3

IRF164N

2009-11-172397.7

1136021.98

22.17

Notes.L

imiting

magnitudes

inthe

Vega

systemforpointsources

neartheexplosion

coordinatesin

theH

STim

ages.Visuallim

itingm

agnitudesare

estimated

byinjecting

apointsource

ofincreasingbrightness

inclose

proximity

tothe

AO

explosioncoordinates,and

identifyingw

hena

sourceis

clearlydetected.T

he3σ

backgrounddetections

arecom

putedusing

therm

softhe

backgroundm

easuredin

aregion

withoutpointsources

orpronouncedbackground

gradients.

ofall

pre-explosionH

STexposures,and

theF435W

(JohnsonB

),F814W

(Wide

I),and

F160W(H

)H

STcoadded

images.

The

Tendulkaretal.(2014)positionw

asreported

relativeto

theW

CS

ofthe

HL

AF814W

image,

andw

euse

ourastrom

etricregistration

ofthe

images

todeterm

inethe

locationof

theTendulkaretal.(2014)position

inourreference

F160Wim

age.T

heSN

2014Jposition

thatwe

measure

isoffsetby

0. ′′08

fromthe

coordinatesw

ecalculate

forthe

Tendulkaret

al.(2014)

F814Wposition

inthe

F160Wim

age.T

heangulardistance

between

theposition

we

estimate

andthe

preliminary

coordinatesreportedby

Tendulkaretal.(2014)may

arisefrom

severaldifferencesbetw

eenourA

Ocoadded

images

andastrom

etricfitting.T

heseinclude

thesubstantially

improved

resolutionofourN

IRC

2A

Oexposures

(0. ′′1)com

paredto

those

analyzedby

Tendulkaret

al.(2014;

0. ′′36),

ourrestriction

ofcross-m

atchedsources

tothose

insideof

thecentral16

′′×16

′′

regionof

the40

′′×40

′′wide-field

NIR

C2

camera

tom

inimize

theeffects

ofresidual

distortion,the

numbers

ofm

atchedsources(68

and8,respectively)incorporated

intothe

astrometric

fitby

thetw

oanalyses,

andour

matching

ofsources

inthe

K-band

NIR

C2

image

againstthe

near-IRH

STF160W

image

asopposed

tothe

I-bandF814W

image

tobe

ableto

minim

izesource

confusionand

theeffects

ofdifferentialreddening.

4.1.Upper

Flux

Limits

As

may

beseen

inthe

representativeim

agesin

Figure2,the

localenvironm

entof

SN2014J

exhibitsstrong

surfacebright-

nessvariations

fromboth

resolvedand

unresolvedsources,as

3

SN 2014JKelly et al. (2014)

Li et al. (2011) via Maoz, Mannucci, & Nelemans (2014)

SN Iax 2012Z3𝜎 depth MV ≈ −3.5

& SN IaxSN Iax 2008ge(Foley et al. 2010)

MV ≳ −6.7

SN Iax 2014dt(Foley et al. 2015) MV ≳ −5.2

McCully et al. (2014) see Curtis McCully talk tomorrow for updates

Galaxy Type

Cum

ulat

ive

Frac

tion

E S0 Sa−Sab Sb Sbc Sc Scd−Sm Irr0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Ia91bg91TIbIcII02cx05E

91bg

05E

Ia

II02cx

Figure 3: The cumulative distribution of host galaxies of SNe from the KAIT SNsurvey. We corrected the classification of a few SN Ib/c hosts using higher-quality obser-vations from the Palomar 60-inch telescope (SN 2005ar, 2006ab, and 2006lc were found tobe hosted by spiral galaxies rather than elliptical galaxies). After correcting the classifi-cation we find that all SNe Ib/c found in early-type galaxies are faint Ca-rich SNe similarto SN 2005E. Note that the SN 2005E-like SN host distribution is very di�erent from thatof other SNe Ib/c, as well 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 (four out ofeight) observed in early-type (elliptical or S0) galaxies. The progenitors of SN 2005E andthe other members of its group are therefore likely to belong to an old, low-mass stellarpopulation. The total numbers of host galaxies included in this figure are 244, 25, 8, 257,30, 63, 14, and 8 for SNe of types Ia, 91bg, 91T, II, Ib, Ic, 02cx, and 05E, respectively.

Perets et al. (2009)

Figure 4: Host galaxy distributions for di↵erent classes of supernovae. Note that the 02cx-likeSNe are found preferentially in late-type galaxies, similar to core-collapse SNe (II, Ib, Ic) anddi↵erent from the bulk of the SN Ia population. However, the 02cx-like objects are alsodistributed similarly to SN 1991T-like SNe Ia, thought to be thermonuclear. This figure isadapted from Perets et al. (2009).

Description of the Observations

We propose to obtain late-time optical WFC3/UVIS V rI photometry of SN 2012Z in NGC

1309 in two epochs, once during Cycle 20 (sometime approximately 400 to 600 days after SN

maximum light), and again during Cycle 21 (sometime approximately 750 to 950 days past

maximum). The few extant HST observations of SNe Ia at these late times have often been

taken in just one or two optical filters; this makes it di⌅cult to get solid 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 obser-

vations 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 a�ord the imprecision in compar-

ing ground-based and HST broad-band magnitudes to make the measurement! We choose

6

all late-type hosts (except SN 2008ge)

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; White et al. 2015)

Iax environments