arXiv subjects

Girish Kulkarni

Publications and source records attributed to Girish Kulkarni.

At least 19 recordsLinked to original sources

arXiv2026

Full-field mapping of spatially varying polarization entanglement generated from spontaneous parametric down-conversion

Two-photon states generated from spontaneous parametric down-conversion (SPDC) can display entanglement in all degrees of freedom (DoFs) of light, including spatial, temporal, and polarization. The coupling between different DoFs of a two-photon state has been shown to display rich structures that enable novel and robust information processing schemes. While existing literature has studied these couplings by post-selecting the SPDC field, a comprehensive understanding of the inherent spatial-polarization coupling produced in the SPDC process is still lacking. This work produces a full spatial map of the polarization entanglement generated across the entire SPDC field, which contains an entire class of near-maximally polarization-entangled states with an average concurrence of 0.8303 +/- 0.0004. The spatial-polarization coupling manifests as radially or linearly varying polarization-entangled states, whose wavefunctions are dependent on the transverse momenta of the down-converted photons and the pump beam, respectively. Our study lays important groundwork for further exploiting the coupling between entanglement in different DoFs for future quantum technologies

quant-ph↗

arXiv2026

From triangles to prisms: towards a geometric extension of concurrence fill for three-qubit mixed states

The quantification of multipartite entanglement remains a long-standing open challenge in quantum information theory with major implications for quantum foundations and quantum technologies. In the context of three-qubit pure states, the concurrence triangle underlies geometric interpretations for a variety of multipartite entanglement measures. In particular, the concurrence fill, which is proportional to the square root of the area of the concurrence triangle, has been shown to be a valid measure of genuine tripartite entanglement. As a result, there is now significant interest in extending the concurrence triangle and concurrence fill to three-qubit mixed states. In this work, we show that any rank-2 three-qubit mixed state can be visualized in terms of concurrence prisms associated with their pure state decompositions. Thus, the concurrence fill of the mixed state obtained through convex-roof extension is proportional to the total prism fill area, defined as the square root of the base area times the height, associated with the prisms minimized over all pure state decompositions. We then consider three-qubit mixed states that are incoherent mixtures of Greenberger-Horne-Zeilinger (GHZ) and W states and analytically perform their convex-roof extension to obtain a closed-form expression for the concurrence fill of these rank-2 mixtures. Finally, we apply the geometric picture of concurrence prisms to these mixtures and their pure state decomposition corresponding to minimum concurrence fill as a tool for visualization.

quant-ph↗

arXiv2026

Forest without Trees is still Fruitful: Constraints on the thermal state of the neutral IGM at $z\approx5.6$ with the 21-cm forest power spectrum

Neutral regions of the intergalactic medium (IGM) during the Epoch of Reionization (EoR) remain largely unexplored due to the limitations of existing probes. Owing to discoveries of numerous high-redshift radio-bright sources, the 21-cm forest, a series of absorption features imprinted by the neutral IGM in the spectra of such sources, now offers an attractive probe of the thermal and ionization state of the predominantly neutral IGM at $z\gtrsim5.5$. We analyse archival upgraded Giant Metrewave Radio Telescope (uGMRT) observations of J352-15, the brightest known radio-loud quasar in the EoR ($z=5.82$), to measure the one-dimensional (1D) power spectrum of the 21-cm forest. By comparing the observed power spectrum with forward-modelled synthetic spectra generated from cosmological simulations spanning a wide range of ionization and X-ray pre-heating scenarios, we perform Bayesian inference even in the absence of a statistical detection. We also present an independent Murchison Widefield Array measurement, although its lower sensitivity prevents competitive constraints. Using uGMRT, we achieve a sensitivity of $3.62\,\rm mJy\,beam^{-1}$ per $6.1\,\rm kHz$ channel. While we do not detect the 21-cm forest statistically, the null detection jointly constrains the mean neutral hydrogen fraction, $\langle x_{\rm HI}\rangle$, and the mean temperature of the neutral IGM, $\langle T_{\rm HI}\rangle$. At the $68\%$ credible level, our analysis disfavours cold and substantially neutral IGM models at $z\approx5.6$, including models with $\langle T_{\rm HI}\rangle \lesssim 27\,\rm K$ for $\langle x_{\rm HI}\rangle=0.1$. These limits probe parameter space allowed by existing Ly$α$ and 21-cm observations, indicating substantial pre-heating of the neutral IGM above the adiabatic cooling floor. This demonstrates that the 21-cm forest has entered the regime of observationally informative statistics.

astro-ph.CO↗

arXiv2026

The impact of source and survey modelling on the connection between [O III] emitters and Ly $α$ forest transmission at z ~ 6

James Webb Space Telescope (JWST) surveys of [O III]-emitting galaxies are offering fresh insight into the connection between galaxies and the intergalactic medium at redshift z ~ 6. Recent measurements of the cross-correlation between [O III]-emitting galaxies and Ly $α$ forest transmission present an apparent challenge to numerical models. Here we improve upon previous theoretical work by constructing an empirical model that connects haloes with the observed population of [O III] emitters and incorporates the geometry and depth of the JWST surveys into mock galaxy survey catalogues. We compare these mocks to recent measurements of [O III] emitter clustering and the one and two dimensional galaxy-Ly $α$ transmission cross-correlation. The large scatter in our mock survey measurements of the cross-correlation enable a statistically good match to the observational data, albeit the peak of the one dimensional correlation in our mocks occurs at a scale $\approx$10 cMpc below that observed. The large scatter implies that, at present, current galaxy-IGM observations may struggle to rule out a broad range of ionising source models. We anticipate that further progress will strongly benefit from increased observational sample sizes, as well as simulations performed in box sizes >250 cMpc that use a variety of source models.

astro-ph.CO↗

arXiv2026

Optimisation of calibration sources for global 21-cm experiments: the REACH case

The spin-flip 21-cm signal from the Cosmic Dawn and the Epoch of Reionization is an essential probe of the conditions that led to the formation of the first luminous objects in the early Universe. However, its detection remains a major challenge owing to its low strength compared to the bright foregrounds and the requirement of precise calibration of the instrument to prevent systematics that could hinder a detection or lead to false inferences. REACH (Radio Experiment for the Analysis of Cosmic Hydrogen) is a radiometer experiment designed to detect this sky-averaged signal in the frequency range of 50--130~MHz. Using a wide-beam antenna, REACH calibration relies on internal reference sources, covering a broad range of temperatures and reflection coefficients. The choice of type and number of calibrators used significantly influences the quality of the calibration. This work investigates these effects and introduces a novel method for selecting an optimal set of calibration sources. With an optimised set, we aim to reduce calibration time, thereby increasing sky integration time while preserving calibration accuracy. We explore two optimisation strategies: one applied across the full receiver band and another performed on a frequency-by-frequency basis. Finally, we demonstrate that, with a total calibration time comparable to the conventional full-calibrator set, an optimised set with fewer calibrators achieves approximately a $15~\%$ reduction in calibrated temperature noise and improved absolute calibration of the instrument. This has implications for better calibration strategies in similar radiometer experiments.

astro-ph.IM↗

arXiv2026

Theory of temporal three-photon interference

The recent demonstrations of cascaded PDC (CPDC) and the hopeful prospects of realizing third-order PDC (TOPDC) for the generation of three-photon entangled states are paving the way for experimental studies on genuine three-photon interference. In this article, we formulate three-photon interference in terms of ``each three-photon interfering only with itself.'' We show that although a generalized two-alternative three-photon interference setup based on CPDC or TOPDC involves eight different length parameters, the interference can be fully characterized in terms of only three independent parameters. The first parameter is the three-photon path-length difference, which has a direct analog in the one-photon and two-photon cases, and the other two parameters quantify the path-asymmetry length. Unlike two-photon interference, which requires only one parameter to quantify path-asymmetry, two independent parameters are needed in three-photon interference. This results in a broader class of nonclassical three-photon effects, including three-photon HOM-type effects. Our work provides the theoretical basis for existing and future three-photon interference experiments exploring the rich and complex quantum correlations associated with three-particle entanglement and potentially enabling the development of novel protocols for harnessing those correlations.

quant-ph↗

arXiv2026

Full Schmidt characterization of spatiotemporally entangled states produced from spontaneous parametric down-conversion

The full Schmidt decomposition of spatiotemporally entangled states generated from spontaneous parametric down-conversion (SPDC) has not been carried out until now due to the immense computational complexity arising from the large dimensionalities of the states. In this Letter, we utilize the rotational symmetry of the states to reduce the complexity by at least four orders of magnitude and carry out the decomposition to reveal the precise forms of the spatiotemporal Schmidt modes and the Schmidt spectrum spanning over 10^4 modes. We show that the Schmidt modes have a phase profile with a transverse spatial vortex structure that endows them with orbital angular momentum at all frequencies. In the high-gain regime, these Schmidt modes broaden and the Schmidt spectrum narrows with increasing pump strength. Our work can spur novel applications at the intersection of quantum imaging and spectroscopy that utilize entangled states produced from SPDC.

quant-ph↗

arXiv2026

ECHO21: a tool for modelling global 21-cm signal from dark ages to reionization

We introduce a Python package called ECHO21 for modelling the global 21-cm signal from the dark ages through cosmic dawn to the end of reionization. Leveraging its analytical framework, ECHO21 generates a single model in $\mathcal{O}(1)\,$s, allowing a large number of signals to be generated efficiently by distributing models across multiple cores. Thus, it is ideal for performing astrophysical or cosmological inference from a given 21-cm dataset. We offer six astrophysical parameters that control the Lyman-$α$ (Ly$α$) emissivity, X-ray emissivity, emissivity of ionizing photons, and star formation rate. Beyond its efficiency some of the attractive and novel features in ECHO21 relative to previously published codes are inclusion of Ly$α$ heating, ability to vary the standard cosmological parameters as easily as the astrophysical parameters, and different models of star formation rate density (physically-motivated, a semi-empirical, and an empirically-motivated). With a number of 21-cm experiments soon to provide cosmic dawn 21-cm data, ECHO21 is a flexible and extensible new open-source package for making quick but sufficiently realistic astrophysical inferences. We make our code publicly available.

astro-ph.CO↗

arXiv2026

TORRCH: Tomographic reconstruction of the reionization of cosmic hydrogen with Ly$α$ emitters and non-Ly$α$-selected galaxies

Tomographic reconstruction of reionization is a long-sought goal. It would move the field beyond global summary statistics, such as the volume-averaged ionised fraction, to direct, field-level constraints on the ionization topology. With this in mind, we present TORRCH (TOmographic Reconstruction of the Reionization of Cosmic Hydrogen), a deep-learning framework that reconstructs the neutral-hydrogen fraction field during the epoch of reionization from the spatial distributions of Ly$α$ emitters (LAEs) and non-Ly$α$-selected galaxies (NLSGs) at luminosity limits comparable to current surveys. Using hydrodynamical simulations post-processed with radiative transfer, we train a deterministic 3D U-Net on mock surveys spanning diverse reionization scenarios and predict the neutral-fraction field. We find that TORRCH recovers the large-scale ionization morphology from synthetic data comparable to current surveys with high fidelity, and reproduces both the one-point distribution and the 2D power spectrum of projected neutral fractions. The predicted galaxy-IGM cross-correlation is also captured well, including the expected small-scale anti-correlation and its decline towards zero at large separations. Reconstruction quality depends on tracer completeness, with deep joint LAE+NLSG samples yielding the most accurate morphology, while LAE-only selections retain bubble-scale topology but with reduced fidelity. Robustness tests show that the method is stable to variations in ionization conditions between training and test data, and to realistic redshift uncertainties. Our results suggest that galaxy-based tomography can potentially deliver reliable reionization maps across realistic survey redshift windows.

astro-ph.CO↗

arXiv2025

Stronger Constraints on Primordial Black Holes as Dark Matter Derived from the Thermal Evolution of the Intergalactic Medium over the Last Twelve Billion Years

Primordial black holes (PBHs) have been explored as potential dark matter candidates, with various astrophysical observations placing upper limits on the fraction $f_\mathrm{PBH}$ of dark matter in the form of PBHs. However, a largely underutilized probe of PBH abundance is the temperature of the intergalactic medium (IGM), inferred from the thermal broadening of absorption lines in the Lyman-$α$ forest of quasar spectra. PBHs inject energy into the IGM via Hawking radiation, altering its thermal evolution. In this work, we constrain this energy injection by self-consistently modeling its interplay with the cosmological ultraviolet background from galaxies and supermassive black holes. Leveraging IGM temperature measurements spanning the past twelve billion years ($z \sim 0$ to $6$), we derive one of the most stringent constraints on PBH-induced heating from light PBHs within the mass range $10^{15}$-$10^{17}$ g. Specifically, for $M_\mathrm{PBH} = 10^{16}$ g, we find $f_\mathrm{PBH} < 5 \times 10^{-5}$ at 95\% confidence, with the bound scaling approximately as $M_\mathrm{PBH}^{4}$ at other masses. Our inclusion of helium reionization and low-redshift temperature measurements strengthens previous IGM-based PBH constraints by an order of magnitude or more. Compared to other existing limits, our result is among the strongest, second only to the constraints from the 511 keV line from the Galactic Center, but with distinct systematics. More broadly, this study highlights the IGM thermal history as a powerful and independent probe of beyond-standard model physics.

astro-ph.CO↗

arXiv2025

The Lyman-$α$ emitter bispectrum as a probe of reionization morphology

Ly$α$ emitters (LAEs) have now been discovered out to redshift $z=13$, and are valuable probes of the reionization history at redshifts beyond the reach of other currently available tracers. Most inferences of the neutral hydrogen fraction from LAE observations rely on one-point and two-point statistics like the luminosity function and the power spectrum. We present here an analysis of the bispectrum of high-redshift LAEs and demonstrate its sensitivity to the Epoch of Reionization. We use the Sherwood-Relics suite of cosmological hydrodynamical simulations post-processed with the GPU-based radiative transfer code ATON-HE to generate realistic LAE mock catalogues for a wide range of reionization models, varying the ionization history and the source populations, including contributions of AGN to hydrogen reionization. We demonstrate that the bispectrum provides greater sensitivity than the power spectrum to both the timing and spatial morphology of reionization. Using reduced-$χ^2$ analysis we further show that the bispectrum also responds more strongly to variations in source population and AGN contribution, apparently more efficiently capturing morphological features missed by two-point statistics. The redshift evolution of the bispectrum reflects the increased clustering of ionizing sources at earlier epochs. The sensitivity of the bispectrum to peculiar velocities underscores the importance of velocity corrections in comparisons to observations. Our findings demonstrate that the LAE bispectrum is a powerful higher-order statistic for probing reionization through current and future LAE surveys using telescopes such as Subaru and JWST.

astro-ph.CO↗

arXiv2025

The impact of faint AGN discovered by JWST on reionization

The relative contribution of emission from stellar sources and accretion onto supermassive black holes to reionization has been brought into focus again by the apparent high abundance of faint Active Galactic Nuclei (AGN) at $4\lesssim z\lesssim11$ uncovered by JWST. We investigate here the contribution of these faint AGN to hydrogen and the early stages of helium reionization using the GPU-based radiative transfer code ATON-HE by post-processing a cosmological hydrodynamical simulation from the sherwood-relics suite of simulations. We study four models: two galaxy-only late-end reionization models, a QSO-assisted and a QSO-only model. In the QSO-assisted model, 1% of the haloes host AGN, with AGN luminosities scaled to contribute 17% of the total hydrogen-ionizing emissivity. In the QSO-only model, quasars account for all the hydrogen-ionizing emissivity, with 10% of the haloes hosting AGN. The SED of AGN is assumed to be a power-law with $α=-1.7$ each with a 10 Myr lifetime. All models are calibrated to the observed mean Lyman-$α$ forest transmission at $5\lesssim z\lesssim6.2$. The QSO-assisted model requires an emissivity similar to the galaxy-only models and fits the observed distribution of the Lyman-$α$ optical depths well. The QSO-only model is inconsistent with the observed Lyman-$α$ optical depths distribution, and produces excessively high IGM temperatures at $z\lesssim 5$ due to an early onset of HeII reionization, unless the escape fraction of HeII-ionizing photons is assumed to be low. Our results suggest that a modest AGN contribution to reionization aligns with the Lyman-$α$ forest data, whereas an AGN dominated scenario is difficult to reconcile.

astro-ph.GA↗

arXiv2025

Efficient neutral-IGM inference from noisy 21-cm forest spectra with latent-space U-Net encoding and XGBoost

The 21-cm forest, comprising narrow absorption features imprinted on the radio spectra of high-redshift radio-loud quasars by intervening neutral hydrogen, offers a uniquely sensitive probe of the thermal state of the neutral intergalactic medium (IGM) during the epoch of reionization. Although over 30 such quasars are now known at $z > 5.5$, the signal remains elusive in practice, owing to instrumental noise, the intrinsic weakness of the absorption features, and the limited brightness of available background sources. Recent studies have focused on the one-dimensional transmission power spectrum as a statistical observable, but this approach also demands high signal-to-noise ratios. Here, we present a systematic comparison of five inference pipelines for recovering IGM parameters from mock 21-cm forest spectra at $z = 6$, incorporating realistic instrumental noise and telescope characteristics. We show that likelihood-free inference based on machine learning substantially outperforms traditional Bayesian methods. In particular, our most effective method dispenses with the power spectrum entirely: we use a convolutional U-Net to extract a latent-space encoding of the input spectrum and perform parameter regression using XGBoost. This approach yields accurate constraints on the IGM neutral fraction and X-ray heating efficiency even with a single 50-hour uGMRT sightline, which is an orders-of-magnitude improvement in integration time relative to existing techniques. We publicly release our code, training data, and models. Beyond the 21-cm forest, these results underscore the promise of hybrid deep learning and gradient-boosted inference techniques for extracting physical information from low-SNR data across astrophysics.

astro-ph.CO↗

arXiv2025

DeepCHART: Mapping the 3D dark matter density field from Ly$α$ forest surveys using deep learning

We present DeepCHART (Deep learning for Cosmological Heterogeneity and Astrophysical Reconstruction via Tomography), a deep learning framework designed to reconstruct the three-dimensional dark matter density field at redshift $z=2.5$ from Ly$α$ forest spectra. Leveraging a 3D variational autoencoder with a U-Net architecture, DeepCHART performs fast, likelihood-free inference, accurately capturing the non-linear gravitational dynamics and baryonic processes embedded in cosmological hydrodynamical simulations. When applied to joint datasets combining Ly$α$ forest absorption and coeval galaxy positions, the reconstruction quality improves further. For current surveys, such as Subaru/PFS, CLAMATO, and LATIS, with an average transverse sightline spacing of $d_\perp=2.4h^{-1}$cMpc, DeepCHART achieves high-fidelity reconstructions over the density range $0.4<Δ_{\rm DM}<15$, with a voxel-wise Pearson correlation coefficient of $ρ\simeq 0.77$. These reconstructions are obtained using Ly$α$ forest spectra with signal-to-noise ratios as low as 2 and instrumental resolution $R=2500$, matching Subaru/PFS specifications. For future high-density surveys enabled by instruments such as ELT/MOSAIC and WST/IFS with $d_\perp\simeq 1h^{-1}\mathrm{cMpc}$, the correlation improves to $ρ\simeq 0.90$ across a wider dynamic range ($0.25<Δ_{\rm DM}<40$). The framework reliably recovers the dark matter density PDF as well as the power spectrum, with only mild suppression at intermediate scales. In terms of cosmic web classification, DeepCHART successfully identifies 81% of voids, 75% of sheets, 63% of filaments, and 43% of nodes. We propose DeepCHART as a powerful and scalable framework for field-level cosmological inference, readily generalisable to other observables, and offering a robust, efficient means of maximising the scientific return of upcoming spectroscopic surveys.

astro-ph.CO↗

arXiv2025

Chronicling the reionization history at $6\lesssim z \lesssim 7$ with emergent quasar damping wings

The spectra of high-redshift ($z\gtrsim 6$) quasars contain valuable information on the progression of the Epoch of Reionization (EoR). At redshifts $z<6$, the observed Lyman-series forest shows that the intergalactic medium (IGM) is nearly ionized, while at $z>7$ the observed quasar damping wings indicate high neutral gas fractions. However, there remains a gap in neutral gas fraction constraints at $6\lesssim z \lesssim 7$ where the Lyman series forest becomes saturated but damping wings have yet to fully emerge. In this work, we use a sample of 18 quasar spectra at redshifts $6.0<z<7.1$ to close this gap. We apply neural networks to reconstruct the quasars' continuum emission around the partially absorbed Lyman $α$ line to normalize their spectra, and stack these continuum-normalized spectra in three redshift bins. To increase the robustness of our results, we compare the stacks to a grid of models from two hydrodynamical simulations, ATON and CROC, and we measure the volume-averaged neutral gas fraction, $\bar{x}_{\rm HI}$, while jointly fitting for the mean quasar lifetime, $t_{\rm Q}$, for each stacked spectrum. We chronicle the evolution of neutral gas fraction using the ATON (CROC) models as follows: $\bar{x}_{\rm HI} = 0.21_{-0.07}^{+0.17}$ ($\bar{x}_{\rm HI} = 0.10_{<10^{-4}}^{+0.73}$) at $\langle z \rangle =6.10$, $\bar{x}_{\rm HI} = 0.21_{-0.07}^{+0.33}$ ($\bar{x}_{\rm HI} =0.57_{-0.47}^{+0.26}$) at $\langle z \rangle =6.46$, and $\bar{x}_{\rm HI} = 0.37_{-0.17}^{+0.17}$ ($\bar{x}_{\rm HI} =0.57_{-0.21}^{+0.26}$) at $\langle z \rangle =6.87$. At the same time we constrain the average quasar lifetime to be $t_{\rm Q} \lesssim 7\ {\rm Myr}$ across all redshift bins, in good agreement with previous studies.

astro-ph.CO↗

arXiv2025

How probable is the Lyman-$α$ damping wing in the spectrum of the redshift z = 5.9896 quasar ULAS J0148+0600?

The shape of the Ly-$α$ transmission in the near zone of the redshift $z=5.9896$ quasar ULAS J0148$+$0600 (hereafter J0148) is consistent with a damping wing arising from an extended neutral hydrogen island in the diffuse intergalactic medium (IGM). Here we use simulations of late-ending reionisation from Sherwood-Relics to assess the expected incidence of quasars with Ly-$α$ and Ly-$β$ absorption similar to the observed J0148 spectrum. We find a late end to reionisation at $z=5.3$ is a necessary requirement for reproducing a Ly-$α$ damping wing consistent with J0148. This occurs in $\sim3$ per cent of our simulated spectra for an IGM neutral fraction $\langle x_{\rm HI}\rangle=0.14$ at $z=6$. However, using standard assumptions for the ionising photon output of J0148, the a priori probability of drawing a simulated quasar spectrum with a Ly-$α$ damping wing profile \emph{and} Ly-$α$ near zone size that simultaneously match J0148 is low, $p<10^{-2}$. This may indicate that the ionising emission from J0148 is variable on timescales $t<10^{5}\rm\,yr$, or alternatively that the Ly-$α$ transmission in the J0148 near zone is impacted by the transverse proximity effect from nearby star-forming galaxies or undetected quasars. We also predict the IGM temperature should be $T\sim 4\times 10^{4}\rm\,K$ within a few proper Mpc of the Ly-$α$ near zone edge due to recent H$\,\rm \scriptstyle I$ and He$\,\rm \scriptstyle II$ photo-heating. Evidence for enhanced thermal broadening in the Ly-$α$ absorption near the damping wing edge would provide further evidence that the final stages of reionisation are occurring at $z<6$.

astro-ph.CO↗

arXiv2025

The connection between high-redshift galaxies and Lyman $α$ transmission in the Sherwood-Relics simulations of patchy reionisation

Recent work has suggested that, during reionisation, spatial variations in the ionising radiation field should produce enhanced Ly $α$ forest transmission at distances of tens of comoving Mpc from high-redshift galaxies. We demonstrate that the Sherwood-Relics suite of hybrid radiation-hydrodynamical simulations are qualitatively consistent with this interpretation. The shape of the galaxy--Ly $α$ transmission cross-correlation is sensitive to both the mass of the haloes hosting the galaxies and the volume averaged fraction of neutral hydrogen in the IGM, $\bar{x}_{\rm HI}$. The reported excess Ly $α$ forest transmission on scales r ~ 10 cMpc at $\langle z \rangle \approx 5.2$ -- as measured using C IV absorbers as proxies for high-redshift galaxies -- is quantitatively reproduced by Sherwood-Relics at z = 6 if we assume the galaxies that produce ionising photons are hosted in haloes with mass $M_{\rm h}\geq 10^{10}~h^{-1}\,{\rm M}_\odot$. However, this redshift mismatch is equivalent to requiring $\bar{x}_{\rm HI}\sim 0.1$ at $z\simeq 5.2$, which is inconsistent with the observed Ly $α$ forest effective optical depth distribution. We suggest this tension may be partly resolved if the minimum C IV absorber host halo mass at z > 5 is larger than $M_{\rm h}=10^{10}~h^{-1}\,{\rm M}_\odot$. After reionisation completes, relic IGM temperature fluctuations will continue to influence the shape of the cross-correlation on scales of a few comoving Mpc at $4 \leq z \leq 5$. Constraining the redshift evolution of the cross-correlation over this period may therefore provide further insight into the timing of reionisation.

astro-ph.CO↗

arXiv2025

Development of a Miniaturized, Automated, and Cost-Effective Device for Enzyme-Linked Immunosorbent Assay

In this work, a miniaturized, automated, and cost-effective ELISA device is designed and implemented, without the utilization of conventional techniques such as pipetting or microfluidic valve technologies. The device has dimensions of 24 cm x 19 cm x 14 cm and weighs <3 Kg. The total hardware cost of the device is estimated to be approximately $1,200, which can be further reduced through optimization during scale-up production. 3D printed disposable parts, including the reagent reservoir disk and the microfluidic connector, have also been developed. IL-6 is used as a model system to demonstrate how the device provides an ELISA measurement. The cost per test is estimated to be less than ten dollars. The compactness, automated operation, along with the cost-effectiveness of this ELISA device, makes it suitable for point-of-care applications in resource-limited regions.

physics.med-ph↗