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Journal articles on the topic 'Spectral degeneracy'

Author: Grafiati

Published: 2 June 2025

Last updated: 31 July 2025

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1

Ceulemans, A., E. Lijnen, P. W. Fowler, R. B. Mallion, and T. Pisanski. "Graph theory and the Jahn–Teller theorem." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 468, no. 2140 (2011): 971–89. http://dx.doi.org/10.1098/rspa.2011.0508.

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The Jahn–Teller (JT) theorem predicts spontaneous symmetry breaking and lifting of degeneracy in degenerate electronic states of (nonlinear) molecular and solid-state systems. In these cases, degeneracy is lifted by geometric distortion. Molecular problems are often modelled using spectral theory for weighted graphs, and the present paper turns this process around and reformulates the JT theorem for general vertex- and edge-weighted graphs themselves. If the eigenvectors and eigenvalues of a general graph are considered as orbitals and energy levels (respectively) to be occupied by electrons,

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2

Марков, Ю. Ф., В. Н. Гурин та К. В. Понкратов. "Рамановское рассеяние кристаллами гексаборидов редких земель с различными изотопами бора". Физика твердого тела 60, № 4 (2018): 715. http://dx.doi.org/10.21883/ftt.2018.04.45681.282.

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AbstractMonocrystals of lanthanum hexaboride LaB_6 containing both natural boron and its isotopes ^10B and ^11B have been produced using the solution-melt method. Polyelement hexaboride rare-earths have been grown and the corresponding ceramics have been synthesized for the first time. All these crystals have been studied by means of various techniques, generally using Raman scattering. The Raman spectra attributed to various spectral lines corresponding to nonanalyzable representations have been obtained and interpreted. Frequencies and half-widths of spectral lines have been obtained, the re

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3

Zhang, Shuo, Hua-Wei Zhang, Georges Comte, et al. "M Subdwarf Research. III. Spectroscopic Diagnostics for Breaking Parameter Degeneracy." Astrophysical Journal 942, no. 1 (2023): 40. http://dx.doi.org/10.3847/1538-4357/aca28d.

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Abstract To understand the parameter degeneracy of M subdwarf spectra at low resolution, we assemble a large number of spectral features in the wavelength range 0.6–2.5 μm with band strength quantified by narrowband indices. Based on the index trends of BT-Settl model sequences, we illustrate how the main atmospheric parameters (T eff, log g, [M/H], and [α/Fe]) affect each spectral feature differently. Furthermore, we propose a four-step process to determine the four parameters sequentially, which extends the basic idea proposed by Jao et al. Each step contains several spectral features that b

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4

Byrohl, C., та M. Gronke. "Variations in shape among observed Lyman-α spectra due to intergalactic absorption". Astronomy & Astrophysics 642 (жовтень 2020): L16. http://dx.doi.org/10.1051/0004-6361/202038685.

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Lyman-α (Lyα) spectra provide insights into the small-scale structure and kinematics of neutral hydrogen (HI) within galaxies as well as the ionization state of the intergalactic medium (IGM). The former defines the intrinsic spectrum of a galaxy, which, in turn, is modified by the latter. These two effects are degenerate. Using the IllustrisTNG100 simulation, we studied the impact of the IGM on Lyα spectral shapes between z ∼ 0 and 5. We computed the distribution of the expected Lyα peaks and of the peak asymmetry for different intrinsic spectra, redshifts, and large-scale environments. We fi

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5

Rickard, M. J., R. Hainich, D. Pauli, et al. "Determining stellar properties of massive stars in NGC346 in the SMC with a Bayesian statistic technique." Astronomy & Astrophysics 692 (December 2024): A149. https://doi.org/10.1051/0004-6361/202450033.

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Context. NGC 346 is a young cluster with numerous hot OB stars. It is part of the Small Magellanic Cloud (SMC), and has an average metallicity that is one-seventh of the Milky Way’s. A detailed study of its stellar content provides a unique opportunity to understand the stellar and wind properties of massive stars in low-metallicity environments, and enables us to improve our understanding of star formation and stellar evolution. Aims. The fundamental stellar parameters defining a star’s spectral appearance are its effective surface temperature, surface gravity, and projected rotational veloci

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Ilyashenko, Alla, and Sergey Kuznetsov. "On degeneracy of dispersive waves at the bulk wave velocities." E3S Web of Conferences 97 (2019): 03004. http://dx.doi.org/10.1051/e3sconf/20199703004.

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Degeneracy of the linear dispersion wave equation at the phase velocities coinciding with the bulk wave velocities is observed and analysed. Spectral analysis of Pochhammer – Chree equation is performed. The corrected analytical solutions for components of the displacement fields are constructed, accounting degeneracy of the secular equations and the corresponding solutions.

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7

Chouaou, Fatiha, Chahira Aichi, and Abbes Benaissa. "Decay estimates for a degenerate wave equation with a dynamic fractional feedback acting on the degenerate boundary." Filomat 35, no. 10 (2021): 3219–39. http://dx.doi.org/10.2298/fil2110219c.

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In this paper, we consider a one-dimensional weakly degenerate wave equation with a dynamic nonlocal boundary feedback of fractional type acting at a degenerate point. First We show well-posedness by using the semigroup theory. Next, we show that our system is not uniformly stable by spectral analysis. Hence, we look for a polynomial decay rate for a smooth initial data by using a result due Borichev and Tomilov which reduces the problem of estimating the rate of energy decay to finding a growth bound for the resolvent of the generator associated with the semigroup. This analysis proves that t

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8

Fedorova, Elena, Lidiia Zadorozhna, Anatolii Tugay, Nadiia Pulatova, Alexander Ganz, and Olexandr Gugnin. "Separating the Spectral Counterparts in NGC 1275/Perseus Cluster in X-Rays." Astronomy 3, no. 4 (2024): 275–88. http://dx.doi.org/10.3390/astronomy3040017.

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We present a model-independent method for separating the spectral counterparts of the active galactic nucleus (AGN) NGC 1275 from the surrounding emission of the Perseus cluster, as observed by Suzaku/XIS cameras. The Perseus cluster emission extends to higher energies than typically observed in AGN environments, reaching up to 9–10 keV. This necessitates precise separation of AGN and cluster spectra. To circumvent the degeneracy arising from numerous spectral fitting parameters, including elemental abundances, thermal and Compton emissions from the nucleus, and spectral parameters of the jet

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9

Sarkar, Shilpa, Indranil Chattopadhyay, and Philippe Laurent. "Two-temperature solutions and emergent spectra from relativistic accretion discs around black holes." Astronomy & Astrophysics 642 (October 2020): A209. http://dx.doi.org/10.1051/0004-6361/202037520.

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Aims. We investigate a two-temperature advective transonic accretion disc around a black hole and analyse its spectrum in the presence of radiative processes such as bremsstrahlung, synchrotron, and inverse-Comptonisation. The aim is to link the emergent spectra with constants of motion of the accretion disc fluid, however, the number of unknowns in two-temperature theory exceeds the number of equations for a given set of constants of motion. We intend to remove the degeneracy using a general methodology and obtain a unique solution, along with its spectrum. Methods. We used hydrodynamic equat

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10

Jagod, Mary-Frances, Charles M. Gabrys, Matthias Rösslein, Dairene Uy, and Takeshi Oka. "Infrared spectrum of CH3+ involving high rovibrationai levels." Canadian Journal of Physics 72, no. 11-12 (1994): 1192–99. http://dx.doi.org/10.1139/p94-153.

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An extensive search of carbo-ion spectra in the infrared region from 3300 cm−1 to 2900 cm−1 has revealed many spectral lines of CH3+, the most fundamental hydrocarbon cation. Out of over 1000 spectral lines that were identified as due to CH3+from their plasma chemical behaviors and linewidths, 356 lines have been assigned to the CH stretch ν3 fundamental band. Most of the remaining lines are thought to belong to the hot bands ν2 + ν3 − ν2 and ν3 + ν4 − ν4. Their analysis was found to be difficult because of the large Coriolis interaction and the near degeneracy of ν2 and ν4. A series of spectr

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11

Greco, Emanuele, Jacco Vink, Marco Miceli, et al. "Unveiling pure-metal ejecta X-ray emission in supernova remnants through their radiative recombination continuum." Astronomy & Astrophysics 638 (June 2020): A101. http://dx.doi.org/10.1051/0004-6361/202038092.

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Context. Spectral analysis of X-ray emission from ejecta in supernova remnants (SNRs) is hampered by the low spectral resolution of CCD detectors, which typically creates a degeneracy between the best-fit values of chemical abundances and the plasma emission measure. The combined contribution of shocked ambient medium and ejecta to the emerging X-ray emission further complicates the determination of the ejecta mass and chemical composition. This degeneracy leads to big uncertainties in mass estimates and can introduce a bias in the comparison between the ejecta chemical composition derived fro

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12

Igisinov, S. Zh, L. D. Zhumaliyeva, A. O. Suleimbekova, and Ye N. Bayandiyev. "Estimates of singular numbers (s-numbers) for a class of degenerate elliptic operators." BULLETIN OF THE KARAGANDA UNIVERSITY-MATHEMATICS 107, no. 3 (2022): 51–58. http://dx.doi.org/10.31489/2022m3/51-58.

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In this paper we study a class of degenerate elliptic equations with an arbitrary power degeneracy on the line. Based on the research carried out in the course of the work, the authors propose methods to overcome various difficulties associated with the behavior of functions from the definition domain for a differential operator with piecewise continuous coefficients in a bounded domain, which affect the spectral characteristics of boundary value problems for degenerate elliptic equations. It is shown the conditions imposed on the coefficients at the lowest terms of the equation, which ensure

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13

Hamann, Wolf-Rainer, Götz Gräfener, and Lars Koesterke. "Wolf-Rayet star parameters from spectral analyses." Symposium - International Astronomical Union 212 (2003): 198–99. http://dx.doi.org/10.1017/s007418090021200x.

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The Potsdam non-LTE code for expanding atmospheres, which accounts for clumping and iron-line blanketing, has been used to establish a grid of model atmospheres for WC stars. A parameter degeneracy is discovered for early-type WC models which do not depend on the ‘stellar temperature’. 15 Galactic WC4-7 stars are analyzed, showing a very uniform carbon abundance (He:C = 55:40) with only few exceptions.

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14

Juvela, M., J. Montillaud, N. Ysard, and T. Lunttila. "The degeneracy between dust colour temperature and spectral index." Astronomy & Astrophysics 556 (July 29, 2013): A63. http://dx.doi.org/10.1051/0004-6361/201220910.

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15

Binggeli, Christian, Erik Zackrisson, Kristiaan Pelckmans, Rubén Cubo, Hannes Jensen, and Ikko Shimizu. "Lyman continuum leakage versus quenching with the James Webb Space Telescope: the spectral signatures of quenched star formation activity in reionization-epoch galaxies." Monthly Notices of the Royal Astronomical Society 479, no. 1 (2018): 368–76. http://dx.doi.org/10.1093/mnras/sty1061.

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ABSTRACT In this paper, we study the effects of a recent drop in star formation rate (SFR) on the spectra of epoch of reionization (EoR) galaxies, and the resulting degeneracy with the spectral features produced by extreme Lyman continuum leakage. In order to study these effects in the wavelength range relevant for the upcoming James Webb Space Telescope (JWST), we utilize synthetic spectra of simulated EoR galaxies from cosmological simulations together with synthetic spectra of partially quenched mock galaxies. We find that rapid declines in the SFR of EoR galaxies could seriously affect the

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16

Kazanov, D. R., and A. M. Monakhov. "Optical Modes in Elliptical Microcavities for Single-Photon Sources." JETP Letters 117, no. 6 (2023): 422–27. http://dx.doi.org/10.1134/s0021364023600325.

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A theory of optical modes in an elliptical microcavity has been developed using Mathieu functions in elliptical coordinates. A key difference from the circular case is the splitting of doubly degenerate modes. Split optical modes have been numerically calculated and their symmetry has been determined. A method has been proposed to choose the parameters of a cavity for a certain wavelength. The difference between the energies of optical modes in the cavity with metallic walls and in the dielectric cavity is no more than ~20%. The dispersion relations of optical modes show the possibility of deg

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17

Sumanasekara, Udugama R., and Sukalyan Bhattacharya. "Detailed finer features in spectra of interfacial waves for characterization of a bubble-laden drop." Journal of Fluid Mechanics 831 (October 17, 2017): 698–718. http://dx.doi.org/10.1017/jfm.2017.607.

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This article describes unexplored details of the intriguing spectral manifestation of the small-amplitude waves at the surfaces of a bubble-laden drop. Its natural frequencies of interfacial pulsation reveal a non-trivial variation with the position of the cavity inside the liquid. This configurational dependence of spectra is calculated for arbitrary location of the void by using a novel approach under low capillary number and low Bond number limits. The analysis is based on expansion in two sets of basis functions where their mutual transformations are utilized to enforce interfacial boundar

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18

Lin, Sheng-Chieh, Yuanyuan Su, Fabio Gastaldello, and Nathan Jacobs. "Semisupervised Learning for Detecting Inverse Compton Emission in Galaxy Clusters." Astrophysical Journal 977, no. 2 (2024): 176. https://doi.org/10.3847/1538-4357/ad8888.

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Abstract Inverse Compton (IC) emission associated with the nonthermal component of the intracluster medium (ICM) has been a long-sought phenomenon in cluster physics. Traditional spectral fitting often suffers from the degeneracy between the two-temperature thermal (2T) spectrum and the one-temperature plus IC power-law (1T+IC) spectrum. We present a semisupervised deep-learning approach to search for IC emission in galaxy clusters. We employ a conditional autoencoder (CAE), which is based on an autoencoder with latent representations trained to constrain the thermal parameters of the ICM. The

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19

Bobrov V. B. "High-frequency asymptotics of one integral in the theory of equilibrium radiation of electron gas." Technical Physics Letters 48, no. 9 (2022): 74. http://dx.doi.org/10.21883/tpl.2022.09.55090.19284.

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It is considered an improper integral that determines the high-frequency asymptotics of the spectral energy distribution of equilibrium radiation in an ideal electron gas. It has been established that in the &quot;high-frequency&quot; limit the asymptotics of this integral has a power-law character, and its value is proportional to the density of the electron gas as a function of temperature and chemical potential for arbitrary degeneracy of electrons. Keywords: equilibrium radiation, spectral energy distribution, electron gas.

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20

MOTAVALLI, HOSSEIN, and AMIN REZAEI AKBARIEH. "KLEIN–GORDON EQUATION FOR THE COULOMB POTENTIAL IN NONCOMMUTATIVE SPACE." Modern Physics Letters A 25, no. 29 (2010): 2523–28. http://dx.doi.org/10.1142/s0217732310033529.

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In this paper the stationary Klein–Gordon equation is considered for the Coulomb potential in noncommutative space. The energy shift due to noncommutativity is obtained via the perturbation theory. Furthermore, we show that the degeneracy of the initial spectral line is broken in transition from commutative space to noncommutative space.

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21

SMALL, A. J. "OSCULATION AND SINGULARITY OF CHARGE 2 (COMPLEXIFIED) BPS MONOPOLES." International Journal of Mathematics 11, no. 07 (2000): 943–48. http://dx.doi.org/10.1142/s0129167x00000453.

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Hurtubise showed that the singular locus of the complexification of a BPS monopole intersects the degeneracy locus of the complex Higgs field in a null curve [Formula: see text] has a dual [Formula: see text]: by adapting a criterion of Hitchin it is shown that for a generic charge 2 monopole, [Formula: see text], the monopole's spectral curve.

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22

Froyland, Gary, Rua Murray, and Ognjen Stancevic. "Spectral degeneracy and escape dynamics for intermittent maps with a hole." Nonlinearity 24, no. 9 (2011): 2435–63. http://dx.doi.org/10.1088/0951-7715/24/9/003.

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23

Juvela, M., and N. Ysard. "The degeneracy between the dust colour temperature and the spectral index." Astronomy & Astrophysics 541 (April 24, 2012): A33. http://dx.doi.org/10.1051/0004-6361/201118596.

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24

Lee, Chang Jae. "Spectral degeneracy of a Dirac electron in a uniform magnetic field." Physics Letters A 195, no. 3-4 (1994): 221–26. http://dx.doi.org/10.1016/0375-9601(94)90156-2.

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25

Mettler, Jean-Noël, Sascha P. Quanz, Ravit Helled, Stephanie L. Olson, and Edward W. Schwieterman. "Earth as an Exoplanet. II. Earth’s Time-variable Thermal Emission and Its Atmospheric Seasonality of Bioindicators." Astrophysical Journal 946, no. 2 (2023): 82. http://dx.doi.org/10.3847/1538-4357/acbe3c.

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Abstract We assess the dependence of Earth’s disk-integrated mid-infrared thermal emission spectrum on observation geometries and investigate which and how spectral features are impacted by seasonality on Earth. We compiled an exclusive data set containing 2690 disk-integrated thermal emission spectra for four different full-disk observing geometries (North and South Pole-centered and Africa and Pacific-centered equatorial views) over four consecutive years. The spectra were derived from 2378 spectral channels in the wavelength range from 3.75–15.4 μm (nominal resolution ≈1200) and were record

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26

Amangeldinov, Islam, and Dmitri Korovaev. "Spectral characterization of elemental emissions, experimental insights and theoretical evaluation." Technobius Physics 2, no. 2 (2024): 0012. http://dx.doi.org/10.54355/tbusphys/2.2.2024.0012.

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This experimental study delves into the spectral analysis of five discrete spectral lamps, namely helium, sodium, mercury, cadmium and zinc, utilizing a suite of scientific instrumentation including an optical spectrometer with converging lenses and a diffraction grating. The primary objective is to determine the wavelengths corresponding to visible spectral lines emitted by these lamps. Calibration of the spectrometer with the helium lamp facilitated the derivation of the diffraction grating constant. Subsequent measurements of diffraction angles allowed for the computation of experimental wa

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Valentini, M. "Combining asteroseismology and spectroscopy for obtaining precise abundances: CoRoT-GES and K2-RAVE." Proceedings of the International Astronomical Union 13, S334 (2017): 162–65. http://dx.doi.org/10.1017/s1743921317009371.

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AbstractThe spectroscopic analysis of red giant stars is hampered by difficulties in determining the surface gravity, log g. The presence of degeneracies, few lines sensitive to log g, limited spectral coverage and bad signal-to-noise, can affect the precision and accuracy of log g and, as a consequence, the quality of the element abundances. We show how the adoption of the seismic surface gravity can improve the spectroscopic analysis of red giants. As examples, we adopted the seismic gravity in the analysis of spectra taken by two different surveys: GES (high resolution) and RAVE (intermedia

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28

Zhao, Yiping, Andrei Galiautdinov, and Jingzhi Tie. "The N-Oscillator Born–Kuhn Model: An In-Depth Analysis of Chiro-Optical Properties in Complex Chiral Systems." Nanomaterials 14, no. 3 (2024): 270. http://dx.doi.org/10.3390/nano14030270.

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A comprehensive theory is developed for the chiral optical response of two configurations of the N-oscillator Born–Kuhn model (NOBK): the helically stacked and the corner stacked models. In the helical NOBK model, there is always a chiral response regardless of the value of N, whereas in the corner NOBK, only configurations with even N demonstrate a chiral response. Generally, the magnitudes of optical rotatory dispersion (ORD) and circular dichroism (CD) increase with N when the parameters of each oscillator are fixed. In cases of weak coupling, the spectral shapes of ORD and CD remain invari

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29

Yu, Wei, Qing-Cui Bu, He-Xin Liu, et al. "A Spectral-timing Study of the Inner Flow Geometry in MAXI J1535-571 with Insight-HXMT and NICER." Astrophysical Journal 953, no. 2 (2023): 191. http://dx.doi.org/10.3847/1538-4357/acd9a2.

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Abstract We have performed a spectral-timing analysis of the black hole X-ray binary MAXI J1535-571 during its 2017 outburst, with the aim of exploring the evolution of the inner accretion flow geometry. X-ray reverberation lags are observed in the hard-intermediate state (HIMS) and soft-intermediate state of the outburst. During the HIMS, the characteristic frequency of the reverberation lags ν 0 (the frequency at which the soft lag turns to zero in lag–frequency spectra) increases when the spectrum softens. This reflects a reduction of the spatial distance between the corona and accretion di

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Бобров, В. Б. "Высокочастотная асимптотика одного интеграла в теории равновесного излучения электронного газа". Письма в журнал технической физики 48, № 18 (2022): 45. http://dx.doi.org/10.21883/pjtf.2022.18.53399.19284.

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It is considered an improper integral that determines the high-frequency asymptotics of the spectral energy distribution of equilibrium radiation in an ideal electron gas. It has been established that in the "high-frequency" limit the asymptotics of this integral has a power-law character, and its value is proportional to the density of the electron gas as a function of temperature and chemical potential for arbitrary degeneracy of electrons

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31

Chen, Jian, Guangwei Hu, Guangtao Cao, et al. "Manipulating mode degeneracy for tunable spectral characteristics in multi-microcavity photonic molecules." Optics Express 29, no. 7 (2021): 11181. http://dx.doi.org/10.1364/oe.420462.

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32

Li 李, Jialu 佳璐, Adwin Boogert, and Alexander G. G. M. Tielens. "On the Interpretation of Mid-infrared Absorption Lines of Gas-phase H₂O as Observed by JWST/MIRI." Astrophysical Journal Supplement Series 273, no. 2 (2024): 32. http://dx.doi.org/10.3847/1538-4365/ad571a.

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Abstract Rovibrational absorption lines of H2O in the 5–8 μm wavelength range selectively probe gas against the mid-infrared continuum-emitting background of the inner regions of young stellar objects and active galactic nuclei and deliver important information about these warm, dust-obscured environments. JWST/Mid-Infrared Instrument (MIRI) detects these lines in many lines of sight at a moderate spectral resolving power of R ∼ 3500 (full width at half-maximum of 85 km s−1). Based on our analysis of high-resolution SOFIA/EXES observations, we find that the interpretation of JWST/MIRI absorpti

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Shinde, Pramod, Loïc Marrec, Aparna Rai, et al. "Symmetry in cancer networks identified: Proposal for multicancer biomarkers." Network Science 7, no. 4 (2019): 541–55. http://dx.doi.org/10.1017/nws.2019.55.

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AbstractOne of the most challenging problems in biomedicine and genomics is the identification of disease biomarkers. In this study, proteomics data from seven major cancers were used to construct two weighted protein–protein interaction networks, i.e., one for the normal and another for the cancer conditions. We developed rigorous, yet mathematically simple, methodology based on the degeneracy at –1 eigenvalues to identify structural symmetry or motif structures in network. Utilizing eigenvectors corresponding to degenerate eigenvalues in the weighted adjacency matrix, we identified structura

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Blaize, Sylvain, Felice Gesuele, Ilan Stefanon, et al. "Real-space observation of spectral degeneracy breaking in a waveguide-coupled disk microresonator." Optics Letters 35, no. 19 (2010): 3168. http://dx.doi.org/10.1364/ol.35.003168.

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Emel’yanov, D. P. "SOLUTION OF A BOUNDARY PROBLEM FOR AN ELLIPTIC EQUATION WITH A SMALL NONINTEGER ORDER DEGENERACY." Дифференциальные уравнения 60, no. 3 (2024): 365–74. http://dx.doi.org/10.31857/s0374064124030069.

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We consider a Dirichlet boundary problem for an elliptic type equation with a non-regular degeneracy of noninteger order in a rectangle. The coefficients of the differential operator are supposed to be analytic. We build a formal solution by using the method for spectral separation of the singularities. The solution is series where its non-analytic dependency on ???? near point ???? = 0 is written explicitly. We proof the convergence of the series to the classical solution using the Green’s function method.

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Peng, Jing-Qiang, Shu Zhang, Qing-Cang Shui, et al. "NICER, NuSTAR, and Insight-HXMT Views to the Newly Discovered Black Hole X-Ray Binary Swift J1727.8-1613." Astrophysical Journal Letters 960, no. 2 (2024): L17. http://dx.doi.org/10.3847/2041-8213/ad17ca.

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Abstract Swift J1727.8–1613 is a black hole X-ray binary newly discovered in 2023. We perform spectral analysis with simultaneous Insight-HXMT, NICER, and NuSTAR observations when the source was approaching the hard intermediate state. Such a joint view reveals an additional hard component apart from the normally observed hard component with reflection in the spectrum, to be distinguished from the usual black hole X-ray binary systems. By including this extra component in the spectrum, we have measured a high spin of 0.98 − 0.07 + 0.02 and an inclination of around 40 − 0.8 + 1.2 °, which is co

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Cagliari, M. S., B. R. Granett, L. Guzzo, et al. "Euclid: Constraining ensemble photometric redshift distributions with stacked spectroscopy." Astronomy & Astrophysics 660 (March 30, 2022): A9. http://dx.doi.org/10.1051/0004-6361/202142224.

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Context. The ESA Euclid mission will produce photometric galaxy samples over 15 000 square degrees of the sky that will be rich for clustering and weak lensing statistics. The accuracy of the cosmological constraints derived from these measurements will depend on the knowledge of the underlying redshift distributions based on photometric redshift calibrations. Aims. A new approach is proposed to use the stacked spectra from Euclid slitless spectroscopy to augment broad-band photometric information to constrain the redshift distribution with spectral energy distribution fitting. The high spectr

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Zhao, Luyang, Dongdong Qi, Lijuan Zhang, Ming Bai, and Xue Cai. "Electronic structures, spectroscopic properties, and reaction activities of porphyrins with alkali metal ions: density functional theory approach to the central metal effects." Journal of Porphyrins and Phthalocyanines 16, no. 07n08 (2012): 927–34. http://dx.doi.org/10.1142/s1088424612501039.

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Density functional theory (DFT) calculation method was employed to investigate a series of nine alkali metal porphyrins (alk-Pors), namely HLiPor , HNaPor , HKPor , Li2Por , LiNaPor , LiKPor , Na2Por , NaKPor , and K2Por . These molecules show different configurations depending on different metal ions which locate over the central hole of the porphyrin ligand. Alk-Pors with larger-radius metal ion have smaller binding energy and thus is more difficult to keep stable. Further detailed molecular stability analysis was carried out by noncovalent interaction and electrostatic interaction via RDG a

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Makri, Nancy. "Electronic frustration, Berry’s phase interference and slow dynamics in some tight-binding systems coupled to harmonic baths." Journal of Physics A: Mathematical and Theoretical 56, no. 14 (2023): 144001. http://dx.doi.org/10.1088/1751-8121/acbff2.

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Abstract Conical intersections in two-state systems require a coordinate-dependent coupling. This paper identifies and investigates conical intersections in cyclic tight-binding system-bath Hamiltonians with an odd number of sites and a constant site-to-site coupling. In the absence of bath degrees of freedom, such tight-binding systems with a positive coupling parameter exhibit electronic frustration and a doubly-degenerate ground state. When these systems interact with a harmonic bath, the degeneracy becomes a conical intersection between the adiabatic ground and first excited states. Under

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Ramezanpour, S., Y. Ra’di, A. Alù, and A. Bogdanov. "Highly Chiral Exceptional Point in Perturbed Coupled Resonators." Journal of Physics: Conference Series 2015, no. 1 (2021): 012122. http://dx.doi.org/10.1088/1742-6596/2015/1/012122.

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Abstract Exceptional point (EP) is a non-Hermitian spectral degeneracy that has application in ultrasensitive sensors and laser mode selectivity. By employing strong chirality in an optical system, the direction of light propagation can be controlled and subwavelength particles can be detected. Here, we show that EP with high chirality can appear in the coupled resonators perturbed by a scatterer, in which both the distance and position of the scatterer can be tuned. We achieve strong chiral EP in two different distances between the resonators, with chirality around 0.99 in both cases.

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Saidi, Abdelali, and Moulay Brahim Sedra. "Spin-one (1 + 3)-dimensional DKP equation with modified Kratzer potential in the non-commutative space." Modern Physics Letters A 35, no. 05 (2019): 2050014. http://dx.doi.org/10.1142/s0217732320500145.

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In this paper, the spin-one Duffin–Kemmer–Petiau equation in (1 + 3) dimensions with a modified Kratzer potential is considered in the non-commutative space framework. The energy eigenvalue equation and the corresponding eigenfunctions are derived analytically. Furthermore, the energy shift due to the space non-commutativity effect is also obtained using the perturbation theory. In particular, it is shown that the degeneracy of the initial spectral line is broken, where the space non-commutativity plays the role of a magnetic field. This behavior is very similar to the Zeeman effect.

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Kany, F., and Y. Boucher. "Spectral lift of degeneracy in a multiple-phase-shifted distributed-feedback structure (MPS-DFB)." Journal de Physique IV (Proceedings) 119 (November 2004): 207–9. http://dx.doi.org/10.1051/jp4:2004119060.

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Gamberale, Luca, and Giovanni Modanese. "Spectral Analysis of Proton Eigenfunctions in Crystalline Environments." Quantum Reports 6, no. 2 (2024): 172–83. http://dx.doi.org/10.3390/quantum6020014.

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The Schrödinger equation and Bloch theorem are applied to examine a system of protons confined within a periodic potential, accounting for deviations from ideal harmonic behavior due to real-world conditions like truncated and non-quadratic potentials, in both one-dimensional and three-dimensional scenarios. Numerical computation of the energy spectrum of bound eigenfunctions in both cases reveals intriguing structures, including bound states with degeneracy matching the site number Nw, reminiscent of a finite harmonic oscillator spectrum. In contrast to electronic energy bands, the proton sys

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Saha, Tathagata, Alex G. Markowitz, and Johannes Buchner. "Inferring the morphology of AGN torus using X-ray spectra: a reliability study." Monthly Notices of the Royal Astronomical Society 509, no. 4 (2021): 5485–510. http://dx.doi.org/10.1093/mnras/stab3250.

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ABSTRACT Numerous X-ray spectral models have been developed to model emission reprocessed by the torus of an active galactic nucleus (AGN), e.g. UXCLUMPY, CTORUS, and MYTORUS. They span a range of assumed torus geometries and morphologies – some posit smooth gas distributions, and others posit distributions of clouds. It is suspected that given the quality of currently available data, certain model parameters, such as coronal power-law photon index and parameters determining the morphology of the AGN torus, may be poorly constrained due to model degeneracies. In this work, we test the reliabil

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Palmerio, J. T., and F. Daigne. "Constraining the intrinsic population of long gamma-ray bursts: Implications for spectral correlations, cosmic evolution, and their use as tracers of star formation." Astronomy & Astrophysics 649 (May 2021): A166. http://dx.doi.org/10.1051/0004-6361/202039929.

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Aims. Long gamma-ray bursts (LGRBs) have been shown to be powerful probes of the Universe, in particular for studying the star formation rate up to very high redshift (z ∼ 9). Since LGRBs are produced by only a small fraction of massive stars, it is paramount to have a good understanding of their underlying intrinsic population in order to use them as cosmological probes without introducing any unwanted bias. The goal of this work is to constrain and characterise this intrinsic population. Methods. We developed a Monte Carlo model where each burst is described by its redshift and its propertie

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Cropper, Mark, Chris Copperwheat, Roberto Soria, and Kinwah Wu. "On the nature of ultra-luminous X-ray sources from optical/IR measurements." Proceedings of the International Astronomical Union 2, S238 (2006): 251–54. http://dx.doi.org/10.1017/s1743921307005078.

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AbstractWe present a model for the prediction of the optical/infra-red emission from ULXs. In the model, ULXs are binary systems with accretion taking place through Roche lobe overflow. We show that irradiation effects and presence of an accretion disk significantly modify the optical/infrared flux compared to single stars, and also that the system orientation is important. We include additional constraints from the mass transfer rate to constrain the parameters of the donor star, and to a lesser extent the mass of the BH. We apply the model to fit photometric data for several ULX counterparts

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Goldhirsch, I., S. H. Noskowicz, and Z. Schuss. "Spectral degeneracy in the one-dimensional Anderson problem: A uniform expansion in the energy band." Physical Review B 49, no. 20 (1994): 14504–22. http://dx.doi.org/10.1103/physrevb.49.14504.

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Chan 詹, James Hung-Hsu 弘旭, Joshua Fagin, Henry Best, and Matthew J. O’Dowd. "Reverberation Mapping of Lamppost and Wind Structures in Accretion Thin Disks." Astrophysical Journal 978, no. 1 (2024): 54. https://doi.org/10.3847/1538-4357/ad93af.

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Abstract To address the discrepancy where disk sizes exceed those predicted by standard models, we explore two extensions to disk size estimates within the UV/optical wavelength range: disk winds and color correction. We provide detailed, self-consistent derivations and analytical formulas, including those based on a power-law temperature approximation, offering efficient tools for analyzing observational data. Applying our model to four type I active galactic nuclei with intensive reverberation mapping observations, we find a shallower temperature slope (T ∝ R −0.66, compared to R −3/4 tradit

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Feng, Jing, and Yi Huang. "Cloud-Assisted Retrieval of Lower-Stratospheric Water Vapor from Nadir-View Satellite Measurements." Journal of Atmospheric and Oceanic Technology 35, no. 3 (2018): 541–53. http://dx.doi.org/10.1175/jtech-d-17-0132.1.

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AbstractThis study examines the feasibility of retrieving lower-stratospheric water vapor using a nadir infrared hyperspectrometer, with the focus on the detectability of small-scale water vapor variability. The feasibility of the retrieval is examined using simulation experiments that model different instrument settings. These experiments show that the infrared spectra, measured with sufficient spectral coverage, resolution, and noise level, contain considerable information content that can be used to retrieve lower-stratospheric water vapor. Interestingly, it is found that the presence of an

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Ren, Wenke, Hengxiao Guo, Yue Shen, et al. "Prior-informed Active Galactic Nucleus Host Spectral Decomposition Using PyQSOFit." Astrophysical Journal 974, no. 2 (2024): 153. http://dx.doi.org/10.3847/1538-4357/ad6e76.

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Abstract We introduce an improved method for decomposing the emission of active galactic nuclei (AGN) and their host galaxies using templates from principal component analysis (PCA). This approach integrates prior information from PCA with a penalized pixel fitting mechanism that improves the precision and effectiveness of the decomposition process. Specifically, we have reduced the degeneracy and overfitting in AGN host decomposition, particularly for those with low signal-to-noise ratios (SNRs), where traditional methods tend to fail. By applying our method to 76,565 Sloan Digital Sky Survey

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