“Radionuclides and Gamma-Ray Line Astronomy”

INTEGRAL School, Les Diablerets (CH) April 2000 Roland Diehl

INTEGRAL School, Les Diablerets (CH), March/April 2000

“Radionuclides and Gamma-Ray Line Astronomy”“Radionuclides and Gamma-Ray Line Astronomy”

Invited LecturesInvited Lecturesby

Roland DiehlMPE Garching

•• Part I:Part I: Gamma-Rays and NucleosynthesisGamma-Rays and Nucleosynthesis–– Nucleosynthesis ProcessesNucleosynthesis Processes

–– Radioactive DecayRadioactive Decay

–– Cosmic Nucleosynthesis SitesCosmic Nucleosynthesis Sites

•• Part II:Part II: Observed Cosmic RadioactivitiesObserved Cosmic Radioactivities–– SupernovaeSupernovae

–– Diffuse Radioactivities & Various ConnectionsDiffuse Radioactivities & Various Connections


Nucleosynthesis Processes: Reading the AbundancesNucleosynthesis Processes: Reading the Abundances

� Observed Abundances Show Striking Patterns:�Abundances Vary Much for Light Elements uf to ~ Fe-Group,

are ~Similar Order of Magnitude for Elements >65�H and He are by far the Most Abundant Elements�Li, Be, B Fall in a Deep Minimum (9 Orders of Magnitude)�Elements C....Ca Show Exponentially-Declining Abundances�There is a Abundance Clear Peak Around Fe�Upon Close Look, There are Two Local Peaks Around Ba and Pb

� Nuclear Processes / Reactions “Connect” NeighbouringIsotopes (Reactions −−−−>>>> n, p, or αααα capture or stripping)

=>�Big-Bang Nucleosynthesis

Formed H and He�Nuclear Equilibrium Burning

Formed Fe Elements�An “αααα-Process” Plays a Leading

Role for Elements C...Ca�Elements Heavier Than Fe

Formed from Fe Elements

Standard Abundances

Bi

Th

PbPt

KrGe

Zn

Ni

Fe

CaAr

SSi

NeC

O

N

Ti

V

Sc

F

Be

LiB

H

Dy

Eu

Ba

Sr

He

0

2

4

6

8

10

12

0 20 40 60 80 100

Element (Z)

Abundance

(lo

g N

, H

=12)

R.Diehl_696_abundnc

fragile elements

αααα elements

...Fe group elements

(most tightly bound)

tighter-bound elements(closed shells)


Cosmic Matter CompositionCosmic Matter Composition

Matter Composition

76

24

8.00E-08

70.683

27.431

1.886

0

20

40

60

80

H He Metals

Mas

s F

ract

ion

(%

)

after Big Bang Nucleosynthesis

in Solar System

R.Diehl / '96 abundnc


Abundances in Different Parts of the UniverseAbundances in Different Parts of the Universe

Abundances: Solar vs. Supernova Ejecta

H

CN

O

F

Ne

Na

Mg

Al

Si

P

S

Ar Ca

Sc

Ti

Fe

Ni

-3

-1

1

3

5

7

9

11

5 10 15 20 25 30 35

Element (atomic number)

Abundan

ce (lo

g N

; Si=

6)

solar

SN87A

rod696abundnc


Circulation of Matter Circulation of Matter

interstellarmedium

densemolecular

cloudscondensation

star formation (~3%)

mixing

SN explosion

106-1010 y

102-106y

108 y

rod0795 matter

compactremnant

(WD,NS,BH)

M~104...6 Mo

SNIa

~90%

infalldustdust

SNR's &hot

bubbles

winds

starsM > 0.08 Mo

stars

Galactic

halo


Radioactivity Traces from NucleosynthesisRadioactivity Traces from Nucleosynthesis

• Long-Lived Isotopes DecayOutside Nucleosynthesis Site

• Radioactive-Decay Gamma-Rays Can Be ObservedThrough Gamma-RayTelescopes

• Isotopic Ratios Can BeObservedin Cosmic Rays, MolecularLines, Stellar Surfaces, ...

• Isotopic-Ratio ModificationsCan Be Measuredin Meteorites (Solar Material,but also Interstellar Grains)

p n

γ

26Al, 44Ti, 56Co, 57Co


Stellar Classification and Radiation OriginStellar Classification and Radiation Origin

• Spectral Classification Encodes Temperature• Plasma Radiation Mechanism Depends on Temperature

�Molecules and Dust�Neutral Atoms� Ionized Atoms

O B A F G K M R N SO B A F G K M R N S Spectral ClassSpectral Class

spectrallineintensity

spectrallineintensity

molecules (T,O,..)

ionized .... neutral metals

hydrogenionized .... neutral helium

after Abell ‘64


Radioactive DecayRadioactive Decay

26Al26Al 26Mg26Mgm 0.228 MeV (T ~ 4 108K)

γγγγ2.938 MeV( 0.3 % )*

e- - captureββββ+ - decay ( 97.3 % )

e- - capture ( 2.7 % )

ββββ+ - decay ( 100 % )

γγγγ1.130 MeV ( 2.4 % )*

γγγγ1.809 MeV ( 99.7 % )* γγγγ1.809 MeV ( 99.7 % )*

ττττ = 9.15 sττττ = 1.04 106 y

2+

2+

0+

0+5+

p n

γ

Al

Mg

Mg


Studies of NucleosynthesisStudies of Nucleosynthesis

• Gamma-Rays from Radioactive Decays Relate Directly to Isotopic Abundance• Different Isotopes Probe Different Parameters of Nucleosynthesis Sites

. .

NucleosynthethisEvent

• MeteoriticStudies

• Atomic Lines inPhotosphere &Corona (opt,UV, X)

• Bolometric Lightin DifferentFrequency Ranges(Comptonized,Thermalized, Dust)

• Gamma-Ray Linesfrom RadioactiveIsotopes


Objectives of Radioactivity Gamma-Ray Astronomy:Objectives of Radioactivity Gamma-Ray Astronomy:Relevant IsotopesRelevant Isotopes

Isotope Decaytime Decay Chain γγγγ -Ray Energy (keV)

7Be 77 d 7Be →→→→ 7Li* 478

56Ni 111 d 56Ni →→→→ 56Co* →→→→56Fe*+e+ 847, 1238

57Ni 390 d 57Co→→→→ 57Fe* 122

22Na 3.8 y 22Na →→→→ 22Ne* + e+ 1275

44Ti 89 y 44Ti→→→→44Sc*→→→→44Ca*+e+ 1157, 78, 68

26Al 1.04 106y 26Al →→→→ 26Mg* + e+ 1809

60Fe 2.0 106y 60Fe →→→→ 60Co* 1173, 1332

e+ …. 105y e++e- →→→→ Ps →→→→ γγγγγγγγ.. 511, <511


COMPTEL Detections of RadioactivityCOMPTEL Detections of Radioactivity

Gamma-Ray Line at 1.809MeV

Attributed to 26Al Decay(Decay Time ττττ ~ 1 MioYears)

Detected and Mapped in the Full Sky

Gamma-Ray Line at 1.157MeV

Attributed to 44Ti Decay(Decay Time ττττ ~ 89 Years)

Detected from317-y-old SN Cas A at 3.4 kpc

SRC Dataset ID: MPE-RFR-20663

Sky circle 1 centered at

Longitude .....: 111.70 deg

Latitude ......: -2.10 deg

with radius 2.00 deg

EHA=0-180 deg;

Number of selected events: 21253

Sky circle 2 centered at

Longitude .....: ???.70 deg

Latitude ......: >40.10 deg

with radius 5.00 deg

chi sq.=36.33, 43 d.o.f.

Number of selected events: 2650

Cas A COMPTEL Phase 1-5

Energy (keV)

Cou

nts

/ bi

n

800 1000 1200 1400 1600 1800

-100

0

100

200

Gamma-Ray Lines at 0.847 and 1.238 MeVAttributed to 56Co Decay(Decay Time ττττ ~ 111 Days)

Detected (marginally) from SN 1991T at ~17MpcDistance


Gamma-Ray Line Astrophysics - The GoalsGamma-Ray Line Astrophysics - The Goals

• Utilize / Open a New Astronomical Window– Penetration of Gamma-Rays– Unique/Direct Inference of Isotope Abundances

• Calibrate Engines of Stars / Novae / Supernovae– Nuclear Reactions as Root Energy Source– Radio-Isotopes Emit Gamma-Ray Lines

• Study Parameters of Nucleosynthesis Sites– Identify Operating Nuclear Reaction Chains per Site

– Constrain Environmental Par’s (T,ρ,τconv)

• Study Energetic-Particle Processes– Acceleration Mechanisms (Solar Flares)– Cosmic Ray Source Regions (Nuclear-Excitation

Lines)


Cosmic RadioactivitiesCosmic Radioactivities

Goals:� Understand the Physical Processes which Shaped the

Pattern of Abundances in (different parts of) the Universe� Provide Complementary Measurements on Cosmic Sites of

Nucleosynthesis

Standard Abundances

Bi

Th

PbPt

KrGe

Zn

Ni

Fe

CaAr

SSi

NeC

O

N

Ti

V

Sc

F

Be

LiB

H

Dy

Eu

Ba

Sr

He

0

2

4

6

8

10

12

0 20 40 60 80 100

Element (Z)

Abu

ndan

ce (

log

N,

H=1

2)

R.Diehl_696_abundnc

fragile elements

αααα elements

...Fe group elements

(most tightly bound)

tighter-bound elements(closed shells)


The Stable Isotopes of MatterThe Stable Isotopes of Matter

Isotope Chart

0

20

40

60

80

100

120

140

0 20 40 60 80 100 120 140 160 180

No. of Neutrons

No. of

Pro

ton

s

rod696abundnc


Nuclear Reactions in Cosmic NucleosynthesisNuclear Reactions in Cosmic Nucleosynthesis

• Strong Interactions�p Capture�n Capture�Heavy-Ion Reactions�Resonances

� Nuclear Force Range: ~10-15 m = fm� Reaction Times 10-16...10-22 s� Coulomb Repulsion -> Tunneling (‘Gamov Peak’)� Stellar Reaction Cross Sections Interpolated from

Measurements at Lab. Energies (‘astrophysical S-Factor’)

• Weak Interactions�n + ννννe �� p + e- ‘ββββ Decays’

� ‘Slow’ Compared to Strong Reactions� log (ft) values with (t >> 10-16s)


The Nuclear Binding Force in Different NucleiThe Nuclear Binding Force in Different Nuclei

Nuclear Binding Energy

-100.00

-80.00

-60.00

-40.00

-20.00

0.00

20.00

40.00

0 50 100 150 200 250

No of Nucleons

Bin

din

g E

ner

gy (M

-A;

12C

.=0

.0)


Cosmic Nucleosynthesis EnvironmentsCosmic Nucleosynthesis Environments

Nuclear Burning Requirements:• <σσσσv> * Q ≥≥≥≥ Local Cooling Rate=>• Dense & Hot Environments

for a Stellar Mass Range of 1-30 Mo:

• Nuclear Burning in Stellar Cores andShells (top)

• Nuclear Burning in Explosive Sites(bottom)

• Gamov Windows (righthand side)


Elementary Nuclear-Reaction CyclesElementary Nuclear-Reaction Cycles

• H Burning: p-p Chains

1H

p2D

p

3He

3He

γ

4He

1H

1H

++++ ++

4He

++

7Be

γ

e- 7Lie+

ν ++ν

++

++p

4He

4He

1H8B

γ

8Be

e+

ν

4He

4He

PP I

PP II

PP III


Elementary Nuclear Burning CyclesElementary Nuclear Burning Cycles

• H Burning: CNO Cycle

12C

13N

13C 14N 17O 18F

19F 20Ne

15O 17F

15N 16O 18O

p,γγγγ p,αααα p,γγγγ

p,γ γγγ

p,γ γγγ

e+ν ννν

e+ν ννν

p,γ γγγ

e+ν ννν

p,αααα

p,αααα

p,αααα

e+ν ννν

p,γγγγp,γγγγ

I II IIIIV

p,γγγγ

slow!

slow!

slow!!!

�Net Burning towards 14N�

12C/13C ~4 (SAD:89)


Elementary Nuclear-Burning CyclesElementary Nuclear-Burning Cycles

• He Burning: 3αααα Cycle

4He + 4He 8Be

8Be + 4He 12C* 12C* 12C

�Lifetime 8Be ~ 7 10-16 s�

8Be(αααα,,,,γγγγγγγγ)12C through Excited Level at 278 keV+ (Salpeter, Hoyle)

� ε ε ε ε ~ T840 −−−−>>>> He Flash

8Be + 4He7.366

12C 0+0.0

12C 2+4.43

12C 0+7.64

12C 3-9.64


Elementary Nuclear-Burning CyclesElementary Nuclear-Burning Cycles

• He Burning: 3αααα Cycle

4He + 4He 8Be

8Be + 4He 12C* 12C* 12C

�Lifetime 8Be ~ 7 10-16 s�

8Be(αααα,,,,γγγγγγγγ)12C through Excited Level at 278 keV+ (Salpeter, Hoyle)

� ε ε ε ε ~ T840 −−−−>>>> He Flash

8Be + 4He7.366

12C 0+0.0

12C 2+4.43

12C 0+7.64

12C 3-9.64


26Alm

28Si26Si

(p,γγγγ)

(p,γγγγ)(p,γγγγ)

(p,γγγγ)(p,γγγγ)

(p,γγγγ)

ββββ+

ββββ+(7.2s)

9.2 s ββββ+

1.07 106 y

ββββ+

(p,αααα)

(p,αααα)

(n,p)

23Na

26Al

27Si

27Al

26Mg25Mg24Mg

25Al

2626Al Nucleosynthesis: Example of a Cosmic Reaction Network,Al Nucleosynthesis: Example of a Cosmic Reaction Network,Common for Intermediate-Mass IsotopesCommon for Intermediate-Mass Isotopes


Production of Elements Beyond the Fe Peak:Production of Elements Beyond the Fe Peak:r-Process and s-Processr-Process and s-Process

• Seed Nuclei (~ Fe-Group Elements) Capture Neutrons

• ββββ Decays Establish Final Abundances� n capture faster than ββββ-decay −−−−>>>> r-process� n capture slower than ββββ-decay −−−−>>>> s-process

30

40

50

60

70

60 70 80 90 100

No. of Neutrons

No.

of

Pro

ton

s

s-only

r-only

N=Z

r-process path

βββ β-d

ecays

s-process path


Process Site Key Isotopes

� H burning pp chains, CNO cycle all stars 4He;13C 14N

� He burning 3-αααα process most stars 12C 16O 20Ne 24Mg

� αααα-process hot burning with excess αααα’s mass. stars, SNae 20Ne 24Mg 28Si 32S 36Ar 40Ca

� Fe-group elements:e-process thermal equilibrium (NSE) SNae (thermonucl) Fe-group elements (~56)

� n-rich heavy elements:s-process n capt. slower than ββββ-decay He-burning stars elements >62 close to

valley of stabilityr-process n capt. faster than ββββ-decay SNae (CC) elements >62, also further

from valley of stability� spallation energetic heavy-ion collision ISM / cosmic rays 6Li 8,9Be 10,11B

� p-rich isotopes:rp-process hot H burning novae p-rich elements <Fe groupp-process n depletion ((((‘γγγγ-process’) ?? p-rich elements >62

� ‘normal’ nuclear reactions [(n,γγγγ), (p,γγγγ), (αααα,,,,γγγγ)...] stars, SNae in-between elements� νννν-process νννν excitation of nuclei SNae (CC) various contributions� x-process unknown; make up for ?? (2H Li Be B)

BBN+Spallation definiency

Nucleosynthesis: “Processes”,“Categories”Nucleosynthesis: “Processes”,“Categories”


Objectives of Radioactivity Gamma-Ray Astronomy:Objectives of Radioactivity Gamma-Ray Astronomy:Nucleosynthesis EnvironmentsNucleosynthesis Environments

Stellar Cores & Shells Nuclear Reaction Networks (T),

Hydrostatic Burning & Convection

Products only from SN & Wind

WR and AGB Stars Convection Enhanced, Wind Feeds

ISM with Products; HBB

Novae Hot Hydrogen Burning

Core Collapse Supernovae Shockfront Burning in Shell-Like Star

Supernovae Type Ia NSE Processing of Stellar Remnant

Interstellar Medium ~Laboratory-like Nuclear Reactions

⇒ Variety of Nucleosynthesis Conditions(Temp., Dens.) and Timescales


Objectives of Radioactivity Gamma-Ray Astronomy:Objectives of Radioactivity Gamma-Ray Astronomy:Different Objectives per Isotope:Different Objectives per Isotope:

7Be: Novae Nova Convection & Nucleosynthesis

56Ni & 57Ni: SN SN Nucleosynthesis & Envelope

Structure

22Na: Novae Binary Evolution, Nucleosynthesis

44Ti: SN SN Mass Cut, SN Rate

26Al, 60Fe, (e+) Galaxy Nucleosynthesis (Location, Rate)


Massive Star Core StructureMassive Star Core Structure

(25 Mo)

1H, 4

He

12C, 16

O

4He

16O, 20Ne, 24

Mg

28Si, 32

S

16O, 24

Mg, 28Si

Si−−−−>>>>Fe,Ni

O−−− −>>> >Si

Ne−−− −>>> >O,Mg

C−>

−>−>

−>Ne,Mg

He−−− −>>> >C,O

H−−− −>>> >He

9.9 9.5 8.9 8.7 8.3 7.0 log T

0.08

0.02

0.15

0.05

0.1

0.6

∆ ∆∆∆m/M

��

��

��

��


ννν

νν

ννν

ννννν

νν

ν

ν

ν

ν

ν

ν

νν

ν

GravitationalCore Collapse

SupernovaShock Wave

Shock RegionExplosive Nucleosynthesis

Proto-Neutron StarNeutrino Heating

of Shock Region from Inside

Shell-StructuredEvolved Massive Star

Core CollapseCore CollapseSupernova ModelSupernova Model


Core Collapse Supernova EvolutionCore Collapse Supernova Evolution

• Phases and Time Scales– Core Collapse– Convection in Inner Zones 50 ms .....– Shock at Fe/Si Interface 100 ms– End of NSE burning 250 ms– End of Convection 400 ms– End of Nuclear Burning 500...700 ms– Explosive-Product Shell/Shock Detachment– Shock at C-O/He Interface 1..5 s– Rayleigh-Taylor Instability Development 1...50 s– Reverse-Shock Deceleration of Ejecta 50..100 s– Beginning of Ballistic Clump Motions 100 s


Gamma-Rays from Supernovae and Their RemnantsGamma-Rays from Supernovae and Their Remnants

• SN Nucleosynthesis −>−>−>−> Radioactivity LineEmission

• SNR Particle Acceleration −>−>−>−> Continuum Emission• SN Blast Wave / ISM Impact −>−>−>−> other Characteristic

Emission• Luminosity Evolution (sketch) in Different Radiation Types:

10 100 1000 10000 105

SN:Optical,~X,~γγγγ(57Co)

γγγγ-Rays 44Ti (ττττ~90y)

γγγγ-Rays 26Al (ττττ~106y)optical

X-ray

Radio,~nonthermal X, γγγγ-rays

SNR Age (years)

Log L


Gamma-Ray Lines from NovaeGamma-Ray Lines from Novae• Nova = Thermonuclear Runaway in

White-Dwarf Shell Accumulated fromLow-Level Accretion in Binary System

• dM/dt~10-9 Mo/y ; Maccr~5 10-5 Mo ; Mejected ~2 10-4 Mo

• ~30% Ne-rich Novae, others CO Novae

• Hot H Burning at T>108K−>−>−>−> p-Capture on CNOSeeds

• Gamma-Ray Sources:� ββββ+ Radioactivity Iγγγγ~1 10-2 ph cm-2 s-1 @1kpc�

7Be (from 3He(αααα,,,,γγγγ))Iγγγγ~2 10-6 ph cm-2 s-1 @1kpc�

22Na (from 20Ne(p,γγγγ)) Iγγγγ~4 10-6 ph cm-2 s-1 @1kpc�

26Al (from 25Mg(p,γγγγ)) Iγγγγ~1 10-10 ph cm-2 s-1 @1kpc

2

1

3

Issues:� Dredge-Up from WD� TNR Rise Time� MWD, Maccr

� Mej

� ....� Need CLOSE Nova� Need Early Exposure

0.1 1 10

Optical (arb.norm.)

1.3 MeV γγγγ-Rays 22Na (ττττ~3.75y)

Nova Age (months)

Log L

0.01

478 keV γγγγ-Rays 7Be (ττττ~77d)

511 keV γγγγ-Rays (b+decay)

“Radionuclides and Gamma-Ray Line Astronomy”

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