Neutrinos from Black Hole Accretion Disks

Transcription

1 Neutrinos from Black Hole Accretion Disks Gail McLaughlin North Carolina State University General remarks about black hole accretion disks Neutrinos and nucleosynthesis - winds Neutrino flavor transformation The nucleosynthesis - neutrino oscillation connection

2 Stellar Collapse Disks: Collapsars Failed Supernova Too much rotation for real collapse & bounce accretion disk jet punches out of star black hole Accretion disks form in rare types of core collapse supernovae. Neutrinos from the disk may provide some of the energy required to power a jet.

3 Compact Object Merger Disks figure from Karobkin 2012 figure from Karobkin 2012

4 Figure from GCM and Surman 2007 Neutrino surfaces:

5 Accretion Disk νe temperatures Surman et al 2008 Caballero et al 2012

6 Neutrinos from ν e and ν e emitting disks Characteristics primarily ν e and ν e for collapsars, all flavors for compact object mergers ν e, ν e, ν µ, ν µ, ν τ, ν τ similar spectra emitted from a fairly different geometry emission surface for neutrinos is larger than for antineutrinos antineutrinos have higher temperature than neutrinos merger disks emit more antineutrinos than neutrinos

7 Nucleosynthesis from black hole accretion disks Three types of environments ejection of neutron rich matter (compact object mergers) explosive burning (collapsars, also mergers, see next talk) accretion disk wind (both) Interesting types of nucleosynthesis r-process p-process 56 Ni and other iron group nuclei

8 Nucleosynthesis in Winds nucleosynthesis accretion disk nuclear physics of the disk black hole, jet outflow neutrino oscillations neutrinos neutrino scattering & emission r-process p-process 56 Ni -light curves! ν-process

9 The weak interaction The only way to convert protons to neutrons and vice-versa beta decay electron (neutrino) capture positron (anti-neutrino) capture n p+e + ν e e +p n+ν e e + +n p+ ν e A few words about neutrinos... They are emitted from complicated neutrino surfaces. General relativistic effects determine their paths and energies. They oscillate! e.g. As a ν e travels it may turn into a combination of ν e, ν µ and ν τ.

10 Compact Object Mergers

11 Simple model of wind nucleosynthesis black hole neutron star merger Schematic of events in outflow Surman et al R-process occurs in the wind, but simplified emission surface of neutrinos

12 ν general relativistic effects - high entropy trajectory Iron group elements yellow - No GR red - ν GR, no rot., a = 0 Stellar wind type trajectory Caballero et al 2012

13 Compact Object Merger Disks: Nickel - 56 n,p 4 He iron peak nuclei heavier nuclei Surman et al 2014

14 Disks from Stellar Collapse - Collapsar

15 Collapsar type disks: Nickel - 56 n,p 4 He iron peak nuclei heavier nuclei Surman et al 2010

16 Collapsar type disks: Neutrinos enhanced light p-nucleosynthesis ν-p process p-rich nuclei Yi/Yi, Mass Number A Kizivat et al 2010 Pruet et al, Surman et al 2005, 2011

17 What about Neutrino Oscillations?

18 Neutrino Oscillations Neutrino propagation in matter: forward scattering on electrons, neutrinos leads to effective potential ν e e e ν µ,τ G F G F e e ν e ν µ,τ Modified wave equation i c d dr ψ ν = CC+NC NC V e +Vν a δm2 4E cos(2θ) Vν b + δm2 4E sin(2θ) V e = V ν e,e V νx,e 2 electrondensityn e (r) V ν = V ν,ν V ν, ν similar idea for ν - νs = 2 2G F N e (r) V ν b + δm2 4E sin(2θ) V e Vν a + δm2 4E cos(2θ) ψ ν

19 Some Types of Oscillations Modified wave equation i c d dr ψ ν = V e +Vν a δm2 4E cos(2θ) Vν b + δm2 4E sin(2θ) MSW δm2 4E V e, sun, supernova Collective: δm 2 4E V ν, supernovae What about V e V ν? V ν b + δm2 4E sin(2θ) V e + Vν a + δm2 4E cos(2θ) ψ ν

20 Neutrino Oscillations above a Merger Disk Survival Probability A P νe P νe B Potential (erg) A V e V νν B Progress (cm) Top panel shows survival probabilities. Looks like no known supernova, solar, or terrestrial type oscillation Malkus, Friedland and GCM 2014

21 Neutrino Oscillations: scales Modified wave equation i c d dr ψ ν = Scales in the problem: V e +Vν a δm2 4E cos(2θ) Vν b + δm2 4E sin(2θ) vacuum scale δm2 4E matter scale V e G F N e (r) V ν b + δm2 4E sin(2θ) V e + Vν a + δm2 4E cos(2θ) ψ ν neutrino self-interaction scale V ν G F N ν angle G F N ν angle V ν has some subtleties. For proto-neutron star neutrinos V ν term declines roughly as 1/r 4, more complex for accretion disk

22 Neutrino-Matter Resonance Transition Survival Probability A P νe P νe B Potential (erg) A V e V νν B Progress (cm) Bottom panel shows potentials. Dotted green line indicates negative potential. Oscillation occurs at crossing. Malkus, Friedland and GCM 2014

23 This behavior suggests System wants to maintain the resonance In order to maintain the resonance the neutrinos change flavor System is stable, i.e. no growth in the off-diagonal neutrino potential Forces the off-diagonals of the neutrinos and antineutrino to cancel Analytic Prediction...

24 Neutrino-Matter Transition: Predictable Behavior Survival Probability V(δm 2 /2E) Single Energy Model Initially Dominated By Neutrinos (V(t)<0) B B ν Numerical Calculation ν Numerical Calculation ν Prediction ν Prediction V νν V e Progress(2E/δm 2 ) The sum of flavor isospin vectors doesn t precess, instead sum vector is restricted to ẑ direction. Malkus, Friedland and GCM 2014

25 Matter-Neutrino Resonance: Collapsar type disks Collapsar type disks are globally deleptonizing, i.e. neutrinos outnumber antineutrinos But, they can be locally leptonizing. Implications: along a neutrino trajectory, the potential can switch sign.

26 Inverted hierarchy, ν dominated first, ν later figure from Malkus, Kneller and GCM 2012 Survival Probability (III) (III) (I) (I) Interaction Strength (erg) Progress (cm) Upper panel: solid red - electron neutrino survival probability Upper panel: dashed red - electron antineutrino survival probability

27 Accretion Disk Nucleosynthesis red - no oscillations, blue - oscillations Malkus, Kneller and GCM 2012

28 Conclusions Disks are rich sources of nucleosynthesis Disk wind nucleosynthesis is strongly influenced by the neutrinos Disk neutrinos exhibit a unique flavor transformation phenomenon We call this a matter-neutrino resonance This transition can change the result of wind nucleosynthesis dramatically More to be considered, e.g. multi-angle effects together with 3-D disk emission surfaces