Miracle-dz/UniFAR-FTUs huggingface dataset:
An Empirical Limit on Extremely High Redshift Galaxies

We apply the Lyman absorption signature to search for galaxies at redshifts z ≈ 6–17 using optical and infrared images of the Hubble Deep Field. The infrared images are sensitive to a point-source 5 σ detection threshold of AB(22,000) = 23.8, which, adopting plausible assumptions to relate rest-frame ultraviolet flux densities to unobscured star formation rates, is easily sufficient to detect the star formation rates expected for massive elliptical galaxy formation to quite high redshifts. For q0 = 0.5, the infrared images are sensitive to an unobscured star formation rate of = 100 h-2 M⊙ yr-1 to redshifts as large as z = 17, and for q0 = 0, the infrared images are sensitive to an unobscured star formation rate of = 300 h-2 M⊙ yr-1 to redshifts as large as z = 14. The primary result of the analysis is that only one extremely high redshift galaxy candidate is identified at the 5 σ level of significance (and four at the 4 σ level). This implies a strict upper limit to the surface density of extremely high redshift galaxies of less than 1.5 arcmin-2 to a limiting magnitude threshold AB(22,000) = 23.8. This also implies a strict upper limit to the volume density of extremely high redshift galaxies if (and only if) such galaxies are not highly obscured by dust.
High-Order Upwind Schemes for Multidimensional Magnetohydrodynamics

A general method for constructing high-order upwind schemes for multidimensional magnetohydrodynamics (MHD), having as a main built-in condition the divergence-free constraint 𝛁 ∙ = 0 for the magnetic field vector , is proposed. The suggested procedure is based on consistency arguments, by taking into account the specific operator structure of MHD equations with respect to the reference Euler equations of gasdynamics. This approach leads in a natural way to a staggered representation of the field numerical data in which the divergence-free condition in the cell-averaged form, corresponding to second-order accurate numerical derivatives, is exactly fulfilled. To extend this property to higher order schemes, we then give general prescriptions to satisfy a (r + 1)th order accurate 𝛁 ∙ = 0 relation for any numerical field having a rth order interpolation accuracy. Consistency arguments lead also to a proper formulation of the upwind procedures needed to integrate the induction equations, assuring the exact conservation in time of the divergence-free condition and the related continuity properties for the vector components. As an application, a third-order code to simulate multidimensional MHD flows of astrophysical interest is developed using essentially nonoscillatory-based reconstruction algorithms. Several test problems to illustrate and validate the proposed approach are finally presented.
Non-Perturbative Isotropic Multi-Particle Production in Yang--Mills Theory

We use singular Euclidean solutions to ﬁnd multi-particle production cross sections in ﬁeld theories. We investigate a family of time-dependent O(3) symmetrical solutions of the Yang–Mills equations, which govern the isotropic high-energy gauge boson production. At low energies our approach reproduces the instanton-induced cross sections. For higher energies we get new results. In particular, we show that the cross section for isotropic multiparticle production remains exponentially small in the running gauge coupling constant. The result applies both to the baryon number violation in the electro-weak theory and to the QCD jet production. We ﬁnd that the isotropic multi-gluon production cross section falls oﬀ approximately as a ninth power of energy but possibly might be observable
Quantum many-body effects in x-ray spectra efficiently computed using a basic graph algorithm

The growing interest in using x-ray spectroscopy for refined materials characterization calls for accurate electronic-structure theory to interpret x-ray near-edge fine structure. In this work, we propose an efficient and unified framework to describe all the many-electron processes in a Fermi liquid after a sudden perturbation (such as a core hole). This problem has been visited by the Mahan-Nozi\'eres-De Dominicis (MND) theory, but it is intractable to implement various Feynman diagrams within first-principles calculations. Here, we adopt a non-diagrammatic approach and treat all the many-electron processes in the MND theory on an equal footing. Starting from a recently introduced determinant formalism [Phys. Rev. Lett. 118, 096402 (2017)], we exploit the linear-dependence of determinants describing different final states involved in the spectral calculations. An elementary graph algorithm, breadth-first search, can be used to quickly identify the important determinants for shaping the spectrum, which avoids the need to evaluate a great number of vanishingly small terms. This search algorithm is performed over the tree-structure of the many-body expansion, which mimics a path-finding process. We demonstrate that the determinantal approach is computationally inexpensive even for obtaining x-ray spectra of extended systems. Using Kohn-Sham orbitals from two self-consistent fields (ground and core-excited state) as input for constructing the determinants, the calculated x-ray spectra for a number of transition metal oxides are in good agreement with experiments. Many-electron aspects beyond the Bethe-Salpeter equation, as captured by this approach, are also discussed, such as shakeup excitations and many-body wave function overlap considered in Anderson's orthogonality catastrophe.
Weak-lensing Mass Calibration of ACTPol Sunyaev–Zel’dovich Clusters with the Hyper Suprime-Cam Survey

We present weak-lensing measurements using the first-year data from the Hyper Suprime-Cam Strategic Survey Program on the Subaru telescope for eight galaxy clusters selected through their thermal Sunyaev–Zel’dovich (SZ) signal measured at 148 GHz with the Atacama Cosmology Telescope Polarimeter experiment. The overlap between the two surveys in this work is 33.8 square degrees, before masking bright stars. The signal-to-noise ratio of individual cluster lensing measurements ranges from 2.2 to 8.7, with a total of 11.1 for the stacked cluster weak-lensing signal. We fit for an average weak-lensing mass distribution using three different profiles, a Navarro–Frenk–White profile, a dark-matter-only emulated profile, and a full cosmological hydrodynamic emulated profile. We interpret the differences among the masses inferred by these models as a systematic error of 10%, which is currently smaller than the statistical error. We obtain the ratio of the SZ-estimated mass to the lensing-estimated mass (the so-called hydrostatic mass bias 1−b) of , which is comparable to previous SZ-selected clusters from the Atacama Cosmology Telescope and from the Planck Satellite. We conclude with a discussion of the implications for cosmological parameters inferred from cluster abundances compared to cosmic microwave background primary anisotropy measurements.
The Gaia ultracool dwarf sample – II. Structure at the end of the main sequence

We identify and investigate known late M, L, and T dwarfs in the Gaia second data release. This sample is being used as a training set in the Gaia data processing chain of the ultracool dwarfs work package. We find 695 objects in the optical spectral range M8–T6 with accurate Gaia coordinates, proper motions, and parallaxes which we combine with published spectral types and photometry from large area optical and infrared sky surveys. We find that 100 objects are in 47 multiple systems, of which 27 systems are published and 20 are new. These will be useful benchmark systems and we discuss the requirements to produce a complete catalogue of multiple systems with an ultracool dwarf component. We examine the magnitudes in the Gaia passbands and find that the GBP magnitudes are unreliable and should not be used for these objects. We examine progressively redder colour–magnitude diagrams and see a notable increase in the main-sequence scatter and a bivariate main sequence for old and young objects. We provide an absolute magnitude – spectral subtype calibration for G and GRP passbands along with linear fits over the range M8–L8 for other passbands.
Experiments on the diffraction of strong blast waves

This paper considers the diffraction of strong shocks over rigid concave comers, and complements an earlier paper (Henderson & Siegenthaler 1980), which dealt with weak shocks. It is shown that the von Neumann theory of strong Mach reflexion does not agree with experiment once the comer signal everywhere overtakes the reflected shock. We show that the difficulty is due to the assumption that the flow is self-similar along the trajectory path passing through the comer and that the theory may be reconstructed by choosing a new path that does not necessarily pass through the comer. The flow is assumed to be self-similar with respect to the new path. The reconstructed theory is in good agreement with experiment. One obtains from it a new model of strong Mach reflexion beyond the catch-up condition that features a length scale apparently introduced into the flow by viscous effects at the comer. The reflected shock is weaker according to the new theory which implies that the blast loading on sloping surfaces will be less after catch-up than predicted by the classical theory. Experimental evidence is also presented on transition between regular and Mach reflexions, and it supports the normal shock criterion first proposed by von Neumann but largely ignored by the textbooks.
Effects of polarization charge on the photovoltaic properties of InGaN solar cells

The effects of interface polarization charge on the photovoltaic characteristics of GaN/InGaN solar cells have been analyzed in detail using 2D drift‐diffusion simulations. The polarization charge at the GaN/InGaN interface creates an electric field that forces carriers generated by light to drift in opposite direction needed for efficient collection and substantially reduces the short circuit current (Isc) and open circuit voltage (Voc). The polarization charge plays an important role in the photovoltaic properties of InGaN solar cells comparable to that of defects. For small interface charge, the potential barrier could increase the Voc.
The Relationship between x-ray variability amplitude and black hole mass in active galactic nuclei

We have investigated the relationship between the X-ray variability amplitude and black hole mass for a sample of 46 radio-quiet active galactic nuclei observed by ASCA. 33 of the objects in our sample exhibited significant variability over a time-scale of ∼40 ks. We determined the normalized excess variance in the 2-10 keV light curves of these objects and found a significant anticorrelation between excess variance and black hole mass. Unlike most previous studies, we have quantified the variability using nearly the same time-scale for all objects. Moreover, we provide a prescription for estimating the uncertainties in variance which accounts both for measurement uncertainties and for the stochastic nature of the variability. We also present an analytical method to predict the excess variance from a model power spectrum accounting for binning, sampling and windowing effects. Using this, we modelled the variance-mass relation assuming all objects have a universal twice-broken power spectrum, with the position of the breaks being dependent on mass. This accounts for the general form of the variance-mass relationship but is formally a poor fit and there is considerable scatter. We investigated this scatter as a function of the X-ray photon index, luminosity and Eddington ratio. After accounting for the primary dependence of excess variance on mass, we find no significant correlation with either luminosity or X-ray spectra] slope. We do find an anticorrelation between excess variance and the Eddington ratio, although this relation might be an artefact owing to the uncertainties in the mass measurements. It remains to be established that enhanced X-ray variability is a property of objects with steep X-ray slopes or large Eddington ratios. Narrow-line Seyfert 1 galaxies, in particular, are consistent with being more variable than their broad-line counterparts solely because they tend to have smaller masses.
X-Ray Temperatures, Luminosities, and Masses from XMM-Newton Follow-upof the First Shear-selected Galaxy Cluster Sample

We continue the study of the first sample of shear-selected clusters from the initial 8.6 square degrees of the Deep Lens Survey (DLS); a sample with well-defined selection criteria corresponding to the highest ranked shear peaks in the survey area. We aim to characterize the weak lensing selection by examining the sample’s X-ray properties. There are multiple X-ray clusters associated with nearly all the shear peaks: 14 X-ray clusters corresponding to seven DLS shear peaks. An additional three X-ray clusters cannot be definitively associated with shear peaks, mainly due to large positional offsets between the X-ray centroid and the shear peak. Here we report on the XMM-Newton properties of the 17 X-ray clusters. The X-ray clusters display a wide range of luminosities and temperatures; the LX−TX relation we determine for the shear-associated X-ray clusters is consistent with X-ray cluster samples selected without regard to dynamical state, while it is inconsistent with self-similarity. For a subset of the sample, we measure X-ray masses using temperature as a proxy, and compare to weak lensing masses determined by the DLS team. The resulting mass comparison is consistent with equality. The X-ray and weak lensing masses show considerable intrinsic scatter (∼48%), which is consistent with X-ray selected samples when their X-ray and weak lensing masses are independently determined.
Chandra View of the Dynamically Young Cluster of Galaxies A1367. II. Point Sources

A 40 ks Chandra ACIS-S observation of the dynamically young cluster A1367 yields new insights on X-ray emission from cluster member galaxies. We detect 59 pointlike sources in the ACIS field, of which eight are identified with known cluster member galaxies. Thus, in total 10 member galaxies are detected in X-rays when three galaxies discussed in Paper I (NGC 3860 is discussed in both papers) are included. The superior spatial resolution and good spectroscopy capability of Chandra allow us to constrain the emission nature of these galaxies. Central nuclei, thermal halos, and stellar components are revealed in their spectra. Two new low-luminosity active galactic nuclei (LLAGNs) are found, including an absorbed one (NGC 3861). Besides these two for sure, two new LLAGN candidates are also found. This discovery makes the LLAGN/AGN content in this part of A1367 very high (≳12%). Thermal halos with temperatures around 0.5-0.8 keV are revealed in the spectra of NGC 3842 and NGC 3837, which suggests that galactic coronae can survive in clusters and that heat conduction must be suppressed. The X-ray spectrum of NGC 3862 (3C 264) resembles a BL Lac object with a photon index of ~2.5. We also present an analysis of other point sources in the field and discuss the apparent source excess (~2.5 σ) in the central field.
Structure and dynamics of a self-propelled semiflexible filament

We investigate structural and dynamical properties of a self-propelled filament using coarse-grained Brownian dynamics simulations. A self-propulsion force is applied along the bond vectors, i.e., tangent to the filament and their locations are considered in two different manners. In case one, force is applied to all beads of the filament, which is termed as homogeneous self-propulsion. Here, we obtain a monotonic decrease in the flexibility of the filament with Peclet number. Hence, radius of gyration also displays the same trend. Moreover, the radius of gyration of the filament shows universal dependence for various bending rigidities with flexure number. The effective diffusivity of the filament shows enhancement with the active force and it increases linearly with force and bending rigidity. In case two, self-propulsion force is applied only to few bond vectors. The location of active forces is chosen in a periodic manner starting from the tail of the filament and leaving the front end without force. In this case, filament acquires various structures such as rod-like, helical, circular, and folded states. The transition from several states is understood in terms of tangent-tangent correlation, bending energy and torsional order parameter. The helical state is identified through a crossover from exponential to oscillatory behavior of the tangent-tangent correlation. A sudden increase in the bending energy separates a helical to a folded states of the filament.
The Dependence of Bar Frequency on Galaxy Mass, Colour, and Gas Content -- and Angular Resolution -- in the Local Universe

I use distance- and mass-limited subsamples of the Spitzer Survey of Stellar Structure in Galaxies (S 4 G) to investigate how the presence of bars in spiral galaxies depends on mass, colour, and gas content and whether large, SDSS-based investigations of bar frequencies agree with local data. Bar frequency reaches a maximum of f bar ≈ 0 . 70 at M (cid:63) ∼ 10 9 . 7 M (cid:12) , declining to both lower and higher masses. It is roughly constant over a wide range of colours ( g − r ≈ 0 . 1–0.8) and atomic gas fractions (log( M H i /M (cid:63) ) ≈ − 2 . 5 to 1). Bars are thus as common in blue, gas-rich galaxies are they are in red, gas-poor galaxies. This is in sharp contrast to many SDSS-based studies of z ∼ 0 . 01–0.1 galaxies, which report f bar increasing strongly to higher masses (from M (cid:63) ∼ 10 10 to 10 11 M (cid:12) ), redder colours, and lower gas fractions. The contradiction can be explained if SDSS-based studies preferentially miss bars in, and underestimate the bar fraction for, lower-mass (bluer, gas-rich) galaxies due to poor spatial resolution and the correlation between bar size and stellar mass. Simulations of SDSS-style observations using the S 4 G galaxies as a parent sample, and assuming that bars below a threshold angular size of twice the PSF FWHM cannot be identiﬁed, successfully reproduce typical SDSS f bar trends for stellar mass and gas mass ratio. Similar considerations may aﬀect high-redshift studies, especially if bars grow in length over cosmic time; simulations suggest that high-redshift bar fractions may thus be systematically underestimated.
Photometric Redshifts from Reconstructed Quasar Templates

From Sloan Digital Sky Survey (SDSS) commissioning photometric and spectroscopic data, we investigate the utility of photometric redshift techniques in the task of estimating QSO redshifts. We consider empirical methods (e.g., nearest neighbor searches and polynomial fitting), standard spectral template fitting, and hybrid approaches (i.e., training spectral templates from spectroscopic and photometric observations of QSOs). We find that in all cases, because of the presence of strong emission lines within the QSO spectra, the nearest neighbor and template-fitting methods are superior to the polynomial-fitting approach. Applying a novel reconstruction technique, we can, from the SDSS multicolor photometry, reconstruct a statistical representation of the underlying SEDs of the SDSS QSOs. Although the reconstructed templates are based on only broadband photometry, the common emission lines present within the QSO spectra can be recovered in the resulting spectral energy distributions. The technique should be useful in searching for spectral differences among QSOs at a given redshift, in searching for spectral evolution of QSOs, in comparing photometric redshifts for objects beyond the SDSS spectroscopic sample with those in the well-calibrated photometric redshifts for objects brighter than 20th magnitude, and in searching for systematic and time-variable effects in the SDSS broadband photometric and spectral photometric calibrations.
Lopsided Spiral Galaxies and a Limit on the Galaxy Accretion Rate

We present a measurement of lopsidedness for the stellar disks of 60 field spiral galaxies in terms of the azimuthal m = 1 Fourier amplitude, A1, of the stellar light. We confirm the previous result (Rix & Zaritsky) that ~30% of field spiral galaxies in a magnitude-limited sample exhibit significant lopsidedness (⟨A1/A0⟩ ≥ 0.2) at large radii (R > 1.5 disk scalelengths). We conjecture that this lopsidedness is caused by tidal interactions and calculate an upper limit on the accretion rate of small galaxies. We exploit the correlation between lopsidedness and photometric measures of recent star formation (Zaritsky) to obtain two independent estimates of the lifetime of these m = 1 distortions. First, we show that lopsided galaxies have an excess of blue luminosity relative to that of symmetric galaxies with the same H I linewidth, which we attribute to a recent star formation episode that was triggered by an interaction between the galaxy and a companion. We use stellar population models (Bruzual & Charlot) to estimate the time since that interaction. Second, we use the N-body simulation of an infalling satellite by Walker, Mihos, & Hernquist to estimate how fast tidally induced m = 1 distortions are erased through phase mixing. Both approaches indicate that the observations are consistent with a hypothesized tidal interaction that occurred about 1 Gyr ago for galaxies that are lopsided at the 20% level. By combining this lifetime estimate for lopsidedness, the observed frequency of such distortions, and a correction to the survey volume that depends on the increase in luminosity during an interaction, we derive an upper limit on the current companion accretion rate of field spiral galaxies (for companion masses ~10% parent galaxy mass) that lies in the range 0.07-0.25 Gyr-1. The principal uncertainty in this limit arises from ambiguities in the interpretation of the correlation between lopsidedness and MB.