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

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

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. 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 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

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

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

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

"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 170 000 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 1987. 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

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

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. 1988. "From neutrinos.....". DK&ER, lecture 10

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

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 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 0.002 accuracy (sec) -54 "From neutrinos.....". DK&ER, lecture 10

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

"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

Road to gravitational collapse Main thermo-nuclear reactions: Reaction Ignition temp. (millions K) 4 1H --> 4He 10 3 4He --> 8Be + 4He --> 12C 100 12C + 4He --> 16O 2 12C --> 4He + 20Ne 600 20Ne + 4He --> n + 23Mg 2 16O --> 4He + 28Si 1500 2 16O --> 2 4He + 24Mg 4000 2 28Si --> 56Fe 6000 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 www.cvconseils.com/etoiles.html 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

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 ~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

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

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

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

"From neutrinos.....". DK&ER, lecture 10 Stellar evolutions Initial 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 Nature of final state black neutron white dwarfs (all 3) hole star Mass of final state 6 1.5 0.8 0.7 0.3 density (g/cm3) 5x1014 3x1015 2x107 1x107 1x106 ze strony www.cvconseils.com/etoiles.html 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 10 15 g/cm 3. On voit (colonne 2) que la densité atteinte par le noyau résiduel de 1,5 Mo est "seulement" de 3 x 10 15 g/cm 3, ce qui explique pourquoi il ne disparaît pas dans un trou noir. "From neutrinos.....". DK&ER, lecture 10

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

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

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

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

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

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

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

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

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

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

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

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

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

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

"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 1987. It was the first Supernova visible with the bare eye since Kepler’s Supernova in 1604. "From neutrinos.....". DK&ER, lecture 10

"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

"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

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

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

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/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. The distribution of electron or positron energy. "From neutrinos.....". DK&ER, lecture 10 arXiv:hep-ph/0408031

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

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

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