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A list of all the posts and pages found on the site. For you robots out there, there is an XML version available for digesting as well.
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Posts
portfolio
publications
Impact of the PSR J0740+6620 radius constraint on the properties of high-density matter
Published in Phys. Rev. D, 2021
Recommended citation: Isaac Legred, Katerina Chatziioannou, Reed Essick, Sophia Han, Philippe Landry, "Impact of the PSR \({\mathrm J0740+6620}\) radius constraint on the properties of high-density matter." Phys. Rev. D, 2021.
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Implicit correlations within phenomenological parametric models of the neutron star equation of state
Published in Physical Review D, 2022
Parametric models impose hidden correlations across density scales in neutron star EOS inference.
Recommended citation: Legred, Isaac N., Chatziioannou, K., Essick, R., & Landry, P. (2022). "Implicit correlations within phenomenological parametric models of the neutron star equation of state." Phys. Rev. D. 105, 043016.
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Simulating neutron stars with a flexible enthalpy-based equation of state parametrization in SpECTRE
Published in Physical Review D, 2023
Introduces an enthalpy-based EOS parametrization implemented in SpECTRE simulations of neutron stars.
Recommended citation: Legred, I., Kim, Y., Deppe, N., Chatziioannou, K., Foucart, F., Hébert, F., Kidder, L. E. (2023). "Simulating neutron stars with a flexible enthalpy-based equation of state parametrization in SpECTRE." Phys. Rev. D. 107, 123017.
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Phase transition phenomenology with nonparametric representations of the neutron star equation of state
Published in Physical Review D, 2023
Explores potential phase-transition behavior in dense matter with nonparametric EOS models.
Recommended citation: Essick, R., Legred, I., Chatziioannou, K., Han, S., & Landry, P. (2023). "Phase transition phenomenology with nonparametric representations of the neutron star equation of state." Phys. Rev. D. 108, 043013.
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Assessing equation of state-independent relations for neutron stars with nonparametric models
Published in Physical Review D, 2024
Re-evaluates universal NS relations (e.g. I-Love-Q) using flexible Gaussian-process EOS models.
Recommended citation: Legred, I., Sy-Garcia, B. O., Chatziioannou, K., & Essick, R. (2024). "Assessing equation of state-independent relations for neutron stars with nonparametric models." Phys. Rev. D. 109, 023020.
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Using equation of state constraints to classify low-mass compact binary mergers
Published in Physical Review D, 2024
Classifies whether low-mass merger components are NS or BH using tidal/ EOS inference.
Recommended citation: Golomb, J., Legred, I., Chatziioannou, K., Dietrich, T., et al. (2024). "Using equation of state constraints to classify low-mass compact binary mergers." Phys. Rev. D.
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Nonlinear Alfvén-wave dynamics and premerger emission from crustal oscillations in neutron star mergers
Published in The Astrophysical Journal Letters, 2024
Simulates Alfvén waves from tidal excitations, predicting electromagnetic precursors before NS mergers.
Recommended citation: Most, E. R., Kim, Y., Chatziioannou, K., & Legred, I. (2024). "Nonlinear Alfvén-wave dynamics and premerger emission from crustal oscillations in neutron star mergers." ApJL. 973, L37.
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The interplay of astrophysics and nuclear physics in determining the properties of neutron stars
Published in Physical Review D, 2025
Joint inference of EOS and population differences between Galactic and GW observed neutron stars.
Recommended citation: Golomb, J., Legred, I., Chatziioannou, K., & Landry, P. (2025). "The interplay of astrophysics and nuclear physics in determining the properties of neutron stars." Phys. Rev. D.
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Nonparametric extensions of nuclear equations of state: probing the breakdown scale of relativistic mean-field theory
Published in arXiv, 2025
Hybrid GP + relativistic mean-field hybrid EOS models to study breakdown scales via future observations.
Recommended citation: Legred, I., Brodie, L., Haber, A., Essick, R., & Chatziioannou, K. (2025). "Nonparametric extensions of nuclear equations of state: probing the breakdown scale of relativistic mean-field theory." arXiv.
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Unified nonparametric equation-of-state inference from the neutron-star crust to perturbative-QCD densities
Published in arXiv, 2025
Integrates pQCD constraints into a GP-based EOS extending from crust through ultra-high densities.
Recommended citation: Finch, E., Legred, I., Chatziioannou, K., Essick, R., Han, S., & Landry, P. (2025). "Unified nonparametric equation-of-state inference from the neutron-star crust to perturbative-QCD densities." arXiv.
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Neutron Stars: Robust Constraints on Dense Matter from Astrophysics
Published in Ph.D. Dissertation, California Institute of Technology, 2025
Ph.D. thesis summarizing Legred’s work using electromagnetic and gravitational-wave observations to constrain dense-matter EOS using nonparametric models.
Recommended citation: Legred, Isaac Norman (2025). "Neutron Stars: Robust Constraints on Dense Matter from Astrophysics." Ph.D. Dissertation, Caltech.
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Inferring the neutron star equation of state with nuclear-physics informed semiparametric models
Published in arXiv, 2025
Combines nuclear-physics meta-model at low density with GP at high density to infer NS EOS from multi-messenger data.
Recommended citation: Ng, S., Legred, I., Suleiman, L., Landry, P., Traylor, L., & Read, J. (2025). "Inferring the neutron star equation of state with nuclear-physics informed semiparametric models." arXiv.
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talks
LIGO SURF introduction to NSs
Published:
A talk given to introduce undergraduates to key concepts in Neutron Star science. Part of a sequence of talks given to undergrads of the LIGO Summer Undergraduate research fellowship program.
teaching
Caltech Physics 1b-c
Undergraduate course, Caltech Physics, 2021
I was a graduate teaching assistant for the introductory undergraduate class in special relativity and electromagnetism intended for physics majors. The two terms covered topics such as introductory special relativity, electrostatics, magnetostatics, circuits, EM waves, and Lorentz transformations of the EM fields.