ShantanuT01/DACTYL-Pretraining huggingface dataset:
The anisotropy in the angular distribution of the fusion-fission and quasifission fragments for the $^{16}$O+$^{238}$U, $^{19}$F+$^{208}$Pb and $^{32}$S+$^{208}$Pb reactions is studied by analyzing the angular momentum distributions of the dinuclear system and compound nucleus which are formed after capture and complete fusion, respectively. The orientation angles of axial symmetry axes of colliding nuclei to the beam direction are taken into account for the calculation of the variance of the projection of the total spin onto the fission axis. It is shown that the deviation of the experimental angular anisotropy from the statistical model picture is connected with the contribution of the quasifission fragments which is dominant in the $^{32}$S+$^{208}$Pb reaction. Enhancement of anisotropy at low energies in the $^{16}$O+$^{238}$U reaction is connected with quasifission of the dinuclear system having low temperature and effective moment of inertia.
We calculate, in a systematic way, the enhancement effect on antiproton-proton and antiproton-nucleus annihilation cross sections at low energy due to the initial state electrostatic interaction between the projectile and the target nucleus. This calculation is aimed at future comparisons between antineutron and antiproton annihilation rates on different targets, for the extraction of pure isospin channels.
We analyse the scatter in the correlation between super-massive black hole (SMBH) mass and bulge stellar mass of the host galaxy, and infer that it cannot be accounted for by mergers alone. The merger-only scenario, where small galaxies merge to establish a proportionality relation between the SMBH and bulge masses, leads to a scatter around the linear proportionality line that increases with the square root of the SMBH (or bulge) mass. By examining a sample of 103 galaxies we find that the intrinsic scatter increases more rapidly than expected from the merger-only scenario. The correlation between SMBH masses and their host galaxy properties is therefore more likely to be determined by a negative feedback mechanism that is driven by an active galactic nucleus. We find a hint that some galaxies with missing stellar mass reside close to the centre of clusters and speculate that ram-pressure stripping of gas off the young galaxy as it moves near the cluster centre, might explain the missing stellar mass at later times.
A naked singularity is formed by the collapse of a Sine-Gordon soliton in 1+1 dimensional dilaton gravity with a negative cosmological constant. We examine the quantum stress tensor resulting from the formation of the singularity. Consistent boundary conditions require that the incoming soliton is accompanied by a flux of incoming radiation across past null infinity, but neglecting the back reaction of the spacetime leads to the absurd conclusion that the total energy entering the system by the time the observer is able to receive information from the singularity is infinite. We conclude that the back reaction must prevent the formation of the naked singularity.
We present spectroscopy of 76 emission-line galaxies (ELGs) in CDF-S taken with the LDSS3 spectrograph on Magellan Telescope. These galaxies are selected to have emission lines with ACS grism data in the Hubble Space Telescope Probing Evolution and Reionization Spectroscopically (PEARS) grism Survey. The ACS grism spectra cover the wavelength range 6000-9700 \AA\ and most PEARS grism redshifts are based on a single emission line + photometric redshifts from broad-band colors; the Magellan spectra cover a wavelength range from 4000 {\AA} to 9000 {\AA}, and provide a check on redshifts derived from PEARS data. We find an accuracy of $\sigma_z$ = 0.006 for the ACS grism redshifts with only one catastrophic outlier. We probe for AGN in our sample via several different methods. In total we find 7 AGNs and AGN candidates out of 76 galaxies. Two AGNs are identified from the X-ray full-band luminosity, $L_{X-ray,FB}>10^{43}$ erg$\;$s$^{-1}$, the line widths and the power-law continuum spectra. Two unobscured faint AGN candidates are identified from the X-ray full-band luminosity $L_{X-ray,FB}\sim10^{41}$ erg$\;$s$^{-1}$, the hardness ratio and the column density, and the emission-line and X-ray derived SFRs. Two candidates are classified based on the line ratio of [NII]\lambda6584/H$\alpha$ versus [OIII]$\lambda$5007/H$\beta$ (BPT diagram), which are between the empirical and theoretical demarcation curves, i.e, the transition region from star-forming galaxies to AGNs. One AGN candidate is identified from the high-ionization emission line HeII{\AA}4686.
The transformation of an atomic nucleus into two excited fission fragments is modeled as a strongly damped evolution of the nuclear shape, until scission occurs at a small critical neck radius, at which point the mass, charge, and shape of each fragment are extracted. The available excitation energy then is divided statistically on the basis of the microscopic level densities. This approach takes account of the important (and energy-dependent) finite-size effects. After the fragments have been fully accelerated and their shapes have relaxed to their equilibrium form, they undergo sequential neutron evaporation. The dependence of the resulting mean neutron multiplicity on the fragment mass, $\bar{\nu}$(A), including the dependence on the initial excitation energy of the fissioning compound nucleus, is in good agreement with the observed behavior, as demonstrated here for $^{235}$U(n,f).
Bulges are not just elliptical subgalaxies situated in the centers of large spirals. It might seem that way from their ages and chemistry, but bulge kinematics have been known to be different since the first long slit spectra were obtained. M31 presents the best opportunity to investigate all the issues of the stellar populations of bulges. This review collects the array of probing data that has been accumulated in the last decade. But the intriguing question `how did it form like this ?' remains.
The phase stability of the various crystalline structures of the super-heavy element Copernicium was determined based on the first-principles calculations with different levels of the relativistic effects. We utilized the Darwin term, mass-velocity, and spin-orbit interaction with the single electron framework of the density functional theory while treating the exchange and correlation effects using local density approximations. It is found that the spin-orbit coupling is the key component to stabilize the body-centered cubic ($bcc$) structure over the hexagonal closed packed ($hcp$) structure, which is in accord with Sol. Stat. Comm. 152 (2012) 530, but in contrast to Sol. Stat. Comm. 201 (2015) 88, Angew. Chem. 46 (2007) 1663, Handbook of Elemental Solids Z=104-112 (Springer 2015). It seems that the main role here is the correct description of the semi-core relativistic $6p_{1/2}$ orbitals. The all other investigated structures, i.e. face-centered cubic ($fcc$), simple cubic ($sc$) as well as rhombohedral ($rh$) structures are higher in energy. The criteria of mechanical stability were investigated based on the calculated elastic constants, identifying the phase instability of $fcc$ and $rh$ structures, but surprisingly confirm the stability of the energetically higher $sc$ structure. In addition, the pressure-induced structural transition between two stable $sc$ and $bcc$ phases has been detected. The ground-state $bcc$ structure exhibits the highest elastic anisotropy from single elements of the Periodic table. At last, we support the experimental findings that Copernicium is a metal.
Following Fermi and NOT observations, Ruffini et al. (2019b) soon identified GRB 190114C as BdHN I at z=0.424, it has been observed since, with unprecedented accuracy, [...] all the way to the successful optical observation of our predicted supernova (SN). This GRB is a twin of GRB 130427A. Here we take advantage of the GBM data and identify in it three different Episodes. Episode 1 represents the precursor which includes the SN breakout and the creation of the new neutron star ($\nu$NS), the hypercritical accretion of the SN ejecta onto the NS binary companion, exceeding the NS critical mass at $t_{rf}=1.9$s. Episode 2 starting at $t_{rf}=1.9$s includes three major events: the formation of the BH, the onset of the GeV emission and the onset of the ultra-relativistic prompt emission (UPE), which extends all the way up to $t_{rf}=3.99$s. Episode 3 which occurs at times following $t_{rf}=3.99$s reveals the presence of a cavity carved out in the SN ejecta by the BH formation. We perform an in depth time-resolved spectral analysis on the entire UPE with the corresponding determination of the spectra best fit by a cut-off power-law and a black body (CPL+BB) model, and then we repeat the spectral analysis in 5 successive time iterations in increasingly shorter time bins: we find a similarity in the spectra in each stage of the iteration revealing clearly a self-similar structure. We find a power-law dependence of the BB temperature with index $-1.56\pm0.38$, a dependence with index $-1.20\pm0.26$ for the gamma-ray luminosity confirming a similar dependence with index $-1.20\pm0.36$ which we find as well in the GeV luminosity, both expressed in the rest-frame. We thus discover in the realm of relativistic astrophysics the existence of a self-similar physical process and power-law dependencies, extensively described in the micro-physical world by the classical works of Heisenberg-Landau-Wilson.
In this paper, we consider the volume of a special kind of flow polytope. We show that its volume satisfies a certain system of differential equations, and conversely, the solution of the system of differential equations is unique up to a constant multiple. In addition, we give an inductive formula for the volume with respect to the rank of the root system of type A.
$0^+$, $1^-$, $2^+$, and $3^-$ excitations of $^{28}\textrm{Si}$ are investigated via proton and $\alpha$ inelastic scattering off $^{28}\textrm{Si}$. The structure calculation of $^{28}\textrm{Si}$ is performed with the energy variation after total angular momentum and parity projections in the framework of antisymmetrized molecular dynamics (AMD). As a result of the AMD calculation, the oblate ground and prolate bands, $0^+$ and $3^-$ excitations, and the $1^-$ and $3^-$ states of the $K^\pi=0^-$ band are obtained. Using the matter and transition densities of $^{28}\textrm{Si}$ obtained by AMD, microscopic coupled-channel calculations of proton and $\alpha$ scattering off $^{28}\textrm{Si}$ are performed. The proton-$^{28}\textrm{Si}$ potentials in the reaction calculation are microscopically derived by folding the Melbourne $g$-matrix $NN$ interaction with the AMD densities of $^{28}\textrm{Si}$. The $\alpha$-$^{28}\textrm{Si}$ potentials are obtained by folding the nucleon-$^{28}\textrm{Si}$ potentials with an $\alpha$ density. The calculation reasonably reproduces the observed elastic and inelastic cross sections of proton and $\alpha$ scattering. Transition properties are discussed by combining the reaction analysis of proton and $\alpha$ scattering and structure features such as transition strengths and form factors. The isoscalar monopole and dipole transitions are focused.
The phenomenon of solar "torsional oscillations" (TO) represents migratory zonal flows associated with the solar cycle. These flows are observed on the solar surface and, according to helioseismology, extend through the convection zone. We study the origin of the TO using results from a global MHD simulation of the solar interior that reproduces several of the observed characteristics of the mean-flows and magnetic fields. Our results indicate that the magnetic tension (MT) in the tachocline region is a key factor for the periodic changes in the angular momentum transport that causes the TO. The torque induced by the MT at the base of the convection zone is positive at the poles and negative at the equator. A rising MT torque at higher latitudes causes the poles to speed-up, whereas a declining negative MT torque at the lower latitudes causes the equator to slow-down. These changes in the zonal flows propagate through the convection zone up to the surface. Additionally, our results suggest that it is the magnetic field at the tachocline that modulates the amplitude of the surface meridional flow rather than the opposite as assumed by flux-transport dynamo models of the solar cycle.
We derive an upper bound on the mass difference between the $\Xi^*$ and $\Theta^+$ pentaquarks which are the manifestly exotic members of the $SU(3)_f$ antidecuplet. The derivation is based on simple assumptions about $SU(3)_f$ symmetry breaking and uses the standard quantum mechanical variational method. The resulting rather robust bound is more than 20 MeV below the experimentally reported $\Xi^*-\Theta^+$ mass difference, emphasizing the need for confirmation of the experimental mass values and placing strong constraints on quark models of the pentaquark structure.
We use high spectral resolution (R=45000) and high signal-to-noise ratio (S/N \~ 35-70 per pixel) spectra of 19 high-redshift (2.1<z_em<3.2) quasars to investigate the metal content of the low-density intergalactic medium using pixel-by-pixel procedures. This high quality homogeneous survey gives the possibility to statistically search for metals at HI optical depths smaller than unity. We find that the gas is enriched in carbon and oxygen for neutral hydrogen optical depths tau(HI)>1. Our observations strongly suggest that the CIV/HI ratio decreases with decreasing tau(HI) with log[tau(CIV)]=1.3xlog[tau(HI)]-3.2. We do not detect CIV absorption statistically associated with gas of tau(HI)<1. However, we observe that a small fraction of the low density gas is associated with strong metal lines as a probable consequence of the IGM enrichment being highly inhomogeneous. We detect the presence of OVI down to tau(HI)~0.2 with log[tau(OVI)/tau(HI)] -2.0. We show that OVI absorption in the lowest density gas is located within ~300 km/s from strong HI lines. This suggests that this OVI phase may be part of winds flowing away from overdense regions. This effect is more important at the largest redshifts (z>2.4). Therefore, at the limit of present surveys, the presence of metals in the underdense regions of the IGM is still to be demonstrated.
We study the large-time and small-time asymptotic behaviors of the spectral heat content for time-changed stable processes, where the time change belongs to a large class of inverse subordinators. For the large-time behavior, the spectral heat content decays polynomially with the decay rate determined by the Laplace exponent of the underlying subordinator, which is in sharp contrast to the exponential decay observed in the case when the time change is a subordinator. On the other hand, the small-time behavior exhibits three different decay regimes, where the decay rate is determined by both the Laplace exponent and the index of the stable process.
The Box-Ball System (BBS) is a one-dimensional cellular automaton in $\{0,1\}^\Z$ introduced by Takahashi and Satsuma \cite{TS}, who also identified conserved sequences called \emph{solitons}. Integers are called boxes and a ball configuration indicates the boxes occupied by balls. For each integer $k\ge1$, a $k$-soliton consists of $k$ boxes occupied by balls and $k$ empty boxes (not necessarily consecutive). Ferrari, Nguyen, Rolla and Wang \cite{FNRW} define the $k$-slots of a configuration as the places where $k$-solitons can be inserted. Labeling the $k$-slots with integer numbers, they define the $k$-component of a configuration as the array $\{\zeta_k(j)\}_{j\in \mathbb Z}$ of elements of $\Z_{\ge0}$ giving the number $\zeta_k(j)$ of $k$-solitons appended to $k$-slot $j\in \mathbb Z$. They also show that if the Palm transform of a translation invariant distribution $\mu$ has independent soliton components, then $\mu$ is invariant for the automaton. We show that for each $\lambda\in[0,1/2)$ the Palm transform of a product Bernoulli measure with parameter $\lambda$ has independent soliton components and that its $k$-component is a product measure of geometric random variables with parameter $1-q_k(\lambda)$, an explicit function of $\lambda$. The construction is used to describe a large family of invariant measures with independent components under the Palm transformation, including Markov measures.
Yellow hypergiants are evolved massive stars that were suggested to be in post-red supergiant stage. Post-red supergiants that evolve back to the blue, hot side of the Hertzsprung-Russell diagram can intersect a temperature domain in which their atmospheres become unstable against pulsations (the Yellow Void or Yellow Wall), and the stars can experience outbursts with short, but violent mass eruptions. The yellow hypergiant Rho Cas is famous for its historical and recent outbursts, during which the star develops a cool, optically thick wind with a very brief but high mass-loss rate, causing a sudden drop in the light curve. Here we report on a new outburst of Rho Cas which occurred in 2013, accompanied by a temperature decrease of ~3000 K and a brightness drop of 0.6 mag. During the outburst TiO bands appear, together with many low excitation metallic atmospheric lines characteristic for a later spectral type. With this new outburst, it appears that the time interval between individual events decreases, which might indicate that Rho Cas is preparing for a major eruption that could help the star to pass through the Yellow Void. We also analysed the emission features that appear during phases of maximum brightness and find that they vary synchronous with the emission in the prominent [CaII] lines. We conclude that the occasionally detected emission in the spectra of Rho Cas, as well as certain asymmetries seen in the absorption lines of low to medium-excitation potential, are circumstellar in nature, and we discuss the possible origin of this material.
The study of fast, eruptive events in the low solar corona is one of the science objectives of the Atmospheric Imaging Assembly (AIA) imagers on the recently launched Solar Dynamics Observatory (SDO), which take full disk images in ten wavelengths with arcsecond resolution and 12 sec cadence. We study with AIA the formation of an impulsive coronal mass ejection (CME) which occurred on June 13, 2010 and was associated with an M1.0 class flare. Specifically, we analyze the formation of the CME EUV bubble and its initial dynamics and thermal evolution in the low corona using AIA images in three wavelengths (171, 193 and 211 A). We derive the first ultra-high cadence measurements of the temporal evolution of the CME bubble aspect ratio (=bubble-height/bubble-radius). Our main result is that the CME formation undergoes three phases: it starts with a slow self-similar expansion followed by a fast but short-lived (~ 70 sec) period of strong lateral over-expansion which essentially creates the CME. Then the CME undergoes another phase of self-similar expansion until it exits the AIA field of view. During the studied interval, the CME height-time profile shows a strong, short-lived, acceleration followed by deceleration. The lateral overexpansion phase coincides with the deceleration phase. The impulsive flare heating and CME acceleration are closely coupled. However, the lateral overexpansion of the CME occurs during the declining phase and is therefore not linked to flare reconnection. In addition, the multi-thermal analysis of the bubble does not show significant evidence of temperature change.
In this chapter, we investigate the structure and composition of hot neutron star matter and proto-neutron stars. Such objects are made of baryonic matter that is several times denser than atomic nuclei and tens of thousands times hotter than the matter in the core of our Sun. The relativistic finite-temperature Green function formalism is used to formulate the expressions that determine the properties of such matter in the framework of the density-dependent mean field approach. Three different sets of nuclear parametrizations are used to solve the many-body equations and to determine the models for the equation of state of ultra-hot and dense stellar matter. The meson-baryon coupling scheme and the role of the \{Delta}(1232) baryon in proto-neutron star matter are investigated in great detail. In addition, using the non-local three-flavor Nambu-Jona-Lasinio model to describe quark matter, the hadron-quark composition of dense baryonic matter at zero temperature is discussed briefly. General relativistic models of non-rotating as well as rotating proto-neutron stars are presented in part two of our study.
Cusp forms for the full modular group can be written as linear combination of double Eisenstein series introduced by Gangl, Kaneko and Zagier. We give an explicit formula for decomposing a Hecke eigenform into double Eisenstein series.
The s-wave meson-baryon interaction in the $S = -1$ sector is studied by means of coupled-channels, using the lowest-order chiral Lagrangian and the N/D method to implement unitarity. The loops are regularized using dimensional renormalization. In addition to the previously studied $\Lambda (1405)$, employing this chiral approach leads to the dynamical generation of two more s-wave hyperon resonances, the $\Lambda(1670)$ and $\Sigma(1620)$ states. We make comparisons with experimental data and look for poles in the complex plane obtaining the couplings of the resonances to the different final states. This allows us to identify the $\Lambda (1405)$ and the $\Lambda(1670)$ resonances with $\bar{K}N$ and $K\Xi$ quasibound states, respectively.
We demonstrate coherent control of cyclotron resonance (CR) in a two-dimensional electron gas (2DEG). We use a sequence of terahertz pulses to control the amplitude of CR oscillations in an arbitrary fashion via phase-dependent coherent interactions. We observe a self-interaction effect, where the 2DEG interacts with the terahertz field emitted by itself within the decoherence time, resulting in a revival and collapse of quantum coherence. These observations are accurately describable using {\em single-particle} optical Bloch equations, showing no signatures of electron-electron interactions, which verifies the validity of Kohn's theorem for CR in the coherent regime.
A new expression for the spin connection of teleparallel gravity is proposed, given by minus the contorsion tensor plus a zero connection. The corresponding minimal coupling is covariant under local Lorentz transformation, and equivalent to the minimal coupling prescription of general relativity. With this coupling prescription, therefore, teleparallel gravity turns out to be fully equivalent to general relativity, even in the presence of spinor fields.
Context: The determination of the underlying mechanisms of the magnetic elements diffusion over the solar surface is still a challenge. Understanding the formation and evolution of the solar network (NE) is a challenge, because it provides a magnetic flux over the solar surface comparable to the flux of active regions at solar maximum. Aims: We investigate the structure and evolution of interior cells of solar supergranulation. From Hinode observations, we explore the motions on solar surface at high spatial and temporal resolution. We derive the main organization of the flows inside supergranules and their effect on the magnetic elements. Method: To probe the superganule interior cell, we used the Trees of Fragmenting Granules (TFG) evolution and their relations to horizontal Results: Evolution of TFG and their mutual interactions result in cumulative effects able to build horizontal coherent flows with longer lifetime than granulation (1 to 2 hours) over a scale up to 12\arcsec. These flows clearly act on the diffusion of the intranetwork (IN) magnetic elements and also on the location and shape of the network. Conclusions: From our analysis during 24 hours, TFG appear as one of the major elements of the supergranules which diffuse and advect the magnetic field on the Sun's surface. The strongest supergranules contribute the most to magnetic flux diffusion in the solar photosphere.