1 / 23

Neutrinos as probes of gamma-ray bursts

Neutrinos as probes of gamma-ray bursts. Hylke Koers. Service de physique théorique, UL Brussels. Based on work in collaboration with: Ralph Wijers (API Amsterdam) Asaf Pe’er (Giacconi fellow, Hubble Space Telescope Science Institute)

regina
Download Presentation

Neutrinos as probes of gamma-ray bursts

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Neutrinos as probes of gamma-ray bursts Hylke Koers Service de physique théorique, UL Brussels Based on work in collaboration with: Ralph Wijers (API Amsterdam) Asaf Pe’er (Giacconi fellow, Hubble Space Telescope Science Institute) Dimitrios Giannios (Max-Planck-Institute for Astrophysics Garching) TexPoint fonts used in EMF. Read the TexPoint manual before you delete this box.:

  2. Outline A gamma-ray burst primer Fireball neutrino cooling Neutrino production in np collisions Neutrino emission from choked GRBs

  3. Motivation Interesting for modelling: unresolved observations and extreme properties Probes of the universe up to z ~ 5, constraining DM and DE Candidate sources of cosmic rays Speculative ideas: constraining Lorentz invariance through arrival times, ... (?) Candidate sources of neutrinos

  4. A GRB primer: observational landmarks • Some observational landmarks: • ’60s: Discovery of very energetic flashes of gamma rays. (military VELA satellites) – distance scale? • >1991: Isotropic distribution found (BATSE all-sky monitor from CGRO) • 1997: Afterglow observations establish cosmological scales (BeppoSAX satellite) • 1998: First identification of a contemporaneous SN – GRB (BeppoSAX / BATSE) • 2004: SWIFT satellite observes shallow decay phase, late energetic flares, and other unexpected phenomena

  5. A GRB primer: prompt emission • Key features of the prompt emission • Irregular lightcurves:“if you’ve seen one GRB...” • Rapid varibility, up to 10-3 sec. • Duration from 10-2 s – 103 s, subdivided intolong GRBs (~20 sec) and short GRBs (~0.2 sec) • Non-thermal spectrum (broken power-law), peaking around ~250 keV; occasionally extending to very high energies (> GeV... TeV?)

  6. A GRB primer: afterglow • Key features of the afterglow • Broad-band spectrum over many decades in energy (radio, optical/IR, X-ray) • Characteristic break energies compatible with synchrotron emission • Slowly declining (typically power-law) lightcurve (sometimes detectable up to years

  7. Initial phase(106.5 cm) Catastrophic event: core-collapse of a massive star (long GRB): Formation of black hole + accretion disk system which launches a fireball Acceleratingphase(108 cm) Fireball accelerates to relativistic velocities G ~ 300by radiation pressure; stops due to energy constraints (baryonic load) Energy dissipation (shock acceleration):gamma-ray burst Coastingphase (1012 cm) Interaction with external environment: afterglow Afterglowphase (1016 cm) A GRB primer: the fireball model Key features Total energy ~ 1052 erg Lorentz factors ~ 300 Collimation Small baryonic load [Cavallo & Rees 1978; Paczynski 1986; Mészáros & Rees 1992, 1993]

  8. n Neutrinos are expected to be very useful probes to gain insight in these issues! A GRB primer: open questions A GRB primer: open questions A GRB primer: open questions • Important (partly) unsolved questions: • How are the jets formed? • What is the nature of the outflow? Dominated by thermal energy (=fireball?) or by electromagnetic energy? • How is shock-acceleration realized? Hylke Koers, Service de Physique Theorique, UL Brussels Hylke Koers, Service de Physique Théorique, UL Brussels

  9. Outline A gamma-ray burst primer Fireball neutrino cooling Neutrino production in np collisions Neutrino emission from choked GRBs Can neutrino cooling stop a developing GRB? [Koers & Wijers, MNRAS, 364, 934, 2005]

  10. n e± n g p Fireball cooling: the fireball fire· ball [‘fIr-”bol]: A tightly coupled plasma of photons, electron-positron pairs and neutrinos(with a small baryonic load) • Environment • Temperature: T ~ 1011 K (20 MeV) • Electrons, positrons: ne ~ 1035 cm-3 • Baryons: nB ~ 1032 cm-3 • Neutrino physics dominated by leptonic • processes Dynamics The fireball expands by radiation pressure to relativistic velocities.

  11. rapid cooling Fireball cooling: neutrino phase diagram Roughly 30% of the initial energy is released as a burst of ~60 MeV neutrinos The fireball is transparant in regions of fast neutrino creation. Here neutrinos just follow the usual hydrodynamic evolution. [HK & Wijers 2005]

  12. Outline A gamma-ray burst primer Fireball neutrino cooling Neutrino production in np collisions Neutrino emission from choked GRBs Can we use neutrinos (or gamma rays) from nucleonic collisions to discriminate between models? [Koers & Giannios, A&A, 471, 395, 2007]

  13. NP decoupling: characteristic radii Accelerating phase Coasting phase Fireball model: AC (magnetic) model:

  14. np gamma rays(fireball only!) prompt GRB (internal shocks) ~100 keV ~10 GeV NP decoupling: neutrinos and gamma rays Fireball (FB) model AC model fluence fromburst at z=0.1 peak energy Both fluence and energy are below IceCube sensitivity!

  15. Outline A gamma-ray burst primer Fireball neutrino cooling Neutrino production in np collisions Neutrino emission from choked GRBs Can neutrino emission indicate the existenceof choked GRBs? [Koers & Wijers, arXiv: 0711.4791]

  16. Choked GRBs: model Hypothesis: suppose that a (large) fraction of supernovae is accompanied by GRB-like outflows that stops below the surface [Mészáros & Waxman 2002] No gamma-ray emission Potential source of neutrinos (largely unconstrained) Motivation: Observed SN – GRB connection Missing ingredient in SN modelling Ubiquity of astrophysical jets

  17. Choked GRBs: protons Scheme: accelerate protons, create mesons,decay to neutrinos Proton shock acceleration VS • Proton energy losses • Synchrotron radiation • Photopion • ... [Razzaque, Mészáros & Waxman 2003, 2004, 2005; Ando & Beacom 2005]

  18. Maximum energy (in jet frame) Choked GRBs: protons

  19. Cooling break Choked GRB: mesons

  20. Cooling break Maximum energy (in jet frame) Choked GRB: mesons

  21. maximum energy Choked GRBs: neutrino spectrum Neutrino spectrum from meson (and muon) decay: cooling break Strong increase in high-energy neutrinos! (at Earth)

  22. Choked GRBs: detection prospects NB: optimistic case of efficient meson injection

  23. Conclusions Neutrino emission is an interesting and promising way to probe the physics of GRBs. However it remains a challenging task to identify concrete realizations of this potential.

More Related