Tootfinder

Infrared spectral signatures of light r-process elements in kilonovae
Anders Jerkstrand, Quentin Pognan, Smaranika Banerjee, Nicholas Sterling, Jon Grumer, Niamh Ferguson, Keith Butler, James Gillanders, Stephen Smartt, Kyohei Kawaguchi, Blanka Vilagos
https://arxiv.org/abs/2510.12410

Infrared spectral signatures of light r-process elements in kilonovae
A central question regarding neutron star mergers is whether they are able to produce all the r-process elements, from first to third peak. The high abundances of first-peak elements (atomic number $Z \sim 31-40$) in the solar composition means they may dominate the ejecta mass in kilonovae. We here study theoretical infrared signatures of such light elements with spectral synthesis modelling. By combining state-of-the-art NLTE physics with new radiative and collisional data for these elements,…

Lanthanide Impact on the Infra-Red Spectra of Nebular Phase Kilonovae
Quentin Pognan, Kyohei Kawaguchi, Shinya Wanajo, Sho Fujibayashi, Anders Jerkstrand
https://arxiv.org/abs/2510.12413

Lanthanide Impact on the Infra-Red Spectra of Nebular Phase Kilonovae
Nebular phase kilonovae (KNe) have significant infra-red (IR) emission thought to be mostly forbidden emission lines from rapid neutron capture (r-process) species in neutron star merger ejecta. Lanthanide elements in particular have complex atomic structures with many IR transitions. Using non-local thermodynamic equilibrium (NLTE) radiative transfer simulations, we explore the impact of lanthanides on the IR spectra of KNe in the nebular phase, exploring a parameter space of ejecta mass and l…

Probing ultrafast heating and ionization dynamics in solid density plasmas with time-resolved resonant X-ray absorption and emission
Lingen Huang, Mikhail Mishchenko, Michal \v{S}m\'id, Oliver Humphries, Thomas R. Preston, Xiayun Pan, Long Yang, Johannes Hagemann, Thea Engler, Yangzhe Cui, Thomas Kluge, Carsten Baehtz, Erik Brambrink, Alejandro Laso Garcia, Sebastian G\"ode, Christian Gutt, Mohamed Hassan, Hauke H\"oppner, Michaela Kozlova, Josefine Metzkes-Ng, Masruri Ma…

Probing ultrafast heating and ionization dynamics in solid density plasmas with time-resolved resonant X-ray absorption and emission
Heating and ionization are among the most fundamental processes in ultra-short, relativistic laser-solid interactions. However, capturing their spatiotemporal evolution experimentally is challenging due to the inherently transient and non-local thermodynamic equilibrium (NLTE) nature. Here, time-resolved resonant X-ray emission spectroscopy, in conjunction with simultaneous X-ray absorption imaging, is employed to investigate such complex dynamics in a thin copper wire driven by an optical high…

Spectral properties of distance Laplacian matrices of complex unit gain graphs
Aniruddha Samanta, Deepshikha
https://arxiv.org/abs/2507.21345 https://arxi…

Spectral properties of distance Laplacian matrices of complex unit gain graphs
A complex unit gain graph ($ \mathbb{T} $-gain graph), $ Φ=(G, φ) $ is a graph where the function $ φ$ assigns a unit complex number to each orientation of an edge of $ G $, and its inverse is assigned to the opposite orientation. In this article, we study several spectral properties of distance Laplacian matrices of $\mathbb{T}$-gain graphs. In particular, we establish a characterization for the balanced $ \mathbb{T}$-gain graph in terms of the nullity of gain distance Laplacian matrices. A…

Soliton-like Rogue Wave Dynamics in Dissipative Higher-Order NLS Models: A Floquet Spectral Perspective
C. M. Schober, A. Islas
https://arxiv.org/abs/2507.20375 https://

Soliton-like Rogue Wave Dynamics in Dissipative Higher-Order NLS Models: A Floquet Spectral Perspective
We investigate rogue wave formation and spectral downshifting in the higher-order nonlinear Schrödinger (HONLS) equation and its dissipative extensions: the nonlinear mean-flow damping model (NLD-HONLS) and the viscous damping model (V-HONLS). By applying Floquet spectral analysis, we characterize i) the structural organization of the dynamical background and ii) the nature of the rogue waves that appear, distinguishing sharply localized, soliton-like structures from more diffuse, spatially ex…

Potassium abundances in extremely metal poor stars: Implications for nucleosynthesis in the final stages of massive star evolution
M. N. Ishigaki, N. Tominaga, W. Aoki, T. Takiwaki, K. Nakamura, N. Iwamoto, K. Nomoto, C. Kobayashi
https://arxiv.org/abs/2508.20484

Potassium abundances in extremely metal poor stars: Implications for nucleosynthesis in the final stages of massive star evolution
We present a potassium (K) abundance analysis in extremely metal-poor (EMP) stars based on high-resolution ($R\sim 60000$) spectra obtained with the High Dispersion Spectrograph on the Subaru Telescope, covering the K I resonance lines at 766 and 769 nm. One-dimensional local thermodynamic equilibrium (LTE) abundances of K and other elements, including Na, Mg, Ca, Ti, Cr, and Ni, were derived using spectral synthesis. Non-local thermodynamic equilibrium (NLTE) corrections were applied to the K …

Systematic Study of Amorphous ABC Heterostructures at the Atomic Scale as a Nonlinear Optical Metamaterial
Martin Mi\v{c}ulka, Jinsong Liu, Sebastian Beer, Raihan Rafi, Denys Sevriukov, Sergiy Yulin, Vladimir Roddatis, Stefan Nolte, Isabelle Staude, Andreas T\"unnermann, Sven Schr\"oder, Adriana Szeghalmi
https://arxiv.org/abs/25…

Systematic Study of Amorphous ABC Heterostructures at the Atomic Scale as a Nonlinear Optical Metamaterial
The systematic exploration of ABC type heterostructures reveals that nanoscale morphological modification markedly improves nonlinear optical properties to maximize the artificial bulk second-order susceptibility. These amorphous birefringent heterostructures are fabricated through cyclic plasma-enhanced atomic layer deposition of three oxides, effectively breaking centrosymmetry. We observe a dependence of optical nonlinearity on the thickness variation of three constituent materials: SiO$_2$ …

Stellar Population Astrophysics (SPA) with the TNG: NLTE atmospheric parameters and abundances of giant stars in 33 Open Clusters
M. Dal Ponte, V. D'Orazi, A. Bragaglia, A. R. Casey, N. Storm, L. Spina, J. Alonso-Santiago, G. Andreuzzi, A. Frasca, J. Kos, S. Lucatello, D. Romano, A. Vallenari, N. Vernekar
https://arxiv.org/a…

Stellar Population Astrophysics (SPA) with the TNG: NLTE atmospheric parameters and abundances of giant stars in 33 Open Clusters
Open clusters serve as important tools for accurately studying the chemical evolution of the Milky Way. By combining precise chemical data from high-resolution spectra with information on their distances and ages, we can effectively uncover the processes that have shaped our Galaxy. This study aims to derive NLTE atmospheric parameters and chemical abundances for approximately one hundred giant stars across 33 open clusters with near-solar metallicity. The clusters span a wide range of ages, en…

Formation and Diagnostic Use of Carbon Lines in Stripped-Envelope Supernovae
Stan Barmentloo, Anders Jerkstrand
https://arxiv.org/abs/2509.19438 https://ar…

Formation and Diagnostic Use of Carbon Lines in Stripped-Envelope Supernovae
Carbon is one of the main end products of nucleosynthesis in massive stars. In this work, we study the emission signatures of carbon in spectra of stripped envelope supernovae (SESNe). A grid of model nebular spectra is created using the NLTE radiative transfer code SUMO, with stellar evolution- and explosion models as inputs. In the models, [C I] λ8727 and [C I] λλ9824, 9850 are identified as the only significant optical carbon lines, with contribution from both the O/C and He/C zones. To o…