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JWST provides a unique dataset to study reionization's earliest stages, promising insights into the first galaxies. Many JWST/NIRSpec prism spectra reveal smooth Lyman-alpha breaks in z>5 galaxies, implying damping wing scattering by neutral hydrogen. We investigate what current prism spectra imply about the intergalactic medium (IGM), and how best to use NIRSpec spectra to recover IGM properties. We use a sample of 99 z~5.5-13 galaxies with high S/N prism spectra in the public archive, including 12 at z>10. We analyse these spectra using damping wing sightlines from inhomogeneous reionizing IGM simulations, mapping between the distance of a source from neutral IGM and the mean IGM neutral fraction. We marginalise over absorption by local HI around galaxies, and Lyman-alpha emission. We observe a decline in the median and variance of flux around the Lyman-alpha break with increasing redshift, consistent with an increasingly neutral IGM, as ionized regions become smaller and rarer. At $z\gtrsim9$ the spectra become consistent with an almost fully neutral IGM. We find S/N>15 per pixel is required to robustly estimate IGM properties from prism spectra. We fit a sub-sample of high S/N spectra and infer mean neutral fractions $\overline{x}_\mathrm{HI}=0.33^{+0.18}_{-0.27}, 0.64^{+0.17}_{-0.23}$ ($>0.70$ excluding GNz11) at $z \approx 6.5, 9.3$. We also investigate local HI absorption, finding median column density $\log_{10}N_\mathrm{HI}\approx10^{20.8}$ cm$^{-2}$, comparable to $z\sim3$ Lyman-break galaxies, with no significant redshift evolution. We find galaxies showing the strongest absorption are more likely to be in close associations (<500 pkpc), implying enhanced absorption in massive dark matter halos. Future deep prism and grating spectroscopy of z>9 sources will provide tighter constraints on the earliest stages of reionization, key for understanding the onset of star formation., Comment: 15 pages, 13 figures, 11 pages in appendices. Submitted to A&A

The James Webb Space Telescope (JWST) is discovering an increasing number of galaxies well into the early stages of the Epoch of Reionization (EoR). Many of these galaxies are clustered with strong Lyman alpha (Ly$\alpha$) emission, motivating the presence of surrounding cosmic HII regions that would facilitate Ly$\alpha$ transmission through the intergalactic medium (IGM). Detecting these HII "bubbles" would allow us to connect their growth to the properties of the galaxies inside them. Here we develop a new forward-modeling framework to estimate the local HII region size and location from Ly$\alpha$ spectra of galaxy groups in the early stages of the EoR. Our model takes advantage of the complementary information provided by neighboring sightlines through the IGM. Our forward models sample the main sources of uncertainty, including: (i) the global neutral fraction; (ii) EoR morphology; (iii) emergent Ly$\alpha$ emission; and (iv) NIRSpec instrument noise. Depending on the availability of complementary nebular lines, $\sim$ 0.006 $\unicode{x2013}$ 0.01 galaxies per cMpc$^3$, are required to be $\gtrsim$95\% confident that the HII bubble location and size recovered by our method is accurate to within $\sim$ 1 comoving Mpc. This corresponds roughly to tens of galaxies at $z\sim7\unicode{x2013}8$ in $\sim$2x2 tiled pointing with JWST NIRSpec. Such a sample is achievable with a targeted survey with completeness down to $M_{\rm UV}^{\rm min}\lesssim$ -19 $\unicode{x2013}$ -17, depending on the over-density of the field. We test our method on 3D EoR simulations as well as misspecified equivalent width distributions, in both cases accurately recovering the HII region surrounding targeted galaxy groups., Comment: 14 pages, 15 figures, submitted to A&A

Ionized bubble sizes during reionization trace physical properties of the first galaxies. JWST's ability to spectroscopically confirm and measure Lyman-alpha (Ly$\alpha$) emission in sub-L* galaxies opens the door to mapping ionized bubbles in 3D. However, existing Lya-based bubble measurement strategies rely on constraints from single galaxies, which are limited by the large variability in intrinsic Ly$\alpha$ emission. As a first step, we present two bubble size estimation methods using Lya spectroscopy of ensembles of galaxies, enabling us to map ionized structures and marginalize over Ly$\alpha$ emission variability. We test our methods using Gpc-scale reionization simulations of the intergalactic medium (IGM). To map bubbles in the plane of the sky, we develop an edge detection method based on the asymmetry of Ly$\alpha$ transmission as a function of spatial position. To map bubbles along the line-of-sight, we develop an algorithm using the tight relation between Ly$\alpha$ transmission and the line-of-sight distance from galaxies to the nearest neutral IGM patch. Both methods can robustly recover bubbles with radius $\gtrsim$10 comoving Mpc, sufficient for mapping bubbles even in the early phases of reionization, when the IGM is $\sim70-90\%$ neutral. These methods require $\gtrsim$0.002-0.004 galaxies/cMpc$^3$, a $5\sigma$ Ly$\alpha$ equivalent width upper limit of $\lesssim$30\r{A} for the faintest targets, and redshift precision $\Delta z \lesssim 0.015$, feasible with JWST spectroscopy. Shallower observations will provide robust lower limits on bubble sizes. Additional constraints on IGM transmission from Ly$\alpha$ escape fractions and line profiles will further refine these methods, paving the way to our first direct understanding of ionized bubble growth., Comment: 15 pages (+ 3 pages in Appendix), 17 figures, submitted to A&A

In semiconducting monolayer transition metal dichalcogenides (ML-TMDs), broken inversion symmetry and strong spin-orbit coupling result in spin-valley lock-in effects so that the valley degeneracy may be lifted by external magnetic fields, potentially leading to real-space structural transformation. Here, we report magnetic field (B)-induced giant electric hysteretic responses to back-gate voltages in ML-MoS2 field-effect transistors (FETs) on SiO2/Si at temperatures < 20 K. The observed hysteresis increases with |B| up to 12 T and is tunable by varying the temperature. Raman spectroscopic and scanning tunneling microscopic studies reveal significant lattice expansion with increasing |B| at 4.2 K, and this lattice expansion becomes asymmetric in ML-MoS2 FETs on rigid SiO2/Si substrates, leading to out-of-plane mirror symmetry breaking and the emergence of a tunable out-of-plane ferroelectric-like polar order. This broken symmetry-induced polarization in ML-MoS2 shows typical ferroelectric butterfly hysteresis in piezo-response force microscopy, adding ML-MoS2 to the single-layer material family that exhibit out-of-plane polar order-induced ferroelectricity, which is promising for such technological applications as cryo-temperature ultracompact non-volatile memories, memtransistors, and ultrasensitive magnetic field sensors. Moreover, the polar effect induced by asymmetric lattice expansion may be further generalized to other ML-TMDs and achieved by nanoscale strain engineering of the substrate without magnetic fields.

In this paper, we introduce two (anti)homomorphisms that preserve the Haar state values of monomials. Together with the modular automorphism, the three (anti)homomorphisms are used in our new algorithm to compute the Haar states of monomials on $\mathcal{O}(SL_q(3))$. Comparing with the algorithm proposed in the author's previous work \cite{lu2023}, the new algorithm reduces the linear relations used in the computation to a half., Comment: Removed text overlap with arXiv:2301.12683. Updated the introduction section and changed title for section 2

Electronic frequency mixers are fundamental building blocks of electronic systems. Harmonic frequency mixing in particular enables broadband electromagnetic signal analysis across octaves of spectrum using a single local oscillator. However, conventional harmonic frequency mixers do not operate beyond hundreds of GHz to a few THz. If extended to the petahertz scale in a compact and scalable form, harmonic mixers would enable field-resolved optical signal analysis spanning octaves of spectra in a monolithic device without the need for frequency conversion using nonlinear crystals. Here we demonstrate lightwave-electronic harmonic frequency mixing beyond 0.350 PHz using plasmonic nanoantennas. We demonstrate that the mixing process enables complete, field-resolved detection of spectral content far outside that of the local oscillator, greatly extending the range of detectable frequencies compared to conventional heterodyning techniques. Our work has important implications for applications where optical signals of interest exhibit coherent femtosecond-scale dynamics spanning multiple harmonics.

Constraining when and how reionisation began is pivotal for understanding when the first galaxies formed. Lyman-alpha (Ly$\alpha$) emission from galaxies is currently our most promising probe of these early stages. At z>7 the majority of galaxies detected with Ly$\alpha$ are in candidate overdensities. Here we quantify the probability of these galaxies residing in large ionised bubbles. We create (1.6 Gpc)$^3$ reionising intergalactic medium (IGM) simulations, providing sufficient volume to robustly measure bubble size distributions around UV-bright galaxies and rare overdensities. We find $M_{\rm UV} \lesssim -16$ galaxies and overdensities are $\gtrsim$10-1000x more likely to trace ionised bubbles compared to randomly selected positions. The brightest galaxies and strongest overdensities have bubble size distributions with highest characteristic size and least scatter. We compare two models: gradual reionisation driven by numerous UV-faint galaxies versus more rapid reionisation by rarer brighter galaxies, producing larger bubbles at fixed neutral fraction. We demonstrate that recently observed z~7 overdensities are highly likely to trace large ionised bubbles, corroborated by their high Ly$\alpha$ detection rates. However, the z~8.7 association of Ly$\alpha$ emitters in EGS and GN-z11, with Ly$\alpha$ at z=10.6, are unlikely to trace large bubbles in our fiducial model -- 11% and 7% probability of >1 proper Mpc bubbles, respectively. Ly$\alpha$ detections at such high redshifts could be explained by: a less neutral IGM than previously expected; larger ionised regions at fixed neutral fraction; or if intrinsic Ly$\alpha$ flux is unusually strong in these galaxies. We discuss how to test these scenarios with JWST and the prospects for using upcoming wide-area surveys to distinguish between reionisation models., Comment: 15 pages (+ 3 pages in Appendix), 13 figures, submitted to MNRAS

This paper shows that to compute the Haar state on $\mathbb{O}(SL_q(n))$, it suffices to compute the Haar states of a special type of monomials which we define as standard monomials. Then, we provide an algorithm to explicitly compute the Haar states of standard monomials on $\mathbb{O}(SL_q(3))$ with reasonable computational cost. The numerical results on $\mathbb{O}(SL_q(3))$ will be used in the future study of the $q$-deformed Weingarten function., Comment: Update the introduction section. Add a new section (Section 3). Add more details on the computation of the Source Matrix (Section 4.1) and the recursive relation of standard monomial in the form of (cdh)^i(ceg)^{m-i} (section 4.2). Remove appendix A and B in the previous version

We describe new JWST/NIRSpec observations of galaxies at $z\gtrsim7$ taken from the CEERS survey. Previous observations of this area have revealed associations of Ly$\alpha$ emitters at redshifts ($z=7.5$, $7.7$, $8.7$) where the intergalactic medium (IGM) is thought to be mostly neutral, leading to suggestions that these systems are situated in large ionized bubbles. We identify 21 $z\gtrsim7$ galaxies with robust redshifts in the CEERS dataset, including 10 in the Ly$\alpha$ associations. Their spectra are indicative of very highly ionized and metal poor gas, with line ratios (O32 $=17.84$ and Ne3O2 $=0.89$, linear scale) and metallicity ($12+\log{(\rm{O/H})}=7.84$) that are rarely seen at lower redshifts. We find that the most extreme spectral properties are found in the six $z\gtrsim7$ Ly$\alpha$ emitters in the sample. Each has a hard ionizing spectrum indicating that their visibility is likely enhanced by efficient ionizing photon production. Ly$\alpha$ velocity offsets are found to be very large ($\gtrsim300$ km s$^{-1}$), likely also contributing to their detectability. We find that Ly$\alpha$ in $z\gtrsim7$ galaxies is $6-12\times$ weaker than in lower redshift samples with matched rest-optical spectral properties. If the bubbles around the Ly$\alpha$ emitters are relatively small ($\lesssim0.5-1$ pMpc), we may expect such significant attenuation of Ly$\alpha$ in these ionized regions. We discuss several other effects that may contribute to weaker Ly$\alpha$ emission at $z\gtrsim7$. Deep spectroscopy of fainter galaxies in the vicinity of the Ly$\alpha$ emitters will better characterize the physical scale of the ionized bubbles in this field., Comment: 31 pages, 22 figures, accepted by MNRAS, references updated

We present the spectroscopic confirmation of a protocluster at $z=7.88$ behind the galaxy cluster Abell2744 (hereafter A2744-z7p9OD). Using JWST NIRSpec, we find seven galaxies within a projected radius of 60kpc. Although the galaxies reside in an overdensity around $>20\times$ greater than a random volume, they do not show strong Lyman-alpha emission. We place 2-$\sigma$ upper limits on the rest-frame equivalent width $<16$-$28$AA. Based on the tight upper limits to the Lyman-alpha emission, we constrain the volume-averaged neutral fraction of hydrogen in the intergalactic medium to be $x_{\rm HI} > 0.45$ (68% CI). Using an empirical $M_{\rm UV}$-$M_{\rm halo}$ relation for individual galaxies, we estimate that the total halo mass of the system is $\gtrsim 4\times10^{11}\,M_\odot$. Likewise, the line of sight velocity dispersion is estimated to be $1100 \pm 200$km/s. Using an empirical relation, we estimate the present-day halo mass of A2744-z7p9OD to be $\sim2\times10^{15}\,M_\odot$, comparable to the Coma cluster. A2744-z7p9OD is the highest redshift spectroscopically confirmed protocluster to date, demonstrating the power of JWST to investigate the connection between dark-matter halo assembly and galaxy formation at very early times with medium-deep observations at $<20$hrs total exposure time. Follow-up spectroscopy of the remaining photometric candidates of the overdensity will further refine the features of this system and help characterize the role of such overdensities in cosmic reionization., Comment: The title has been updated to reflect the published numbering; a minor change has been made to Figure 1 with regard to the MSA shutters on the rgb stamp image. NASA press release article can be found at: https://www.nasa.gov/feature/goddard/2023/webb-reveals-early-universe-prequel-to-huge-galaxy-cluster

The Hubble constant ($H_{0}$) is a measurement to describe the expansion rate of the Universe in the current era. However, there is a $4.4\sigma$ discrepancy between the measurements from the early Universe and the late Universe. In this research, we propose a model-free and distance-free method to constrain $H_{0}$. Combining Friedman-Lema\^itre-Robertson-Walker cosmology with geometrical relation of the proper motion of extragalactic jets, the lower limit ($H_{\rm 0,min}$) of $H_{0}$ can be determined using only three cosmology-free observables: the redshifts of the host galaxies, as well as the approaching and receding angular velocities of radio jets. Using these, we propose to use the Kolmogorov-Smirnov test (K-S test) between cumulative distribution functions of $H_{\rm 0,min}$ to differentiate cosmology. We simulate 100, 200, and 500 extragalactic jets with 3 levels of accuracy of the proper motion ($\mu_{a}$ and $\mu_{r}$), at $10\%$, $5\%$, and $1\%$, corresponding to the accuracies of the current and future radio interferometers. We perform K-S tests between the simulated samples as theoretical distributions with different $H_{0}$ and power-law index of velocity distribution of jets and mock observational data. Our result suggests increasing sample sizes leads to tighter constraints on both power-law index and the Hubble constant at moderate accuracy (i.e., $10\%$ and $5\%$) while at $1\%$ accuracy, increasing sample sizes leads to tighter constraints on power-law index more. Improving accuracy results in better constraints in the Hubble constant compared with the power-law index in all cases but it alleviates the degeneracy., Comment: 13 pages, 14 figures, accepted for publication in MNRAS

Addressing how strong UV radiation affects galaxy formation is central to understanding their evolution. The quenching of star formation via strong UV radiation (from starbursts or AGN) has been proposed in various scenes to solve certain astrophysical problems. Around luminous sources, some evidence of decreased star formation has been found but is limited to a handful of individual cases. No direct, conclusive evidence on the actual role of strong UV radiation in quenching star formation has been found. Here we present statistical evidence of decreased number density of faint (AB magnitude $\geq$ 24.75 mag) Ly\alpha emitters (LAEs) around bright (AB magnitude < 24.75 mag) LAEs even when the radius goes up to 10 pMpc for $z$ $\simeq$ 5.7 LAEs. A similar trend is found for z $\simeq$ 6.6 LAEs but only within 1 pMpc radius from the bright LAEs. We use a large sample of 1077 (962) LAEs at $z$ $\simeq$ 5.7 ($z$ $\simeq$ 6.6) selected in total areas of 14 (21) deg$^2$ with Subaru/Hyper Suprime-Cam narrow-band data, and thus, the result is of statistical significance for the first time at these high redshift ranges. A simple analytical calculation indicates that the radiation from the central LAE is not enough to suppress LAEs with AB mag $\geq$ 24.75 mag around them, suggesting additional physical mechanisms we are unaware of are at work. Our results clearly show that the environment is at work for the galaxy formation at $z$ $\sim$ 6 in the Universe., Comment: Accepted for publication at MNRAS