Award Abstract # 1748621
CAREER: Dense Phases in Neutron Stars

NSF Org: PHY
Division Of Physics
Recipient: KENT STATE UNIVERSITY
Initial Amendment Date: June 20, 2018
Latest Amendment Date: August 7, 2024
Award Number: 1748621
Award Instrument: Continuing Grant
Program Manager: Bogdan Mihaila
bmihaila@nsf.gov
 (703)292-8235
PHY
 Division Of Physics
MPS
 Directorate for Mathematical and Physical Sciences
Start Date: July 1, 2018
End Date: October 31, 2024 (Estimated)
Total Intended Award Amount: $425,000.00
Total Awarded Amount to Date: $549,998.00
Funds Obligated to Date: FY 2018 = $85,000.00
FY 2019 = $85,000.00

FY 2020 = $85,000.00

FY 2021 = $209,999.00

FY 2023 = $84,999.00
History of Investigator:
  • Veronica Dexheimer (Principal Investigator)
    vdexheim@kent.edu
Recipient Sponsored Research Office: Kent State University
1500 HORNING RD
KENT
OH  US  44242-0001
(330)672-2070
Sponsor Congressional District: 14
Primary Place of Performance: Kent State University
Physics Dept. PO Box 5190
Kent
OH  US  44242-0001
Primary Place of Performance
Congressional District:
14
Unique Entity Identifier (UEI): KXNVA7JCC5K6
Parent UEI:
NSF Program(s): NUCLEAR THEORY
Primary Program Source: 01001819DB NSF RESEARCH & RELATED ACTIVIT
01001920DB NSF RESEARCH & RELATED ACTIVIT

01002021DB NSF RESEARCH & RELATED ACTIVIT

01002122DB NSF RESEARCH & RELATED ACTIVIT

01002223DB NSF RESEARCH & RELATED ACTIVIT

01002324DB NSF RESEARCH & RELATED ACTIVIT

01002021DB NSF RESEARCH & RELATED ACTIVIT

01002122DB NSF RESEARCH & RELATED ACTIVIT
Program Reference Code(s): 069Z, 1045
Program Element Code(s): 128500
Award Agency Code: 4900
Fund Agency Code: 4900
Assistance Listing Number(s): 47.049

ABSTRACT

With the exception of black holes, neutron stars are the densest objects in the Universe. Inside these objects, exotic particles such as hyperons and deconfined quarks that do not exist in a stable form anywhere else in the universe can be created. This project proposes an in-depth investigation of new kinds of matter inside neutron stars as well as the effects of incredibly strong magnetic fields, many orders of magnitude larger than the one present inside the Sun, on these phases of matter. The results of this research will be used by the astrophysics community to search for clear signals of stable exotic matter in neutrinos bursts and gravitational waves. The project involves the training of high school, undergraduate and graduate students in astrophysics research, and includes a series of seminars open for the community that highlights the role of female astrophysicists.

The project will pursue an extension of a realistic description of hadronic and quark phases in the core of neutron stars to include magnetic fields together with finite temperature effects. This will enable effects of strong magnetic fields to be studied in different regions of stars, not only for cold neutron stars but also for proto-neutron stars. For the latter case, this project will also study the effects of neutrinos and entropy per particle on the structure of phase transitions. With these ingredients in hand, complete data tables will be built from a realistic equation of state to be used by others in dynamical simulations of supernova explosions, compact binary mergers, and neutron star cooling, to answer a fundamental question in astrophysics: Do exotic degrees of freedom play a role in the above phenomena? Having the first extensive data table built from a single realistic description will be extremely useful and allow for more accurate dynamical calculations of astrophysical phenomena. The students involved in the project will make meaningful contributions to state-of-the-art research. Finally, this project will support a series of seminars open for the community that highlights the role of female astrophysicists.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH

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(Showing: 1 - 10 of 50)
Aryal, K. and Constantinou, C. and Farias, R.L.S. and Dexheimer, V. "High-energy phase diagrams with charge and isospin axes under heavy-ion collision and stellar conditions" Physical Review D , v.102 , 2020 https://doi.org/10.1103/PhysRevD.102.076016 Citation Details
Aryal, Krishna and Constantinou, Constantinos and Farias, Ricardo L. and Dexheimer, Veronica "The Effect of Charge, Isospin, and Strangeness in the QCD Phase Diagram Critical End Point" Universe , v.7 , 2021 https://doi.org/10.3390/universe7110454 Citation Details
Brown, Connor and Dexheimer, Veronica and Jacobsen, Rafael Ban and Farias, Ricardo "Approaching the Conformal Limit of Quark Matter with Different Chemical Potentials" Symmetry , v.16 , 2024 https://doi.org/10.3390/sym16070852 Citation Details
Clevinger, A. and Corkish, J. and Aryal, K. and Dexheimer, V. "Hybrid equations of state for neutron stars with hyperons and deltas" The European Physical Journal A , v.58 , 2022 https://doi.org/10.1140/epja/s10050-022-00745-3 Citation Details
Clevinger, Alexander and Dexheimer, Veronica and Peterson, Jeffrey "Dense-matter equation of state at zero & finite temperature" EPJ Web of Conferences , v.296 , 2024 https://doi.org/10.1051/epjconf/202429614002 Citation Details
Dexheimer, V. "Equation of State at High-baryon Density and Compact Stellar Objects" Acta Physica Polonica B Proceedings Supplement , v.16 , 2023 https://doi.org/10.5506/APhysPolBSupp.16.1-A13 Citation Details
Dexheimer, V. and Aryal, K. and Constantinou, C. and Peterson, J. and Farias, R. L. "3-Dimensional QCD Phase Diagrams for Strange Matter" Journal of Physics: Conference Series , v.1602 , 2020 https://doi.org/10.1088/1742-6596/1602/1/012013 Citation Details
Dexheimer, V. and Gomes, R. O. and Klähn, T. and Han, S. and Salinas, M. "GW190814 as a massive rapidly rotating neutron star with exotic degrees of freedom" Physical Review C , v.103 , 2021 https://doi.org/10.1103/PhysRevC.103.025808 Citation Details
Dexheimer, V. and Soethe, L. T. and Roark, J. and Gomes, R. O. and Kepler, S. O. and Schramm, S. "Phase transitions in neutron stars" International Journal of Modern Physics E , v.27 , 2018 10.1142/S0218301318300084 Citation Details
Dexheimer, Veronica and Aryal, Krishna "Strangeness in astrophysics: Theoretical developments" EPJ Web of Conferences , v.259 , 2022 https://doi.org/10.1051/epjconf/202225905001 Citation Details
Dexheimer, Veronica and Aryal, Krishna and Wolf, Madison and Constantinou, Constantinos and Farias, Ricardo L. S. "Deconfinement phase transition under chemical equilibrium" Astronomische Nachrichten , v.342 , 2021 https://doi.org/10.1002/asna.202113932 Citation Details
(Showing: 1 - 10 of 50)

PROJECT OUTCOMES REPORT

Disclaimer

This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.

In this project, we studied dense matter at finite temperature, focusing on deconfinement to quark matter, the most important feature predicted by Quantum Chromodynamics (QCD) to take place at high energy. We quantified the effects of strangeness, isospin, different strong-force couplings, deconfinement phase-transition strengths, and magnetic fields. We constructed multidimensional QCD phase diagrams highlighting trajectories followed by neutron stars, proto-neutron stars, neutron star mergers, and laboratory particle collisions of different energies. We concluded that, once the exact conditions are found for deconfinement to take place in the laboratory at large densities (a given baryon chemical potential and temperature), this has to be carefully translated to the conditions in astrophysical scenarios, as both net strangeness and isospin affect the deconfinement baryon chemical potential and temperature by tens of MeV’s. The same can also be said for the case that the exact conditions are found for deconfinement in astrophysics. In the latter case, we also found a smoking gun for deconfinement in neutron star mergers, by identifying together with our collaborators that a strong first-order phase transition to deconfined quark matter would shorten the post-merger gravitational wave signal, without affecting the pre-merger signal. This could be soon measured by the LIGO-Virgo collaborations.

This work produced data tables with the description of dense matter that were made available for the entire scientific community through the CompOSE repository. These have already been used by several groups around the globe to e.g., study the effects of temperature on the production of strange particles and run simulations of stellar cooling. Our group used our description to investigate in addition magnetic white dwarfs, the possibility of magnetic twin stars, the role of spin 3/2 resonances in magnetic stars, fast rotating neutron stars, and the possibility of reproducing very massive or small neutron stars. We made successful comparisons with lattice QCD, perturbative QCD and other models, such as the PNJL. We investigated how physics at lower density (that can be more easily be studied in the laboratory) can affect astrophysics, e.g., by investigating the effects of the symmetry energy or hyperon potentials in dense matter and on quark deconfinement and the QCD phase diagram. We also studied in detail which kind of nuclear interactions, especially the ones that give rise to repulsion, are necessary to reproduce the conditions observed in specific observations of neutron stars and their mergers, both made electromagnetically and gravitationally. We found that those necessarily include higher-order terms and mixed terms that contain isospin.

We completed 3 PhD theses and published 51 papers and conference proceedings (being 3 selected as Editor’s suggestion and 4 published as letters). We delivered many talks to the scientific community discussing this project’s results in conferences, workshops, universities, and laboratories, in addition to graduate summer schools. To reach a larger audience, several public lectures in e.g., libraries were delivered. The project involved the PI, one postdoc, and three graduate students, in addition to several undergraduate students and high school students. This project also included a series of events to highlight the work of female astrophysicists, as a way to attract more young girls into science. Unfortunately, many of the planed events were canceled due to the COVID pandemic. Still, we managed to organize several colloquia, in addition to one "Science Cafe" at a local coffee shop, lunches with undergraduate and graduate female students, an event organized to bring for middle school girls from the Ohio public school system to the university called WOMEN IN STEM DAY, and an event in collaboration with the local Women's Center to discuss the role of African-American women in our society.

 


Last Modified: 02/28/2025
Modified by: Veronica   Dexheimer

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