arXiv subjects

C. Yang

Publications and source records attributed to C. Yang.

At least 55 records · Page 3Linked to original sources

arXiv2020

Etching glass in the early Universe: Luminous HF and water emission in a QSO-SMG pair at z=4.7

(abridged) We present ALMA observations of hydrogen fluoride, HF J=1-0, H20 (220-211), and the 1.2 THz rest-frame continuum emission from the z=4.7 system BR1202-0725. BR1202-0725 is a galaxy group consisting of a QSO, a sub-millimeter galaxy (SMG), and two Ly-alpha emitters. We detected HF in emission in the QSO and possibly in absorption in the SMG, while water is detected in emission in both the QSO and SMG. The QSO is the most luminous HF emitter yet found and has the same ratio of HF emission line to infrared luminosity as a sample of local AGN and the Orion Bar. This consistency covers about 10 orders-of-magnitude in infrared luminosity, L_IR. Based on the conclusions of a study of HF emission in the Orion Bar and modeling, the HF emission in the QSO is either excited by collisions with electrons and H2 in molecular plasmas irradiated by the AGN and intense star formation or predominately by collisions with H2, with a modest contribution from electrons, in a relatively high temperature (~120 K), dense (~10^5 cm^-3) medium. Although HF should be an excellent tracer of molecular outflows, we do not find strong evidence for outflows in HF in either the QSO or the SMG. From a putative absorption feature in HF in the SMG, we estimate an upper limit on the outflow rate, dM/dt_outflow <~45 M_sun/yr. The ratio of the outflow rate to the star formation rate is <5% for the SMG. The broadness of the H2O line in the SMG, FWHM~1020 km/s, may suggest that either the gas on large scales (>4 kpc) is significantly more disturbed and turbulent due either to interactions and mass exchange with the other members of the group or to the dissipation of the energy of the intense star formation or both. The lack of significant molecular outflows in either source may imply that much of the energy from the intense star formation and AGN activity in this pair is being dissipated in their ISM.

astro-ph.GA↗

arXiv2020

Dissipative engineering a tripartite Greenberger-Horne-Zeilinger state for neutral atoms

The multipartite Greenberger-Horne-Zeilinger (GHZ) states are indispensable elements for various quantum information processing tasks. Here we put forward two deterministic proposals to dissipatively prepare tripartite GHZ states in a neutral atom system. The first scheme can be considered as an extension of a recent work [T. M. Wintermantel, Y. Wang, G. Lochead, \textit{et al}, {Phys. Rev. Lett. \textbf{124}, 070503 (2020)}]. By virtue of the polychromatic driving fields and the engineered spontaneous emission, a multipartite GHZ state with odd numbers of atoms are generated with a high efficiency. This scheme effectively overcomes the problem of dependence on the initial state but sensitive to the decay of Rydberg state. In the second scenario, we exploit the spontaneous emission of the Rydberg states as a resource, thence a steady tripartite GHZ state with fidelity around $98\%$ can be obtained by simultaneously integrating the switching driving of unconventional Rydberg pumping and the Rydberg antiblockade effect.

quant-ph↗

arXiv2020

First detection of the 448 GHz ortho-H2O line at high redshift: probing the structure of a starburst nucleus at z = 3.63

Submillimeter rotational lines of H2O are a powerful probe in warm gas regions of the ISM, tracing scales and structures ranging from kpc disks to the most compact and dust-obscured regions of galactic nuclei. The ortho-H2O(423-330) line at 448 GHz, which was recently detected in a local luminous infrared galaxy (Pereira-Santaella et al. 2017), offers a unique constraint on the excitation conditions and ISM properties in deeply buried galaxy nuclei since the line requires high far-IR optical depths to be excited. In this letter, we report the first high-redshift detection of the 448 GHz H2O(423-330) line using ALMA, in a strongly lensed submillimeter galaxy (SMG) at z=3.63. After correcting for magnification, the luminosity of the 448 GHz H2O line is ~10^6 L_sun. In combination with three other previously detected H2O lines, we build a model that "resolves" the dusty ISM structure of the SMG, and find that it is composed of a ~1 kpc optically thin (optical depth at 100μm τ_{100}~0.3) disk component with dust temperature T_{dust} \approx 50 K emitting a total infrared power of 5e12 L_sun with surface density Σ_{IR}=4e11 L_sun kpc^{-2}, and a very compact (0.1 kpc) heavily dust-obscured (τ_{100} \gtrsim 1) nuclear core with very warm dust (100 K) and Σ_{IR}=8e12 L_sun kpc^{-2}. The H2O abundance in the core component, X_{H2O}~(0.3-5)e{-5}, is at least one order of magnitude higher than in the disk component. The optically thick core has the characteristic properties of an Eddington-limited starburst, providing evidence that radiation pressure on dust is capable of supporting the ISM in buried nuclei at high redshifts. The multi-component ISM structure revealed by our models illustrates that dust and molecules such as H2O are present in regions characterized by highly differing conditions and scales, extending from the nucleus to more extended regions of SMGs.

astro-ph.GA↗

arXiv2020

A hyper luminous starburst at z=4.72 magnified by a lensing galaxy pair at z=1.48

[Abridged] We discovered in the Herschel Reference Survey an extremely bright IR source with $S_{500}$~120mJy (Red Virgo 4 - RV4). Based on IRAM/EMIR and IRAM/NOEMA detections of the CO(5-4), CO(4-3), and [CI] lines, RV4 is located at z=4.724, yielding a total observed L$_{IR}$ of 1.1+/-0.6x0$^{14}$L$_{\odot}$. At the position of the Herschel emission, three blobs are detected with the VLA at 10cm. The CO(5-4) line detection of each blob confirms that they are at the same redshift with the same line width, indicating that they are multiple images of the same source. In Spitzer and deep optical observations, two sources, High-z Lens 1 (HL1) West and HL1 East, are detected at the center of the three VLA/NOEMA blobs. These two sources are placed at z=1.48 with XSHOOTER spectra, suggesting that they could be merging and gravitationally lensing the emission of RV4. HL1 is the second most distant lens known to date in strong lensing systems. The Einstein radius of the lensing system is 2.2"+/-0.2 (20kpc). The high redshift of HL1 and the large Einstein radius are highly unusual for a strong lensing system. We present the ISM properties of the background source RV4. Different estimates of the gas depletion time yield low values suggesting that RV4 is a SB galaxy. Among all high-z SMGs, this source exhibits one of the lowest L$_{[CI]}$ to L$_{IR}$ ratios, 3.2+/-0.9x10$^{-6}$, suggesting an extremely short gas tdepl of only 14+/-5Myr. It also shows a relatively high L$_{[CI]}$ to L$_{CO(4-3)}$ ratio (0.7+/-0.2) and low L$_{CO(5-4)}$ to L$_{IR}$ ratio (only ~50% of the value expected for normal galaxies) hinting a low density of gas. Finally, we discuss that the short tdepl of RV4 can be explained by either a very high SFE, which is difficult to reconcile with major mergers simulations of high-z galaxies, or a rapid decrease of SF, which would bias the estimate of tdepl toward low value.

astro-ph.GA↗

arXiv2019

NOEMA redshift measurements of bright Herschel galaxies

Using the IRAM NOrthern Extended Millimeter Array (NOEMA), we conducted a program to measure redshifts for 13 bright galaxies detected in the Herschel Astrophysical Large Area Survey (H-ATLAS) with $S_{500μ\rm m}\ge$80 mJy. We report reliable spectroscopic redshifts for 12 individual sources, which are derived from scans of the 3 and 2 mm bands, covering up to 31 GHz in each band, and are based on the detection of at least two emission lines. The spectroscopic redshifts are in the range $2.08 10^{13}\,L_\odot$ galaxies. We also present a reanalysis of the spectral energy distributions including the continuum flux densities measured at 3 and 2 mm to derive the overall properties of the sources. Future prospects based on these efficient measurements of redshifts of high-z galaxies using NOEMA are outlined, including a comprehensive survey of all the brightest Herschel galaxies.

astro-ph.GA↗

arXiv2019

A SCUBA-2 Selected Herschel-SPIRE Dropout and the Nature of this Population

Dusty star-forming galaxies (DSFGs) detected at $z > 4$ provide important examples of the first generations of massive galaxies. However, few examples with spectroscopic confirmation are currently known, with Hershel struggling to detect significant numbers of $z > 6$ DSFGs. NGP6_D1 is a bright 850 $μm$ source (12.3 $\pm$ 2.5 mJy) with no counterparts at shorter wavelengths (a SPIRE dropout). Interferometric observations confirm it is a single source, with no evidence for any optical or NIR emission, or nearby likely foreground lensing sources. No $>3σ$ detected lines are seen in both LMT RSR and IRAM 30m EMIR spectra of NGP6_D1 across 32 $GHz$ of bandwidth despite reaching detection limits of $\sim 1 mJy/500 km~s^{-1}$, so the redshift remains unknown. Template fitting suggests that NGP6_D1 is most likely between $z = 5.8$ and 8.3. SED analysis finds that NGP6_D1 is a ULIRG, with a dust mass $\sim 10^8$ - $10^9$ $M_{\odot}$ and a SFR of $\sim$ 500 $M_{\odot}~yr^{-1}$. We place upper limits on the gas mass of NGP6_D1 of $M_{H2}$ $ < (1.1~\pm~3.5) \times 10^{11}$ $M_{\odot}$, consistent with a gas-to-dust ratio of $\sim$ 100 - 1000. We discuss the nature of NGP6_D1 in the context of the broader submm population, and find that comparable SPIRE dropouts account for $\sim$ 20% of all SCUBA-2 detected sources, but with a similar flux density distribution to the general population.

astro-ph.GA↗

arXiv2019

Fast optical absorption spectra calculations for periodic solid state systems

We present a method to construct an efficient approximation to the bare exchange and screened direct interaction kernels of the Bethe-Salpeter Hamiltonian for periodic solid state systems via the interpolative separable density fitting technique. We show that the cost of constructing the approximate Bethe-Salpeter Hamiltonian scales nearly optimally as $\mathcal{O}(N_k)$ with respect to the number of samples in the Brillouin zone $N_k$. In addition, we show that the cost for applying the Bethe-Salpeter Hamiltonian to a vector scales as $\mathcal{O}(N_k \log N_k)$. Therefore the optical absorption spectrum, as well as selected excitation energies can be efficiently computed via iterative methods such as the Lanczos method. This is a significant reduction from the $\mathcal{O}(N_k^2)$ and $\mathcal{O}(N_k^3)$ scaling associated with a brute force approach for constructing the Hamiltonian and diagonalizing the Hamiltonian respectively. We demonstrate the efficiency and accuracy of this approach with both one-dimensional model problems and three-dimensional real materials (graphene and diamond). For the diamond system with $N_k=2197$, it takes $6$ hours to assemble the Bethe-Salpeter Hamiltonian and $4$ hours to fully diagonalize the Hamiltonian using $169$ cores when the brute force approach is used. The new method takes less than $3$ minutes to set up the Hamiltonian and $24$ minutes to compute the absorption spectrum on a single core.

physics.comp-ph↗

arXiv2019

CO, H2O, H2O+ line and dust emission in a z = 3.63 strongly lensed starburst merger at sub-kiloparsec scales

Using ALMA, we report high angular-resolution observations of the redshift z=3.63 galaxy, G09v1.97, one of the most luminous strongly lensed galaxies discovered by the H-ATLAS survey. We present 0"2-0"4 resolution images of the rest-frame 188 and 419$μ$m dust continuum and the CO(6-5), H2O(211-202) and J=2 H2O+ line emission. We also report the detection of H$_2^{18}$O in this source. The dust continuum and molecular gas emission are resolved into a nearly complete ~1"5 diameter Einstein ring plus a weaker image in the center, which is caused by a special dual deflector lensing configuration. The observed line profiles of the CO, H2O and H2O+ lines are strikingly similar. In the source plane, we reconstruct the dust continuum images and the spectral cubes of the line emission at sub-kpc scales. The reconstructed dust emission in the source plane is dominated by a compact disk with an effective radius of 0.7kpc plus an overlapping extended disk with a radius twice as large. While the average magnification for the dust continuum is $μ$~10-11, the magnification of the line emission varies 5 to 22 across different velocity components. The emission lines have similar spatial and kinematic distributions. The molecular gas and dust content reveal that G09v1.97 is a gas-rich major merger in its pre-coalescence phase. Both of the merging companions are intrinsically ULIRGs with LIR reaching $\gtrsim 4\times10^{12}L_\odot$, and the total LIR of G09v1.97 is $1.4\times10^{13}L_\odot$. The approaching southern galaxy shows no obvious kinematic structure with a semi-major half-light radius a_s=0.4kpc, while the receding galaxy resembles an a_s=1.2kpc rotating disk. The two galaxies are separated by a projected distance of 1.3kpc, bridged by weak line emission that is co-spatially located with the cold-dust-emission peak, suggesting a large amount of cold ISM in the interacting region. (abridged)

astro-ph.GA↗

arXiv2019

Thermodynamic heterogeneity and crossover in the supercritical state of matter

A hallmark of a thermodynamic phase transition is the qualitative change of system thermodynamic properties such as energy and heat capacity. On the other hand, no phase transition is thought to operate in the supercritical state of matter and, for this reason, it was believed that supercritical thermodynamic properties vary smoothly and without any qualitative changes. Here, we perform extensive molecular dynamics simulations in a wide temperature range and find that a deeply supercritical state is thermodynamically heterogeneous, as witnessed by different temperature dependence of energy, heat capacity and its derivatives at low and high temperature. The evidence comes from three different methods of analysis, two of which are model-independent. We propose a new definition of the relative width of the thermodynamic crossover and calculate it to be in the fairly narrow relative range of 13-20\%. On the basis of our results, we relate the crossover to the supercritical Frenkel line.

cond-mat.stat-mech↗

arXiv2019

The nature of collective excitations and their crossover at extreme supercritical conditions

Physical properties of an interacting system are governed by collective excitations, but their nature at extreme supercritical conditions is unknown. Here, we present direct evidence for propagating solid-like longitudinal phonon-like excitations with wavelengths extending to interatomic separations deep in the supercritical state at temperatures up to 3,300 times the critical temperature. We observe that the crossover of dispersion curves develops at $k$ points reducing with temperature. We interpret this effect as the crossover from the collective phonon to the collisional mean-free path regime of particle dynamics and find that the crossover points are close to both the inverse of the shortest available wavelength in the system and to the particle mean free path inferred from experiments and theory. Notably, both the shortest wavelength and mean free path scale with temperature with the same power law, lending further support to our findings.

cond-mat.stat-mech↗

arXiv2018

Planck's Dusty GEMS. VII. Atomic carbon and molecular gas in dusty starburst galaxies at z=2 to 4

The bright [CI] 1-0 and [CI] 2-1 lines of atomic carbon are becoming more and more widely employed tracers of the cold neutral gas in high-redshift galaxies. Here we present observations of these lines in the 11 galaxies of the set of Planck's Dusty GEMS, the brightest gravitationally lensed galaxies on the extragalactic submillimeter sky probed by the Planck satellite. We have [CI] 1-0 measurements for seven, and [CI] 2-1 measurements for eight galaxies, including four galaxies where both lines are measured. We use our observations to constrain the gas excitation mechanism, excitation temperatures, optical depths, atomic carbon and molecular gas masses, and carbon abundances. Ratios of L_CI/L_ FIR are similar to those found in the local Universe, and suggest that the total cooling budget through atomic carbon has not strongly changed in the last 12 Gyr. Both lines are optically thin and trace 1 - 6 x 10^7 M_sun of atomic carbon. Carbon abundance ratios with H_2, X_CI, are between 2.5 and 4 x 10^-5, for a "ULIRG" CO-to-H_2 conversion factor of alpha_CO=0.8 M_sun/ [K km s^-1 pc^2]. Ratios of molecular gas masses derived from [CI] 1-0 and CO agree within the measurement uncertainties for five galaxies, and to better than a factor of 2 for another two with [CI] 1-0 measurements, after taking CO excitation carefully into account. This does not support the idea that intense, high-redshift starburst galaxies host large quantities of "CO-dark" gas. These results also support the common assumptions underlying most molecular gas mass estimates made for massive, dusty, high-redshift starburst galaxies, although the good agreement between the masses obtained with both tracers cannot be taken as an independent confirmation of either alpha_CO or X_CI.

astro-ph.GA↗

arXiv2018

Planck's dusty GEMS. VI. Multi-J CO excitation and interstellar medium conditions in dusty starburst galaxies at z=2-4

We present an extensive CO emission-line survey of the Planck's dusty GEMS, a small set of 11 strongly lensed dusty star-forming galaxies at z = 2-4 discovered with Planck and Herschel satellites, using EMIR on the IRAM 30-m telescope. We detected a total of 45 CO rotational lines from Jup=3 to Jup=11, and up to eight transitions per source, allowing a detailed analysis of the gas excitation and interstellar medium conditions within these extremely bright, vigorous starbursts. We applied radiative transfer models using the large velocity gradient approach to infer the spatially-averaged molecular gas densities, $n_{H_2}$~10$^{2.6-4.1}$ cm$^{-3}$, and kinetic temperatures, $T_k$~30-1000 K. In five sources, we find evidence of two distinct gas phases with different properties and model their CO ladder with two excitation components. The warm (70-320 K) and dense gas reservoirs in these galaxies are highly excited, while the cooler (15-60 K) and more extended low-excitation components cover a range of gas densities. In two sources, the latter is associated with diffuse Milky Way-like gas phases, which provides evidence that a significant fraction of the total gas masses of dusty starburst galaxies can be embedded in cool, low-density reservoirs. Finally, we show that the CO line luminosity ratios are consistent with those predicted by models of photon-dominated regions and disfavor scenarios of gas clouds irradiated by intense X-ray fields from active galactic nuclei. By combining CO, [CI] and [CII] line diagnostics, we obtain average PDR gas densities significantly higher than in normal star-forming galaxies at low-redshift, and far-ultraviolet radiation fields at least 100 times more intense than in the Milky Way. These spatially-averaged conditions are consistent with those in high-redshift SMGs and in a range of low-redshift environments.

astro-ph.GA↗

arXiv2018

VALES V: A kinematic analysis of the molecular gas content in $H$-ATLAS galaxies at $z\sim0.03-0.35$ using ALMA

We present Atacama Large Millimeter/submillimeter Array (ALMA) resolved observations of molecular gas in galaxies up to $z=0.35$ to characterise the role of global galactic dynamics on the global interstellar medium (ISM) properties. These observations consist of a sub-sample of 39 galaxies taken from the Valparaíso ALMA Line Emission Survey (VALES). From the CO($J=1-0)$ emission line, we quantify the kinematic parameters by modelling the velocity fields. We find that the IR luminosity increases with the rotational to dispersion velocity ratio ($V_{\rm rot}/σ_v$, corrected for inclination). We find a dependence between $V_{\rm rot}/σ_v$ and the [CII]/IR ratio, suggesting that the so-called `[CII] deficit' is related to the dynamical state of the galaxies. We find that global pressure support is needed to reconcile the dynamical mass estimates with the stellar masses in our systems with low $V_{\rm rot}/σ_v$ values. The star formation rate (SFR) is weakly correlated with the molecular gas fraction ($f_{\rm H_2}$) in our sample, suggesting that the release of gravitational energy from cold gas may not be the main energy source of the turbulent motions seen in the VALES galaxies. By defining a proxy of the `star formation efficiency' parameter as the SFR divided by the CO luminosity (SFE$'\equiv$ SFR/L$'_{\rm CO}$), we find a constant SFE$'$ per crossing time ($t_{\rm cross}$). We suggest that $t_{\rm cross}$ may be the controlling timescale in which the star formation occurs in dusty $z\sim0.03-0.35$ galaxies.

astro-ph.GA↗

arXiv2017

VALES: IV. Exploring the transition of star formation efficiencies between normal and starburst galaxies using APEX/SEPIA Band-5 and ALMA at low redshift

In this work we present new APEX/SEPIA Band-5 observations targeting the CO ($J=2\text{-}1$) emission line of 24 Herschel-detected galaxies at $z=0.1-0.2$. Combining this sample {with} our recent new Valparaíso ALMA Line Emission Survey (VALES), we investigate the star formation efficiencies (SFEs = SFR/$M_{\rm H_{2}}$) of galaxies at low redshift. We find the SFE of our sample bridges the gap between normal star-forming galaxies and Ultra-Luminous Infrared Galaxies (ULIRGs), which are thought to be triggered by different star formation modes. Considering the $\rm SFE'$ as the SFR and the $L'_{\rm CO}$ ratio, our data show a continuous and smooth increment as a function of infrared luminosity (or star formation rate) with a scatter about 0.5 dex, instead of a steep jump with a bimodal behaviour. This result is due to the use of a sample with a much larger range of sSFR/sSFR$_{\rm ms}$ using LIRGs, with luminosities covering the range between normal and ULIRGs. We conclude that the main parameters controlling the scatter of the SFE in star-forming galaxies are the systematic uncertainty of the $α_{\rm CO}$ conversion factor, the gas fraction and physical size.

astro-ph.GA↗

arXiv2017

Coherent J/$ψ$ photoproduction in hadronic heavy-ion collisions

A significant excess of J/$ψ$ yield at very low transverse momentum ($p_T < 0.3$ GeV/c) was observed by the ALICE and STAR collaborations in peripheral A+A collisions, which points to evidence of coherent photoproduction of J/$ψ$ in violent hadronic interactions. Theoretically, the photoproduction of J$/ψ$ in hadronic collisions raises questions about how spectator and non-spectator nucleons participate in the coherent reaction. For the first time, we argue that the strong interactions in the overlapping region of incoming nuclei may disturb the coherent production, leaving room for different coupling assumptions. Furthermore, first considerations of the destructive interference between photoproduction on ions moving in opposite directions in hadronic heavy-ion collisions are included. This letter presents calculations of J$/ψ$ production from coherent photon-nucleus ($γ+ A \rightarrow \text{J}/ψ+ A$) interactions in hadronic A+A collisions at RHIC and LHC energies with both nucleus and spectator coupling hypotheses. The coherent J/$ψ$ yield as a function of centrality and differential distributions as a function of transverse momentum, azimuthal angle and rapidity in different centrality bins are shown and found to be significantly different for different coupling scenarios, calling for future experimental measurements.

nucl-th↗

arXiv2017

Molecular gas in the Herschel-selected strongly lensed submillimeter galaxies at z~2-4 as probed by multi-J CO lines

(abridged) We present the IRAM-30m observations of multiple-J CO and CI line emission in a sample of redshift ~2-4 Herschel-ATLAS SMGs. A non-negligible effect of differential lensing is found for the CO emission lines, which could have caused significant underestimations of the linewidths, hence of the dynamical masses. The CO SLEDs are found to be similar to those of the local starburst-dominated ULIRGs and of the previously studied SMGs. After correcting for lensing amplification, we derived the global properties of the bulk of molecular gas in the SMGs using non-LTE radiative transfer modelling. The gas thermal pressure is found to be correlated with star formation efficiency. Further decomposing the CO SLEDs into two excitation components, we find a low-excitation component, which is less correlated with star formation, and a high-excitation one which is tightly related to the on-going star-forming activity. Additionally, tight linear correlations between the FIR and CO line luminosities have been confirmed for the $J \ge 5$ CO lines, implying that these CO lines are good tracers of star formation. The [CI](2-1) lines follow the tight linear correlation between the luminosities of the [CI](2-1) and the CO(1-0) line found in local starbursts, indicating that CI lines could serve as good total molecular gas mass tracers for high-redshift SMGs. The total mass of the molecular gas reservoir, $(1-30) \times 10^{10} M_\odot$, suggests a typical molecular gas depletion time ~20-100 Myr and a gas to dust mass ratio $δ_{\rm GDR}$~30-100. The ratio between CO line luminosity and the dust mass appears to be slowly increasing with redshift for the SMGs, which need to be further confirmed. Finally, through comparing the linewidth of CO and H2O lines, we find that they agree well in almost all our SMGs, confirming that the emitting regions are co-spatially located.

astro-ph.GA↗

arXiv2017

The Herschel Bright Sources (HerBS): Sample definition and SCUBA-2 observations

We present the Herschel Bright Sources (HerBS) sample, a sample of bright, high-redshift Herschel sources detected in the 616.4 square degree H-ATLAS survey. The HerBS sample contains 209 galaxies, selected with a 500 μm flux density greater than 80 mJy and an estimated redshift greater than 2. The sample consists of a combination of HyLIRGs and lensed ULIRGs during the epoch of peak cosmic star formation. In this paper, we present SCUBA-2 observations at 850 $μ$m of 189 galaxies of the HerBS sample, 152 of these sources were detected. We fit a spectral template to the Herschel-SPIRE and 850 $μ$m SCUBA-2 flux densities of 22 sources with spectroscopically determined redshifts, using a two-component modified blackbody spectrum as a template. We find a cold- and hot-dust temperature of 21.29 K and 45.80 K, a cold-to-hot dust mass ratio of 26.62 and a $β$ of 1.83. The poor quality of the fit suggests that the sample of galaxies is too diverse to be explained by our simple model. Comparison of our sample to a galaxy evolution model indicates that the fraction of lenses is high. Out of the 152 SCUBA-2 detected galaxies, the model predicts 128.4 $\pm$ 2.1 of those galaxies to be lensed (84.5%). The SPIRE 500 $μ$m flux suggests that out of all 209 HerBS sources, we expect 158.1 $\pm$ 1.7 lensed sources, giving a total lensing fraction of 76 per cent.

astro-ph.GA↗

arXiv2017

Emergence and evolution of $k$-gap in spectra of liquid and supercritical states

Fundamental understanding of strongly-interacting systems necessarily involves collective modes, but their nature and evolution is not generally understood in dynamically disordered and strongly-interacting systems such as liquids and supercritical fluids. We report the results of extensive molecular dynamics simulations and provide direct evidence that liquids develop a gap in solid-like transverse spectrum in the reciprocal space, with no propagating modes between zero and a threshold value. In addition to the liquid state, this result importantly applies to the supercritical state of matter. We show that the emerging gap increases with the inverse of liquid relaxation time and discuss how the gap affects properties of liquid and supercritical states.

cond-mat.soft↗