arXiv subjects

A. Hegedus

Publications and source records attributed to A. Hegedus.

7 recordsLinked to original sources

arXiv2025

Identifying Habitable Exoplanets with Radio Telescopes on the Lunar Farside

The search for habitable conditions beyond Earth is a top priority in astrophysics. The discovery of habitable exoplanets beyond our solar system will require a suite of instruments providing long-term monitoring for detection (e.g. with space and ground-based radial velocity observations), spectroscopic characterization of atmospheric and surface properties, and eventually deep chronograph-aided observations from e.g. JWST, Roman Space Telescope, and the Habitable Worlds Observatory (HWO). Detection of exoplanet magnetospheres is necessary to identify the most promising targets for follow-up characterization of biosignatures with these assets, and to provide an ensemble of objects for studies of magnetospheric conditions and atmospheric composition. Only observations of low-frequency radio emission will distinguish exoplanet magnetospheres (Hallinan et al. 2021). In this white paper, we present the two lunar radio array concepts under development that would be suitable to detect these exoplanet radio emissions. In addition, we also discuss the human exploration needed prior to construction of such lunar radio arrays while highlighting preferred candidate sites (Krolikowski & Elvis 2024) for the radio telescope.

astro-ph.IM↗

arXiv2019

A Space-based Decametric Wavelength Radio Telescope Concept

This paper reports a design study for a space-based decametric wavelength telescope. While not a new concept, this design study focused on many of the operational aspects that would be required for an actual mission. This design optimized the number of spacecraft to insure good visibility of approx. 80% of the radio galaxies -- the primary science target for the mission. A 5,000 km lunar orbit was selected to guarantee minimal gravitational perturbations from Earth and lower radio interference. Optimal schemes for data downlink, spacecraft ranging, and power consumption were identified. An optimal mission duration of 1 year was chosen based on science goals, payload complexity, and other factors. Finally, preliminary simulations showing image reconstruction were conducted to confirm viability of the mission. This work is intended to show the viability and science benefits of conducting multi-spacecraft networked radio astronomy missions in the next few years.

astro-ph.IM↗

arXiv2019

On the finite volume expectation values of local operators in the sine-Gordon model

In this paper we present sets of linear integral equations which make possible to compute the finite volume expectation values of the trace of the stress energy tensor ($Θ$) and the $U(1)$ current ($J_μ$) in any eigenstate of the Hamiltonian of the sine-Gordon model. The solution of these equations in the large volume limit allows one to get exact analytical formulas for the expectation values in the Bethe-Yang limit. These analytical formulas are used to test an earlier conjecture for the Bethe-Yang limit of expectation values in non-diagonally scattering theories. The analytical tests have been carried out upto three particle states and gave agreement with the conjectured formula, provided the definition of polarized symmetric diagonal form-factors is modified appropriately. Nevertheless, we point out that our results provide only a partial confirmation of the conjecture and further investigations are necessary to fully determine its validity. The most important missing piece in the confirmation is the mathematical proof of the finiteness of the symmetric diagonal limit of form-factors in a non-diagonally scattering theory.

hep-th↗

arXiv2005

TBA equations for the mass gap in the O(2r) non-linear sigma-models

We propose TBA integral equations for 1-particle states in the O(n) non-linear sigma-model for even n. The equations are conjectured on the basis of the analytic properties of the large volume asymptotics of the problem, which is explicitly constructed starting from Luscher's asymptotic formula. For small volumes the mass gap values computed numerically from the TBA equations agree very well with results of three-loop perturbation theory calculations, providing support for the validity of the proposed TBA system.

hep-th↗

arXiv2004

TBA equations for excited states in the O(3) and O(4) nonlinear $σ$-model

TBA integral equations are proposed for 1-particle states in the sausage- and SS-models and their $σ$-model limits. Combined with the ground state TBA equations the exact mass gap is computed in the O(3) and O(4) nonlinear $σ$-model and the results are compared to 3-loop perturbation theory and Monte Carlo data.

hep-th↗

arXiv2003

TBA equations for excited states in the Sine-Gordon model

We propose TBA integral equations for multiparticle soliton (fermion) states in the Sine-Gordon (massive Thirring) model. This is based on T-system and Y-system equations, which follow from the Bethe Ansatz solution in the light-cone lattice formulation of the model. Even and odd charge sectors are treated on an equal footing, corresponding to periodic and twisted boundary conditions, respectively. The analytic properties of the Y-system functions are conjectured on the basis of the large volume solution of the system, which we find explicitly. A simple relation between the TBA Y-functions and the counting function variable of the alternative non-linear integral equation (Destri-deVega equation) description of the model is given.

hep-th↗

arXiv2001

Virial expansion and TBA in O(N) sigma models

We study the free energy of the 1+1 dimensional O(N) nonlinear sigma-models for even N using the TBA equations proposed recently. We give explicit formulae for the constant solution of the TBA equations (Y-system) and calculate the first two virial coefficients. The free energy is also compared to the leading large N result.

hep-th↗