arXiv subjects

Jiasheng Huang

Publications and source records attributed to Jiasheng Huang.

At least 19 recordsLinked to original sources

arXiv2026

One Click to Leak: Characterizing the Real-World Usage and Threat Impact of MNO-based Single Sign-On Websites

Mobile Network Operator (MNO)-based Single Sign-On (MSSO) is a password-free authentication framework relying on mobile data sessions. Unlike traditional SSO, it shifts the Identity Provider (IdP) to the MNO and the authentication anchor to the Service Provider (SP). MSSO is increasingly deployed and has expanded from mobile apps to websites, yet its web ecosystem and security risks remain largely unexplored. We analyze mainstream MSSO deployments and identify a 3-phase workflow with three trust defects enabling trust hijacking. We further demonstrate One-Click-to-Leak (OCL) attacks, where a single webpage visit can leak sensitive identity information (e.g., phone numbers). With a leading security company, we conduct the first large-scale, longitudinal study of web-based MSSO. We design a hierarchical detection framework using passive DNS correlations and URL reconstruction from search data to identify MSSO-enabled websites. Over one year, we identified 116,852 website URLs across 729 apex domains. Of these URLs, 73.6% exhibit at least one trust defect: 69.4% expose developer credentials, and 27.1% issue high-privilege tokens before user consent, indicating widespread OCL-enabling trust defects. Among the 729 apex domains, 31.8% rely on Resellers, obscuring the downstream SP from the MNO in the analyzed flows. Script analysis identifies 101 websites strongly associated with OCL attack behavior. With our partner, we trace a representative upstream platform subsequently seized by law enforcement and uncover a monetized underground ecosystem. Sanitized backend data shows that it collected 14,100 users' phone numbers within three days and linked them to sensitive information such as browsing activity. Our work provides a comprehensive study of web-based MSSO deployment and security implications. Through responsible disclosure, our work helps secure the mobile authentication ecosystem.

cs.CR↗

arXiv2026

ULTIMATE-deblending I. A 50-band Ultraviolet to Mid-infrared Photometric Catalog Combining Space- and Ground-based Data in the JWST/PRIMER survey

Our understanding of the early Universe has long been limited by biased galaxy samples selected through various color criteria. With deep JWST infrared imaging, mass-complete galaxy samples can now be studied up to $z \sim 8$ for the first time. However, recent work has revealed systematic uncertainties in measuring physical properties of galaxies based solely on JWST/NIRCam and HST photometry, due to their limited wavelength coverage. This highlights the need for supplementary data, particularly in the rest-frame UV and near-infrared. Here we present the ULTIMATE-deblending project, which will eventually deliver self-consistent UV to radio photometry for galaxies detected in deep JWST surveys, including both NIRCam and MIRI data. In this first paper, we release a 50-band photometric catalog spanning CFHT/U to JWST/MIRI F1800W, covering a total of 627.1 arcmin$^2$ across two JWST/PRIMER fields. We detail the reduction of the JWST imaging data, the photometric procedures, and the spectral-energy-distribution-fitting methodology used to derive the galaxy properties. Compared with photometry including only HST and JWST bands, the inclusion of deblended low-resolution photometry from ground-based telescopes improves the accuracy of photometric redshifts by $\sim$40%, while reducing the outlier fraction by $\sim$60%. This galaxy sample can serve as a key reference for statistical studies of galaxy formation and evolution in the early Universe. The UV-to-MIR catalogs and JWST mosaics from the ULTIMATE-deblending project have been made publicly available.

astro-ph.GA↗

arXiv2025

Noema formIng Cluster survEy (NICE): A Census of Star Formation and Cold Gas Properties in Massive protoclusters at 1.5<z<4

Massive protoclusters at z~1.5-4, the peak of the cosmic star formation history, are key to understanding the formation mechanisms of massive galaxies in today's clusters. However, studies of protoclusters at these high redshifts remain limited, primarily due to small sample sizes and heterogeneous selection criteria. In this work, we conduct a systematic investigation of the star formation and cold gas properties of member galaxies of eight massive protoclusters in the COSMOS field, using the statistical and homogeneously selected sample from the Noema formIng Cluster survEy (NICE). Our analysis reveals a steep increase in the star formation rates per halo mass ($Σ_{\rm SFR} /M_{\rm halo}$) with redshifts in these intensively star-forming protoclusters, reaching values one to two orders of magnitude higher than those observed in the field at z>2. We further show that, instead of an enhancement of starbursts, this increase is largely driven by the concentration of massive and gas-rich star-forming galaxies in the protocluster cores. The member galaxies still generally follow the same star formation main sequence as in the field, with a moderate enhancement at the low mass end. Notably, the most massive protocluster galaxies ($M_\star$>8$\times$10$^{10}$M$_\odot$) exhibit higher $f_{\rm gas}$ and $τ_{\rm gas}$ than their field counterparts, while remaining on the star forming main sequence. These gas-rich, massive, and star-forming galaxies are predominantly concentrated in the protocluster cores and are likely progenitors of massive ellipticals in the center of today's clusters. These results suggest that the formation of massive galaxies in such environments is sustained by substantial gas reservoirs, which support persistent star formation and drive early mass assembly in forming cluster cores.

astro-ph.GA↗

arXiv2024

NOEMA formIng Cluster survEy (NICE): Characterizing eight massive galaxy groups at $1.5 < z < 4$ in the COSMOS field

The NOEMA formIng Cluster survEy (NICE) is a large program targeting 69 massive galaxy group candidates at $z>2$ in six deep fields. We report spectroscopic confirmation of eight groups at $1.65\leq z\leq3.61$ in COSMOS. Homogeneously selected as significant overdensities of red IRAC sources with red Herschel colors, four groups are confirmed by CO and [CI] with NOEMA 3mm observations, three are confirmed with ALMA, and one is confirmed by H$α$ from Subaru/FMOS. We constructed the integrated FIR SEDs for the eight groups, obtaining total IR SFR $=260-1300~{\rm M_\odot}$~yr$^{-1}$. We adopted six methods to estimate the dark matter masses, including stellar mass to halo mass relations, overdensity with galaxy bias, and NFW profile fitting to radial stellar mass density. We found the radial stellar mass density are consistent with a NFW profile, supporting that they are collapsed structures hosted by a single dark matter halo. The best halo mass estimates are $\log(M_{\rm h}/{\rm M_\odot})=12.8-13.7$ with uncertainty of 0.3 dex. From halo mass estimates, we derive baryonic accretion rate ${\rm BAR}=(1-8)\times10^{3}\,{\rm M_{\odot}/yr}$ for this sample. We find a quasi-linear correlation between the integrated SFR/BAR and the theoretical halo mass limit for cold streams, $M_{\rm stream}/M_{\rm h}$, with ${\rm SFR/BAR}=10^{-0.46\pm0.22}\left({M_{\rm stream}/M_{\rm h}}\right)^{0.71\pm0.16}$ with a scatter of $0.40\,{\rm dex}$. Further, we compare halo masses and stellar masses with simulations, and find all structures are consistent with being progenitors of $M_{\rm h}(z=0)>10^{14}\,{\rm M_{\odot}}$ galaxy clusters, and the most massive central galaxies have stellar masses consistent with brightest cluster galaxies (BCGs) progenitors in the TNG300 simulation. The results strongly suggest these structures are forming massive galaxy clusters via baryonic and dark matter accretion.

astro-ph.GA↗

arXiv2024

Infall Motions in the Hot Core Associated with Hypercompact HII Region G345.0061+01.794 B

We report high angular resolution observations, made with the Atacama Large Millimeter Array in band 6, of high excitation molecular lines of $\rm CH_3CN$ and $\rm SO_2$ and of the H29$α$ radio recombination line towards the G345.0061+01.794 B HC H II region, in order to investigate the physical and kinematical characteristics of its surroundings. Emission was detected in all observed components of the J=14$\rightarrow$13 rotational ladder of $\rm CH_3CN$ and in the $30_{4,26}-30_{3,27}$ and $32_{4,28}-32_{3,29}$ lines of $\rm SO_2$. The peak of the velocity integrated molecular emission is located $\sim$0$\,.\!\!^{\prime\prime}$4 northwest of the peak of the continuum emission. The first-order moment images and channel maps show a velocity gradient, of 1.1 km s$^{-1}$ arcsec$^{-1}$, across the source, and a distinctive spot of blueshifted emission towards the peak of the zero-order moment. The rotational temperature is found to decrease from 252$\pm24$ Kelvin at the peak position to 166$\pm16$ Kelvin at its edge, indicating that our molecular observations are probing a hot molecular core that is internally excited. The emission in the H29$α$ line arises from a region of 0$\,.\!\!^{\prime\prime}$65 in size, where its peak coincides with that of the dust continuum. We model the kinematical characteristics of the "central blue spot" feature as due to infalling motions, suggesting a central mass of 172.8$\pm8.8 M_{\odot}$. Our observations indicate that this HC H II region is surrounded by a compact structure of hot molecular gas, which is rotating and infalling toward a central mass, that is most likely confining the ionized region. The observed scenario is reminiscent of a "butterfly pattern" with an approximately edge-on torus and ionized gas roughly parallel to its rotation axis.

astro-ph.GA↗

arXiv2024

Noema formIng Cluster survEy (NICE): Discovery of a starbursting galaxy group with a radio-luminous core at z=3.95

The study of distant galaxy groups and clusters at the peak epoch of star formation is limited by the lack of a statistically and homogeneously selected and spectroscopically confirmed sample. Recent discoveries of concentrated starburst activities in cluster cores have opened a new window to hunt for these structures based on their integrated IR luminosities. Hereby we carry out the large NOEMA (NOrthern Extended Millimeter Array) program targeting a statistical sample of infrared-luminous sources associated with overdensities of massive galaxies at z>2, the Noema formIng Cluster survEy (NICE). We present the first result from the ongoing NICE survey, a compact group at z=3.95 in the Lockman Hole field (LH-SBC3), confirmed via four massive (M_star>10^10.5M_sun) galaxies detected in CO(4-3) and [CI](1-0) lines. The four CO-detected members of LH-SBC3 are distributed over a 180 kpc physical scale, and the entire structure has an estimated halo mass of ~10^13Msun and total star formation rate (SFR) of ~4000Msun/yr. In addition, the most massive galaxy hosts a radio-loud AGN with L_1.4GHz, rest = 3.0*10^25W/Hz. The discovery of LH-SBC3 demonstrates the feasibility of our method to efficiently identify high-z compact groups or forming cluster cores. The existence of these starbursting cluster cores up to z~4 provides critical insights into the mass assembly history of the central massive galaxies in clusters.

astro-ph.GA↗

arXiv2022

High emission rate from a Purcell-enhanced, triggered source of pure single photons in the telecom C-band

Several emission features mark semiconductor quantum dots as promising non-classical light sources for prospective quantum implementations. For long-distance transmission [1] and Si-based on-chip processing[2, 3], the possibility to match the telecom C-band [4] stands out, while source brightness and high single-photon purity are key features in virtually any quantum implementation [5, 6]. Here we present an InAs/InGaAs/GaAs quantum dot emitting in the telecom C-band coupled to a circular Bragg grating. The Purcell enhancement of the emission enables a simultaneously high brightness with a fiber-coupled single-photon count rate of 13.9MHz for an excitation repetition rate of 228MHz (first-lens collection efficiency ca. 17% for NA = 0.6), while maintaining a low multi-photon contribution of g(2)(0) = 0.0052. Moreover, the compatibility with temperatures of up to 40K attainable with compact cryo coolers, further underlines the suitability for out-of-the-lab implementations.

quant-ph↗

arXiv2022

Close Major Merger Pairs at $z=0$: Bulge-to-Total Ratio and Star Formation Enhancement

We present a study of the bulge-to-total ratio (B/T) of a Ks-band-selected sample of 88 close major-merger pairs of galaxies (H-KPAIR) based on 2-D decomposition of SDSS r-band images with \textsc{galfit}. We investigate the dependence of the interaction-induced specific star formation rate enhancement ($\rm sSFR_{enh}$) on the B/T ratio, and the effects of this dependence on the differences between star-forming galaxies (SFGs) in spiral+spiral (S+S) and spiral+elliptical (S+E) pairs. Of all 132 spiral galaxies in H-KPAIR, the 44 in S+E pairs show higher B/T than those in the 44 S+S pairs, with means of $\rm B/T = 0.35 \pm 0.05$ and $\rm B/T = 0.26 \pm 0.03$, respectively. There is a strong negative dependence of $\rm sSFR_{enh}$ on the B/T ratio and only paired SFGs with $\rm B/T<0.3$ show significant ($>5σ$) enhancement. Paired SFGs in S+S pairs show a similar trend, and many disky SFGs ($\rm B/T<0.1$) in S+S have strong sSFR enhancements ($\rm sSFR_{enh} > 0.7$~dex). For SFGs in S+E, the sSFR has no clear B/T dependence, nor any significant enhancement in any B/T bin. Disky SFGs in S+S show significant ($>4σ$) enhancement in the molecular gas content ($\rm M_{H_2}/M_{star}$), while SFGs in S+E have no such enhancement in any B/T bin. No significant enhancement on total gas content ($\rm M_{gas}/M_{star}$) is found in any B/T bin for paired galaxies. The star formation efficiency of either the total gas ($\rm SFE_{gas} = SFR/M_{gas}$) or the molecular gas ($\rm SFE_{H_2} = SFR/M_{H_2}$) does not depend on the B/T ratio. The only significant ($>4σ$) SFE enhancement found for paired SFGs is the $\rm SFE_{gas}$ for disky SFGs in S+S pairs.

astro-ph.GA↗

arXiv2022

Groups and protocluster candidates in the CLAUDS and HSC-SSP joint deep surveys

Using the extended halo-based group finder developed by Yang et al. (2021), which is able to deal with galaxies via spectroscopic and photometric redshifts simultaneously, we construct galaxy group and candidate protocluster catalogs in a wide redshift range ($0 < z < 6$) from the joint CFHT Large Area $U$-band Deep Survey (CLAUDS) and Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) deep data set. Based on a selection of 5,607,052 galaxies with $i$-band magnitude $m_{i} < 26$ and a sky coverage of $34.41\ {\rm deg}^2$, we identify a total of 2,232,134 groups, within which 402,947 groups have at least three member galaxies. We have visually checked and discussed the general properties of those richest groups at redshift $z>2.0$. By checking the galaxy number distributions within a $5-7\ h^{-1}\mathrm{Mpc}$ projected separation and a redshift difference $Δz \le 0.1$ around those richest groups at redshift $z>2$, we identified a list of 761, 343 and 43 protocluster candidates in the redshift bins $2\leq z<3$, $3\leq z<4$ and $z \geq 4$, respectively. In general, these catalogs of galaxy groups and protocluster candidates will provide useful environmental information in probing galaxy evolution along the cosmic time.

astro-ph.CO↗

arXiv2021

GOLDRUSH. IV. Luminosity Functions and Clustering Revealed with ~4,000,000 Galaxies at z~2-7: Galaxy-AGN Transition, Star Formation Efficiency, and Implication for Evolution at z>10

We present new measurements of rest-UV luminosity functions and angular correlation functions from 4,100,221 galaxies at z~2-7 identified in the Subaru/Hyper Suprime-Cam survey and CFHT Large-Area U-band Survey. The obtained luminosity functions at z~4-7 cover a very wide UV luminosity range of ~0.002-2000L*uv combined with previous studies, revealing that the dropout luminosity function is a superposition of the AGN luminosity function dominant at Muv<-24 mag and the galaxy luminosity function dominant at Muv>-22 mag, consistent with galaxy fractions based on 1037 spectroscopically-identified sources. Galaxy luminosity functions estimated from the spectroscopic galaxy fractions show the bright end excess beyond the Schechter function at >2sigma levels, which is possibly made by inefficient mass quenching, low dust obscuration, and/or hidden AGN activity. By analyzing the correlation functions at z~2-6 with halo occupation distribution models, we find a weak redshift evolution (within 0.3 dex) of the ratio of the star formation rate (SFR) to the dark matter accretion rate, SFR/(dMh/dt), indicating the almost constant star formation efficiency at z~2-6, as suggested by our earlier work at z~4-7. Meanwhile, the ratio gradually increases with decreasing redshift at z<5 within 0.3 dex, which quantitatively reproduces the redshift evolution of the cosmic SFR density, suggesting that the evolution is primarily driven by the increase of the halo number density due to the structure formation, and the decrease of the accretion rate due to the cosmic expansion. Extrapolating this calculation to higher redshifts assuming the constant efficiency suggests a rapid decrease of the SFR density at z>10 with $\propto10^{-0.5(1+z)}$, which will be directly tested with JWST.

astro-ph.GA↗

arXiv2021

Spectroscopically Identified Emission Line Galaxy Pairs in the WISP survey

We identify a sample of spectroscopically measured emission line galaxy (ELG) pairs up to z=1.6 from the WFC3 Infrared Spectroscopic Parallels (WISP) survey. WISP obtained slitless, near-infrared grism spectroscopy along with direct imaging in the J and H bands by observing in the pure-parallel mode with the Wide Field Camera Three (WFC3) on the Hubble Space Telescope (HST). From our search of 419 WISP fields covering an area of ~0.5 deg$^{2}$, we find 413 ELG pair systems, mostly Halpha emitters. We then derive reliable star formation rates (SFRs) based on the attenuation-corrected Halpha fluxes. Compared to isolated galaxies, we find an average SFR enhancement of 40%-65%, which is stronger for major pairs and pairs with smaller velocity separations (Delta_v < 300 km/s). Based on the stacked spectra from various subsamples, we study the trends of emission line ratios in pairs, and find a general consistency with enhanced lower-ionization lines. We study the pair fraction among ELGs, and find a marginally significant increase with redshift $f \propto (1+z)^α$, where the power-law index α=0.58$\pm$0.17 from $z\sim$0.2 to $z\sim$1.6. The fraction of Active galactic Nuclei (AGNs), is found to be the same in the ELG pairs as compared to isolated ELGs.

astro-ph.GA↗

arXiv2021

Thin-Film InGaAs Metamorphic Buffer for telecom C-band InAs Quantum Dots and Optical Resonators on GaAs Platform

The GaAs-based material system is well-known for the implementation of InAs quantum dots (QDs) with outstanding optical properties. However, these dots typically emit at a wavelength of around 900nm. The insertion of a metamorphic buffer (MMB) can shift the emission to the technologically attractive telecom C-band range centered at 1550nm. However, the thickness of common MMB designs limits their compatibility with most photonic resonator types. Here we report on the MOVPE growth of a novel InGaAs MMB with a non-linear indium content grading profile designed to maximize plastic relaxation within minimal layer thickness. Single-photon emission at 1550nm from InAs QDs deposited on top of this thin-film MMB is demonstrated. The strength of the new design is proven by integrating it into a bullseye cavity via nano-structuring techniques. The presented advances in the epitaxial growth of QD/MMB structures form the basis for the fabrication of high-quality telecom non-classical light sources as a key component of photonic quantum technologies.

physics.optics↗

arXiv2021

Bright Purcell enhanced single-photon source in the telecom O-band based on a quantum dot in a circular Bragg grating

The combination of semiconductor quantum dots (QDs) with photonic cavities is a promising way to realize non-classical light sources with state-of-the-art performances in terms of brightness, indistinguishability and repetition rate. In the present work we demonstrate the coupling of an InGaAs/GaAs QDs emitting in the telecom O-band to a circular Bragg grating cavity. We demonstrate a broadband geometric extraction efficiency enhancement by investigating two emission lines under above-band excitation, inside and detuned from the cavity mode, respectively. In the first case, a Purcell enhancement of 4 is attained. For the latter case, an end-to-end brightness of 1.4% with a brightness at the first lens of 23% is achieved. Using p-shell pumping, a combination of high count rate with pure single-photon emission (g(2)(0) = 0.01 in saturation) is achieved. Finally a good single-photon purity (g(2)(0) = 0.13) together with a high detector count rate of 191kcps is demonstrated for a temperature of up to 77K.

physics.optics↗

arXiv2020

ALMA Imaging of the CO(7-6) Line Emission in the Submillimeter Galaxy LESS 073 at redshift 4.755$^\star$

In this paper we present our imaging observations on the CO(7-6) line and its underlying continuum emission of the young submillimeter galaxy LESS 073 at redshift 4.755, using the Atacama Large Millimeter/submillimeter Array (ALMA). At the achieved resolution of $\sim$$1^{\prime\prime}.2\times0^{\prime\prime}.9$ ($8\times6$~kpc$^2$), the CO(7-6) emission is largely unresolved (with a deconvolved size of $1^{\prime\prime}.1(\pm0^{\prime\prime}.5) \times 0^{\prime\prime}.9(\pm0^{\prime\prime}.8)$), and the continuum emission is totally unresolved. The CO(7-6) line emission has an integrated flux of $0.86\pm0.08$~Jy km/s, and a line width of $343\pm40$ km/s. The continuum emission has a flux density of 0.51 mJy. By fitting the observed far-infrared (FIR) spectral energy distribution of LESS 073 with a single-temperature modified blackbody function, we obtained a dust temperature $T_{\rm dust}=57.6\pm3.5$ K, 60-to-100 $μ$m flux density ratio $f_{60}/f_{100}=0.86\pm0.08$, and total infrared luminosity $L_{\rm IR}=(5.8\pm0.9) \times 10^{12}~L_\odot$. The SED-fit-based $f_{60}/f_{100}$ is consistent with those estimated from various line ratios as advocated by our earlier work, indicating that those proposed line-ratio-based method can be used to practically derive $f_{60}/f_{100}$ for high-$z$ sources. The total molecular gas mass of LESS 073 is $(3.3\pm1.7) \times10^{10}~M_\odot$, and the inferred gas depletion time is about 43 Myr.

astro-ph.GA↗

arXiv2019

The CFHT Large Area U-band Deep Survey (CLAUDS)

The CFHT Large Area U-band Deep Survey (CLAUDS) uses data taken with the MegaCam mosaic imager on CFHT to produce images of 18.60 deg2 with median seeing of FWHM=0.92 arcsec and to a median depth of U = 27.1 AB (5 sigma in 2 arcsec apertures), with selected areas that total 1.36 deg2 reaching a median depth of U=27.7 AB. These are the deepest U-band images assembled to date over this large an area. These data are located in four fields also imaged to comparably faint levels in grizy and several narrowband filters as part of the Hyper Suprime-Cam (HSC) Subaru Strategic Program (HSC-SSP). These CFHT and Subaru datasets will remain unmatched in their combination of area and depth until the advent of the Large Synoptic Survey Telescope (LSST). This paper provides an overview of the scientific motivation for CLAUDS and gives details of the observing strategy, observations, data reduction, and data merging with the HSC-SSP. Three early applications of these deep data are used to illustrate the potential of the dataset: deep U-band galaxy number counts, z~3 Lyman break galaxy (LBG) selection, and photometric redshifts improved by adding CLAUDS U to the Subaru HSC grizy photometry.

astro-ph.GA↗

arXiv2018

Near-Infrared Survey and Photometric Redshifts in the Extended GOODS-North field

We present deep $J$ and $H$-band images in the extended Great Observatories Origins Deep Survey-North (GOODS-N) field covering an area of 0.22 $\rm{deg}^{2}$. The observations were taken using WIRCam on the 3.6-m Canada France Hawaii Telescope (CFHT). Together with the reprocessed $K_{\rm s}$-band image, the $5σ$ limiting AB magnitudes (in 2" diameter apertures) are 24.7, 24.2, and 24.4 AB mag in the $J$, $H$, and $K_{\rm s}$ bands, respectively. We also release a multi-band photometry and photometric redshift catalog containing 93598 sources. For non-X-ray sources, we obtained a photometric redshift accuracy $σ_{\mathrm{NMAD}}=0.036$ with an outlier fraction $η= 7.3\%$. For X-ray sources, which are mainly active galactic nuclei (AGNs), we cross-matched our catalog with the updated 2M-CDFN X-ray catalog from Xue et al. (2016) and found that 658 out of 683 X-ray sources have counterparts. $GALEX$ UV data are included in the photometric redshift computation for the X-ray sources to give $σ_{\mathrm{NMAD}} = 0.040$ with $η=10.5\%$. Our approach yields more accurate photometric redshift estimates compared to previous works in this field. In particular, by adopting AGN-galaxy hybrid templates, our approach delivers photometric redshifts for the X-ray counterparts with fewer outliers compared to the 3D-HST catalog, which fit these sources with galaxy-only templates.

astro-ph.GA↗

arXiv2018

CO (7-6), [CI] 370 micron and [NII] 205 micron Line Emission of the QSO BRI 1335-0417 at Redshift 4.407

We present the results from our Atacama Large Millimeter/submillimeter Array (ALMA) imaging observations of the CO (7-6), [CI] 370 um (hereafter [CI]) and [NII] 205 um (hereafter [NI]I) lines and their underlying continuum emission of BRI 1335-0417, an infrared bright quasar at z = 4.407. At the achieved resolutions of 1.1" to 1.2" (or 7.5 to 8.2 kpc), the continuum at 205 and 372 um (rest-frame), the CO (7-6), and the [CI] emissions are at best barely resolved whereas the [NII] emission is well resolved with an ALMA beam de-convolved major axis of 1.3" (+/- 0.3") or 9 (+/-2) kpc. As a warm dense gas tracer, the CO (7-6) emission shows a more compact spatial distribution and a significantly higher peak velocity dispersion than the other two lines that probe lower density gas, a picture favoring a merger-triggered star formation (SF) scenario over an orderly rotating SF disk. The CO (7-6) data also indicate a possible QSO-driven gas outflow that reaches a maximum line-of-sight velocity of 500 to 600 km/s. The far-infrared (FIR) dust temperature (T_dust) of 41.5 K from a gray-body fit to the continuum agrees well with the average T_dust inferred from various line luminosity ratios. The resulting L_CO(7-6)/L_FIR luminosity ratio is consistent with that of local luminous infrared galaxies powered predominantly by SF. The CO(7-6) luminosity-inferred SF rate is 5.1 (+/-1.5) x 10^3 M_solar/yr . The system has an effective star-forming region of 1.7 (+1.7/-0.8) kpc in diameter and a molecular gas reservoir of ~5 x 10^{11} M_solar.

astro-ph.GA↗

arXiv2016

Dynamical System of Scalar Field from 2-Dimension to 3-D and its Cosmological Implication

We give the three-dimensional dynamical autonomous systems for most of the popular scalar field dark energy models including (phantom) quintessence, (phantom) tachyon, k-essence and general non-canonical scalar field models, change the dynamical variables from variables $(x, y, λ)$ to observable related variables $(w_ϕ, Ω_ϕ, λ)$, and show the intimate relationships between those scalar fields that the three-dimensional system of k-essence can reduce to (phantom) tachyon, general non-canonical scalar field can reduce to (phantom) quintessence and k-essence can also reduce to (phantom) quintessence for some special cases. For the applications of the three-dimensional dynamical systems, we investigate several special cases and give the exactly dynamical solutions in detail. In the end of this paper, we argue that, it is more convenient and also has more physical meaning to express the differential equations of dynamical systems in $(w_ϕ, Ω_ϕ, λ)$ instead of variables $(x, y, λ)$ and to investigate the dynamical system in 3-Dimension instead of 2-Dimension. We also raise a question about the possibility of the chaotic behavior in the spatially flat single scalar field FRW cosmological models in the presence of ordinary matter.

gr-qc↗