THE PHYSICS OF COSMOLOGICALLY RELEVANT  TYPE   IA   SUPERNOVAE

WHAT IS OLD AND WHAT IS NEW  (among news: natura facit saltus)(among news: natura facit saltus) 

Amedeo TornambéAmedeo Tornambé

OA ROMA‐INAF

SIF – BOLOGNA – SETTEMBRE 2010

TYPE IA SUPERNOVAE ARE:TYPE IA SUPERNOVAE ARE:

PARAMOUNT COSMOLOGICAL TOOLS

IN FACT: They are  powerfull distance indicators

IRON PRODUCERS

INTRIGUING (ASTRO)PHYS LABSINTRIGUING (ASTRO)PHYS. LABS

(GWR, URCA neutrinos, energy transport ….

OBSERVATIONAL PROPERTIES OF TYPE IA SUPERNOVAE

OBSERVATIONAL PROPERTIES OF TYPE IA SUPERNOVAETYPE IA SUPERNOVAETYPE IA SUPERNOVAE

EXPLOSION ENERGY: ergs (no neutrinos no 5110EXPLOSION ENERGY: ergs (no neutrinos,no compact remnants)

10

BOTH IN YOUNG AND IN OLD STELLAR POLPULATIONS (but the only ones in OLD)POLPULATIONS (but the only ones in OLD)

LIGHT CURVE REACHING MAXIMUM IN ABOUT 15 LIGHT CURVE REACHING MAXIMUM IN ABOUT 15 DAYS THEN DECLINING WITH TWO STEEPNES.

SIMILAR BUT NOT EQUAL LIGHT CURVES (BELIEVED ABSOLUTELY EQUAL UP TO SOME YEARS AGO)

SN 2000Ein NGC 6951in NGC 6951NIR(AZT-24)

SN 2001Vin NGC 3987NIR(AZT-24)

SN 2002boin NGC 3190NIR(AZT-24)

Barbon, Ciatti and Rosino 1973

THEY WERE THOUGHT TO BETHEY WERE THOUGHT TO BE   

STANDARD CANDELS

THIS IS NO MORE TRUETHIS IS NO MORE TRUE 

BUT 

THEY CAN BE STANDARDISED

ADDITIONAL OBSERVATIONAL ISSUES ARE:ADDITIONAL OBSERVATIONAL ISSUES ARE:

SNIA in ellipticals less luminous than those in spyrals (as a mean)

SNIA rates linked both with SFR and with the whole mass of the parent systeme o e ass o e pa e sys e

Half production occurring in a short time after theHalf production occurring in a short time after the birth of the parent population (hundreds mill. Yrs)

PER POTERLE UTILIZZARE CON TRANQUILLITA’ OCCORRE SAPERNE DI PIU’OCCORRE SAPERNE DI PIU

cosa sono esattamente e quale è stata q

l’evoluzione dei progenitori stellari?

Ci sono più famiglie??p g

Da dove proviene l’energia che alimenta 

l’esplosione?l esplosione?

Perché sono ‘auto‐simili’? 

STATO Dell’ ARTESTATO  Dell  ARTE

(i1 SOLAR MASS OF INCINERATED C+O (i.e.:FULLY & SUDDENLY  BURNED TO IRON GROUP ELEMENTS)  PROVIDES           ERGS

5110

(RECOGNISED SOME 50 YRS AGO)

NECESSARIO UN AMBIENTE AD ALTANECESSARIO UN AMBIENTE AD ALTA DEGENERAZIONE ELETTRONICA

( THE CHANDRASEKHAR MASS)( THE CHANDRASEKHAR MASS)

St i t th k t th di tStars exist thanks to the pressure gradient

I “ l” t th f ti l d i tIn “normal” stars the free particles pressure dominates and the standard EOS is at work

In Dwarf Stars it is the pressure of the degenerate electrons to dominateelectrons to dominate

The mass of Degenerate Stars cannot exceed theThe mass of Degenerate Stars cannot exceed the Chandrasekhar limiting mass. If they exceed they will collapse or explode.

CHANDRASEKHAR MASSCHANDRASEKHAR MASS

222/35.02 )/()32/9( ench YmGcM −= hπ265 YM ≅ 6.5 ech YM ≅

limiting masses in standard conditionslimiting masses in standard conditions  

H dominated matter Sh MM 65≈ Sunch MM 6.5≈

Helium, Carbon, Oxygen Sunch MM 4.1≈

Iron  Sunch MM 1.1≈

Single stars cannot attain the Ch d M !!!!Chandra Mass !!!!

Lets inquire on the evolution of qbinary systems

ORIGINAL SYSTEM

MM 7=

ORIGINAL SYSTEM

sunMM 7 1 =

sunMM 52 =

A binary system with two intermediate mass stars.

Say: 7 and 5 solar masses and original separation ASay: 7 and 5 solar masses and original separation A

DEGENERATEDEGENERATE CO CORE

CONVECTIVE EXPANDED ENVELOPE

After the end of central He burning the primary develops a degenerate CO core and the envelope expands to red giant conditions

FIRST COMMON ENVELOPE EPISODE

A Common Envelope phase ensues The convectiveA Common Envelope phase ensues. The convective envelope of the primary expands and engulfs the secondary. While the envelope matter becomes lost y pfrom the external lagrangian points the separation is reduced.

FIRST INTERMEDIATE PHASE

2' /MMAMA = 121R /MM AMA =

The outcome of the first CE episode is a bare COThe outcome of the first CE episode is a bare CO white dwarf and a normal star almost unaffected by the CE stage.g

ONE POSSIBLE EVOLUTIONARY CHANNEL(depending on mass and separation)

C OC+O dwarf H rich star

Low H transferM&

STEADY H MASS TRANSFER AT LOW RATE,

NOVA LIKE PHENOMENA.

H burning into He and He burnong into C+O requiredrequired

A DIFFERENT EVOLUTIONARY CHANNEL

(depending on mass and separation)

DEGENERATE CORE

CONVECTIVE EXPANDED ENVELOPE

IF SEPARATION IS RATHER LARGE THE SECONDARY EVOLVES UP

TO RED GIANT DIMENSION BEFORE STARTING INTERACION

EVOLUTION ALONG THE SECOND CHANNEL

SECOND COMMON ENVELOPE PHASE

THE INTERACTION OF THE EXPANDEDTHE INTERACTION OF THE EXPANDED CONVECTIVE ENVELOPE WITH THE REMNANT OF THE PRIMARY GIVES RISE TO A SECOND CE EPISODE. ONCE AGAIN THE ENVELOPE BECOMES LOST.

A SECOND POSSIBLE EVOLUTIONARY CHANNEL

Ω21R1R2R

' M/ M MAA =f

GWRGWR

Ω 1R1R2Rf

GWR

A SYSTEM OF TWO VERY CLOSE WDsA SYSTEM OF TWO VERY CLOSE WDs

SEPARATION SHRINKS BECAUSE OFSEPARATION SHRINKS BECAUSE OF

GRAVITATIONAL WAVE EMISSION

MERGING TIMEMERGING TIME

yrsMMMMA RRRRfmerg ))(/(10 5.1 212148 +=τ

FOR OF THE ORDER OF THE SOLAR RADIUS fA

AND M OF THE ORDER OF

f

THE SOLAR MASS THE MERGING TIME IS ONLY

yrs 108 (BUT IT CAN BE ALSO SEVERAL BILLION

YEARS)

AMBEDUE IAMBEDUE I CANALICANALI PRESENTANOPRESENTANO DIFFICOLTA’DIFFICOLTA’

SUMMARISING:SUMMARISING:WHAT  SEEMS TO BE KNOWN:HOW THEY EXPLODE (THE ENGINE)

WHAT IS UNKNOWN:HOW THEY MANAGE TO SWITCH ON THE ENGINEHOW THEY MANAGE TO  SWITCH ON THE ENGINE (i.e. HOW THEY TUNE THE MASS  ACCRETION)

REQUIREMENTS TO BE FULFILLED ARE: &IT HAS TO BE A BINARY SYSTEM & TIME SCALES MUST 

RANGE FROM FEW  10^8 yrs TO THE PROTON DECAY TIME

A RECENT APPROACH TO THE WD MERGING ISSUE

INTRODUCE ROTATION IN MODEL

A RECENT APPROACH TO THE WDs MERGING ISSUE

INTRODUCE ROTATION IN MODEL COMPUTATION

ΩTWO WDs IN A TIGHT BINARY

ΩSYSTEM MERGE BECAUSE OF GWR EMISSION

M1 M2

THEY BECOME SYNCHRONISED WELL BEFORE MERGING.

M1 M2

M1>M2 M1 M2>1 4 M

ONCE SYNCHRONISATION IS ATTAINED IT WILL BE NEVER LOST.M1>M2 M1+M2>1.4 Msun LOST.

Ω THE LESS MASSIVE WD IS DISSOLVEDTHE LESS MASSIVE WD IS DISSOLVED IN A DISK

ACCRETION DISK PRODUCED BY THE LESS MASSIVE WD

THE MORE MASSIVE WD ACCRETESMASS AND MOMENTUM

NUMERICAL RESULTSNUMERICAL RESULTS:ACCRETION IS SELF-TUNED ON A-PARAMETRIC PHYSICAL PARAMETERS OF THE SYSTEM

IN FACT:Phase 1

IN FACT:Ω=Ωcrit

EVOLUTIONARY STEPS:EVOLUTIONARY STEPS:

VERY SOON CRITICAL ROTATIONAL VELOCITY IS ATTAINED.

ACCRETION COMES TO A HALT

IN ADDITION THERE IS AN ENERGYEXCESS STORED IN THE EXTERNALLAYERS.

AS SOON AS THE ENERGY EXCESS IS

ACCRETING MASS ANDANGULAR MOMENTUM

REMOUVED (TRANSFERRED TO THE CENTRAL LAYERS) THE DWARF BECOMES SUBCRITICAL.

ACCRETION RESTARTS.

Phase 2Phase 2

At the end of phase 1 the accreting WD has 

Become so fast spinning and so compressed

To become secularly unstable to a deformation

Into a triaxial Jacobi ellipsoidInto a triaxial Jacobi ellipsoid  

EE / approaches grot EE / =γ 14.0 ≈crγ

EMISSION  OF  GWR  BEGINS  AND  LASTS  FOR

A LONG TIMEA  LONG  TIME

Phase 2GWR  REMOVES ANGULAR MOMENTUM 

According to Chandrasekar 1970 and Friedman & Schutz 1975

GWRtJdtdJ τ/1/ −− GWRtGWR eJdtdJ ττ /1

0 / −=

Where [ ] 65)

8 (/ 10 −− −≈ ωγγτ CRGWR Rc

And  grot EE / =γ

Phase 3Phase 3Accretion rate drops as the accreting WDAccretion  rate  drops as the accreting WD 

turns back into a stable MacLaurin speroid

But the mass has already been incresed 

much over the ‘non‐rotating’ Chanrasekhar 

mass.

Viscous interaction with the remnant of theViscous interaction with the remnant of the 

disk brakes down the WD and leads it to 

explode

SO FAR FOR RIGID ROTATIONSO FAR FOR RIGID ROTATION

(MASS SPREADS BETWEEN 1.4 AND 1.5(

SOLAR MASSES)

INTRODUCE A VERY NEW (PROVOCATIVE) ROAD ( )

WHAT IS REALLY NEW:WHAT IS REALLY NEW:

THE EVOLUTIONARY SCENARIO IN 

CASE  OF DIFFERENTIAL ROTATION:

(NATURA ABHORRET CHANDRA)

IN CASO DI ROTAZIONE DIFFERENZIALE….

UNA STRUTTURA PUO’ ESSERE STABILE FINO A 

4 MASSE SOLARI (!)4 MASSE SOLARI (!)

DURANTE TUTTA LA FASE DI ACCRESCIMENTO 

RIMANE ATTIVA LA ROTAZIONE DIFFERENZIALERIMANE ATTIVA LA ROTAZIONE DIFFERENZIALE 

ED E’  POSSIBILE TRASFERIRE TUTTA LA MASSA 

DISPONIBILE ANCHE OLTRE LA Mch CLASSICA (in 

pratica nel mondo reale fino a 2 2 masse solari)pratica, nel mondo reale, fino a 2.2 masse solari) 

FINITO L’ACCRESCIMENTO,  LA ROTAZIONE 

DIFFERENZIALE TENDE AD ESTINGUERSI. 

A QUESTO PUNTO QUESTE STRUTTURE SI

DESTABILIZZANO IN MODO NATURALE E

NON POSSONO FARE ALTRO CHE CONTRARRENON POSSONO FARE ALTRO CHE CONTRARRE 

VIOLENTEMENTE, INNESCARE IL BRUCIAMENTO ,

CENTRALE DEGENERE DEL CARBONIO ED 

ESPLODERE

LA PRIMA CONSEGUENZA E’ UNLA PRIMA CONSEGUENZA E’ UN REALE CAMBIO DI PROSPETTIVAREALE CAMBIO DI PROSPETTIVA

IN NATURA IL PROCESSO NON E’ PIU’ QUELLO DI

RAGGIUNGERE UNA MASSA CRITICA MA 

QUELLO DI RECEDERE DA UNA CONDIZIONE DIQUELLO DI RECEDERE DA UNA CONDIZIONE DI

sovra‐STABILITA’ (di nuovo come nelle cc SNe)

Sub chandra SI – Chandra NO (!)Sub‐chandra SI – Chandra NO (!)

IL BILANCIO ENERGETICO:IL BILANCIO ENERGETICO:

STORED ROTATIONAL ENERGY MAY AMOUNT

UP TO MORE THAN 5x10^50 ergs (i.e. 0.5 solarUP TO MORE THAN 5x10 50 ergs (i.e. 0.5 solar

masses of eq. Ni) DEPENDING ON THE MASS

AS A MEAN AN INCREASE OF 0 1 Msun IN THEAS A MEAN AN INCREASE OF 0.1 Msun IN THE 

TOTAL MASS AT EXPLOSION CORRESPONDS TO 

AN INCREASE OF LUMINOSITY  OF MORE THAN 

ONE TENTH OF magnitudeONE  TENTH OF magnitude

ADDITIONAL CONSEQUENCES of the new scenario are:

• Mass spectrum of SNe no more peaked at around 1.4 solar masses

• Masses will range from 1.38 up to 2.2 Msun

more massive more brightmore massive more bright

• There is a difference between short and long living systems: brighter sooner

• A second stage of GWR is identified after theA second stage of GWR is identified after the starting of the merging process

Observational Evidence:Sooner ‐ Brighter

(Gallagher et al. 2005)

Theoretical Prediction:Sooner ‐ Brighter

CONCLUSIONSSelected systems of intermediate mass stars may finish their lives with fireworks

Differential rotation plays a pivotal role in p y pproducing fireworks AND A NEW PERSPECTIVEon how these occur has to be assumed 

The DD scenario including diff. rotation is able to gaccount for a  variety of observational issues: brighter sooner, rates, fast/slow evolving systemsg , , / g y

Predictions can be done: GWR 

conseguenze cosmologiche:conseguenze cosmologiche:

NON EMERGE NESSUN INDIZIO CHE POSSA FARNON EMERGE NESSUN INDIZIO CHE POSSA FAR 

CONSIDERARE  LE SUPERNOVAE PRIMORDIALI   

INTRINSECAMENTE DIVERSE RISPETTO A QUELLE 

ATTUALIATTUALI

THE END