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August 21, 2024 at 10:15:00 AM

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Detection of the large-scale tidal field with galaxy multiplet alignment in the DESI Y1 spectroscopic survey

We explore correlations between the orientations of small galaxy groups, or “multiplets”, and the large-scale gravitational tidal field. Using data from the Dark Energy Spectroscopic Instrument (DESI) Y1 survey, we detect the intrinsic alignment (IA) of multiplets to the galaxy-traced matter field out to separations of 100ℎ
−1Mpc. Unlike traditional IA measurements of individual galaxies, this estimator is not limited by imaging of galaxy shapes and allows for direct IA detection beyond redshift 𝑧 = 1. Multiplet alignment is a form of higher-order clustering, for which the scale-dependence traces the underlying tidal field and amplitude is a result of small-scale (< 1ℎ −1Mpc) dynamics. Within samples of bright galaxies (BGS), luminous red galaxies
(LRG) and emission-line galaxies (ELG), we find similar scale-dependence regardless of intrinsic luminosity or colour. This is promising for measuring tidal alignment in galaxy samples that typically display no intrinsic alignment. DESI’s LRG mock galaxy catalogues created from the AbacusSummit N-body simulations produce a similar alignment signal, though with a 33% lower amplitude at all scales. An analytic model using a non-linear power spectrum (NLA) only matches the signal down to 20ℎ −1Mpc. Our detection demonstrates that galaxy clustering in the non-linear regime of structure formation preserves an interpretable memory of the large-scale tidal field. Multiplet alignment complements traditional two-point measurements by retaining directional information imprinted by tidal forces, and contains additional line-of-sight information compared to weak lensing. This is a more effective estimator than the alignment of individual galaxies in dense, blue, or faint galaxy samples.

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https://doi.wikipt.org/10/1490/77009901/567tpl

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Theoretical Physics Letters
2024 ° 22(08) ° 11-11
https://www.wikipt.org/tphysicsletters
DOI: 10.1490/77009901.568tpl

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: data analysis, cosmology, large-scale structure of Universe, dark energy

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June 26, 2024 at 1:15:00 PM

Violation of γ in Brans-Dicke gravity

The Brans Class I solution in Brans-Dicke gravity, discovered in 1961, is a pivotal element in the examination of gravitational theories extending beyond General Relativity. This solution characterizes the external vacuum of a spherical Brans-Dicke star and is distinguished by two adjustable parameters. Notably, a rigorous establishment of the relationship between these parameters and the star's properties is currently lacking. In this work, we endeavor to address this gap by deriving the comprehensive exterior solution of Brans Class I, articulated in relation to the total energy and total pressure of the spherically symmetric gravity source. This derived solution facilitates the precise computation of all post-Newtonian parameters in Brans-Dicke gravity for the distant field regions of a spherical source. Specifically, we obtain an alternative analytical expression for the γ parameter, denoted as γ exact = ω+1+(ω+2) Θ ω+2+(ω+1) Θ, where Θ represents the ratio of the total pressure P∗∥ + 2P∗⊥ to the total energy E∗ contained within the mass source. Our non-perturbative γ formula is universally applicable across varying field strengths and types of matter comprising the mass source. As a result, observational constraints on γ concurrently establish limits on ω and Θ. Significantly, the latter serves as a global characteristic of the mass source. On a broader scope, our formula underscores the significance of pressure (when Θ ̸= 0) in spherical Brans-Dicke stars and potentially in stars within other modified theories of gravitation.

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https://doi.wikipt.org/1490/774565/871tpl

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Theoretical Physics Letters
2024 ° 026(06) ° 11-10
https://www.wikipt.org/tphysicsletters
DOI: 10.1490/77009901.567tpl

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Brans-Dicke gravity, astrophysics, gama, modern physics, theoretical physics

Observations and detectability of young Suns’ flaring and CME activity in optical spectra

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June 4, 2024 at 9:30:00 AM

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Observations and detectability of young Suns’ flaring and CME activity in optical spectra

The Sun’s history is still a subject of interest to modern astrophysics. Observationally constrained CME rates of young solar analogues are still lacking, as those require dedicated monitoring. We present medium resolution optical spectroscopic monitoring of a small sample of bright and prominent solar analogues over a period of three years using the 0.5m telescope at observatory Lustbühel Graz (OLG) of the University of Graz, Austria. The aim is the detection of flares and CMEs from those spectra. In more than 1700 hours of spectroscopic monitoring we found signatures of four flares and one filament eruption on EK Dra which has been reported in previous literature, but we complementarily extended the data to cover the latter phase. The other stars did not reveal detectable signatures of activity. For these non-detections we derive upper limits of occurrence rates of very massive CMEs, which are detectable with our observational setup, ranging from 0.1 to 2.2 day−1 , but these may be even smaller than the given rates considering observational biases. Furthermore, we investigate the detectability of flares/CMEs in OLG spectra by utilizing solar 2D Hα spectra from MEES solar observatory. We find that solar-sized events are not detectable within our observations. By scaling up the size of the solar event, we show that with a fractional active region area of 18% in residual spectra and 72% in equivalent width time series derived from the same residuals that solar events are detectable if they had hypothetically occurred on HN Peg.

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9.5

Theoretical Physics Letters
2024 ° 04(06) ° 11-09
https://www.wikipt.org/tphysicsletters
DOI: 10.1490/774565.871tpl

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8

stars, chromospheres, flare, late-type, EK Dra, Coronal Mass Ejections

Non-Hermitian unidirectional routing of photonic qubits

April 2, 2024 at 7:15:00 AM

Non-Hermitian unidirectional routing of photonic qubits

Efficient and tunable qubit unidirectional routers and spin-wave diodes play an important role in
both classical and quantum information processing domains. Here, we reveal that multi-level neutral
cold atoms can mediate both dissipative and coherent couplings. Interestingly, we investigate and
practically implement this paradigm in experiments, successfully synthesizing a system with dual
functionality as both a photonic qubit unidirectional router and a spin-wave diode. By manipulating
the helicity of the field, we can effectively balance the coherence coupling and dissipative channel,
thereby ensuring the unidirectional transfer of photonic qubits. The qubit fidelity exceeds 97.49 ±
0.39%, and the isolation ratio achieves 16.8 ± 0.11 dB while the insertion loss is lower than 0.36 dB.
Furthermore, we show that the spin-wave diode can effectively achieve unidirectional information
transfer by appropriately setting the coherent coupling parameters. Our work not only provides
new ideas for the design of extensive components in quantum network, but also opens up new
possibilities for non-Hermitian quantum physics, complex quantum networks, and unidirectional
quantum information transfer.

Electronic and thermal sequential transport in metallic and superconducting two-junction arrays

10.1490/466489.476tpl

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March 5, 2024 at 7:00:00 PM

Electronic and thermal sequential transport in metallic and superconducting two-junction arrays

The description of transport phenomena in devices consisting of arrays of tunnel junctions, and the experimental confirmation of these predictions is one of the great successes of mesoscopic physics. The aim of this paper is to give a self-consistent review of sequential transport processes in such devices, based on the so-called ”orthodox” model. We calculate numerically the current-voltage (I–V ) curves, the conductance versus bias voltage (G–V ) curves, and the associated thermal transport in symmetric and asymmetric two-junction arrays such as Coulomb-blockade thermometers (CBTs), superconducting-insulator-normal-insulator-superconducting (SINIS) structures, and superconducting single-electron transistors (SETs). We investigate the behaviour of these systems at the singularity-matching bias points, the dependence of micro refrigeration effects on the charging energy of the island, and the effect of a finite superconducting gap on Coulomb-blockade thermometry.

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https://doi.wikipt.org/11/1490/3728tpl

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Electronic and thermal sequential, superconducting two-junction arrays, superconductor, tunnel junction, solid state devices, applied physics

Tunable structure-activity correlations of molybdenum dichalcogenides (MoX2; X=S, Se, Te) electrocatalysts via hydrothermal methods: insight into optimizing the electrocatalytic performance for hydrogen generation

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February 25, 2024 at 6:30:00 AM

Tunable structure-activity correlations of molybdenum dichalcogenides (MoX2; X=S, Se, Te) electrocatalysts via hydrothermal methods: insight into optimizing the electrocatalytic performance for hydrogen generation

Hydrogen Evolution Reaction (HER) has always gained wide attention as one of the eco-friendly and sustainable pathways for efficient hydrogen generation and storage; also, two-dimensional molybdenum dichalcogenide (MoX2, where X stands for S, Se, Te) layers have emerged as a class of quasi-ideal electrocatalysts because of their large surface area, rich reserves and outstanding conductivity. However, besides greater HER activity, the maturity and diversity of modification strategies result in a more puzzling relationship between electrocatalytic mechanisms and the corresponding practical performance. In this article, based on a comprehensive review of fundamentals, principles and interconnected similarities of the MoX2 family, we focus on the structure-activity correlation of layered MoX2 for HER enhancement via hydrothermal synthesis. This method is summarized from different experimental systems to efficiently modulate the crystal structure and surface for boosted HER activity. Here, with the adjustment of three key experimental parameters: the categories of MoX2, reaction temperature and the molar amount of added reactants, the optimum HER performance can be obtained at the best conditions (MoSe2 species, 180℃ and a vast ratio of the reductant or metal precursor), and more microscopically, a controlled structure-activity relationship can be inducted. This summary may pave a new path for the controllable synthesis and modification of MoX2-based catalyst materials.

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https://doi.wikipt.org/11/1490/874831tpl

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Theoretical Physics Letters, 2023 ° dd(mm) ° 6584-6621
https://www.wikipt.org/tphysicsletters
DOI: doi.wikipt.org/11/1490/3728tpl

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8

molybdenum dichalcogenides, structure-activity analysis, tunable, phase transition, active sites, hydrogen evolution;, hydrothermal

Probing supermassive black hole seed scenarios with gravitational wave measurements

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December 6, 2023 at 12:15:00 PM

Probing supermassive black hole seed scenarios with gravitational wave measurements

The process whereby the supermassive black holes populating the centers of galaxies have been assembled remains to be established, with the relative importance of seeds provided by collapsed Population-III stars, black holes formed in nuclear star clusters via repeated mergers, or direct collapses of protogalactic disks yet to be determined. In this paper we study the prospects for casting light on this issue by future measurements of gravitational waves emitted during the inspirals and mergers of pairs of intermediate-mass black holes, discussing in particular the roles of prospective measurements by LISA and the proposed atom interferometers AION and AEDGE.

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Theoretical Physics Letters
2023 ° 18(06) ° 0631-3657
https://www.wikipt.org/tphysicsletters
DOI: https://doi.wikipt.org/11/1490/874831tpl

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primordial black holes, supermassive black hole, : galaxies – polarization, large-scale structure of Universe

Protoplanetary disks in Ks-band total intensity and polarized light

doi.wikipt.org/10/1490/3486tpl

Citation (36)

https://doi.wikipt.org/10/1490/4506tpl

October 13, 2023 at 12:15:00 PM

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Protoplanetary disks in Ks-band total intensity and polarized light

Abstract

Diverse morphology in protoplanetary disks can result from planet-disk interaction, suggesting the presence of forming planets. Characterizing disks can inform the formation environments of planets. To date, most imaging campaigns have probed the polarized light from disks, which is only a fraction of the total scattered light and not very sensitive to planetary emission. Aims. We aim to observe and characterize protoplanetary disk systems in the near-infrared in both polarized and total intensity light, to carry out an unprecedented study of the dust scattering properties of disks, as well as of any possible planetary companions. Methods. Using the star-hopping mode of the SPHERE instrument at the Very Large Telescope, we observed 29 young stars hosting protoplanetary disks and their reference stars in the Ks-band polarized light. We extracted disk signals in total intensity by removing stellar light using the corresponding reference star observations, by adopting the data imputation concept with sequential non-negative matrix factorization (DI-sNMF).

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Theoretical Physics Letters
2023 ° 03(10) ° 0631-3486
https://www.wikipt.org/tphysicsletters

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10

protoplanetary disks, – planets and satellites, high angular resolution, : image processing, astrophysics, space science

Searching for H→hh→bb¯ττ in the 2HDM Type-I at the LHC

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October 7, 2023 at 10:15:00 AM

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Searching for H→hh→bb¯ττ in the 2HDM Type-I at the LHC

Abstract

Unlike other realisations of the 2-Higgs Doublet Model (2HDM), the so-called Type-I allows for a very light Higgs boson spectrum. Specifically, herein, the heaviest of the two CP-even neutral Higgs states, H, can be the one discovered at the Large Hadron Collider (LHC) in 2012, with a mass of ≈ 125 GeV and couplings consistent with those predicted by the Standard Model (SM). In such a condition of the model, referred to as ‘inverted mass hierarchy’, the decay of the SM-like Higgs state into pairs of the lightest CP-even neutral Higgs boson, h, is possible, for masses of the latter ranging from MH/2 ≈ 65 GeV down to 15 GeV or so, all compatible with experimental constraints. In this paper, we investigate the scope of the LHC in accessing the process gg → H → hh → b ¯bτ τ by performing a Monte Carlo (MC) analysis aimed at extracting this signal from the SM backgrounds, in presence of a dedicated trigger choice and kinematic selection. We prove that some sensitivity to such a channel exists already at Run 3 of the LHC while the High-Luminosity LHC (HL-LHC) will be able to either confirm or disprove this theoretical scenario over sizable regions of its parameter space.

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9.2

Theoretical Physics Letters
2023 ° 03(10) ° 0631-4506
https://www.wikipt.org/tphysicsletters
DOI: https://doi.wikipt.org/10/1490/4506tpl

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8

astronomy, large hadron collider, lhc, elementary physics

Surface-Enhanced Raman Scattering from Au Nanorods, Nanotriangles, and Nanostars with Tuned Plasmon Resonances

doi.wikipt.org/10/1490/9586tpl

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October 3, 2023 at 11:45:00 AM

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Surface-Enhanced Raman Scattering from Au Nanorods, Nanotriangles, and Nanostars with Tuned Plasmon Resonances

Abstract

Electromagnetic theory predicts that the optimal value of the localized plasmon resonance (LPR) wavelength for the maximal SERS enhancement factor (EF) is half the sum of the laser and Raman wavelengths. For small Raman shifts, the theoretical EF scales as the fourth power of the local field. However, experimental data often disagree with these theoretical conclusions, leaving the question of choosing the optimal plasmon resonance for the maximal SERS signal unresolved. Here, we present experimental data for gold nanorods (AuNRs), gold nanotriangles (AuNTs), and gold nanostars (AuNSTs) simulating 1D, 2D, and 3D plasmonic nanostructures, respectively. The LPR wavelengths were tuned by chemical etching within 550 1050 nm at constant number concentrations of the particles. The particles were functionalized with Cy7.5 and NBT, and the dependence of the intensity at 940 cm-1 (Cy7.5) and 1343 cm-1 (NBT) on the LPR wavelength was examined for laser wavelengths of 633 nm and 785 nm. The electromagnetic SERS EFs were calculated by averaging the product of the local field intensities at the laser and Raman wavelengths over the particle surface and their random orientations. The calculated SERS plasmonic profiles were redshifted compared to the laser wavelength. For 785- nm excitation, the calculated EFs were five to seven times higher than those for 633-nm excitation. With AuNR@Cy7.5 and AuNT@ Cy7.5, the experimental SERS was 35-fold stronger than it was with NBT-functionalized particles, but with AuNST@Cy7.5 and AuNST@NBT, the SERS responses were similar. With all nanoparticles tested, the SERS plasmonic profiles after 785 nm excitation were slightly blue-shifted, as compared with the laser wavelength, possibly owing to the inner filter effect. After 633-nm excitation, the SERS profiles were redshifted, in agreement with EM theory. In all cases, the plasmonic EF profiles were much broadened compared to the calculated ones and did not follow the four-power law.

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9.2

Theoretical Physics Letters
2023 ° 03(10) ° 0631-9586
https://www.wikipt.org/tphysicsletters
DOI: https://www.doi.wikipt.org/10/1490/9586tpl

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8

gold nanorods, gold nanotriangles, gold nanostars, SERS, localized plasmon resonance, T-matrix and COMSOL simulations

Optical Cluster Cosmology with SDSS redMaPPer clusters and HSC-Y3 lensing measurements

doi.wikipt.org/10/1490/6587450tpl

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September 25, 2023 at 6:30:00 AM

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Optical Cluster Cosmology with SDSS redMaPPer clusters and HSC-Y3 lensing measurements

Abstract

We present cosmology results obtained from a blind joint analysis of the abundance, projected clustering, and weak lensing of galaxy clusters measured from the Sloan Digital Sky Survey (SDSS) redMaPPer cluster catalog and the Hyper-Suprime Cam (HSC) Year3 shape catalog. We present a full-forward model for the cluster observables, which includes empirical modeling for the anisotropic boosts on the lensing and clustering signals of optical clusters. We validate our analysis via mock cluster catalogs which include observational systematics, such as the projection effect and the effect of baryonic feedback, and find that our analysis can robustly constrain cosmological parameters in an unbiased manner without any informative priors on our model parameters. The joint analysis of our observables in the context of the flat ΛCDM model results in cosmological constraints for 𝑆8 ≡ 𝜎8 √︁ Ωm/0.3 = 0.816+0.041 −0.039. Our result is consistent with the 𝑆8 inference from other cosmic microwave background- and large scale structure-based cosmology analyses, including the result from the Planck 2018 primary CMB analysis.

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9.5

Theoretical Physics Letters
2023 ° 25(09) ° 0631-6901
https://www.wikipt.org/tphysicsletters
DOI: https://www.doi.wikipt.org/10/1490/6587450tpl

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large-scale structure of Universe, cosmology

A search for faint resolved galaxies beyond the Milky Way in DES Year 6: A new faint, diffuse dwarf satellite of NGC 55

doi.wikipt.org/10/1490/687400tpl

Citation (30)

September 11, 2023 at 3:15:00 PM

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A search for faint resolved galaxies beyond the Milky Way in DES Year 6: A new faint, diffuse dwarf satellite of NGC 55

Electromagnetic theory predicts that the optimal value of the localized plasmon resonance (LPR) wavelength for the maximal SERS enhancement factor (EF) is half the sum of the laser and Raman wavelengths. For small Raman shifts, the theoretical EF scales as the fourth power of the local field. However, experimental data often disagree with these theoretical conclusions, leaving the question of choosing the optimal plasmon resonance for the maximal SERS signal unresolved. Here, we present experimental data for gold nanorods (AuNRs), gold nanotriangles (AuNTs), and gold nanostars (AuNSTs) simulating 1D, 2D, and 3D plasmonic nanostructures, respectively. The LPR wavelengths were tuned by chemical etching within 550 1050 nm at constant number concentrations of the particles. The particles were functionalized with Cy7.5 and NBT, and the dependence of the intensity at 940 cm-1 (Cy7.5) and 1343 cm-1 (NBT) on the LPR wavelength was examined for laser wavelengths of 633 nm and 785 nm. The electromagnetic SERS EFs were calculated by averaging the product of the local field intensities at the laser and Raman wavelengths over the particle surface and their random orientations. The calculated SERS plasmonic profiles were redshifted compared to the laser wavelength. For 785- nm excitation, the calculated EFs were five to seven times higher than those for 633-nm excitation. With AuNR@Cy7.5 and AuNT@ Cy7.5, the experimental SERS was 35-fold stronger than it was with NBT-functionalized particles, but with AuNST@Cy7.5 and AuNST@NBT, the SERS responses were similar. With all nanoparticles tested, the SERS plasmonic profiles after 785 nm excitation were slightly blue-shifted, as compared with the laser wavelength, possibly owing to the inner filter effect. After 633-nm excitation, the SERS profiles were redshifted, in agreement with EM theory. In all cases, the plasmonic EF profiles were much broadened compared to the calculated ones and did not follow the four-power law.

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9