arXiv subjects

T. Zhang

Publications and source records attributed to T. Zhang.

At least 19 recordsLinked to original sources

arXiv2026

Photometric redshifts for active galactic nuclei with LePHARE for the Vera C. Rubin Observatory

Active Galactic Nuclei (AGN) play a crucial role in galaxy evolution, but they are a minority of extragalactic sources with diverse Spectral Energy Distributions (SEDs), which depend on their means of selection. Upcoming large-scale surveys such as LSST will identify many AGN, but analysis tools are not optimized for them. The limited number of photometric bands in these surveys impacts the calculation of photometric redshifts for AGN, which are essential for scientific advancement. We use LePHARE to demonstrate the impact that a limited number of bands and erroneous assumptions have on the determination of the photometric redshifts of AGN. We conduct tests on six AGN samples selected using X-ray, radio, infrared, variability, color, and spectroscopic criteria in the COSMOS field, using photometry from HSC-CLAUDS, which is closest in depth and wavelength coverage to LSST. We present the LSST pipeline for LePHARE within the Redshift Assessment Infrastructure Layers (RAIL), facilitating comparison between SED fitting and machine learning algorithms. AGN that appear as point-like sources in optical data will be assigned highly unreliable photometric redshifts if they are processed using galaxy templates. Additionally, shallow all-sky surveys (like eROSITA, WISE, and ZTF) miss many AGN. As a result, these "hidden" AGN are often misidentified as galaxies in public survey data, leading to incorrect photometric redshift. We provide the configurations that are suggested for each type of AGN alongside measures of expected performance as a function of redshift, magnitude, and selection. To facilitate studies with a panchromatic view of AGN, we also release photometric redshifts and posterior distributions for all AGN sources identified in the COSMOS field using the six criteria, based on 28-band photometry.

astro-ph.GA↗

arXiv2026

ALMAGAL IX. The chemical complexity of AG318.9477-00.1960: A line-identification template for ALMAGAL

We present a detailed molecular line analysis of one of the most chemically rich cores in the ALMAGAL sample, the high-mass core~9 in the AG318.9477-00.1960 clump (AG318-c9), located at a heliocentric distance of \sim 10.4\,\rm kpc. We further assessed whether the emission of selected COMs, that is, ethylene glycol ((CH_2OH)_2; EG), glycolaldehyde (CH_2(OH)CHO; GA), and methyl formate (CH_3OCHO; MF), can be used to trace the innermost regions of hot molecular cores (HMCs). We analysed ALMA Band~6 observations (\sim 217-221GHz). Spectral line identification and local thermodynamic equilibrium modelling were performed using the software MADCUBA. We derived the physical parameters, including the column density (N), excitation temperature (Tex), velocity, line width, and molecular abundances relative to H_2, for all detected species. The chemical inventory of AG318-c9 was compared with that of the HMC G31.41+0.31 (G31). In addition, we performed a pixel-by-pixel analysis of EG, GA, and MF to generate spatially resolved N and Tex maps and corresponding radial profiles.

astro-ph.GA↗

arXiv2026

From Narrow-gap Semiconductor to Metallic Altermagnet: Optical Fingerprints of Co-Doped FeSb2

The realization of bulk metallic altermagnetism has remained elusive despite the growing number of candidate materials. Here, we present evidence that moderate cobalt substitution ($\sim$15%) drives the correlated narrow-gap semiconductor FeSb$_2$ into a metallic altermagnetic state persisting up to room temperature. The infrared optical conductivity reveals low-energy interband transitions near 0.1 eV that emerge upon doping and grow with Co concentration. Density functional theory calculations show that these transitions originate exclusively from altermagnetic spin ordering, with spin split bands ($\sim$0.2 eV) of non-relativistic origin, together with spin-orbit coupling induced band splitting of the order of $\sim$5 meV near the Fermi level. Co substitution further leads to Fano lineshapes and mode mixing in the infrared-active phonons, reflecting enhanced electron-phonon coupling and local inversion symmetry breaking, while leaving the altermagnetic spin symmetry intact. Our results establish carrier-tuned FeSb$_2$ as a platform for exploring metallic $d$-wave altermagnetism and its coupling to lattice degrees of freedom.

cond-mat.mtrl-sci↗

arXiv2026

Emergent superconductivity at 16.3 K in an altermagnetic candidate Na$_{2-x}$V$_2$Se$_2$O with broken inversion symmetry

Altermagnets (AMs), characterized by zero net magnetization and momentum-dependent spin splitting, are anticipated to hold significant potential for generating multiple exotic and uncommon superconducting states. However, superconductivity has not yet been realized in AMs to date. Recently, two-dimensional (2D) V$_2$Ch$_2$O (Ch = Se, Te) monolayers, as well as AV$_2$Ch$_2$O (A = K, Rb, Cs) crystals containing [V$_2$Ch$_2$O]$^{\delta -}$ building layers, have been predicted and/or demonstrated to be promising altermagnetic materials. Our preliminary attempts to explore superconductivity in these materials by applying pressure or chemical doping were unsuccessful. Here we report the discovery of superconductivity at a relatively high transition temperature of ~ 16.3 K in a newly synthesized layered compound, Na$_{2-x}$V$_2$Se$_2$O, a variant of AV$_2$Ch$_2$O. In this structure, the [V$_2$Ch$_2$O]$^{\delta -}$ layers are interspersed with double layers of Na$^+$ instead of a single layer of A$^+$, with sodium sites being only half-filled. This new family of layered vanadium oxychalcogenides, lacking inversion symmetry, represents an intriguing platform for exploring altermagnetic superconductors, and holds the potential to reveal novel phenomena, such as topological states, van Hove singularities, and finite-momentum superconductivity. Furthermore, this material acts as a "bridge" between the cuprate/nickelate and iron-pnictide high temperature superconductors, providing new hope and opportunity to expand the category of layered superconductors with higher critical temperatures (T$_c$) and enhancing our understanding of the underlying mechanisms in these systems.

cond-mat.supr-con↗

arXiv2026

ALMAGAL VIII. Early phases of triggered star formation in source AG286.0716$-$1.8229

Several theoretical and observational studies have shown that new waves of triggered star-formation can be induced by the feedback from newly formed massive protostars, due to the expansion of H II regions. We used the millimeter dust continuum data of the ALMAGAL survey and the Anderson et al. 2014 catalog of H II regions and selected one ALMAGAL source for ALMA follow-up observations. In fact, in source AG286.0716$-$1.8229 six cores were detected at a resolution of $\sim7600$ au, but only two at a higher resolution. The 4 cores not detected at higher resolution are prestellar core candidates. We used archival data from the SMGPS and RACS to confirm whether an H II region is present in the field. We observed the source with with ALMA in Band 4, covering the emission of DCO$^+$ (2$-$1), N$_2$D$^+$ (2$-$1), DCN (2$-$1), and CH$_3$CCH (9$-$8), to estimates whether these cores are in an early phase of the star-formation process. The new Band 4 continuum image revealed three cores outside of the ALMAGAL field of view, for a total of 9 cores in the region, 8 of which are located along an arch of radius $\sim0.75$ pc. We have derived a spectral index between -0.14 and -0.4, in the frequency range of 0.8-1.6 GHz for the candidate H II region, which is consistent with optically thin free-free emission. Using plausible temperature ranges, based on the information from chemical tracers and the dust continuum, we derived mass ranges for the cores ($\sim2-16\,$M$_{\odot}$) and ranges for the virial parameter ($\sim0.3-5$). All the cores along the arch have virial parameters $\lesssim$2, with only one exception. Comparing the typical separation and mass of the cores with those expected in the case of the collect and collapse scenario and with the thermal Jean length and mass, the best agreement is found with the characteristic scales in the case of triggered star formation.

astro-ph.GA↗

arXiv2026

Fast Radio Bursts in the Era of the Vera C. Rubin Observatory's Legacy Survey of Space and Time

Identifying the host galaxies of fast radio bursts (FRBs), and comparing their redshifts and dispersion measures, has unlocked a new probe of the cosmological distribution of ionised gas. However the necessary optical observations to identify FRB hosts, and measure their redshifts, are becoming increasingly onerous as the detection rate of precisely localised FRBs increases. Here we analyse the ability of the Legacy Survey of Space and Time (LSST), being conducted by the Vera C. Rubin Observatory, to identify FRB host galaxies, and the utility of LSST photometric redshifts for FRB cosmology. By combining a model of FRB host galaxy r-band magnitudes, $m_r$, with predictions for the FRB z-DM distribution, we create a method to predict the $m_r(z)$ distribution for the host galaxies of FRBs detected by radio surveys. We then predict these distributions for the coherent modes of the Australian Square Kilometre Array Pathfinder (ASKAP) and MeerKAT. We find that even a single visit with Rubin will be able to identify 65% of FRB host galaxies detected by ASKAP's coherent upgrade, `CRACO'; while the final 10 year co-added images will identify 81% of those from MeerKAT's tied array beams. We also simulate the impact of using photometric redshifts for a simplified analysis to determine $H_0$, finding that estimated photo-z errors result in a decreased precision of only 7% on $H_0$ for ASKAP's CRACO system. The impact of missing faint FRB hosts, which are likely at higher redshifts, is more significant, and might degrade sensitivity to $H_0$ by 47%, or 62% when combined with photo-z errors. All told, Rubin's LSST will be an incredibly powerful survey for facilitating FRB cosmology, although supplemental observations may be useful for particularly faint and distant host galaxies.

astro-ph.HE↗

arXiv2025

ALMAGAL VI. The spatial distribution of dense cores during the evolution of cluster-forming massive clump

High-mass stars and star clusters form from the fragmentation of massive dense clumps driven by gravity, turbulence, and magnetic fields. The ALMAGAL project observed $\sim1000$ clumps at $\sim$1000\,au resolution, enabling a statistically significant characterization of this process across a large range of clump physical parameters and evolutionary stages. In this work, we investigated the spatial distribution of dense cores in the 514 massive, potentially cluster-forming, clumps hosting at least 4 cores, to trace fragmentation's initial conditions and early evolution. We used quantitative descriptors, evaluated against the clump bolometric luminosity-to-mass ratio as an indicator of evolution. Core separations were measured with the minimum spanning tree method (MST) and compared with the Jeans gravitational fragmentation theory. We used the $Q$ parameter and the mass segregation ratio, $\Lambda_{MSR}$, to evaluate whether cores have specific arrangements or differences depending on their masses. ALMAGAL cores are usually arranged in elliptical groups with an axis ratio $e\sim2.2$, but $e\geq$5 is also observed. A single characteristic core separation per clump is found in $\sim76$% of cases, but signatures of multiple fragmentation lengths not rare. Typical core separations are compatible with the clump-averaged thermal Jeans length, $\lambda^{th}_{J}$, though a population, typical of low-fragmented/young clumps, has wider separations with $l\approx3\times\lambda^{th}_{J}$. The core separation decreases on average from $l\sim22000$ au in younger systems to $l\sim7000$ au in more evolved ones. Cores are typically distributed in fractal-type subclusters, with centrally concentrated patterns appearing only at later stages, but without a progressive evolutionary transition. Finally, mass segregation is found in 110 systems, with its occurrence increasing with evolution.

astro-ph.GA↗

arXiv2025

Cosmic Shear constraints from HSC Year 3 with clustering calibration of the tomographic redshift distributions from DESI

We reanalyze cosmological constraints from Hyper Suprime-Cam (HSC) Y3 shear-shear correlation function using new calibration of the tomographic redshift distribution via the clustering redshifts method with DESI spectroscopy presented in Choppin de Janvry et al. (2025a). We present both importance sampling of the original MCMC chains by HSC, applying the weights of our newly calibrated $\Delta z$ priors, as well as full MCMC analysis with new photometric redshift distributions, finding consistent results between the two. We obtain the growth of structure parameter $S_8\equiv\sigma_8\sqrt{\Omega_m/0.3}=0.805\pm{0.018}$, compared to previous HSC Y3 result of $S_8=0.769^{+0.031}_{-0.034}$, which is a 1.8 reduction of error due to the improved clustering redshift calibrations, with the central value shifting considerably higher towards Planck cosmology. With the new photometric redshift calibration, HSC Y3 has comparable constraining power to the recent KIDS Legacy and DES Y6 results.

astro-ph.CO↗

arXiv2025

Full calibration of the tomographic redshift distribution from the HSC PDR3 Shape Catalog with DESI

The calibration of tomographic redshift distributions is essential for cosmological analysis of weak lensing data. In this work, we calibrate all four tomographic bins of the Hyper Suprime Camera (HSC) weak lensing catalog with the Dark Energy Spectroscopic Instrument (DESI) Data Release 1 and 2 using the clustering redshifts technique. We include z > 1.2 redshift sources such as emission line galaxies (ELG) and quasars (QSO) sources in our calibration, which were not available in the previous HSC calibration (Rau et al. 2022), allowing a complete calibration of all the redshift bins. We find the first tomographic bin exhibits a small shift towards low redshifts. The second bin is in good agreement with the photometric calibration, while third and fourth bin exhibit a shift towards higher redshifts. However, these shifts are considerably smaller than the shifts obtained in the HSC Year 3 cosmic shear analyses. We evaluate the impact of galaxy bias and magnification effects from all the samples on the measurements, finding them to be small, and we propose corrections to reduce them further. Specifically, we relax the assumption of linear bias and only assume no redshift evolution of the cross-correlation coefficient, allowing us to leverage smaller clustering scales. We model the redshift distributions with splines and compare our results to previous analyses as well as to other parameterizations found in literature. For the two high-redshift tomographic bins, we find the shifts to higher redshifts with respect to the measurements performed in Rau+2022 to be $\Delta z_3=-0.043^{+0.022}_{-0.020}$ and $\Delta z_4=-0.050^{+0.012}_{-0.012}$.

astro-ph.CO↗

arXiv2025

The SolarEV City Paradox: A Critical Review of the Fragmented Integration of Rooftop Photovoltaics and Electric Vehicles for Urban Decarbonization

Urban decarbonization is central to meeting global climate goals, yet progress toward integrated low-carbon energy systems remains slow. The SolarEV City Concept, linking rooftop photovoltaics with electric vehicles as mobile storage offers a technically robust pathway for deep CO2 reduction, potentially meeting 60-95 percent of municipal electricity demand when deployed synergistically. Despite rapid global growth of PVs and EVs, integration through bidirectional Vehicle-to-Home and Vehicle-to-Grid systems has lagged, revealing a persistent SolarEV paradox. This review examines that paradox through a socio-technical framework across four dimensions, technology, economics, policy, and society. Cross-national comparison shows that while technical feasibility is well established, large-scale implementation is limited by fragmented charging-protocol standards, immature and often non-profitable V2G business models, regulatory misalignments between energy and transport sectors, and social-equity barriers that restrict participation mainly to high-income homeowners. Emerging national archetypes from Japans resilience-driven model to Europes regulation-first trajectory highlight strong path dependence in current integration strategies. The analysis concludes that advancing SolarEV Cities requires a shift from parallel PV-EV promotion toward coordinated policy frameworks, interoperable digital infrastructure, and inclusive market designs that distribute economic and resilience benefits more equitably. Achieving this integrated energy transition will require strategic collaboration among researchers, governments, industries, and communities to build adaptive, resilient, and socially just urban energy systems.

physics.soc-ph↗

arXiv2025

ALMAGAL V. Relations between the core populations and the parent clump physical properties

Context. The fragmentation of massive molecular clumps into smaller, potentially star-forming cores plays a key role in the processes of high-mass star formation. The ALMAGAL project offers high-resolution data to investigate these processes across various evolutionary stages in the Galactic plane. Aims. This study aims at correlating the fragmentation properties of massive clumps, obtained from ALMA observations, with their global physical parameters (e.g., mass, surface density, and temperature) and evolutionary indicators (such as luminosity-to-mass ratio and bolometric temperature) obtained from Herschel observations. It seeks to assess whether the cores evolve in number and mass in tandem with their host clumps, and to determine the possible factors influencing the formation of massive cores (M > 24M_\odot). Methods. We analyzed the masses of 6348 fragments, estimated from 1.4 mm continuum data for 1007 ALMAGAL clumps. Leveraging this unprecedentedly large data set, we evaluated statistical relationships between clump parameters, estimated over about 0.1 pc scales, and fragment properties, corresponding to scales of a few 1000 au, while accounting for potential biases related to distance and observational resolution. Our results were further compared with predictions from numerical simulations. Results. The fragmentation level correlates preferentially with clump surface density, supporting a scenario of density-driven fragmentation, whereas it does not show any clear dependence on total clump mass. Both the mass of the most massive core and the core formation efficiency show a broad range and increase on average by an order of magnitude in the intervals spanned by evolutionary indicators such as clump dust temperature and the luminosity-to-mass ratio. This suggests that core growth continues throughout the clump evolution, favoring clump-fed over core-fed theoretical scenarios.

astro-ph.GA↗

arXiv2025

Reconstruction of neutrino events in the Accelerator Neutrino Neutron Interaction Experiment: Part I

The Accelerator Neutrino Neutron Interaction Experiment (ANNIE) was designed to reconstruct neutrino events from the Fermilab Booster Neutrino Beam (BNB) with the parallel goals of measuring neutron production in interactions with oxygen and serving as a testbed for new technology. The ANNIE detector consists of a 26-ton water Cherenkov target tank instrumented with conventional photomultiplier tubes (PMTs), a downstream tracking muon spectrometer, and an upstream double wall of plastic scintillator to serve to veto charged particles incoming from neutrino events that occur upstream of the experimental setup. ANNIE has also deployed multiple Large-Area Picosecond PhotoDetectors (LAPPDs) and a test vessel of water-based liquid scintillator (WbLS). This paper describes the event reconstruction performance of the detector before implementation of these novel technologies, which will serve as a baseline against which their impact can be measured. That said, even the techniques used for event reconstruction using only the conventional PMT array and muon spectrometer are significantly different than those used in other water Cherenkov detectors due to the small size of ANNIE (which makes nanosecond-scale timing not as useful as in a large detector) and the availability of reconstruction information from the tracking muon spectrometer. We demonstrate that combining the information from these two elements into a single fit using only pattern recognition yields a muon vertex uncertainty of 60 cm, a directional uncertainty of 13.2 degrees, and energy reconstruction uncertainty of about 10\% for BNB muon neutrino Charged Current Zero Pion (CC0pi) events.

hep-ex↗

arXiv2025

From two dimensions to wire networks in a dice-lattice Josephson array

We investigate Josephson arrays consisting of a dice-lattice network of superconducting weak links surrounding rhombic plaquettes of proximitized semiconductor. Josephson coupling of the weak links and electron density in the plaquettes are independently controlled by separate electrostatic gates. Applied magnetic flux results in an intricate pattern of switching currents associated with frustration, $f$. For depleted plaquettes, the switching current is nearly periodic in $f$, expected for a phase-only description, while occupied plaquettes yield a decreasing envelope of switching currents with increasing $f$. A model of flux dependence based on ballistic small-area junctions and diffusive large-area plaquettes yields excellent agreement with experiment.

cond-mat.mes-hall↗

arXiv2025

Photometric Redshift Estimation for Rubin Observatory Data Preview 1 with Redshift Assessment Infrastructure Layers (RAIL)

We present the first systematic analysis of photometric redshifts (photo-z) estimated from the Rubin Observatory Data Preview 1 (DP1) data taken with the Legacy Survey of Space and Time (LSST) Commissioning Camera. Employing the Redshift Assessment Infrastructure Layers (RAIL) framework, we apply eight photo-z algorithms to the DP1 photometry, using deep ugrizy coverage in the Extended Chandra Deep Field South (ECDFS) field and griz data in the Rubin_SV_38_7 field. In the ECDFS field, we construct a reference catalog from spectroscopic redshift (spec-z), grism redshift (grism-z), and multiband photo-z for training and validating photo-z. Performance metrics of the photo-z are evaluated using spec-zs from ECDFS and Dark Energy Spectroscopic Instrument Data Release 1 samples. Across the algorithms, we achieve per-galaxy photo-z scatter of $\sigma_{\rm NMAD} \sim 0.03$ and outlier fractions around 10% in the 6-band data, with performance degrading at faint magnitudes and z>1.2. The overall bias and scatter of our machine-learning based photo-zs satisfy the LSST Y1 requirement. We also use our photo-z to infer the ensemble redshift distribution n(z). We study the photo-z improvement by including near-infrared photometry from the Euclid mission, and find that Euclid photometry improves photo-z at z>1.2. Our results validate the RAIL pipeline for Rubin photo-z production and demonstrate promising initial performance.

astro-ph.IM↗

arXiv2025

Signatures of a high-temperature collective electronic phase with superconductivity-like characteristics and a giant pressure effect in networks of boron-doped ultrathin carbon nanotubes

We present data consistent with a high-temperature collective electronic phase with superconductivity-like characteristics in three dimensional networks of boron doped, ultrathin carbon nanotubes (CNTs) grown inside the 5 Angstrom channels of ZSM-5 zeolite. Confinement stabilizes (2,1) CNTs that are otherwise dynamically unstable, while boron doping shifts the Fermi level towards a van Hove singularity, as supported by ab-initio calculations. The resulting CNT network exhibits multiple, mutually consistent signatures of an electronic condensate with the typical characteristics of a high temperature superconductor at ambient pressure. DC magnetization and AC susceptibility measurements reveal the onset of a Meissner response between 220 and 250K, with compacted samples achieving up to 93 percent of full diamagnetic screening. Electrical transport shows a sharp resistive transition with extrapolated Tc = 239K and vanishing resistance in optimized samples. Specific heat measurements display a reproducible anomaly at 233 to 236 K that broadens under magnetic field, consistent with strong fluctuations. Point contact spectroscopy identifies three energy gaps, including a leading gap of 30 meV whose temperature dependence follows BCS expectations for Tc = 224K, and exhibits particle-hole symmetry and Andreev reflection. Remarkably, applying pressures below 0.1 kbar enhances Tc by nearly 100K and modulates the room temperature resistance by more than three orders of magnitude, suggesting a pressure driven 1D to 3D crossover in the CNT network. These results identify boron doped ultrathin CNT networks as a promising carbon-based platform for near ambient temperature superconductivity and reveal an unusually large pressure sensitivity with potential technological relevance.

cond-mat.supr-con↗

arXiv2025

Correlation-driven 3d Heavy Fermion behavior in LiV2O4

LiV2O4 is a spinel-structured compound that stands out as the first known 3d-electron system exhibiting typical heavy fermion behavior. A central question is how such strong mass renormalization emerges in the absence of f-electrons. In this work, we investigate the three-dimensional electronic structure of LiV2O4 thin films using angle-resolved photoemission spectroscopy (ARPES). We identify that an electron-like flat band is derived from a1g orbitals, along with a highly dispersive e'g band strongly coupled with phonons. The overall agreement with dynamical mean-field theory (DMFT) calculations highlights the essential role of inter-orbital Hund's coupling in reducing the a1g bandwidth to 25 meV, approaching a Mott state. Notably, we find that heavy-fermion behavior arises from additional renormalization at the a1g band near the Fermi level, likely driven by many-body interactions at energy scales down to a few meV and potentially linked to geometric frustration inherent to the spinel lattice. These results provide crucial insights into the origin of the heavy fermion behavior in 3d-electron systems.

cond-mat.str-el↗

arXiv2025

Reliable Clutter Suppression for Slow-Moving Weak Target Radar Detection

Reliable slow-moving weak target detection in complicated environments is challenging due to the masking effects from the surrounding strong reflectors. The traditional Moving Target Indication (MTI) may suppress the echoes from not only the static interference objects (IOs), but also the desired slow-moving weak target. According to the low-rank and sparse properties of the range-velocity maps across different radar scans, a novel clutter suppression scheme based on the Go decomposition (Godec) framework is proposed in this paper. The simulation results show that with the existence of masking effects, the target detection scheme based on Godec clutter suppression can reliably detect the slow-moving weak target, compared to the traditional MTI-based scheme. Besides, the time consumption comparison is conducted, demonstrating that the proposed solution is one that sacrifices time complexity in exchange for enhanced reliability. Additionally, the tradeoffs among the number of false alarm cells, the detection probability and the iteration times for convergence have been revealed, guiding parameter settings of the proposed solution in practical applications. Experiment validation is also conducted to verify the proposed solution, providing further insight into the scenarios where the solution is most applicable.

eess.SP↗

arXiv2025

Demonstrating the velocity response of a table-top EPR Speedmeter

The sensitivity of gravitational-wave interferometers is fundamentally limited by quantum noise, as dictated by the Heisenberg uncertainty principle, due to their continuous position measurement of the end mirrors. Speedmeter configurations, which measure mirror velocity rather than position, have been proposed as a means to suppress quantum back-action noise, but practical implementations remain at an early stage. In this work, we present a table-top realisation of the Einstein- Podolsky-Rosen (EPR) Speedmeter concept, employing an optical readout scheme based on two orthogonal polarisation modes that probe the interferometer with different effective bandwidths. Using a triangular cavity, we demonstrate that the differential optical response between the linear p- and s-polarised modes exhibits a speed-like frequency dependence: vanishing at DC and increasing linearly with signal frequency, up to the bandwidth of the slower mode. With this we show that an optical system equivalent to the EPR Speedmeter indeed performs a velocity readout of the end mirror.

astro-ph.IM↗