arXiv subjects

Qiong Li

Publications and source records attributed to Qiong Li.

At least 37 records · Page 2Linked to original sources

arXiv2025

(SHERRY) JCMT-SCUBA2 High Redshift Bright Quasar Survey -- II: the environment of z~6 quasars in sub-millimeter band

The formation of the first supermassive black holes is expected to have occurred in some most pronounced matter and galaxy overdensities in the early universe. We have conducted a sub-mm wavelength continuum survey of 54 $z\sim6$ quasars using the Submillimeter Common-User Bolometre Array-2 (SCUBA2) on the James Clerk Maxwell Telescope (JCMT) to study the environments around $z \sim 6$ quasars. We identified 170 submillimeter galaxies (SMGs) with above 3.5$σ$ detections at 450 or 850 \um\, maps. Their FIR luminosities are 2.2 - 6.4 $\times$ 10$^{12} L_{\odot}$, and star formation rates are $\sim$ 400 - 1200 M$_{\odot}$ yr$^{-1}$. We also calculated the SMGs differential and cumulative number counts in a combined area of $\sim$ 620 arcmin$^2$. To a $4σ$ detection (at $\sim$ 5.5 mJy), SMGs overdensity is $0.68^{+0.21}_{-0.19}$($\pm0.19$), exceeding the blank field source counts by a factor of 1.68. We find that 13/54 quasars show overdensities (at $\sim$ 5.5 mJy) of $δ_{SMG}\sim$ 1.5 - 5.4. The combined area of these 13 quasars exceeds the blank field counts with the overdensity to 5.5 mJy of \dsmg $\sim$ $2.46^{+0.64}_{-0.55}$($\pm0.25$) in the regions of $\sim$ 150 arcmin$^2$. However, the excess is insignificant on the bright end (e.g., 7.5 mJy). We also compare results with previous environmental studies of Lyman alpha emitters (LAEs) and Lyman-Break Galaxies (LBGs) on a similar scale. Our survey presents the first systematic study of the environment of quasars at $z\sim6$. The newly discovered SMGs provide essential candidates for follow-up spectroscopic observations to test whether they reside in the same large-scale structures as the quasars and search for protoclusters at an early epoch.

astro-ph.GA↗

arXiv2025

Nonlinear ferroelectric characteristics of barium titanate nanocrystals determined via a polymer nanocomposite approach

The growing demand for high energy storage materials has garnered substantial attention towards lead-free ferroelectric nanocrystals (NCs), such as BaTiO3 (BTO), for next-generation multilayer ceramic capacitors. Notably, it remains challenging to accurately measure the dielectric constant and polarization-electric field (P-E) hysteresis loop for BTO NCs. Herein, we report on nonlinear ferroelectric characteristics of BTO NCs via a polymer nanocomposite approach. Specifically, poly(vinyl pyrrolidone)(PVP)/BTO nanocomposite films of 3-10 μm thickness, containing 380 nm tetragonal-phased and 60 nm cubic-phased BTO NCs with uniform particle dispersion, were prepared. Theoretical deconvolution of the broad experimental P-E loops of the PVP/BTO NC composite films revealed three contributions, that is, the linear deformational polarization of the nanocomposites, the polarization of BTO NCs (Pp ), and the polarization from strong particle-particle interactions. Using different mixing rules and nonlinear dielectric analysis, the overall dielectric constants of BTO NCs were obtained, from which the internal field in the BTO NCs (Ep ) was estimated. Consequently, the Pp-Ep hysteresis loops were obtained for the BTO380 and BTO60 NCs. Interestingly, BTO380 exhibited square-shaped ferroelectric loops, whereas BTO60 displayed slim paraelectric loops. This work presents a robust and versatile route to extract the Pp-Ep loops of ferroelectric NCs from polymer/ceramic nanocomposites.

cond-mat.mtrl-sci↗

arXiv2025

Galaxy Mergers in the Epoch of Reionization I: A JWST Study of Pair Fractions, Merger Rates, and Stellar Mass Accretion Rates at $z = 4.5-11.5$

We present a full analysis of galaxy major merger pair fractions, merger rates, and mass accretion rates, thus uncovering the role of mergers in galaxy formation at the earliest previously unexplored epoch of $4.5<z<11.5$. We target galaxies with masses $\log_{10}(\mathrm{M}_*/\mathrm{M}_\odot) = 8.0 - 10.0$, utilizing data from eight JWST Cycle-1 fields (CEERS, JADES GOODS-S, NEP-TDF, NGDEEP, GLASS, El-Gordo, SMACS-0723, MACS-0416), covering an unmasked area of 189.36 $\mathrm{arcmin}^2$. We develop a new probabilistic pair-counting methodology that integrates full photometric redshift posteriors and corrects for detection incompleteness to quantify close pairs with physical projected separations between 20 and 50 kpc. Our analysis reveals an increase in pair fractions up to $z = 8$, reaching $0.211 \pm 0.065$, followed by a statistically flat evolution to $z = 11.5$. We find that the galaxy merger rate increases from the local Universe up to $z = 6$ and then stabilizes at a value of $\sim 6$ Gyr$^{-1}$ up to $z = 11.5$. The redshift evolution of both pair fractions and merger rates is well described by a power-law plus exponential model. In addition, we measure that the average galaxy increases its stellar mass due to mergers by a factor of $2.77 \pm 0.99$ from redshift $z = 10.5$ to $z = 5.0$. Lastly, we investigate the impact of mergers on galaxy stellar mass growth, revealing that mergers contribute as much as $71 \pm 25\%$ to galaxy stellar mass growth. This indicates that mergers drive about half of galaxy assembly at high redshift.

astro-ph.GA↗

arXiv2025

Enable Lightweight and Precision-Scalable Posit/IEEE-754 Arithmetic in RISC-V Cores for Transprecision Computing

While posit format offers superior dynamic range and accuracy for transprecision computing, its adoption in RISC-V processors is hindered by the lack of a unified solution for lightweight, precision-scalable, and IEEE-754 arithmetic compatible hardware implementation. To address these challenges, we enhance RISC-V processors by 1) integrating dedicated posit codecs into the original FPU for lightweight implementation, 2) incorporating multi/mixed-precision support with dynamic exponent size for precision-scalability, and 3) reusing and customizing ISA extensions for IEEE-754 compatible posit operations. Our comprehensive evaluation spans the modified FPU, RISC-V core, and SoC levels. It demonstrates that our implementation achieves 47.9% LUTs and 57.4% FFs reduction compared to state-of-the-art posit-enabled RISC-V processors, while achieving up to 2.54$\times$ throughput improvement in various GEMM kernels.

cs.AR↗

arXiv2025

Behind the Spotlight: A systematic assessment of outshining using NIRCam medium-bands in the JADES Origins Field

The spatial resolution and sensitivity of JWST's NIRCam instrument has revolutionised our ability to probe the internal structure of early galaxies. By leveraging deep medium-band imaging in the Jades Origins Field, we assemble comprehensive spectral energy distributions (SEDs) using 19 photometric bands for over 200 high-redshift galaxies ($z \geq 4.5$). We present an analysis of this sample with particular emphasis on investigating the "outshining" phenomenon, which can bias the inferred stellar populations by masking the presence of evolved stellar populations ($\geq$ 100 Myr) with the light of bright, young O and B-type stars. We address this problem by performing spatially-resolved SED-fitting of both binned and full pixel-by-pixel photometry, which we compare to the traditional integrated approach. We find evidence for systematic underestimation of stellar mass in low-mass galaxies ($\leq 10^9 \rm M_\odot$) with bursty star formation, which can exceed a factor of 10 in individual cases, but on average is typically a factor of 1.25-2.5, depending on the binning methodology and SFH model used. The observed mass offset correlates with burstiness (SFR$_{10 \ \rm Myr}$/SFR$_{100 \ \rm Myr}$) and sSFR, such that galaxies with recently rising SFHs have larger mass offsets. The integrated SFH models which produce the most consistent stellar masses are the double power-law and non-parametric `continuity' models, although no integrated model fully reproduces all resolved SFHs. We apply an outshining correction factor to the Stellar Mass Function at $z=7$, finding little impact within the uncertainties. We conclude that outshining can be important in individual low-mass galaxies, but the overall impact is limited and should be considered alongside other systematic SED fitting effects.

astro-ph.GA↗

arXiv2025

JWSTs PEARLS: NIRCam imaging and NIRISS spectroscopy of a $z=3.6$ star-forming galaxy lensed into a near-Einstein Ring by a $z=1.258$ massive elliptical galaxy

We present the discovery, and initial lensing analysis, of a high-redshift galaxy-galaxy lensing system within the JWST-PEARLS/HST-TREASUREHUNT North Ecliptic Pole Time Domain Field (designated NEPJ172238.9+655143.1). The lensing geometry shears a $z=3.6\pm0.1$ star-forming galaxy into a near-Einstein ring with a radius of 0\farcs92, consisting of 4 primary images, around a foreground massive elliptical galaxy at $z=1.258\pm0.005$. The system is fortuitously located within the NIRISS F200W footprint of the PEARLS survey, enabling spectroscopic identification of the 8500A TiO band in the foreground galaxy and allowing tight constraints to be placed on the redshift of the background galaxy based on its continuum detection and lack of strong emission lines. We calculate magnification factors of $2.6<μ<8.4$ for the four images and a total lensing mass of $(4.08 \pm 0.07)\times10^{11}M_\odot$. SED fitting of the foreground elliptical galaxy within the Einstein radius reveals a stellar mass of $\sim1.26\times10^{11}M_\odot$, providing a mass/light ratio of 3.24. Employing simple scaling relations and assumptions, an NFW dark matter halo is found to provide the correct remaining mass within $0.12^{+0.21}_{-0.09}$dex. However, if a bottom-heavy IMF for elliptical galaxies is employed, stellar mass estimations increase and can account for the majority of the lensing mass (up to $\sim$83\%), reducing the need for dark matter. This system further demonstrates the new discovery space that the combined wavelength coverage, sensitivity and resolution of JWST now enables.

astro-ph.GA↗

arXiv2025

Large-Scale FPGA-Based Privacy Amplification Exceeding $10^8$ Bits for Quantum Key Distribution

Privacy Amplification (PA) is indispensable in Quantum Key Distribution (QKD) post-processing, as it eliminates information leakage to eavesdroppers. Field-programmable gate arrays (FPGAs) are highly attractive for QKD systems due to their flexibility and high integration. However, due to limited resources, input and output sizes remain the primary bottleneck in FPGA-based PA schemes for Discrete Variable (DV)-QKD systems. In this paper, we present a large-scale FPGA-based PA scheme that supports both input block sizes and output key sizes exceeding $10^8$ bits, effectively addressing the challenges posed by the finite-size effect. To accommodate the large input and output sizes, we propose a novel PA algorithm and prove its security. We implement and evaluate this scheme on a Xilinx XCKU095 FPGA platform. Experimental results demonstrate that our PA implementation can handle an input block size of $10^8$ bits with flexible output sizes up to the input size. For DV-QKD systems, our PA scheme supports an input block size nearly two orders of magnitude larger than current FPGA-based PA schemes, significantly mitigating the impact of the finite-size effect on the final secure key rate.

quant-ph↗

arXiv2025

EPOCHS XI: The Structure and Morphology of Galaxies in the Epoch of Reionization to z ~ 12.5

We present a structural analysis of 521 galaxy candidates at 6.5 < z < 12.5, with $SNR > 10σ$ in the F444W filter, taken from the EPOCHS v1 sample, consisting of uniformly reduced deep JWST NIRCam data, covering the CEERS, JADES GOOD-S, NGDEEP, SMACS0723, GLASS and PEARLS surveys. We use standard software to fit single Sérsic models to each galaxy in the rest-frame optical and extract their parametric structural parameters (Sérsic index, half-light radius and axis-ratio), and \texttt{Morfometryka} to measure their non-parametric concentration and asymmetry parameters. We find a wide range of sizes for these early galaxies, but with a strong galaxy-size mass correlation up to $z \sim 12$ such that galaxy sizes continue to get progressively smaller in the high-redshift regime, following $R_{e} = 2.74 \pm 0.49 \left( 1 + z \right) ^{-0.79 \pm 0.08}$ kpc. Using non-parametric methods we find that galaxy merger fractions, classified through asymmetry parameters, at these redshifts remain consistent with those in literature, maintaining a value of $f_{m} \sim 0.12 \pm 0.07$ showing little dependence with redshift when combined with literature at $z > 4$. We find that galaxies which are smaller in size also appear rounder, with an excess of high axis-ratio objects. Finally, we artificially redshift a subsample of our objects to determine how robust the observational trends we see are, determining that observed trends are due to real evolutionary effects, rather than being a consequence of redshift effects.

astro-ph.GA↗

arXiv2025

Like a candle in the wind: The embers of once aflame, now smouldering galaxies at $5 < z < 8$

We develop a photometric search method for identifying smouldering galaxies at $5< z < 8$, which are defined to have weak emission lines and thus generally have low specific star formation rates and may even be in a state of (temporary) quiescence. The deep NIRCam imaging (${\sim}29.5$ AB mag, 5$σ$) from the JADES second data release is essential for finding these systems, as they are faint, relatively quiescent dwarf galaxies ($M_* \sim 10^{8}$-$10^9$ $\mathrm{M}_\odot)$ in the Epoch of Reionisation (EoR). Moreover, medium-band imaging is key, enabling a clear identification of the lack of emission lines in these galaxies, thus betraying their dormant flame. Owing to the young age of the Universe, combined with the likely bursty star formation in these first dwarf galaxies, conventional colour-selection methods like the UVJ diagram likely miss a large fraction of the quiescent population in the EoR. Indeed, we find that smouldering galaxies constitute a considerable fraction (0.05-0.35) of the EoR dwarf galaxy population ($M_* \sim 10^{8}$-$10^{9}$ $\mathrm{M}_\odot$). As predicted by simulations, these first dwarf galaxies are fragile, the star formation in their shallow potential wells easily snuffed out by feedback-driven winds triggered by secular or merger-driven starbursts, with the smouldering fraction increasing with decreasing stellar mass. Finally, we provide observational constraints on the smouldering galaxy comoving number density (${\sim}10^{-4}$-$10^{-5}$ dex$^{-1}$ Mpc$^{-3}$), which, although hampered by incompleteness, should aid in our understanding of the primordial baryon cycle, as current simulations greatly disagree on whether these systems are rare (${\sim}1\%$) or common (${\sim}50\%$) in the EoR.

astro-ph.GA↗

arXiv2025

Galaxy Mergers in the Epoch of Reionization II: Major Merger-Triggered Star Formation and AGN Activities at $z =$ 4.5-8.5

Galaxy mergers are a key driver of galaxy formation and evolution, including the triggering of AGN and star formation to a still unknown degree. We thus investigate the impact of galaxy mergers on star formation and AGN activity using a sample of 3,330 galaxies at $z = [4.5, 8.5]$ from eight JWST fields (CEERS, JADES GOODS-S, NEP-TDF, NGDEEP, GLASS, El-Gordo, SMACS-0723, and MACS-0416), collectively covering an unmasked area of 189 arcmin$^2$. We focuses on star formation rate (SFR) enhancement, AGN fraction, and AGN excess in major merger ($μ> 1/4$) close-pair samples, defined by $Δz < 0.3$ and projected separations $r_p < 100$ kpc, compared to non-merger samples. We find that SFR enhancement occurs only at $r_p < 20$ kpc, with values of $0.25 \pm 0.10$ dex and $0.26 \pm 0.11$ dex above the non-merger medians for $z = [4.5, 6.5]$ and $z = [6.5, 8.5]$. No other statistically significant enhancements in galaxy sSFR or stellar mass are observed at any projected separation or redshift bin. We also compare our observational results with predictions from the SC-SAM simulation and find no evidence of star formation enhancement in the simulations at any separation range. Finally, we examine the AGN fraction and AGN excess, finding that the fraction of AGNs in AGN-galaxy pairs, relative to the total AGN population, is $3.25^{+1.50}_{-1.06}$ times greater than the fraction of galaxy pairs relative to the overall galaxy population at the same redshift. We find that nearly all AGNs have a companion within 100 kpc and observe an excess AGN fraction in close-pair samples compared to non-merger samples. This excess is found to be $1.26 \pm 0.06$ and $1.34 \pm 0.06$ for AGNs identified via the inferred BPT diagram and photometric SED selection, respectively.

astro-ph.GA↗

arXiv2025

EPOCHS IV: SED Modelling Assumptions and their impact on the Stellar Mass Function at 6.5 < z < 13.5 using PEARLS and public JWST observations

We utilize deep JWST NIRCam observations for the first direct constraints on the Galaxy Stellar Mass Function (GSMF) at $z>10$. Our EPOCHS v1 sample includes 1120 galaxy candidates at $6.5<z<13.5$ taken from a consistent reduction and analysis of publicly available deep JWST NIRCam data covering the PEARLS, CEERS, GLASS, JADES GOOD-S, NGDEEP, and SMACS0723 surveys, totalling 187 arcmin$^2$. We investigate the impact of SED fitting methods, assumed star formation histories (SFH), dust laws, and priors on galaxy masses and the resultant GSMF. Whilst our fiducial GSMF agrees with the literature at $z<13.5$, we find that the assumed SFH model has a large impact on the GSMF and stellar mass density (SMD), finding a 0.75~dex increase in the SMD at $z=10.5$ between a flexible non-parametric and standard parametric SFH. Overall, we find a flatter SMD evolution at $z \geq 9$ than some studies predict, suggesting a rapid buildup of stellar mass in the early Universe. We find no incompatibility between our results and those of standard cosmological models, as suggested previously, although the most massive galaxies may require a high star formation efficiency. We find that the "Little Red Dot" galaxies dominate the $z=7$ GSMF at high-masses, necessitating a better understanding of the relative contributions of AGN and stellar emission. We show that assuming a theoretically motivated top-heavy IMF reduces stellar mass by 0.5~dex without affecting fit quality, but our results remain consistent with existing cosmological models with a standard IMF.

astro-ph.GA↗

arXiv2025

MAMMOTH-Subaru IV. Large Scale Structure and Clustering Analysis of Ly$α$ Emitters and Ly$α$ Blobs at $z=2.2-2.3$

We report the large scale structure and clustering analysis of Ly$α$ emitters (LAEs) and Ly$α$ blobs (LABs) at $z=2.2-2.3$. Using 3,341 LAEs, 117 LABs, and 58 bright (Ly$α$ luminosity $L_{\rm Lyα}>10^{43.4}$ erg s$^{-1}$) LABs at $z=2.2-2.3$ selected with Subaru/Hyper Suprime-Cam, we calculate the LAE overdensity to investigate the large scale structure at $z=2$. We show that $79\%$ LABs and $83\%$ bright LABs locate in overdense regions, which is consistent with the trend found by previous studies that LABs generally locate in overdense regions. We find that one of our 8 fields dubbed J1349 contains $39/117\approx33\%$ of our LABs and $22/58\approx38\%$ of our bright LABs. A unique and overdense $24'\times12'$ ($40\times20$ comoving Mpc$^2$) region (J1347 protocluster) has 12 LABs (8 bright LABs). By comparing to SSA22 that is one of the most overdense LAB regions found by previous studies, we show that the J1347 protocluster region has a higher bright LAB density than the SSA22 protocluster region with a $1σ$ significance. We calculate the angular correlation functions (ACFs) of LAEs and LABs in the unique J1349 field and fit the ACFs with a power-law function to measure the slopes. The bright LABs show a $5σ$ larger slope suggesting that bright LABs are more clustered than faint LAEs. Our LABs have a large galaxy bias of $\sim 5-7$, which suggests that LABs generally reside in more massive dark matter halos (halo masses $M \gtrsim 10^{13}$ M$_{\odot}$) than faint LAEs.

astro-ph.GA↗

arXiv2025

Direct high-resolution observation of feedback and chemical enrichment in the circumgalactic medium at redshift z ~ 2.8

The circumgalactic medium (CGM) plays a vital role in galaxy evolution, however, studying the emission from CGM is challenging due to its low surface brightness and the complexities involved in interpreting resonant lines such as Ly$α$. The near-infrared coverage, unprecedented sensitivity, and high spatial resolution of JWST enable us to study the optical strong lines associated with the extended Ly$α$ "nebulae" at redshifts of 2--3. These lines serve as diagnostic tools to infer the physical conditions in the CGM gas reservoir of these systems. In deep medium-band images taken by the JWST, we serendipitously discovered the [O III] emission from the CGM around a massive interacting galaxy system at a redshift z~2.8, known to be embedded in a bright extended (100 kpc) Ly$α$ "nebula." This is the first time that the [O III] lines have been detected from a Ly$α$ "nebula." The JWST images reveal that the CGM gas actually resides in narrow (~ 2.5 kpc) filamentary structures with strong [O III] emission, tracing the same extent as the Ly$α$ emission. An analysis of the [O III] suggests that the emitting CGM is fully ionized and is energetically dominated by mechanical heating. We also find that the density and pressure are higher than those commonly predicted by simulations of the CGM. We conclude that the observed CGM emission originates from the gas expelled by the episodic feedback processes, cooling down and enriching the CGM, while traveling a distance of at least 60 kpc. These observations demonstrate how intensive feedback processes shape gas distribution and properties in the CGM around massive halos. While access to such deep, high-resolution imaging opens up a new discovery space for investigating the CGM, it also challenges numerical simulations with respect to explaining and reproducing the exquisitely complex structures revealed by the observations.

astro-ph.GA↗

arXiv2025

New Methods of Identifying AGN in the Early Universe using Spectroscopy and Photometry in the JWST Era

We explore spectroscopic and photometric methods for identifying high-redshift galaxies containing an Active Galactic Nucleus (AGN) with JWST observations. After demonstrating the limitations of standard optical methods, which appear ineffective in the low-metallicity environment of the early universe, we evaluate alternative diagnostic techniques using the current JWST observational capabilities. Our analysis focuses on line ratios and equivalent widths (EWs) of UV emission lines: CIV, HeII $λ$1640, OIII] $λ$1665, and CIII], and the faint optical line, HeII $λ$4686. We find that the most valuable diagnostic quantities for finding AGN are the line ratios: (CIII] + CIV) / HeII $λ$1640 and CIII] / HeII $λ$1640, as well as the EW of HeII $λ$1640. For more reliable AGN identification, the HeII $λ$1640 and OIII] $λ$1665 lines would need to be detected separately. We show that the HeII $λ$1640/H$β$ ratio effectively separates AGN from star-forming galaxies, though it is contingent on a low dust content. We also show that in order to effectively use these diagnostics, future observations require longer exposure times, especially for galaxies at $z > 6$. Subsequently, we plot three real high-redshift sources on these diagrams which present strong UV emission lines. However, in order to classify them as strong AGN candidates, further study is needed due to the blending of HeII + OIII] and unreliable optical lines. Lastly, we carry out a selection process using spectral energy distribution (SED) fitting with EAZY to identify strong AGN candidates in the JADES NIRCam photometry. One galaxy in our sample emerged as a strong AGN candidate, supported by both photometric selection and strong UV emission. We present a sample of similar AGN candidates in the JADES data based on this method.

astro-ph.GA↗

arXiv2025

Improving key rates by tighter information reconciliation leakage estimation for quantum key distribution

Previous research has aimed to precisely estimate information leakage to improve the secure key rate (SKR) and maximum transmission distance in quantum key distribution (QKD). However, existing methods repeatedly considerd the information of the multi-photon pulses known to Eve before and after information reconciliation, resulting in an overestimation of the leakage amount. We propose a novel approach that considers the quantum part's effect on post-processing, providing a more accurate estimation of information reconciliation leakage to improve the SKR. Theoretical analysis shows that our method more accurately estimates the information reconciliation leakage, significantly improving the SKR at any distance as well as the maximum transmission distance. It is worth mentioning that previous studies treat information leakage of the error correction as Shannon bound $Nh(e)$, and our method can estimate it more tightly. Simulation results for decoy-BB84 and measurement-device-independent (MDI) protocols using Cascade are consistent with the theoretical analysis. The farther the transmission distance, the greater the growth rate of SKR. When the error rate is 33%, compared with the original method, the SKR growth rate of decoy-BB84 at 100KM is 100.4%, and the transmission distance of MDI increases by 22KM.

quant-ph↗

arXiv2025

Extend the random-walk shielding-potential viscosity model to hot temperature regime

The transport properties of matter have been widely investigated. In particular, shear viscosity over a wide parameter space is crucial for various applications, such as designing inertial confinement fusion (ICF) targets and determining the Rayleigh-Taylor instability. In this work, an extended random-walk shielding-potential viscosity model (ext-RWSP-VM) based on the statistics of random-walk ions and the Debye shielding effect is proposed to elevate the temperature limit of RWSP-VM [Phys. Rev. E 106, 014142] in evaluating the shear viscosity of one component plasma. In the extended model, we reconsider the collision distance that is introduced by hard-sphere concept, hence, it is applicable in wide temperature regime rather than a narrower one in which RWSP-VM is applicable. The results of H, C, Al, Fe, Ge, W, and U show that the extended model provides a systematic way to calculate the shear viscosity of arbitrary one component plasma at the densities from about 0.1 to 10 times the normal density (the density at room temperature and 1 standard atmosphere). This work will help to develop viscosity model in wide regime when combined with our previous low temperature viscosity model [AIP Adv. 11, 015043].

cond-mat.stat-mech↗

arXiv2024

MAMMOTH-Subaru. II. Diverse Populations of Circumgalactic Ly$α$ Nebulae at Cosmic Noon

Circumgalactic Lyman-alpha (Ly$α$) nebulae are gaseous halos around galaxies exhibiting luminous extended Ly$α$ emission. This work investigates Ly$α$ nebulae from deep imaging of $\sim12~\mathrm{deg}^2$ sky, targeted by the MAMMOTH-Subaru survey. Utilizing the wide-field capability of Hyper Suprime-Cam (HSC), we present one of the largest blind Ly$α$ nebula selections, including QSO nebulae, Ly$α$ blobs, and radio galaxy nebulae down to typical $2σ$ Ly$α$ surface brightness of $(5-10)\times10^{-18}\mathrm{~erg~s^{-1}~cm^{-2}~arcsec^{-2}}$. The sample contains 117 nebulae with Ly$α$ sizes of 40 - 400 kpc, and the most gigantic one spans about 365 kpc, referred to as the Ivory Nebula. Combining multiwavelength data, we investigate diverse nebula populations and associated galaxies. We find a small fraction of Ly$α$ nebulae have QSOs ($\sim7\%$), luminous infrared galaxies ($\sim1\%$), and radio galaxies ($\sim 2\%$). Remarkably, among the 28 enormous Ly$α$ nebulae (ELANe) exceeding 100 kpc, about 80\% are associated with UV-faint galaxies ($M_\mathrm{UV} > -22$), categorized as Type II ELANe. We underscore that Type II ELANe constitute the majority but remain largely hidden in current galaxy and QSO surveys. Dusty starburst and obscured AGN activity are proposed to explain the nature of Type II ELANe. The SED of stacking all Ly$α$ nebulae also reveals signs of massive dusty star-forming galaxies with obscured AGNs. We propose a model to explain the dusty nature where the diverse populations of Ly$α$ nebulae capture massive galaxies at different evolutionary stages undergoing violent assembling. Ly$α$ nebulae provide critical insights into the formation and evolution of today's massive cluster galaxies at cosmic noon.

astro-ph.GA↗

arXiv2024

JWST view of four infant galaxies at z=8.31-8.49 in the MACS0416 field and implications for reionization

New JWST/NIRCam wide-field slitless spectroscopy provides redshifts for four z>8 galaxies located behind the lensing cluster MACS J0416.1-2403. Two of them, "Y1" and "JD", have previously reported spectroscopic redshifts based on ALMA measurements of [OIII] 88 $μ$m and/or [CII] 157.7 $μ$m lines. Y1 is a merging system of three components, and the existing redshift z=8.31 is confirmed. However, JD is at z=8.34 instead of the previously claimed z=9.28. JD's close companion, "JD-N", which was a previously discovered z>8 candidate, is now identified at the same redshift as JD. JD and JD-N form an interacting pair. A new candidate at z>8, "f090d_018", is also confirmed and is at z=8.49. These four objects are likely part of an overdensity that signposts a large structure extending ~165 kpc in projected distance and ~48.7 Mpc in radial distance. They are magnified by less than one magnitude and have intrinsic $M_{UV}$ ranging from -19.57 to -20.83 mag. Their spectral energy distributions show that the galaxies are all very young with ages ~ 4-18 Myr and stellar masses about $10^{7-8}$ ${\rm M_\odot}$. These infant galaxies have very different star formation rates ranging from a few to over a hundred $\rm{M_\odot}$ yr$^{-1}$, but only two of them (JD and f090d_018) have blue rest-frame UV slopes $β<-2.0$ indicative of a high Lyman-continuum photon escape fraction that could contribute significantly to the cosmic hydrogen-reionizing background. Interestingly, these two galaxies are the least massive and least active ones among the four. The other two systems have much flatter UV slopes largely because of their high dust extinction ($A_{\rm V}$=0.9-1.0 mag). Their much lower indicated escape fractions show that even very young, actively star-forming galaxies can have negligible contribution to reionization when they quickly form dust throughout their bodies.

astro-ph.GA↗