the quest for type ia supernova progenitors · sn ia progenitors carles badenes university of...

Carles Badenes

Tel-Aviv University /Weizmann Institute of Science

University of PittsburghPittsburgh, January 20, 2011

The Quest for Type Ia Supernova Progenitors

Motivation and Outline

Carles Badenes University of Pittsburgh Jan 20 2011 2

● Introduction: Supernovae (SNe). The Type Ia SN progenitor problem. The delay time distribution.

● Supernova Remnants (SNRs): SNR basics. SNRs as probes of the SN Ia phenomenon.

● Binary White Dwarfs (WDs): The SWARMS survey.

● Conclusions: Future perspectives and opportunities.

We know very little about the progenitors of Type Ia SNe

The Milky Way

SN 1994D in NGC 4526

Supernovae: Thermonuclear vs. Core Collapse


Wavelength [A]

Rel

ativ

e Fl

ux ● Classification by optical spectra:

● Type I: no H (Ia: Si, Ib: He, Ic: neither He nor Si).

● Type II: Strong H.

● Core collapse SNe (Type II, Ib, Ic): death of massive stars (M≥8M

⊙).

Several progenitors identified.

● Thermonuclear SNe (Type Ia) ⇒ this talk.

Supernovae (SNe) are rare, transient optical phenomena that last for a few weeks/months and reach peak magnitudes that rival

their host galaxies

Type Ia Supernovae


REVIEWS: Branch+ 95; Branch & Khokhlov 95; Hillebrandt & Niemeyer 00.

● Fundamentals are well understood: energy budget, no H in spectra, rate of light curve decay.

● Some key details remain obscure: explosion mechanism, progenitor systems.

● Light curves and spectra are strikingly uniform LC width / ⇒luminosity relation (56Ni mass) ⇒Cosmology.Supernova

Cosmology Project

Type Ia SNe are the result of the thermonuclear explosion of a C+O white dwarf prompted by accretion in a binary system

SN Ia: Progenitor Scenarios


Nature of the WD companion: ● A normal star: Single Degenerate (SD)

systems. Slow accretion explosion. ⇒Many known examples of WD+star binaries [Parthasarathy+ 07]. Problems: getting the WD close to MCh avoiding novae; getting rid of H.

● Another WD: Double Degenerate (DD) systems. Gravitational wave emission ⇒merging explosion. No known ⇒examples [Nelemans+ 05]. Problems: rate; explosion vs. accretion induced collapse.

A critical reappraisal of our ideas about SN Ia progenitors may be in

order [Maoz 08]DD System

SD System

SN Ia Progenitors: Observations


SN 2006dd

NGC 1316

Maoz & Mannucci 08

Panagia+ 06

Leonard 07

SN 2005cf(354 days)

● No H, not even in nebular spectra [Leonard 07].

● Faint. Not detected in pre-explosion images [Maoz & Mannucci 08; Voss & Nelemans 08].

● No prompt emission in the radio or X-ray (CSM interaction) [Panagia+ 06; Hughes+ 07].

● CC SNe: Bright, massive progenitors [Smartt 09], many examples of prompt emission [Weiler+ 02].

● Direct detection is a tough observational problem ⇒need very nearby SN Ia.

SN Ia Progenitors: Observations


Sullivan+ 06

DimSN Ia

Spirals

E/S0

BrightSN Ia

● No direct observations ⇒ constrain progenitors using SN host galaxies.

● There might be evidence for two populations of SN Ia progenitors:

● 'Prompt' ⇒ 'younger' progenitors in star forming galaxies, SN rate star ⇔formation rate, brighter Type Ia SNe.

● 'Delayed' 'older' progenitors in ⇒passive galaxies, SN rate total ⇔stellar mass, dimmer Type Ia SNe.

● Bimodality not required by the data.

All these results involve averaging over entire host galaxies!

SN Ia Progenitors: The Delay Time Distribution


DTD: Delay Time Distribution. SN Ia rate as a function of time after a SF burst. Controversial subject, many techniques:

● Field galaxies vs. redshift [Poznanski+ 07; Greggio+ 08] ⇒ SN Ia rate traces cosmic SFH.

● Local universe [Mannucci + 05; Scannapieco & Bildsten 06; Brandt+ 10; Maoz+ 10] ⇒ 'Prompt' component ~100-500 Myr.

● Clusters [Sharon+ 07] ⇒ Most SN Ia explode at high redshift.

Comparison of observed DTDs and theoretical models should validate specific progenitor scenarios.

We should worry about averaging.

Maoz+ 10

Botticella+ 08

SN Ia Progenitors


● We have not identified the progenitors of Type Ia SNe.

● Theoretical scenarios (SD/DD) have problems.

● SN observations ⇒ indirect studies.

● The DTD is the key.

Supernova Remnants (SNRs)


Tycho SNRFe L Si K 4-6 keV

Warren+ (incl CB) 05

SNR: Interaction between SN ejecta and ambient medium (AM)

● Young SNRs are often X-ray bright ⇒ excellent Chandra and XMM-Newton data [Review: Badenes 10].

● No longer a single line of sight into a distant object!

⇒ detailed view of the ejecta structure and immediate surroundings.

● Key limitation: data analysis and interpretation.

⇐ Tycho SNR

WISE Image

Some Reflections on (X-ray) Spectroscopy


● Spectroscopy ⇒ what? (easy) how much? (hard).

● In order to interpret spectra in terms of abundances (yields), it is necessary to model the physics of the emitting object.

● Different technical challenges for different objects.

Yes, it will be a long time before people learn what I know. How much of iron and other metal there is in the sun and the

stars is easy to find out, but anything that exposes our swinishness is difficult, terribly difficult!

Lev Nikolayevich Tolstoy (1828-1910), The Kreutzer SonataThanks to Martin Laming for the quote!

Modeling the X-ray Spectra of SNRs


X-ray spectrum coupled to the hydrodynamics

HD+NEI simulations: Hydrodynamics, NEI, physics of collisionless shocks, electron-ion coupling, radiative + ionization losses, ... [Hamilton & Sarazin 84; Badenes+ 03, 05; Sorokina+ 04] .

[ tSNR , ρAM, β]

HD+NEIHydrodynamics

NEIX-ray emission

Si CIESi NEI

SNR plasma ⇒ Nonequilibrium Ionization (NEI)

SN Ia Explosion Model (DDTe) Synthetic X-ray Spectrum (DDTe; t=430 yr, ρAM=10-24 g cm-3)

Tycho SNR: A Normal Type Ia SN


Bright SN Ia

Normal SN Ia

Dim SN Ia

Age is known (SN1572). SNR size forces a correlation between D and ρAM:

● Only 1D DDT models can reproduce both X-ray spectrum and SNR dynamics.

● Hydro + spectra ⇒ Crucial sanity check on yields ⇒ 56Ni mass ⇒ SN brightness.

56Ni

DDTa-c-eρAM=2x10-24

Tycho SNR: Light Echoes


SN

Dust Cloud

Earth

● Tycho SNR: M56Ni=0.74 M⊙ [Badenes+06]

⇒ a normal SN Ia.● Later confirmed by light echo spectroscopy [Rest+ 08, Krause+ 08]. Badenes+ 06

Krause+ 08

Light Echo

1572

2008

Independent calibration of the same measurement with two

different techniques

SNR 0509-67.5: A Bright Type Ia SN


HD+NEIModels

● Method can be applied to any young, X-ray bright Type Ia SNR. Need at least a good estimate of the age.

● SNR 0509-67.5 in the LMC ⇒ M56Ni=0.97 M

⊙ (bright SN Ia) [Badenes + 08].

Also confirmed by light echo [Rest+ 08].3 Bright Type Ia SNe

Badenes+ 08

Rest+ 08

The Key Advantage of SNRs


Typical SDSS galaxy[Tojeiro+ 09]

● Much of what we know about Type Ia SN progenitors comes from the stellar populations in their host galaxies ⇒ metallicities, ages, SFRs, SFHs. Issues:

● Unresolved stellar populations ⇒ luminosity weighted spectra/SED [Conroy+ 09, Schiavon+ 02].

● Measurements are not local ⇒ age and metallicity gradients.

● By using supernova remnants (SNRs), it possible to study resolved stellar populations (RSPs) at the location of the SN progenitors ⇒ Milky Way, LMC, SMC, M31, M33...

● Individual SNRs to entire populations!

SDSS Supernovae

The Large Magellanic Cloud (MCELS)


Core Collapse SNRs in the LMC


Badenes+ 09

Type Ia SNRs in the LMC


Badenes+ 09

Beyond Individual Objects: SNR Populations


● There are 77 known SNRs in the MCs (54 in the LMC, 23 in the SMC) clean ⇒record of the environments where SNe explode SN 'survey'.⇒

● The sample is fairly complete (faintest SNRs >> 5σ radio sensitivity).

● We don't know the types or the ages, we just know the sizes ⇒ control time.

The SN Rate and DTD in the Magellanic Clouds


● Magellanic Clouds ⇒ SFH from resolved stellar populations.● SNR catalog + evolution model ⇒ SNR visibility times [Badenes, Maoz & Draine 10].● SN rates + DTD for the Magellanic Clouds (1st DTD with resolved stellar population) [Maoz & Badenes 10].

Rates typical of dwarf galaxies

Prompt (<330 Myr)SNe Ia detected > 95%

SNRs as Probes of the SN Ia Phenomenon


● X-ray emission from SNRs ⇒ distinguish CC / Ia SNe, bright / dim SN Ia.

● SNRs+RSPs ⇒ unique insights into SN Ia progenitors.

● SNR populations in nearby galaxies ⇒ SN rates and DTDs.

DD SN Ia Progenitors


● The merging of binary WDs due to gravitational wave emission was suggested as SN Ia progenitor scenario in the 1980s [Webbink 84; Iben & Tutukov 84].

● The only scenario that naturally explains the lack of H in SN Ia spectra.

● Can produce both short and long delay times [Yungelson & Livio 99].

● Caveat: it is unclear whether WD mergers lead to SN Ia explosions or end in accretion induced collapse [Saio & Nomoto 85] ignition if dM/dt>M⇒ crit (~10-5 M

⊙yr-1).

Depends on the final accretion phase ⇒multi-D simulations.

● Something interesting will happen anyway! Loren-Aguilar+ 09

Where are the DD SN Ia Progenitors?


● Are there enough WD+WD systems with M1+M2 > MCh & tMerge < tHubble ?

● Not a single such system is known (a few claims have been disproved).

● Theoretical uncertainties are large [Nelemans & Tout 05] ⇒ Observations are crucial.

● SPY Survey [Napiwotzki+ 01]: ~1000 known WDs with B<16.5 using ESO VLT ⇒ ~100 DD systems [Napiwotzki+ 04], masses and periods only published for 26 systems [Nelemans+ 05]. Of these, only 5 pre-mergers.

● Now we can do better...

A Twist to SDSS


● SDSS ⇒ largest spectroscopic data base in astronomy (1.5 million spectra): galaxies, quasars, stars...

● ALL these spectra were taken in 3 or more separate ~15 minute sub-exposures to reject cosmic rays.

● This opens the possibility to do time-resolved spectroscopy in SDSS.

● Up to DR7, SDSS collected ~15,000 WD spectra (15xSPY!).

● Well suited to search for DD SN Ia progenitors (short period, large RV shifts).

● Many more possibilities....

Distribution of baselines:

The SWARMS Survey


S W A R M SSloan White dwArf Radial velocity data Mining Survey

GOALS: ● Find the double degenerate WD (DDWD) SN Ia progenitors (WD binaries

with MA+MB≥MCh and tMerge<tHubble ), if they exist.

● Characterize the population of (pre-merging) WD binaries in the Galaxy binary fraction, mass ratio distribution, separation distribution... ⇒ merger

rates.

PEOPLE: C. Badenes [PI] (TAU/WIS). M.Kilic (CfA), T. Matheson (NOAO), F. Mullally (NASA/Ames), R. Romani (Stanford), S. Thompson (NASA/Ames).

S W A R M SSloan White dwArf Radial velocity data Mining Survey

SDSS 1257+5428: Discovery


● Classified as DA by E06; Mg=16.8.

● RV shift of ~8 Å (~490 km s-1) between exposures 0, 1 (taken 10/03/2003) and 2 (taken 10/04).

SDSS 1257+5428: Follow-up


● Follow-up observations: APO ARC 3.5m telescope on 02/2009.

● RV curve is well fit by a circular orbit with P=4.5550±0.0007 hr; KA=322.7±6.3 km s-1.

● System must be tight and/or have massive components.

SDSS 1436+5010: Discovery


● Classified as DA by E06; Mg=18.2.

● RV shifts can be detected between consecutive SDSS exposures!

The Changing Landscape of WD Binaries


● SWARMS has become the most efficient survey for discovering massive WD binaries [Badenes+ 09].

● SDSS 1257+5428 ⇒ might be above MCh, but probably not a SN Ia progenitor [Badenes+ 09, Marsh+ 10, Kulkarni & van Kerkwijk 10].

● SDSS 1436+5010 and 1053+5200 ⇒ shortest period DD WDs [Mullally, Badenes+ 09, Kilic+10].

● Independent discovery of several ELMWD binaries, including SDSS 0923+3028 [Brown+ 11].

● Follow-up of individual systems continues (1st KPNO run 10/10, 2nd 04/11) ⇒ papers in prep.

The Future of SWARMS


● Individual systems are interesting, but SWARMS can also be used to statistically characterize the DDWD population in the Milky Way.

● Distribution of RV shifts in the ~15,000 WDs ⇔ Monte Carlo simulations of DDWDs with different period and mass ratio distributions [Maxted & Marsh 99].

● End result: rate of WD mergers as a function of mass.

● What about the DTD? If mergers are driven by GR, and separation distribution is a powerlaw, DTD should be proportional to 1/t [Maoz+ 10].

Merger time (GR):

Separation distribution[Öpik 24, Poveda+ 06]:

ϵ~-1

Poveda & Allen 04

Binary WDs and the SWARMS Survey


● DD WD Binaries ⇒ promising SN Ia progenitors.

● SWARMS exploits the capabilities of SDSS to find DD WD Binaries.

● Deliver individual discoveries and DD WD merger rate.

● Expect DTD∝ 1/t from DD WDs.

Wrapping up: The SN Ia DTD Revisited


Current knowledge of the DTD [Maoz+10]: ● For t < 1 Gyr, the situation is unclear. Measurements do not agree with each other ⇒ diversity? biases?● For t > 1 Gyr, 1/t fits the data quite well ⇒ DD WD mergers? If so, rate too high for M > MCh events [van Kerkwijk+ 10].

Galaxy clustersMC SNRs

0.4<z<1.2 ellipticalsNearby galaxies

● Early times ⇒ RSPs + SNR catalogues in nearby galaxies will provide the best (least biased) DTDs.

● Late times ⇒ DD WDs are promising, but rate is too high. SWARMS will settle this.

Maoz+ 10

Collaborators


SNe and SNRs:Eduardo Bravo (UPC), Jack Hughes, Kris Eriksen (Rutgers), Bruce Draine (Princeton), Dan Maoz (Tel-Aviv), Avishay Gal-Yam, Iair Arcavi (Weizmann)

SWARMS:Tom Matheson (NOAO), Mukremin Kilic (Harvard/CfA), Fergal Mullally, Susan Thompson (NASA Ames), Dan Maoz (Tel-Aviv), Steve Bickerton (Princeton), Tsevi Mazeh, Lev Tal-Or (Tel-Aviv), Avishay Gal-Yam (Weizmann)

Conclusions


● We have not identified the progenitors of Type Ia SNe.● Theoretical scenarios (SD/DD) have problems.● SN observations ⇒ indirect studies.● The DTD is the key.

● SNRs in X-rays ⇒ distinguish CC / Ia SNe, bright / dim SN Ia.● SNRs+RSPs ⇒ unique insights into SN Ia progenitors. ● SNR populations in nearby galaxies ⇒ SN rates and DTDs.

● DD WD Binaries ⇒ promising SN Ia progenitors.● SWARMS ⇒ use SDSS to find DD WD Binaries.● Deliver individual discoveries and DD WD merger rate.● Expect DTD∝ 1/t from DD WDs.

● Early times ⇒ RSPs + SNRs.● Late times ⇒ DD WDs? (SWARMS).

DTD

the quest for type ia supernova progenitors · sn ia progenitors carles badenes university of...

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