PaperPanorama
FAQ

Nuclear Theory·nucl-th

Friday·February 5, 2021

10 papers—6 primary·4 cross-listed

All10Primary6Cross-lists4
  1. 07

    [Submitted on 3 Feb 2021] (cross-list from astro-ph.HE)

    Tight multi-messenger constraints on the neutron star equation of state from GW170817 and a forward model for kilonova light curve synthesis

    Matt Nicholl🇬🇧 · Ben Margalit🇺🇸 · Patricia Schmidt🇬🇧 · Graham P. Smith🇬🇧 · Evan J. Ridley🇬🇧 · James Nuttall🇬🇧

    We present a rapid analytic framework for predicting kilonova light curves following neutron star (NS) mergers, where the main input parameters are binary-based properties measurable by gravitational wave detectors (chirp mass and mass ratio, orbital inclination) and properties dependent on the nuclear equation of state (tidal deformability, maximum NS mass). This enables synthesis of a kilonova sample for any NS source population, or determination of the observing depth needed to detect a live kilonova given gravitational wave source parameters in low latency. We validate this code, implemented in the public MOSFiT package, by fitting it to GW170817. A Bayes factor analysis overwhelmingly () favours the inclusion of an additional luminosity source in addition to lanthanide-poor dynamical ejecta during the first day. This is well fit by a shock-heated cocoon model, though differences in the ejecta structure, opacity or nuclear heating rate cannot be ruled out as alternatives. The emission thereafter is dominated by a lanthanide-rich viscous wind. We find the mass ratio of the binary is (90% credible interval). We place tight constraints on the maximum stable NS mass, M. For a uniform prior in tidal deformability, the radius of a 1.4 M NS is km. Re-weighting with a prior based on equations of state that support our credible range in , we derive a final measurement km. Applying our code to the second gravitationally-detected neutron star merger, GW190425, we estimate that an associated kilonova would have been fainter (by mag at one day post-merger) and declined faster than GW170817, underlining the importance of tuning follow-up strategies individually for each GW-detected NS merger.

    Comments:
    Updated to match accepted version in MNRAS
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
    arXiv:
    2102.02229 [pdf]
    MNRAS(2021)·108 citations
  2. 08

    [Submitted on 4 Feb 2021] (cross-list from hep-ph)

    Phase diagram of interacting pion matter and isospin charge fluctuations

    O. S. Stashko🇺🇦 · O. V. Savchuk🇩🇪 · R. V. Poberezhnyuk🇺🇦 · V. Vovchenko🇺🇸 · M. I. Gorenstein🇺🇸

    Equation of state and electric (isospin) charge fluctuations are studied for matter composed of interacting pions. The pion matter is described by self interacting scalar fields via a type Lagrangian. The mean-field approximation is used, and interaction parameters are fixed by fitting lattice QCD results on the isospin density as a function of the isospin chemical potential at zero temperature. Two scenarios for fixing the model parameters -- with and without the first order phase transition -- are considered, both yielding a satisfactory description of the lattice data. Thermodynamic functions and isospin charge fluctuations are studied and systematically compared for these two scenarios, yielding qualitative differences in the behavior of isospin charge susceptibilities. These differences can be probed by lattice simulations at temperatures MeV.

    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2102.02567 [pdf]
    PRC(2021)·4 citations
  3. 09

    [Submitted on 4 Feb 2021] (cross-list from nucl-ex)

    Unperturbed inverse kinematics nucleon knockout measurements with a 48 GeV/c carbon beam

    M. Patsyuk · J. Kahlbow · G. Laskaris · M. Duer · V. Lenivenko · E.P. Segarra · T. Atovullaev · G. Johansson · T. Aumann · A. Corsi · O. Hen · M. Kapishin and 157 other authors

    From superconductors to atomic nuclei, strongly-interacting many-body systems are ubiquitous in nature. Measuring the microscopic structure of such systems is a formidable challenge, often met by particle knockout scattering experiments. While such measurements are fundamental for mapping the structure of atomic nuclei, their interpretation is often challenged by quantum mechanical initial- and final-state interactions (ISI/FSI) of the incoming and scattered particles. Here we overcome this fundamental limitation by measuring the quasi-free scattering of 48 GeV/c 12C ions from hydrogen. The distribution of single protons is studied by detecting two protons at large angles in coincidence with an intact 11B nucleus. The 11B detection is shown to select the transparent part of the reaction and exclude the otherwise large ISI/FSI that would break the 11B apart. By further detecting residual 10B and 10Be nuclei, we also identified short-range correlated (SRC) nucleon-nucleon pairs, and provide direct experimental evidence for the separation of the pair wave-function from that of the residual many-body nuclear system. All measured reactions are well described by theoretical calculations that do not contain ISI/FSI distortions. Our results thus showcase a new ability to study the short-distance structure of short-lived radioactive atomic nuclei at the forthcoming FAIR and FRIB facilities. These studies will be pivotal for developing a ground-breaking microscopic understanding of the structure and properties of nuclei far from stability and the formation of visible matter in the universe.

    Comments:
    Accepted for publication in Nature Physics. 28 pages, 19 figures, and 1 table including main text, Methods, and Supplementary materials
    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2102.02626 [pdf]
    Nat.Phys.(2021)·67 citations
  4. 10

    [Submitted on 4 Feb 2021] (cross-list from astro-ph.HE)

    Resonance suppression of the r-mode instability in superfluid neutron stars: Accounting for muons and entrainment

    Elena M. Kantor🇷🇺 · Mikhail E. Gusakov🇷🇺 · Vasiliy A. Dommes🇷🇺

    We calculate the finite-temperature r-mode spectrum of a superfluid neutron star accounting for both muons in the core and the entrainment between neutrons and protons. We show that the standard perturbation scheme, considering the rotation rate as an expansion parameter, breaks down in this case. We develop an original perturbation scheme which circumvents this problem by treating both the perturbations due to rotation and (weak) entrainment simultaneously. Applying this scheme, we propose a simple method for calculating the superfluid r-mode eigenfrequency in the limit of vanishing rotation rate. We also calculate the r-mode spectrum at finite rotation rate for realistic microphysics input (adopting, however, the Newtonian framework and Cowling approximation when considering perturbed oscillation equations) and show that the normal r-mode exhibits resonances with superfluid r-modes at certain values of temperatures and rotation frequencies in the parameter range relevant to neutron stars in low-mass X-ray binaries (LMXBs). This turns the recently suggested phenomenological model of resonance r-mode stabilization into a quantitative theory, capable of explaining observations. A strong dependence of resonance rotation rates and temperatures on the neutron superfluidity model allows us to constrain the latter by confronting our calculations with the observations of neutron stars in LMXBs.

    Comments:
    20 pages, 5 figures, published in Phys. Rev. D
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
    arXiv:
    2102.02716 [pdf]
    PRD(2021)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE