Simulations for Multi-Messenger Astronomy (S4MMA): Nuclear matter and opacities

Perspective

From the S4MMA site: "concerns have been raised over whether NSF is providing sufficient support to the theory side of Multi-Messenger Astronomy"
I think a more "holistic" perspective might be useful, long-range plan (preparing for 2025?)

NSF and DOE?
More research funds: graduate students or postdocs, hubs or single-PI grants?
More tenure-track positions?
More software engineers?
More open-source and/or open data?
More career development? TALENT, etc?

My claim: the single biggest challenge to our field at this level isn't NSF funding, it's diversity, equity, and inclusion.

Physics Challenges

Nuclear matter and the
nucleon-nucleon interaction

Neutron matter above saturation
Nuclear matter

Equation of state

T=0, T>0
composition and exotica
NS crust
superconductivity and superfluidity

Transport properties

Neutrinos

mean field
RPA
beyond

Viscosity
Others?

Connection to nuclear structure and reactions

Practical Challenges

Microphysics in simulations significantly lags progress in theory

More on the Computing Side

Sanjay: Community software tools for modeling central engines (supernovae, NS-SN and NS-BH mergers, etc.) with standarized (EOS, opacities, magnetic fields, etc.) input and output (multimessenger signals) is urgently needed
Can we break up our codes into "pluggable components/modules" or APIs so we can create community frameworks?

Fundamental Science Questions

Can we identify the correct degrees of freedom at all relevant densities and temperatures?
What are the uncertainties in the EOS for neutron matter beyond nuclear saturation?
Can we predict nuclear saturation rather than fitting to the "empirical saturation point"?
How can we more effectively quantify the uncertainties associated with the EOS and transport phenomena in astrophysical environments?
How can we better connect the EOS and other properties of the NNI to experiments and observations?
Can we simultaneously describe light nuclei, heavy nuclei, and nuclear matter with the same Hamiltonian?

End

I'm happy to update this (or it's on github)
Now, other comments, questions, and suggestions from WG7 and others...

* Prakash: Coordinating between stellarcollapse.org and Compose framework
* Dexheimer: Compose conference in February (http://www.pharos.ice.csic.es/wg1-wg2-shorkshop-2021)
* Hix: code-comparison with fiducial EOS vs. EOS comparisons. Curation?
* Reddy: Curation: one framework with parameters you can 
change
* Radice: A framework with parameters is important for mergers
* Prakash: Phase transitions and extremes
(I lost track sorry...)
* Richers: how will constraints on EOS change CCSN simulations?
* Prakash: NICER will help with radius measurements for NSs with known masses
* Dexheimer: finite temperature is still a problem; improve repository by imposing constraints from recent observations
* Wilcox: are there HPC simulations which we need to invest in?
* Prakash: unless gaps are large, CCSN people don't have to worry about superfluidity
* Reddy: Andersson and Comer have some work on superfluidity for NSMs; relevant for pre-merger evolution
* Tews: We require a lot of parameters to describe the EOS space, how big of a space can we probe in simulations
* Radice: We can do 10-100 simulations per year
* Gandolfi: Less important how many parameters there are, in comparison to what the most important parameters are. 
* Prakash: What about magnetic fields in mergers?
* Radice: All MHD merger simulations are ideal MHD with polytropes; simulations have trouble when matter is magnetically-dominated, e.g. at low-densities
* Campanelli: Working on MHD mergers
* Lattimer: these MHD problems mimic challenges in hydro codes which lead to negative temperatures
* Campanelli: we should collaborate to solve these MHD problems
* Endeve: lot of work in applied math on maintaining postive internal energies in polytropes, this is harder with tabulated EOSs
* Prakash: Different interpolation schemes led to problems
* Reddy: Jeremy has new finite T EOSs not based in mean field theory
* Holt: Developing new UQ techniques for finite T, time is ripe for building a group to improve finite T EOSs
* Mezzacappa: what about neutrino opacities? 
* Reddy: very density-dependent; not as much UQ. Next 3-4 years. 
* Steiner: spin-response?
* Horowitz: lattice-QFT calcuations at low-density and high temperatures; needs more work for charged current. At high densities, the uncertainties won't go away.

WG7: Nuclear Matter and Neutrino Opacities

Andrew W. Steiner

Perspective

Perspective

Physics Challenges

Practical Challenges

More on the Computing Side

Fundamental Science Questions

End