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wiki:core_collapse_supernovae_neutron_star_mergers_and_grbs_hix_ott

Core collapse Supernovae, neutron star mergers and GRBs, and Neutrinos

Participants

Christian Ott - Caltech, Raph Hix - Ornl, Carla Frohlich, Chris Fryer, Rebecca Surman, Almudena Arcones, Derek Fox, Sam Austin, Anna Simon, Artemis Spyrou, Miguel Madurga, Kate Jones, Jeff Blackmon, Thomas Rauscher, Mohammed El Houssiny, Yong Qian, Christine Hampton, Evan O'Connor, Cecilia Lunardini, Peter Kalmus, Dan Kasen, Gail McLaughlin, Hyeyoung Lee, Brad Meyer, George Fuller, Jim Kneller, Christian Cardall, Annalia Palumbo, Remco Zegers, DongLiang Fang, Chris Sullivan

Agenda

19:00-19:20 CCSN multi-messenger observations (Kasen, Lunardini & Kalmus)
  • precursor - early warning: neutrino emission in silicon burning, gives early warning
  • pulsational mass loss close to explosion?
  • messengers complement each other
  • Fuller: in this table the astrophysical things are accessed by the thing you detect, but it coud be the other way around. The nucleosynthesis, for example, could tell you something about the neutrinos.
  • Kneller: can see shock in neutrino signal, test stalled shock paradigm
  • Advances in simulations; need more realistic 3D simulations with better physics; some still approximations. Same simulation can now be used to predict neutrino and GW properties. Moving towards including also photons.
  • photons: lots of advances, wide field optical surveys, large database of lightcurves and spectra. Have seen shock breakout → constraints on progenitor radii. Discovery of progenitors in archival data. Discovery of new extreme cases: very low and very high energy explosions. Spectrapolarimetry shows asymmetry in explosions. Effort to develop radiation transport capabilities.
  • How optimize multi-messenger detection given that CCSN may not be primary science target of various detectors?
  • Kneller: LIGO + SNEWS? Ott: In the future to be discussed.
  • Need better transport; need to understand how good approximate methods are.
  • Fuller: Don't forget oscillations. Flavor transformation question in the pre-explosion phase still open.
  • Is it really possible to include oscillation physics in simulations.
  • Fryer: can probably do tricks, but probably most work still in postprocessing.
  • Hix: first need Boltzmann, full Boltzmann is a decade away
  • Fuller: self-consistent quantum Boltzmann extremely expensive. Want to do it as postprocessing to see how important. Doing it with Monte Carlo may be a possiblitity.
  • Hix: Perhaps don't need Boltzmann. MGFLD may not be good enought, but there are higher-order schemes.
  • Not just push to get better simulations, also need parameter studies.
  • Progenitor identification: is difficult; relies on single-star evolution models. Big uncertainty, because of binary issue.
  • if GW and neutrinos, SN will be so close that we will get good EM data.
  • need full 3D models from explosion onset to surface + lightcurve
  • Kneller: understanding neutrino signal will be a challenge
  • difficult to get clear nuclear EOS signature out; lots of degeneracies, but EOS dependence of GW/nu signal exists. May be able to get constraints on mass-radius plot.
  • outcomes: what make supernovae, what make black holes, multi-messenger will be crucial; can determine BH formation
  • need multi-D modeling to understand effect on mixing on spectrum (too many Ics?)
  • Fuller: Status of surveys looking just for stars that disappear. Ott: Ohio state is doing this (Kochanek).
  • Kneller → Lunardini: some constraints on BH formation from failed supernovae in diffuse background.
  • Need to make sure detectors are online – neutrinos: ~100%, GW detectors 60-80% duty cycle is not good. Will get better with more detectors.
  • Neutrinos: need very large underground detector, need to detect e-. Does the volume of the detector make sense? For liquid argon, valume important; need high statistics
  • Photons: trigger from GW/neutrino; need rapid response; get localization from neutrinos. need wide-field imager that can respond quickly. Could discover nearby supernova on its own (without GW/neutrinos) early on if it is nearby. Shock breakout: space-based UV Galactic supernova: likely to occur in dusty plane. may not see light, need to look at longer wavelength or at X-ray. Could catch it in X-ray (shock breakout) early on.
  • Fryer: X-ray potential in teh future? Lobster? Perhaps okay for a decade.
  • Fox: nothing coming along; must pray for for Swift/Chandra/XMM to live.
  • Do we have pre-supernova imagine of all possible progenitors? How could we get pre-explosion images of all potential progenitors? → Gaia? Could get spectroscopy of progenitors
  • Needs: computing time, computer architectures may be problematic, exascale - is that what we need. need interaction with applied mathematicians. need support for manpower working on these problems. need influx of younger people. keep vibrant community. how can we organize the community to take advantage of multimessenger phenomena. need formal setup to compare results from different codes. need forum for interdisciplinary discussion between multi-messenger areas.
19:20-19:40 CCSN mechanism modeling (O'Connor & Cardall)
  • can blow up low mass massive stars stars in 1D
  • 2D successful explosions by multiple groups
  • 2D explosions underenergetic
  • importance of everything
  • problem: need to explain explosions, 1.0e51 ergs
  • if underresolved driving of turbulence low
  • big open question: role of magnetic fields and rotation need resolution
  • will take more than a decade to resolve MRI (Fryer)
  • challenge: connect to observations
  • remnant populations
  • impact of multi-D stellar evolution – are we wasting millions of CPU hours evolving wrong initial data.
  • we have to put pressure on stellar evolution community
  • connection to collapsars / GRBs
  • microphysics: EOS will have quantiative impact on mechanism. self-consistent neutrino interactions need quantitative predictions capture rates during collapse
  • Zegers: can make significant improvment to capture rates with better experiments and shell model calculations. FRIB!
  • Fryer: how big an uncertainty will capture be in a decade?
  • Zegers: Even models that are not so good, if you go to sufficiently high temperature, models don't matter any more; all give very similar rates. you are saved by the fact that you are not so sensitive to details. cannot measure easily.
  • Fryer: have seen NIF talks about experimental measurements of excited states in nuclei. Hix/Fuller/Bludmon: is for very light nuclei, not what we are dealing with in supernovae.
  • Austin: Chris, you made models in which 2D and 3D were very similar. Chris: this was very broad brushed statement. Don't know detailed differenced between 2D and 3D.
  • Qian: what can you learn about progenitor from EM? Kasen: radius, composition of outer progenitor layers Qian: can distinguish between 2 different 15 Msun models? Kasen: no, only if large differences
19:40-20:00 GRB Central Engines (Fox, Duez, Quataert)
  • GRBs: high-energy neutrinos constrained by IceCube
  • more GRB-SNe found
  • accelerated hadronic component in jet?
  • GRBs → UHECR
  • long burst nucleosynthesis ← Ott
  • short bursts: merger models passed first tests
  • fast fading emission from SHB 080503: matches Metzger model. Perley+09
  • r-process from mergers
  • good site?
  • will know about merger rate thanks to LIGO
  • near-term science totally driven by LIGO
  • GW-EM
  • get host galaxy, merger environs
  • get bursts themselves
  • need better sky coverage for GRBs, faster positions
  • need real time alerts and multi-facility coincident analysis (as per Kasen, Lunardini, Kalmus talk)
  • merger theory:
    1. need better models; include more physics, neutrinos
    2. not going to resolve MRI for a decade…
    3. need higher resolution, better treatment of magnetosphere
    4. get outflow right, follow directly to significant distance in terms of nuclear physics
    5. hot EOS effects on HMNS remnants
    6. need better inspirals; need 20-30 orbits before merger
  • how many NS-NS mergers make GRBs?
  • need to understand HMNS evolution and collapse.
  • nu-driven wind → baryon loading
  • neutrino emission can have influence by p → n via capture of neutrinos.
  • need more communication between communities to help merger people.
  • Gail McLaughlin: need to also consider disk wind for nucleosynthesis
  • desired resources (Derek): worried about missing bright GRBs on the sky; need to do better job of monitoring - BlackCAT proposal as NASA mission of opportunity, >3 sterad sky coverage, 200 bursts/year. X-ray 1-20 keV
  • Lifetime for Swift: budget limited
  • Astrophysics Multimessenger Observatory Network - coincident analysis of data from multiple high-energy / multimessenger facilities, including IceCube, Antares, Swift, HAWC - to include Auger, LIGO, Fermi
20:00-20:20 CCSN Nucleosynthesis (Fryer & Frohlich)

Progress

  • Mesa open source progenitor code has brought transparency to stellar evolution calculations.
  • New algorithms for mixing by Meakin and Arnett, based on insights from multi-dimensional models, have been included in 1D simulations.
  • Multi-dimensional supernova models with spectral transport and updated neutrino opacities are allowing us to examine nucleosynthesis beyond piston models.
  • Broad sensitivity studies have been conducted.

Key Questions

  • What affects the structure and composition of the stellar core:
    1. rotation
    2. reaction rates
    3. metallicity
    4. multi-dimensional phenomena
    5. single vs binary evolution?
  • What are the properties of the neutrino source?
  • What is the neutron fraction of the ejecta and how does is it influenced by neutrino physics, mechanism?
  • How do nuclear physics and neutrino physics uncertainties influence the nucleosynthesis?
  • What are the energetics of the explosion, its asymmetry, and timing and how do these impact the nucleosynthesis?

Future

  • Need to characterize the effects of uncertainties on the nucleosynthesis, and identify the physics that needs to improve.
  • While we wait for the final answer of the explosion mechanism, we must construct less-costly but still characteristic models to study nucleosynthesis, evaluate sensitivity, etc. beyond the limits of the piston models.
  • We need comparable models at all stages and we must characterize the uncertainties at all stages. We need to employ consistent nuclear data across stages.
  • Comment Rauscher: explosive nucleosynthesis does not only happen in deepest layers; perhaps different treatment (parameterized) possible to make it simpler? different sensitivities to shockwave and progenitor properties…
20:20-20:40 r-process (Surman & Jones)

Progress

  • Theoretical studies have found that reaction rate sensitivity depends on masses near the drip line, some neutron capture rates closer to stability and many beta decays throughout.
  • Wide range of mass measurements have been made using … and Penning Traps.
  • Beta Decay measurements now reach beyond the N=50 shell in Ga-Ge region. Beta decay measurements at Riken are now verging on the r-process waiting points in the Rb-Zr region. Beta-delayed neutron measurements were recently undertaken at HRIBF and ATLAS, enabled by new neutron detectors.
  • Measurements of (d,p) surrogate reactions have shed light on (n,gamma) rates previously determined to be of interest to the r-process. (Comment Rauscher: direct (d,p) identifies levels needed in rate calculation but do not immediately provide the neutron capture rates at r-process temperatures; additional theory required.)

Open Questions

  • Need to identify the r-process site both by performing detailed calculations of all proposed sites and by analyzing the r-process abundances in detail to reveal the thermodynamic conditions that are capable of producing the observed abundances.
  • Need to prepare for FRIB by continuing workforce development and developing of experimental equipment at existing facilities.

Future

  • CARIBU has begun re-accelerating beams. With FRIB we will roughly double the nuclei for which measurements can be made.
  • On the downside, the amount of beamtime available has fallen by more than a factor of 2 in the past 10 years. This highlights the need to maximize the use of beamtime, for example, by performing multiple simultaneous measurements.
  • Astrophysical simulations need consistent treatment of masses and rates with frequent updates.
  • Rauscher: Since the site of the r-process is unknown, parameterized studies need to explore wide ranges of conditions and trajectories (e.g., low Ye in NS mergers moves the path close to dripline, beta-decays, 2neutron captures and direct reactions at dripline become relevant) also nuclear physics has to be known from stability to dripline (unfortunately).
  • Meyer: Parameterized studies may not provide unique set of conditions when compared to r-abundances; neutron-to-seed ratio critical but, e.g., different trajectories etc may yield different conditions (and position of r-path).
20:40-21:00 wrap-up (Ott & Hix)

Questions

  • 1) What are the major recent accomplishments?
    A) In observations.
    B) In modeling.
    C) In GRBs
    D) In nucleosynthesis
    E) In r-process
  • 2) What are the specific compelling open questions? (Unexplained observations, problems in theoretical modeling, etc)
  • How can one address these open questions? What are the high impact nuclear experiments, observations, theoretical studies that need to be done?
  • What kinds of experiments, theoretical work, and observations are needed?
  • In which direction should this area evolve in light of expected new observational, theoretical, and experimental capabilities?
  • How does this subfield intersect with other subfields? (For example, is there work needed in other subfields to move this subfield forward)
    A) In observations.
    B) In modeling.
    C) In GRBs
    D) In nucleosynthesis
    E) In r-process

Suggestion In regards to the experimental part of the r-process (and perhaps this is thinking too far ahead) but shouldn't there be some specific mention of the SHE (super heavy elements) since they are important in determining the upper end of the nucleosynthesis flow. Thanks. - Annalia

wiki/core_collapse_supernovae_neutron_star_mergers_and_grbs_hix_ott.txt · Last modified: 2013/01/10 17:47 (external edit)