"From neutrinos.....". DK&ER, lecture 10
Neutrinos from supernovaeNeutrinos from supernovae
Gravitational collapse Observations of SN1987A What could be learned about neutrinos
"From neutrinos.....". DK&ER, lecture 10
Natural sources of neutrinosNatural sources of neutrinos
at 10 kpci.e. Galaxy center
"From neutrinos.....". DK&ER, lecture 10
Previous Supernovae observed in our Galaxy
Previous Supernovae observed in our Galaxy
A supernova explosion observed in 1054 AD created a neutron star in the Crab nebula..
It has a diameter of only 20-30 km, has about the same mass as the sun and rotates 30 times per second. Hot gas is pulled towards the neutron star and emits X-rays.
"From neutrinos.....". DK&ER, lecture 10
Previous Supernovae observed in our Galaxy
Previous Supernovae observed in our Galaxy
The remnants of the supernova that Tycho Brahe observed in 1572-still scorching -10 million °C hot.
The most recent SNvisible with the bare eyewas observed by Keplerin 1604
"From neutrinos.....". DK&ER, lecture 10
Previous Supernovae observed in our Galaxy
Previous Supernovae observed in our Galaxy
The most recent SNvisible with the bare eyewas observed by Keplerin 1604
yellow – Hubble (visible)red – Spitzer (infrared)green/blue – Chandra (rtg)
yellow – Hubble (visible)red – Spitzer (infrared)green/blue – Chandra (rtg)
"From neutrinos.....". DK&ER, lecture 10
Supernova Remnant Puppis ASupernova Remnant Puppis A
insert: - a small source of rtg emission- probably a young - neutron star running away with velocity of 960km/s
"From neutrinos.....". DK&ER, lecture 10
Previous Supernovae observed in our Galaxy
Previous Supernovae observed in our Galaxy
Only 8 supernovae have been observed in our Galaxy:
Chinese records: 185, 386, 392 and 1006Later: 1054, 1181, 1572, 1604
Only 8 supernovae have been observed in our Galaxy:
Chinese records: 185, 386, 392 and 1006Later: 1054, 1181, 1572, 1604
However all of them were relatively close to solar system.More distant SN are invisible – hidden by interstellar gas
Currently many SNs are observed in other gallaxies
"From neutrinos.....". DK&ER, lecture 10
Supernova 1987ASupernova 1987A
On Feb 23, 1987 a supernova was observed optically in the Large Magellanic Cloud at a distance of 170 000 light years (50 kpc)
At that time 2 large underground detectors searched for proton decays: Kamiokande and IMB. They inspected their signals and found
4 hours earlier......
Feb 1984 Mar 8, 1987
"From neutrinos.....". DK&ER, lecture 10
Detector IMB
"From neutrinos.....". DK&ER, lecture 10
Observations of SN1987AIMB (Irvine-Michigan-Brookhaven)Observations of SN1987AIMB (Irvine-Michigan-Brookhaven)
Raw data After standard analysis rejecting atmospheric muons
"From neutrinos.....". DK&ER, lecture 10
Neutrinos from Supernova 1987A in Kamiokande
Neutrinos from Supernova 1987A in Kamiokande
Universal timeon Feb
23, 1987
Neutrinos arrived 3-4 hours earlier than photons because
photons could not get through the outer
layers of SN before they thinned enough.
"From neutrinos.....". DK&ER, lecture 10
IMBevents
"From neutrinos.....". DK&ER, lecture 10
IMB Kamiokande BaksanLSD
Location Ohio,US Japan Russia France (Mont
Blanc)
Detector type water Cerenkov liquid scintillatorDetector mass 6800 2140 200
90 (tons)Threshold(MeV) 19 7.5 10 5
Number of events 8 11 5 ???
Time of 1st 7:35:41 7:35:35 7:36:12 2:52:37 event (UT)Absolute time 0.05 60 +2 0.002accuracy (sec) -54
Observations of neutrinos from SN 1987A Observations of neutrinos from SN 1987A
"From neutrinos.....". DK&ER, lecture 10
Neutrinos from SupernovaeNeutrinos from Supernovae
"From neutrinos.....". DK&ER, lecture 10
Stellar evolutionStellar evolution
"From neutrinos.....". DK&ER, lecture 10
Road to gravitational collapseRoad to gravitational collapseMain thermo-nuclear reactions:
Reaction Ignition temp. (millions K)
4 1H --> 4He 103 4He --> 8Be + 4He --> 12C 10012C + 4He --> 16O 2 12C --> 4He + 20Ne 60020Ne + 4He --> n + 23Mg 2 16O --> 4He + 28Si 15002 16O --> 2 4He + 24Mg 4000 2 28Si --> 56Fe 6000
When mass of the iron core exceeds1.4 solar masses the gravitation wins.
gravitational collapse
SN produce much of the material in the universe. Heavy elements are only produced in supernovae, so all of us carry the remnants of these distant explosions within our own bodies.
SN produce much of the material in the universe. Heavy elements are only produced in supernovae, so all of us carry the remnants of these distant explosions within our own bodies.
"From neutrinos.....". DK&ER, lecture 10
Interplanetary nebula
ProtostarStar
Red Giant
Black Dwarf
White Dwarf
Red Super-Giant
SN
Neutron
Star
Black
Hole
M ~
M ~
M ~ 8M
M >>
Stellar evolution
A large, dense, cool nebula (up to 106 Mo, temp.~10 K)
A gravitating matter condensation grows to ~10-100 Mo Gravitation energy is transformed
into heat; a gas-dust cocoon forms.
Stellar wind carries away a fraction of mass. Fusion reactions start changing H into He, a hydrostatic equilibrium sets in..
Energy supply is depleted, radiation pressure decreases. Stellar core contracts, its temperature grows, igniting hydrogen in the envelope. New energy supply leads to expansion of external layers.
Increase of surface with a constant energy production rate leads to decreased power and envelope temperature.
Stellar core contracts, temperature rises, making possible nuclear fusion of heavier elements.
"From neutrinos.....". DK&ER, lecture 10
Stellar Evolution
"From neutrinos.....". DK&ER, lecture 10
Stellar Dimensions
1. White dwarf2. Red dwarf3. Sun4. Red Giant5. Blue Giant
1. White dwarf2. Red dwarf3. Sun4. Red Giant5. Blue Giant
"From neutrinos.....". DK&ER, lecture 10
Stellar Evolution
"From neutrinos.....". DK&ER, lecture 10
Stellar evolutionsStellar evolutionsInitial star mass 30 10 3 1 0.3 (in solar masses)
Luminosity (sun=1) 10000 1000 100 1 0.004 (during principal sequence)Livetime during princ. seq. 0.06 0.1 0.3 10 800 (in billion years)Livetime as red giant 0.01 0.03 0.10 0.30 0.80 (billions of years)Nuclear reactions stop at iron silicon oxygen carbon helium
Final fate SN SN planetary solar solar nebula wind wind
Ejected mass 24 8.5 2.2 0.3 0.01 (in solar masses)Nature of final state black neutron white dwarfs (all 3)
hole starMass of final state 6 1.5 0.8 0.7 0.3
density (g/cm3) 5x1014 3x1015 2x107 1x107 1x106
"From neutrinos.....". DK&ER, lecture 10
Gravitational Collapse
"From neutrinos.....". DK&ER, lecture 10
Neutrinos from SupernovaeNeutrinos from Supernovae•56Fe has maximum binding energy no more fusion and no more heat production
• When a core of iron reaches a Chandrasekhar mass of the gravitation wins and the core collapses• Electrons of iron atoms are absorbed by protons:
ee p n prompt neutrinos neutron star
0
0
0
e ee e Z
e e Z
e e Z
thermal neutrinos
• Heat gives rise to gammas which produce e+ e- pairs and then:
1.4 ⋅Me
"From neutrinos.....". DK&ER, lecture 10
Beacom and Vogel
ergsEB53103
%66,,,
%,17
%,17
e
e
MeVTe
5.3
MeVTe
5
MeVT 0.8""
SN neutrino properties
Neutrino luminosityvs time
Thermal spectra(Fermi-Dirac distribution)
"From neutrinos.....". DK&ER, lecture 10
Neutrinos from SN 1987A – E vs angleNeutrinos from SN 1987A – E vs angle
e p e n
x xe e
Distribution of the angle with respect to the direction from SN Isotropic distribution
indicates mostly:
rather than:
However some anisotropyremains puzzling.
(cross section smaller by orders of magnitude.)
"From neutrinos.....". DK&ER, lecture 10
Neutrinos from SN 1987A – E vs timeNeutrinos from SN 1987A – E vs time
2
2 21 2
19.4
1 1
tm
DE E
( ) 11em eV
For 2 events of energies E1, E2 in MeV and time difference t sec the neutrino mass in eV:
where D is distance in kpc
Note thresholds: Kamiokande 7.5 MeV IMB 19 MeV
"From neutrinos.....". DK&ER, lecture 10
Neutrinos from gravitational collapse
Neutrinos from gravitational collapse
Occurs for a star heavier than 8 solar masses when its core exceeds Chandrasekar’s limit of M=1.4 solar mass. A neutron star of a radius of r about 20 km is formed.
The released energy is „neutron star binding energy”:
531 13 10 ergs ( )B
ME M R r
r R r
99% of this energy is carried away by neutrinos;neutrino luminosity L~ 3x1053 ergs
1% goes into kinetic energy of the envelope particlesOnly 0.01% goes into light
And yet it’s 1049 ergs while our sun emits 1033 ergs/sec
One SN shines as 1016 Suns!
"From neutrinos.....". DK&ER, lecture 10
Neutrinos from gravitational collapse Neutrinos from gravitational collapse
Prompt pulse lasts only several msec
hence its total luminosity is small
Total neutrino luminosity L~ 3x1053 ergs
Almost all L is carried away by thermal neutrinos approximately obeying „equipartition of energy”:
( ) ( ) ( ) ( ) ( ) ( )e eL L L L L L
Howeverenergies of and are less degraded by interactions than that of e
"From neutrinos.....". DK&ER, lecture 10
Analysis of the observed eventsAnalysis of the observed events
2
3
1 exp( )
3.15
const E dEd
ETT
E T
Thermal neutrinos should be described by Fermi-Dirac distribution. Their fluence (i.e. flux integrated over time):
T – temperatureE – neutrino energy
From the measurements of on Earthone can calculate
52 210
1.5 10 ( )50 10
DL T
L in ergsfluence in cm-2
T in MeVD distance in kpc
this spectrum was assumed for the
analysis
"From neutrinos.....". DK&ER, lecture 10
Experiment: IMB Kamiokande
Temperature (MeV)
Fluence (x 1010cm-2)
Average energy (MeV)
Total e energy (x1052 ergs)
Total energy released (x1053 ergs)
Neutrinos from SN 1987A- results
Neutrinos from SN 1987A- results
Assuming :a) a distance of 49 kpc b)equipartition of energy between different flavors
1.0 0.70.8 0.54.2 2.6
0.79 0.28 1.98 0.60
3.1 2.22.5 1.713.2 8.2
4.8 1.7 7.8 2.4
2.9 1.0 4.7 1.5
"From neutrinos.....". DK&ER, lecture 10
What have we learned about neutrinos from SN1987A
What have we learned about neutrinos from SN1987A
Lifetime 55 10 ( / )m eV
Mass ( ) 11em eV sec
m2 =19.4 ⋅t
D1E1
2 −1E2
2
⎛
⎝⎜⎞
⎠⎟
For 2 neutrinos of energies E1 (MeV) and E2 (MeV) and the difference between their flight times δt (sec) their mass m (eV) :
For 2 neutrinos of energies E1 (MeV) and E2 (MeV) and the difference between their flight times δt (sec) their mass m (eV) :
where D (kpc) is the distancefrom the supernova.where D (kpc) is the distancefrom the supernova.
However one has to take into account a possibility that the time profile of the neutrino emission can mimick the pulse modulation due to the finite mass
However one has to take into account a possibility that the time profile of the neutrino emission can mimick the pulse modulation due to the finite mass
"From neutrinos.....". DK&ER, lecture 10
What have we learned about neutrinos from SN1987A
What have we learned about neutrinos from SN1987A
11( ) 0.8 10e B Magnetic moment
elmgt interaction would flip ν helicity into RH and ν would carry away energy without interacting - contrary to the observation that almost all the binding energy has been accounted for
Electric charge 171 10e
Q
Q
a charged would experience an energy dependent delay due to its curved path in the intergalactic and galactic mgt field.
"From neutrinos.....". DK&ER, lecture 10
Test of equivalence principleTest of equivalence principle
The fact that the fermions (neutrinos) and bosons (photons) reached the
Earth within 3 hours provides a unique test of the equivalence principle of
general relativity. The gravitational field of our Galaxy causes a signifcant
time delay, about 5 months, in the transit time of photons from the
SN1987A.
The observation of Feb. 23, 1987, proved that the neutrinos and the
recorded photons are acted by the same gravitationally induced time delay
within 0.5%
"From neutrinos.....". DK&ER, lecture 10
Actually neutrinos arrived earlier...Actually neutrinos arrived earlier...
About 3 hours earlier than light.Photons had to wait until the envelope gets thin enough to pass through.
About 3 hours earlier than light.Photons had to wait until the envelope gets thin enough to pass through.
"From neutrinos.....". DK&ER, lecture 10
SN1987A
"From neutrinos.....". DK&ER, lecture 10
SN 1987A
Seven years later.. photos by Hubble Space Telescope
"From neutrinos.....". DK&ER, lecture 10
SN 1987A
"From neutrinos.....". DK&ER, lecture 10
"From neutrinos.....". DK&ER, lecture 10
Expected signals from future SN
Andromeda M31in Super-Kamiokande:
Eg. for an SN in the Galactic center at 10 kpc:
16
7300 oddz.
300 oddz.
100 oddz.
e
e
p e n
e e
O e X
Hopefully other than electron antineutrinos could be studied .
SN neutrinos are already flying to us
"From neutrinos.....". DK&ER, lecture 10
Expected signals from future SN
In ICARUS:
e + 40Ar→ e− + 40K * (Ethr = 1,5 MeV) 40K * → 40K + γ (4.4 MeV)
ν e + 40Ar→ e+ + 40Cl* (Ethr = 7,5 MeV)
CC current:CC current:
NC current:NC current:
+ 40Ar→ ν + 40Ar* 40Ar* → 40Ar + γ (1.5 MeV)
ν + e− → ν + e−
There is a possibility to separate electron neutrinos and antineutrinosand study very low energy part of the neutrino spectrum.
"From neutrinos.....". DK&ER, lecture 10
Expected signals from SN remnants(SNR neutrinos)
Observation of a single SN relies on a very brief signal – trivial separation from background but a very rare event.However the Universe is full of neutrinos from all previous SN flying around. One only needs to separate them from background of other neutrinos.The expected rate of SNR neutrinos is very model dependent but experimentally we may be close to detect them.
Observation of a single SN relies on a very brief signal – trivial separation from background but a very rare event.However the Universe is full of neutrinos from all previous SN flying around. One only needs to separate them from background of other neutrinos.The expected rate of SNR neutrinos is very model dependent but experimentally we may be close to detect them.
arXiv:hep-ph/0408031arXiv:hep-ph/0408031
"From neutrinos.....". DK&ER, lecture 10
Expected signals from SN remnants(SNR neutrinos)
Expected rate of SNR events in a future 3 kton Icarus type detector.
Expected rate of SNR events in a future 3 kton Icarus type detector.
The distribution of electron or positron energy.The distribution of electron or positron energy.
arXiv:hep-ph/0408031arXiv:hep-ph/0408031
"From neutrinos.....". DK&ER, lecture 10
Expected rate of gravitational collapse in Milky Way
Estimates from:Estimates from:
• Historical observations: only 8 observed, however all within 5 kpc from the Sun (other obscured by dust in galactic disk). When one corrects for this and for the fact that not all observed SN resulted from core collapse one gets: one SN per 20 years
• Historical observations: only 8 observed, however all within 5 kpc from the Sun (other obscured by dust in galactic disk). When one corrects for this and for the fact that not all observed SN resulted from core collapse one gets: one SN per 20 years
• Birth rate of pulsars – model dependent: one SN per 10 or 100 years All pulsars result from core collapse, but not all SN leave a pulsar behind
• Birth rate of pulsars – model dependent: one SN per 10 or 100 years All pulsars result from core collapse, but not all SN leave a pulsar behind
• Oxygen abundance in the Galaxy: one SN per 10 years. Most of oxygen originates in core collapses.• Oxygen abundance in the Galaxy: one SN per 10 years. Most of oxygen originates in core collapses.
"From neutrinos.....". DK&ER, lecture 10
Supernovae with and without core collapse.
Core collapse only for SN II and Ib.
SN Ia: A binary system including e.g. a white dwarf.White dwarf (carbon/oxygen) accretes matter from the companion and increases its mass until new fusion reaction starts. The whole star is destroyed in the explosion.
SN Ia: A binary system including e.g. a white dwarf.White dwarf (carbon/oxygen) accretes matter from the companion and increases its mass until new fusion reaction starts. The whole star is destroyed in the explosion.
"From neutrinos.....". DK&ER, lecture 10
Future observations of neutrinos from SN
Future observations of neutrinos from SN
Super-Kamiokande can „see” a few neutrinos from the near-by galaxy, M31, in the Andromeda constellation, 2.1 million light years away
One SN in 10-50 years in our Galaxy but mostly invisible in optical spectrum
For a Galactic SN thousands of events in SK and hundreds in Icarus
Network of instant SN warning exists to point telescopes in a SN direction. Experiments should minimize their dead time.
Possible observation of neutrinos from cumulated SNR
Unique way to learn about collapsing mechanism and about neutrinos
"From neutrinos.....". DK&ER, lecture 10
Future observations of neutrinos from SN
Future observations of neutrinos from SN
Eta Carinae is a massive and unstable star with strong stellar winds. Perhaps a future supernova?