ShantanuT01/DACTYL-Pretraining huggingface dataset:
The initial shear field plays a central role in the formation of large-scale structures, and in shaping the geometry, morphology, and topology of the cosmic web. We discuss a recent theoretical framework for the shear tensor, termed the `peak/dip picture', which accounts for the fact that halos/voids may form from local extrema of the density field - rather than from random spatial positions; the standard Doroshkevich's formalism is generalized, to include correlations between the density Hessian and shear field at special points in space around which halos/voids may form. We then present the `peak/dip excursion-set-based' algorithm, along with its most recent applications - merging peaks theory with the standard excursion set approach.
In this article we study the inverse problem of recovering a space-dependent coefficient of the Moore-Gibson-Thompson (MGT) equation, from knowledge of the trace of the solution on some open subset of the boundary. We obtain the Lipschitz stability for this inverse problem, and we design a convergent algorithm for the reconstruction of the unknown coefficient. The techniques used are based on Carleman inequalities for wave equations and properties of the MGT equation.
We report on the serendipitous discovery of the brightest Lyman Break Galaxy (LBG) currently known, a galaxy at z=2.73 that is being strongly lensed by the z=0.38 Luminous Red Galaxy (LRG) SDSS J002240.91+143110.4. The arc of this gravitational lens system, which we have dubbed the "8 o'clock arc" due to its time of discovery, was initially identified in the imaging data of the Sloan Digital Sky Survey Data Release 4 (SDSS DR4); followup observations on the Astrophysical Research Consortium (ARC) 3.5m telescope at Apache Point Observatory confirmed the lensing nature of this system and led to the identification of the arc's spectrum as that of an LBG. The arc has a spectrum and a redshift remarkably similar to those of the previous record-holder for brightest LBG (MS 1512-cB58, a.k.a "cB58"), but, with an estimated total magnitude of (g,r,i) = (20.0,19.2,19.0) and surface brightness of (mu_g,mu_r,mu_i) = (23.3, 22.5, 22.3) mag/arcsec^2, the 8 o'clock arc is thrice as bright. The 8 o'clock arc, which consists of three lensed images of the LBG, is 162deg (9.6arcsec) long and has a length-to-width ratio of 6:1. A fourth image of the LBG -- a counter-image -- can also be identified in the ARC 3.5m g-band images. A simple lens model for the system assuming a singular isothermal ellipsoid potential yields an Einstein radius of 2.91+/-0.14 arcsec, a total mass for the lensing LRG (within the (10.6+/-0.5)/h kpc enclosed by the lensed images) of 1.04x10^12/h Msun, and a magnification factor for the LBG of 12.3(+15/-3.6). The LBG itself is intrinsically quite luminous (approximately 6L*) and shows indications of massive recent star formation, perhaps as high as 160/h Msun/year.
We assemble 207 variable quasars from the Sloan Digital Sky Survey, all with at least 3 observations, to analyze C IV narrow absorption doublets, and obtain 328 C IV narrow absorption line systems. We find that 19 out of 328 C IV narrow absorption line systems were changed by $\mid\Delta W_r^{\lambda1548}\mid\ge3\sigma_{\Delta W_r^{\lambda1548}}$ on timescales from 15.9 to 1477 days at rest-frame. Among the 19 obviously variable C IV systems, we find that (1) 14 systems have relative velocities $\upsilon_r>0.01c$ and 4 systems have $\upsilon_r>0.1c$, where $c$ is the speed of light; (2) 13 systems are accompanied by other variable C IV systems; (3) 9 systems were changed continuously during multiple observations; and (4) 1 system with $\upsilon_{\rm r}=16~862$ km/s was enhanced by $\Delta W_r^{\lambda1548}=2.7\sigma_{\Delta W_r^{\lambda1548}}$ in 0.67 day at rest-frame. The variations of absorption lines are inversely correlated with the changes in the ionizing continuum. We also find that large variations of C IV narrow absorption lines are difficult to form on a short timescale.
Intraband and interband contributions to the current-driven spin-orbit torque in magnetic materials lacking inversion symmetry are theoretically studied using Kubo formula. In addition to the current-driven field-like torque ${\bf T}_{\rm FL}= \tau_{\rm FL}{\bf m}\times{\bf u}_{\rm so}$ (${\bf u}_{\rm so}$ being a unit vector determined by the symmetry of the spin-orbit coupling), we explore the intrinsic contribution arising from impurity-independent interband transitions and producing an anti-damping-like torque of the form ${\bf T}_{\rm DL}= \tau_{\rm DL}{\bf m}\times({\bf u}_{\rm so}\times{\bf m})$. Analytical expressions are obtained in the model case of a magnetic Rashba two-dimensional electron gas, while numerical calculations have been performed on a dilute magnetic semiconductor (Ga,Mn)As modeled by the Kohn-Luttinger Hamiltonian exchanged coupled to the Mn moments. Parametric dependences of the different torque components and similarities to the analytical results of the Rashba two-dimensional electron gas in the weak disorder limit are described.
We study the nonequilibrium steady states of an Ising chain in a transverse field, h, by investigating the effect of a field, lambda, which drives the current of energy. The zero-temperature, h-lambda phase diagram is determined exactly and it is found that the energy current appears continuously above a threshold, lambda > lambda_c(h). The long-range magnetic order (present for h<h_c, lambda < lambda_c) is destroyed in the current-carrying state where the correlations are characterized by power-law, oscillatory decay. The mechanism which generates the power-law correlations in the current-carrying state is discussed.
We study a generalization of a conjecture made by Beauville on the Chow ring of hyper-K\"ahler algebraic varieties. Namely we prove in a number of cases that polynomial cohomological relations involving only CH^1(X) and the Chern classes of X are satisfied in CH(X). These cases are : punctual Hilbert schemes of a K3 surface S parameterizing subschemes of length n, for n<2b_2(S)_tr+5; Fano varieties of lines in a cubic fourfold.
In order to be in a long-lived configuration, the density in a fluid disk should be constant along streamlines to prevent compressional (PdV) work from being done cyclically around every orbit. In a pure Kepler potential, flow along aligned, elliptical streamlines of constant eccentricity will satisfy this condition. For most density profiles, differential precession driven by the pressure gradient will destroy the alignment; however, in the razor-thin approximation there is a family of simple equilibria in which the precession frequency is the same at all radii. These disks may therefore be long-lived at significant eccentricities. The density can be made axisymmetric as r goes to 0, while maintaining the precession rate, by relaxing the requirement of constancy along streamlines in an arbitrarily small transition region near the center. In the limit of small eccentricity, the models can be seen as acoustically perturbed axisymmetric disks, and the precession rate is shown to agree with linear theory. The perturbation is a traveling wave similar to an ocean wave, with the fluid rising and falling epicyclically in the gravitational field of the central mass. The expected emission line profiles from the eccentric disks are shown to be strongly asymmetric in general, and, in extreme cases, prone to misinterpretation as single narrow lines with significant velocity offsets.
The transport properties of micrometer scale structures fabricated from high-mobility HgTe quantum-wells have been investigated. A special photoresist and Ti masks were used, which allow for the fabrication of devices with characteristic dimensions down to 0.45 $\mu$m. Evidence that the transport properties are dominated by ballistic effects in these structures is presented. Monte Carlo simulations of semi-classical electron trajectories show good agreement with the experiment.
We study the gauge dependence of the neutrino mass renormalization in a two Higgs doublet model, that is extended with one singlet seesaw neutrino. This model gives only one light neutrino a mass at tree level, while the second light mass is generated at loop level via the interaction with the second Higgs doublet. At one loop level, one neutrino stays massless. We use multiplicative renormalization constants to define counterterms. The renormalized mass parameters are defined as the complex poles of the propagators, using the complex mass scheme for mass renormalization. With this setup, we analytically get the expressions for the neutrino mass counterterms and isolate the gauge dependent part. We show, how relating this gauge dependent part with the tadpole renormalization leads to gauge independent counterterm definitions, hence gauge independent bare masses for neutrinos.
We derive bounds on the electric and chromo-electric dipole moments of the charm quark. The second one turns out to be particularly strong, and we quantify its impact on models that allow for a sizeable flavour violation in the up quark sector, like flavour alignment and Generic U(2)^3. In particular we show how the bounds coming from the charm and up CEDMs constrain the size of new physics contributions to direct flavour violation in D decays. We also specialize our analysis to the cases of Supersymmetry with split families and composite Higgs models. The results exposed in this paper motivate both an increase in experimental sensitivity to fundamental hadronic dipoles, and a further exploration of the SM contribution to flavour violating D decays.
We have constructed an all-sky catalog of optical AGNs with $z < 0.09$, based on optical spectroscopy, from the parent sample of galaxies in the 2MASS Redshift Survey (2MRS), a near-complete census of the nearby universe. Our catalog consists of 1929 broad line AGNs, and 6562 narrow line AGNs which satisfy the \citet{Kauffmann03} criteria, of which 3607 also satisfy the \citet{Kewley01} criteria. We also report emission line widths, fluxes, flux errors, and signal-to-noise ratios of all the galaxies in our spectroscopic sample, allowing users to customize the selection criteria. Although we uniformly processed the spectra of galaxies from a homogeneous parent sample, inhomogeneities persist due to the differences in the quality of the obtained spectra, taken with different instruments, and the unavailability of spectra for $\sim$20\% of the galaxies. We quantify how the differences in spectral quality affect not only the AGN detection rates but also broad line to narrow line AGN ratios. We find that the inhomogeneities primarily stem from the continuum signal-to-noise (S/N) in the spectra near the emission lines of interest. We fit for the AGN fraction as a function of continuum S/N and assign AGN likelihoods to galaxies which were not identified as AGNs using the available spectra. This correction results in a catalog suitable for statistical studies. This work also paves the way for a truly homogeneous and complete nearby AGN catalog by identifying galaxies whose AGN status needs to be verified with higher quality spectra, quantifying the spectral quality necessary to do so.
The question of thermodynamic consistence and $\Phi$-derivability of the asymptotic limit of high spatial dimensions for quantum itinerant models is addressed. It is shown that although the irreducible $n$-particle Green functions are local, reducible vertex functions retain different momentum dependence. As a consequence, the vertex corrections to conductivity do not generally vanish in the mean-field limit. The mean-field theory is a $\Phi$-derivable approximation only if regular nonlocal or anomalous local external sources are admitted.
A model for a quantum register $\cal R$ made of $N$ replicas of a $d$-dimensional quantum system (cell) coupled with the environment, is studied by means of a Born-Markov Master Equation (ME). Dissipation and decoherence are discussed in various cases in which a sub-decoherent enconding can be rigorously found. For the qubit case ($d=2$) we have solved, for small $N,$ the ME by numerical direct integration and studied, as a function of the coherence length $\xi_c$ of the bath, fidelity and decoherence rates of states of the register. For large enough $\xi_c$ the singlet states of the global $su(2)$ pseudo-spin algebra of the register (noiseless at $\xi_c=\infty$) are shown to have a much smaller decoherence rates than the rest of the Hilbert space.
In present work we study the production of ground and excited charmonium pairs in $e^- e^+ \rightarrow \Psi(nS)+ \chi_{cJ}(nP)$ for $J=0,1$ and $n=1,2$, through leading order (LO) tree-level diagrams $\sim O(\alpha_{em} \alpha_s)$, which proceed through exchange of a virtual photon and an internal gluon line connecting two quark lines (in the triangle quark loop part of the diagram), in the framework of $4\times 4$ Bethe-Salpeter equation, at center of mass energy, $\sqrt{s}=10.6 GeV.$ We have tried to show that the cross sections for this process calculated with use of the four leading order $\sim O(\alpha_{em} \alpha_s)$ diagrams using BSE approach come close to experimental data, which might be mainly due to the consistent treatment of motion of quarks inside the hadrons in the BSE framework.
We suggest the procedure of direct derivation of the symmetry energy from the shift of neutron-proton chemical potentials \Delta\lambda=\lambda_{n}- \lambda_{p} for nuclei beyond the beta-stability line. We observe the presence of anomalous strong (about 15%) shell oscillations at the symmetry energy coefficient b_{sym}. Our results do not confirm the existence of exceptionally large values of the symmetry energy coefficient at mass number A\approx 100 which was earlier reported in Ref.[2]. Using the fitting procedure, we have evaluated the volume, b_{sym,vol}, and surface, b_{sym,surf}, contributions to the symmetry energy. We have estimated the experimental value of surface-to-volume ratio as r_{S/V}=|b_{sym,surf}}|/b_{sym,vol}\approx 1.7 for the fitting interval A\geq 50.
We study questions of multiplicities of discriminants for degenerations coming from projective duality over discrete valuation rings. The main result is a type of discriminant-different formula in the sense of classical algebraic number theory, and we relate it to Artin conductors via Bloch's conjecture. In the case of discriminants of planar curves we can calculate the different precisely. In general these multiplicities encode topological invariants of the singular fibers and in the case of characteristic $p$, wild ramification data in the form of Swan conductors.
The recent discovery of two Earth-mass planets in close orbits around an evolved star has raised questions as to whether substellar companions can survive encounters with their host stars. We consider whether these companions could have been stripped of significant amounts of mass during the phase when they orbited through the dense inner envelopes of the giant. We apply the criterion derived by Murray et al. for disruption of gravitationally bound objects by ram pressure, to determine whether mass loss may have played a role in the histories of these and other recently discovered low-mass companions to evolved stars. We find that the brown dwarf and Jovian mass objects circling WD 0137-349, SDSS J08205+0008, and HIP 13044 are most unlikely to have lost significant mass during the common envelope phase. However, the Earth-mass planets found around KIC 05807616 could well be the remnant of one or two Jovian mass planets that lost extensive mass during the common envelope phase.
In this study we introduce and analyze the statistical structural properties of a model of growing networks which may be relevant to social networks. At each step a new node is added which selects 'k' possible partners from the existing network and joins them with probability delta by undirected edges. The 'activity' of the node ends here; it will get new partners only if it is selected by a newcomer. The model produces an infinite-order phase transition when a giant component appears at a specific value of delta, which depends on k. The average component size is discontinuous at the transition. In contrast, the network behaves significantly different for k=1. There is no giant component formed for any delta and thus in this sense there is no phase transition. However, the average component size diverges for delta greater or equal than one half.
Below 360 mK, Fe magnetic molecular clusters are in the pure quantum relaxation regime and we show that the predicted square-root time relaxation is obeyed, allowing us to develop a new method for watching the evolution of the distribution of molecular spin states in the sample. We measure as a function of applied field H the statistical distribution P(\xi_H) of magnetic energy bias \xi_H$ acting on the molecules. Tunneling initially causes rapid transitions of molecules, thereby digging a hole in P(\xi_H) (around the resonant condition \xi_H = 0). For small initial magnetization values, the hole width shows an intrinsic broadening which may be due to nuclear spins.
A tight far-infrared - radio correlation similar to that in star-forming late-type galaxies is also indicated in star-forming blue early-type galaxies, in which the nuclear optical-line emissions are primarily due to star-forming activities without a significant contribution from active galactic nuclei. The average value of far-infrared to 1.4 GHz radio flux-ratio commonly represented as the $'q'$ parameter is estimated to be $2.35\pm0.05$ with a scatter of 0.16 dex. The average star formation rate estimated using 1.4 GHz radio continuum is $\sim6$ M$_{\odot}$ yr$^{-1}$ in good agreement with those estimated using far-infrared and H$\alpha$ luminosities. The radio emission is detected mainly from central region which could be associated with the star-forming activities, most likely triggered by recent tidal interactions. The average thermal contribution to total radio flux is estimated to be $\sim12$ per cent. The average value of the magnetic field strengths in the star-forming early-type galaxies is estimated to be 12$^{+11}_{-4}$ $\mu$G. These magnetic fields are very likely generated via fast amplification in small-scale turbulent dynamos acting in the star-bursting regions.
Single-reference coupled-cluster theory is an accurate and affordable computational method for the nuclear many-body problem. For open-shell nuclei, the reference state typically breaks rotational invariance and angular momentum must be restored as a good quantum number. We perform angular-momentum projection after variation and employ the disentangled coupled-cluster formalism and a Hermitian approach. We compare our results with benchmarks for $^8$Be and $^{20}$Ne using a two-nucleon interaction from chiral effective field theory and for $pf$-shell nuclei within the traditional shell model. We compute the rotational band in the exotic nucleus $^{34}$Mg and find agreement with data.
Inelastic neutron scattering measurements have been performed on single crystal samples of Co3V2O8 and Ni3V2O8. The magnetic system in these compounds is believed to be frustrated, as the magnetic ions Co2+ with S=3/2 and Ni2+ with S=1 adopt a buckled version of the Kagome lattice. Magnetic excitations have been observed in both samples using a time-of-flight neutron spectrometer. The excitation spectrum is dispersive for both samples and has a considerable gap in the low temperature phases, while the intermediate temperature phases are marked by a significant softening of the excitations energy.
All Type IIn supernovae (SNe IIn) show narrow hydrogen emission lines in their spectra. Apart from this common feature, they demonstrate very broad diversity in brightness, duration, and morphology of their light curves, which indicates that they likely come from a variety of progenitor systems and explosion channels. A particular subset of SNe IIn, the so called SNe IIn-P, exhibit $\sim$100 days plateau phases that are very similar to the ones of the ordinary hydrogen-rich SNe (SNe II). In the past, SNe IIn-P were explained by the models of sub-energetic electron capture explosions surrounded by dense extended winds. In this work, we attempt to explain this class of SNe with standard red supergiant (RSG) progenitors that experience outbursts several month before the final explosion. The outburst energies that show the best agreement between our models and the data ($5\times10^{46}\,{\rm erg}$) fall at the low range of the outburst energies that have been observed for SNe IIn (between few times $10^{46}\,{\rm erg}$ and $10^{49}\,{\rm erg}$). Instead, the inferred explosion energy of SN 2005cl is relatively high ($1-2\times10^{51}\,{\rm erg}$) compared to the explosion energies of the ordinary SNe II. Our models provide alternative explanation of SNe IIn-P to the previously proposed scenarios.
We combine electromagnetic (EM) and gravitational wave (GW) information on the binary neutron star (NS) merger GW170817 in order to constrain the radii $R_{\rm ns}$ and maximum mass $M_{\rm max}$ of NSs. GW170817 was followed by a range of EM counterparts, including a weak gamma-ray burst (GRB), kilonova (KN) emission from the radioactive decay of the merger ejecta, and X-ray/radio emission consistent with being the synchrotron afterglow of a more powerful off-axis jet. The type of compact remnant produced in the immediate merger aftermath, and its predicted EM signal, depend sensitively on the high-density NS equation of state (EOS). For a soft EOS which supports a low $M_{\rm max}$, the merger undergoes a prompt collapse accompanied by a small quantity of shock-heated or disk wind ejecta, inconsistent with the large quantity $\gtrsim 10^{-2}M_{\odot}$ of lanthanide-free ejecta inferred from the KN. On the other hand, if $M_{\rm max}$ is sufficiently large, then the merger product is a rapidly-rotating supramassive NS (SMNS), which must spin-down before collapsing into a black hole. A fraction of the enormous rotational energy necessarily released by the SMNS during this process is transferred to the ejecta, either into the GRB jet (energy $E_{\rm GRB}$) or the KN ejecta (energy $E_{\rm ej}$), also inconsistent with observations. By combining the total binary mass of GW170817 inferred from the GW signal with conservative upper limits on $E_{\rm GRB}$ and $E_{\rm ej}$ from EM observations, we constrain the likelihood probability of a wide-range of previously-allowed EOS. These two constraints delineate an allowed region of the $M_{\rm max}-R_{\rm ns}$ parameter space, which once marginalized over NS radius places an upper limit of $M_{\rm max} \lesssim 2.17M_{\odot}$ (90\%), which is tighter or arguably less model-dependent than other current constraints.
We study characteristic (quasinormal) modes of a $D$-dimensional Schwarzshild black hole. It proves out that the real parts of the complex quasinormal modes, representing the real oscillation frequencies, are proportional to the product of the number of dimensions and inverse horizon radius $\sim D r_{0}^{-1}$. The asymptotic formula for large multipole number $l$ and arbitrary $D$ is derived. In addition the WKB formula for computing QN modes, developed to the 3rd order beyond the eikonal approximation, is extended to the 6th order here. This gives us an accurate and economic way to compute quasinormal frequencies.