1. Neutrinos from supernovae
Gravitational collapse
Observations of SN1987A
What could be learned
about neutrinos
"From neutrinos.....". DK&ER, lecture 10

2. Natural sources of neutrinos
at 10 kpc
i.e. Galaxy
center
"From neutrinos.....". DK&ER, lecture 10

3. 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 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.
A supernova explosion observed in 1054 AD created a neutron star in the Crab nebula. It has a diameter of only 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

4. 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 SN
visible with the bare eye
was observed by Kepler
in 1604
"From neutrinos.....". DK&ER, lecture 10

5. Previous Supernovae observed in our Galaxy
The most recent SN
visible with the bare eye
was observed by Kepler
in 1604
yellow – Hubble (visible)
red – Spitzer (infrared)
green/blue – Chandra (rtg)
"From neutrinos.....". DK&ER, lecture 10

6. Supernova 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

7. Previous Supernovae observed in our Galaxy
Only 8 supernovae have been observed in our Galaxy:
Chinese records: 185, 386, 392 and 1006
Later: 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

8. "From neutrinos.....". DK&ER, lecture 10
Supernova 1987A
Mar 8, 1987
Feb 1984
On Feb 23, 1987 a supernova was observed optically in the Large Magellanic Cloud at a distance of light years (50 kpc)
Supernova 1987A in the Large Magellanic Cloud galaxy at a distance of 170,000 light years
was observed optically on 24 February It was the first Supernova visible with the bare eye
since Kepler’s Supernova in 1604.
At that time 2 large underground detectors searched for proton decays: Kamiokande and IMB. They inspected their signals and found
4 hours earlier......
"From neutrinos.....". DK&ER, lecture 10

9. "From neutrinos.....". DK&ER, lecture 10
Detector IMB
"From neutrinos.....". DK&ER, lecture 10

10. Observations of SN1987A IMB (Irvine-Michigan-Brookhaven)
After standard analysis rejecting atmospheric muons
Raw data
Events with less than 100 ring photomultipliers recorded in
IMB from 7:00:00 to 8:00:00 UT on February 23, 1987: a) the sample of
unprocessed data events, b) the sample selected by the routine computer
processing programs. For every event the number of ring photomultipliers
is plotted versus its time of occurrence. Seven out of eight supernova events
are clearly seen as a vertical line.
"From neutrinos.....". DK&ER, lecture 10

11. Neutrinos from Supernova 1987A in Kamiokande
Universal time
on 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.
the 1016 neutrinos hitting the Kamiokande experiment, only 12 were detected.
Fig. 5 Each vertical line represents the relative energy of a muon (dashed lines) or of an electron (solid lines). Events µ1 - µ4 are
muon events preceeding the electron bursts at time 0. The background events with NHIT<20 are largely due to decay of 214Bi,
a decay product of 222Rn. From Hirata et al
"From neutrinos.....". DK&ER, lecture 10

12. "From neutrinos.....". DK&ER, lecture 10
IMB
events
"From neutrinos.....". DK&ER, lecture 10

13. Observations of neutrinos from SN 1987A
IMB Kamiokande Baksan LSD
Location Ohio,US Japan Russia France
(Mont Blanc)
Detector type water Cerenkov liquid scintillator
Detector mass
(tons)
Threshold(MeV)
Number of events ???
Time of 1st 7:35:41 7:35:35 7:36: :52:37
event (UT)
Absolute time
accuracy (sec)
"From neutrinos.....". DK&ER, lecture 10

14. Neutrinos from Supernovae
"From neutrinos.....". DK&ER, lecture 10

15. "From neutrinos.....". DK&ER, lecture 10
Stellar evolution
Ze strony: zebu.uoregon.edu/textbook/se.html
Stellar Evolution is driven entirely by the never ending battle between Pressure and Gravity . As imbalances are reached, the star is driven to find a new Energy source. Each new stage in stellar evolution is hence marked by a different energy generation mechansism. These stages are discussed below:
Structure of a Main Sequence Star Here see that a main sequence star has a simple structure. Pressure and gravitational forces are equal, the star is stable and its core is sufficiently hot to fuse
Eventually the core of the main sequence star will become pure Helium and that will mark a new evolutionary phase for the star. -
"From neutrinos.....". DK&ER, lecture 10

16. Road to gravitational collapse
Main thermo-nuclear reactions:
Reaction Ignition temp.
(millions K)
4 1H --> 4He
3 4He --> 8Be + 4He --> 12C C + 4He --> 16O
2 12C --> 4He + 20Ne Ne + 4He --> n + 23Mg
2 16O --> 4He + 28Si O --> 2 4He + 24Mg 4000
2 28Si --> 56Fe
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.
ze strony
Seule la dissociation du fer par les rayons gamma est endothermique; ce refroidissement provoque l'implosion du coeur de l'étoile et son explosion en supernova.
When mass of the iron core exceeds
1.4 solar masses the gravitation wins.
gravitational collapse
"From neutrinos.....". DK&ER, lecture 10

17. Stellar evolution Interplanetary nebula Protostar Star Red Giant
Black Dwarf
White Dwarf
Red Super-Giant SN
Neutron
Black
Hole
M ~
M ~ 8M
M >>
A large, dense, cool nebula (up to 106 Mo, temp.~10 K)
A gravitating matter condensation grows to
~ 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

18. "From neutrinos.....". DK&ER, lecture 10
Stellar Evolution
"From neutrinos.....". DK&ER, lecture 10

19. "From neutrinos.....". DK&ER, lecture 10
Stellar Dimensions
White dwarf
Red dwarf
Sun
Red Giant
Blue Giant
"From neutrinos.....". DK&ER, lecture 10

20. "From neutrinos.....". DK&ER, lecture 10
Stellar Evolution
"From neutrinos.....". DK&ER, lecture 10

21. "From neutrinos.....". DK&ER, lecture 10
Stellar evolutions
Initial star mass
(in solar masses)
Luminosity (sun=1)
(during principal sequence)
Livetime during princ. seq
(in billion years)
Livetime as red giant
(billions of years)
Nuclear reactions stop at iron silicon oxygen carbon helium
Final fate SN SN planetary solar solar
nebula wind wind
Ejected mass
Nature of final state black neutron white dwarfs (all 3)
hole star
Mass of final state
density (g/cm3) 5x x x x x106
ze strony
La densité moyenne d'un trou noir diminue en proportion de l'inverse du carré de la masse qui y est enfermée. Ainsi, la densité qu'il faudrait atteindre pour faire un trou noir au moyen d'une masse de 1,5 Mo est de 8 x g/cm 3. On voit (colonne 2) que la densité atteinte par le noyau résiduel de 1,5 Mo est "seulement" de 3 x g/cm 3, ce qui explique pourquoi il ne disparaît pas dans un trou noir.
"From neutrinos.....". DK&ER, lecture 10

22. Gravitational Collapse
"From neutrinos.....". DK&ER, lecture 10

23. Neutrinos 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:
prompt neutrinos
neutron star
Heat gives rise to gammas which produce e+ e- pairs and then:
thermal neutrinos
"From neutrinos.....". DK&ER, lecture 10

24. SN neutrino properties
Neutrino luminosity
vs time
Thermal spectra
(Fermi-Dirac distribution)
Beacom and Vogel
"From neutrinos.....". DK&ER, lecture 10

25. Neutrinos from SN 1987A – E vs angle
Distribution of the angle with respect to the direction from SN
Isotropic distribution
indicates mostly:
rather than:
(cross section smaller by orders of magnitude.)
Fig. 4 Scatter plot of the detected electron
energy and the cosine of the angle between the
measured electron direction and the direction
of the Large Magellanic Cloud. The number on
each entry is the time-sequential event number.
The direction of the positron from an anti-neutrino
reaction has very small correlation with
the direction of the neutrino. From Hirata et al.
1987.
However some anisotropy
remains puzzling.
"From neutrinos.....". DK&ER, lecture 10

26. Neutrinos from SN 1987A – E vs time
For 2 events of energies E1, E2 in MeV and time difference dt 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

27. 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”:
99% of this energy is carried away by neutrinos;
neutrino luminosity L~ 3x1053 ergs
1% goes into kinetic energy of the envelope particles
Only 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

28. Neutrinos from gravitational collapse
Total neutrino luminosity L~ 3x1053 ergs
Prompt pulse lasts only several msec
hence its total luminosity is small
Almost all L is carried away by thermal neutrinos
approximately obeying „equipartition of energy”:
However energies of νμ and ντ are less degraded by interactions than that of νe
"From neutrinos.....". DK&ER, lecture 10

29. Analysis of the observed events
Thermal neutrinos should be described by Fermi-Dirac distribution.
Their fluence F (i.e. flux integrated over time):
T – temperature
E – neutrino energy
this spectrum was assumed for the analysis
From the measurements of F on
Earth one can calculate:
L in ergs
Φ fluence in cm-2
T in MeV
D distance in kpc
"From neutrinos.....". DK&ER, lecture 10

30. Neutrinos from SN 1987A- results
Experiment: IMB Kamiokande
Temperature (MeV)
Fluence (x 1010cm-2)
Average energy (MeV)
Total νe energy (x1052 ergs)
Total energy released
(x1053 ergs)
Assuming :a) a distance of 49 kpc
b)equipartition of energy between different flavors
"From neutrinos.....". DK&ER, lecture 10

31. What have we learned about neutrinos from SN1987A
Lifetime
sec
Mass
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 distance
from 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
"From neutrinos.....". DK&ER, lecture 10

32. What have we learned about neutrinos from SN1987A
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
a charged ν would experience an energy
dependent delay due to its curved path
in the intergalactic and galactic mgt field.
Electric charge
"From neutrinos.....". DK&ER, lecture 10

33. Test 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

34. Actually neutrinos arrived earlier...
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

35. "From neutrinos.....". DK&ER, lecture 10
SN1987A
"From neutrinos.....". DK&ER, lecture 10

36. "From neutrinos.....". DK&ER, lecture 10
SN 1987A
Seven years later.. photos by Hubble Space Telescope
Supernova 1987A in the Large Magellanic Cloud galaxy at a distance of 170,000 light years
was observed optically on 24 February It was the first Supernova visible with the bare eye
since Kepler’s Supernova in 1604.
"From neutrinos.....". DK&ER, lecture 10

37. "From neutrinos.....". DK&ER, lecture 10
SN 1987A
A ring of glowing debris encircles the remains of supernova 1987A in the Large Magellanic Cloud galaxy. This cosmic pearl necklace is about 1.4 light-years in diameter and was likely shed by the star thousands of years ago as it began to collapse. The debris was heated to some 20,000 degrees Fahrenheit (11,100 degrees Celsius) by the blast wave when the star exploded. Supernova 1987A is expected to glow for decades to come.
"From neutrinos.....". DK&ER, lecture 10

38. "From neutrinos.....". DK&ER, lecture 10
Sheets of debris from an exploded star swirl in the Large Magellanic Cloud (LMC) galaxy in this Hubble Space Telescope image. At a distance of about 180,000 light years, the LMC galaxy is a relatively close neighbor of the Milky Way. It can be spotted from the Earth's Southern Hemisphere without a telescope.
"From neutrinos.....". DK&ER, lecture 10

39. Expected signals from future SN
in Super-Kamiokande:
Andromeda M31
Eg. for an SN in the Galactic center at 10 kpc:
Hopefully other than electron antineutrinos could be studied .
SN neutrinos are already flying to us
"From neutrinos.....". DK&ER, lecture 10

40. Expected signals from future SN
In ICARUS:
CC current:
NC current:
There is a possibility to separate
electron neutrinos and antineutrinos
and study very low energy part of the neutrino spectrum.
"From neutrinos.....". DK&ER, lecture 10

41. 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.
arXiv:hep-ph/
"From neutrinos.....". DK&ER, lecture 10

42. Expected signals from SN remnants (SNR neutrinos)
Expected rate of SNR events in a future 3 kton Icarus type detector.
The distribution of electron
or positron energy.
"From neutrinos.....". DK&ER, lecture 10
arXiv:hep-ph/

43. Expected rate of gravitational collapse in Milky Way
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
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.
"From neutrinos.....". DK&ER, lecture 10

44. 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.
"From neutrinos.....". DK&ER, lecture 10

45. 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 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

46. Future observations of neutrinos from SN
Eta Carinae is a massive and unstable star with strong stellar winds. Perhaps a future supernova?
"From neutrinos.....". DK&ER, lecture 10