ShantanuT01/DACTYL-Pretraining huggingface dataset:
We present the results of the deepest optically identified X-ray survey yet made. The X-ray survey was made with the ROSAT PSPC and reaches a flux limit of 1.6x10^-15 erg cm^-2 s^-1 (0.5--2.0 keV). Above a flux limit of 2x10^-15 erg cm^-2 s^-1 we define a complete sample of 70 sources of which 59 are identified. Some (5) other sources have tentative identifications and in a further 4 the X-ray error-boxes are blank to R=23 mag. At the brighter flux levels (>= 10^-14 erg cm^-2 s^-1) we confirm the results of previous less deep X-ray surveys with 84% of the sources begin QSOs. At fainter fluxes, however, the survey is dominated by a population of galaxies with narrow optical emission lines (NELGs). In addition, a number of groups and clusters of galaxies are found at intermediate fluxes. Most of these are poor systems of low X-ray luminosity and are generally found at redshifts of > 0.3. Their numbers are consistent with a zero evolutionary scenario, in contrast to the situation for high luminosity clusters at the same redshift. We discuss the significance of these results to the determination of the cosmic soft X-ray background (XRB) and show that at 2x10^-15 erg cm^-2 s^-1, we have resolved more than 50% of the background. We also briefly consider the probable importance of NELG objects to the residual background and look at some of the properties of these unusual objects.
We seek to design experimentally feasible broadband, temporally multiplexed optical quantum memory with near-term applications to telecom bands. Specifically, we devise dispersion compensation for an impedance-matched narrow-band quantum memory by exploiting Raman processes over two three-level atomic subensembles, one for memory and the other for dispersion compensation. Dispersion compensation provides impedance matching over more than a full cavity linewidth. Combined with one second spin-coherence lifetime the memory could be capable of power efficiency exceeding 90% leading to 106 modes for temporal multiplexing. Our design could lead to significant multiplexing enhancement for quantum repeaters to be used for telecom quantum networks.
We report the first ab initio density-functional study of <111> screw dislocations cores in the bcc transition metals Mo and Ta. Our results suggest a new picture of bcc plasticity with symmetric and compact dislocation cores, contrary to the presently accepted picture based on continuum and interatomic potentials. Core energy scales in this new picture are in much better agreement with the Peierls energy barriers to dislocation motion suggested by experiments.
Chiral superfields have been used, and extensively, almost ever since supersymmetry has been discovered. Complex linear superfields afford an alternate representation of matter, but are widely misbelieved to be 'physically equivalent' to chiral ones. We prove the opposite is true. Curiously, this re-enables a previously thwarted interpretation of the low-energy (super)field limit of superstrings.
Surface differential rotation (DR) is one major ingredient of the magnetic field generation process in the Sun and likely in other stars. The term solar-like differential rotation describes the observation that solar equatorial regions rotate faster than polar ones. The opposite effect of polar regions rotating faster than equatorial ones (termed as antisolar DR) has only been observed in a few stars, although there is evidence from theoretical dynamo models. We present a new method to detect the sign of DR (i.e. solar-like or antisolar DR) by analyzing long-term high-precision light curves with the Lomb-Scargle periodogram.We compute the Lomb-Scargle periodogram and identify a set of significant periods $P_k$, which we associate with active regions located at different latitudes on the the stellar surface. If detectable, the first harmonics ($P_k'$) of these periods were identified to compute their peak-height-ratios $r_k:=h(P_k')/h(P_k)$. Spots rotating at lower latitudes generate less sine-shaped light curves, which requires additional power in the harmonics, and results in larger ratios $r_k$. Comparing different ratios $r_k$ and the associated periods $P_k$ yields information about the spot latitudes, and reveals the sign of DR. We tested our method on different sets of synthetic light curves all exhibiting solar-like DR. The number of cases where our method detects antisolar DR is the false-positive rate of our method. Depending on the set of light curves, the noise level, the required minimum peak separation, and the presence or absence of spot evolution, our method fails to detect the correct sign in at most 20%. We applied our method to 50 Kepler G stars and found 21-34 stars with solar-like DR and 5-10 stars with antisolar DR, depending on the minimum peak separation.
We present high resolution (9$^{\prime \prime}$) imaging of the Sunyaev-Zel'dovich Effect (SZE) toward two massive galaxy clusters, MACS J0647.7+7015 ($z=0.591$) and MACS J1206.2-0847 ($z=0.439$). We compare these 90 GHz measurements, taken with the MUSTANG receiver on the Green Bank Telescope, with generalized Navarro-Frenk-White (gNFW) models derived from Bolocam 140 GHz SZE data as well as maps of the thermal gas derived from {\it Chandra} X-ray observations. For MACS J0647.7+7015, we find a gNFW profile with core slope parameter $\gamma= 0.9$ fits the MUSTANG image with $\chi^{2}_{red}=1.005$ and probability to exceed (PTE) = 0.34. For MACS J1206.2-0847, we find $\gamma=0.7$, $\chi^{2}_{red}=0.993$, and PTE = 0.70. In addition, we find a significant ($>$3-$\sigma$) residual SZE feature in MACS J1206.2-0847 coincident with a group of galaxies identified in VLT data and filamentary structure found in a weak-lensing mass reconstruction. We suggest the detected sub-structure may be the SZE decrement from a low mass foreground group or an infalling group. GMRT measurements at 610 MHz reveal diffuse extended radio emission to the west, which we posit is either an AGN-driven radio lobe, a bubble expanding away from disturbed gas associated with the SZE signal, or a bubble detached and perhaps re-accelerated by sloshing within the cluster. Using the spectroscopic redshifts available, we find evidence for a foreground ($z=0.423$) or infalling group, coincident with the residual SZE feature.
We present a detailed study of the gamma-ray emission from the direction of the star-forming region W30 based on a decade of the Fermi Large Area Telescope data in the 0.3-300 GeV photon energy range. The morphological and spectral analyses allow us to resolve the gamma-ray emission into two extended structures from different origins. One of them mostly overlaps with the supernova remnant (SNR) G8.7-0.1 and has a soft spectrum that resembles with the spectra of other middle-aged SNRs interacting with molecular clouds. The other shows remarkable spatial and spectral consistency with the TeV emission from HESS J1804-216, and its spectrum could be naturally explained by inverse Compton scattering of electrons like a number of TeV gamma-ray emitting pulsar wind nebulae. Thus we attribute this source to the nebula around the pulsar PSR J1803-2137.
We review the effect of the commonly-used Limber and flat-sky approximations on the calculation of shear power spectra and correlation functions for galaxy weak lensing. These approximations are accurate at small scales, but it has been claimed recently that their impact on low multipoles could lead to an increase in the amplitude of the mass fluctuations inferred from surveys such as CFHTLenS, reducing the tension between galaxy weak lensing and the amplitude determined by Planck from observations of the cosmic microwave background. Here, we explore the impact of these approximations on cosmological parameters derived from weak lensing surveys, using the CFHTLenS data as a test case. We conclude that the use of small-angle approximations for cosmological parameter estimation is negligible for current data, and does not contribute to the tension between current weak lensing surveys and Planck.
We investigate random walks in independent, identically distributed random sceneries under the assumption that the scenery variables satisfy Cramer's condition. We prove moderate deviation principles in dimensions two and larger, covering all those regimes where rate and speed do not depend on the actual distribution of the scenery. In the case of dimension four and larger we even obtain precise asymptotics for the annealed probability of a moderate deviation, extending a classical central limit theorem of Kesten and Spitzer. In dimension three and larger, an important ingredient in the proofs are new concentration inequalities for self-intersection local times of random walks, which are of independent interest, whilst in dimension two we use a recent moderate deviation result for self-intersection local times, which is due to Bass, Chen and Rosen.
A comparison between full few-body Faddeev/Alt-Grassberger-Sandhas (Faddeev/AGS) and continuum-discretized coupled channels (CDCC) calculations is made for the resonant and nonresonant breakup of $^{11}$Be on proton target at 63.7 MeV/u incident energy. A simplified two-body model is used for $^{11}$Be which involves an inert $^{10}$Be(0$^+$) core and a valence neutron. The sensitivity of the calculated observables to the nucleon-nucleon potential dynamical input is analysed. We show that with the present NN and N-core dynamics the results remain a puzzle for the few-body problem of scattering from light exotic halo nuclei.
We report on an extensive investigation of the multiferroic compound TbMnO$_3$. Non-resonant x-ray magnetic scattering (NRXMS) revealed a dominant $A$-type domain. The temperature dependence of the intensity and wavevector associated with the incommensurate magnetic order was found to be in good agreement with neutron scattering data. XRS experiments were performed in the vicinity of the Mn $K$ and Tb $L_3$ edges in the high-temperature collinear phase, the intermediate temperature cycloidal/ferroelectric phase, and the low-temperature phase. In the collinear phase resonant $E1-E1$ satellites were found at the Mn $K$ edge associated with $A$-type but also $F$-type peaks. The azimuthal dependence of the $F$-type satellites (and their absence in the NRXMS experiments) indicates that they are most likely non-magnetic in origin. We suggest instead that they may be associated with an induced charge multipole. At the Tb $L_3$ edge resonant $A$- and $F$-type satellites ($E1-E1$) were observed in the collinear phase. These we attribute to a polarisation of the Tb 5$d$ states by the ordering of the Mn sublattice. In the cycloidal/ferroelectric phase a new set of resonant satellites appear corresponding to $C$-type order. These appear at the Tb $L_3$ edge only. In addition to a dominant $E1-E1$ component in the $\sigma-\pi^\prime$ channel, a weaker component is found in the pre-edge with $\sigma-\sigma^\prime$ polarization. Calculations of the XRS were performed using the $FDMNES$ code showing that the unrotated $\sigma-\sigma^\prime$ component of the Tb $L_3$ $C$-type peaks appearing in the ferroelectric phase contains a contribution from a multipole that is odd with respect to both space and time, known in various contexts as the anapole.
The transition from a flowing to a static state in a granular material is studied using large-scale, 3D particle simulations. Similar to glasses, this transition is manifested in the development of a plateau in the contact normal force distribution P(f) at small forces, along with the splitting of the second peak in the pair correlation function g(r), suggesting compaction and local ordering. The mechanical state changes from one dominated by plastic intergrain contacts in the flowing state to one dominated by elastic contacts in the static state. We define a staticity index that determines how close the system is to an isostatic state, and show that for our systems, the static state is not isostatic.
We study the two-impurity Anderson model on finite chains using numerical techniques. We discuss the departure of magnetic correlations as a function of the interimpurity distance from a pure 2k_F oscillation due to open boundary conditions. We observe qualitatively different behaviors in the interimpurity spin correlations and in transport properties at different values of the impurity couplings. We relate these different behaviors to a change in the relative dominance between the Kondo effect and the Ruderman-Kittel-Kasuya-Yoshida (RKKY) interaction. We also observe that when RKKY dominates there is a definite relation between interimpurity magnetic correlations and transport properties. In this case, there is a recovery of 2k_F periodicity when the on-site Coulomb repulsion on the chain is increased at quarter-filling. The present results could be relevant for electronic nanodevices implementing a non-local control between two quantum dots that could be located at variable distance along a wire.
Here we discuss the jet production efficiency in a sample of 17 young radio galaxies with measured redshifts, kinematic ages, and nuclear X-ray fluxes, for which the observed luminosities of compact jets/lobes and accretion disks correspond to the same episode of the AGN activity. For the targets, we analyze the available optical data, estimating the bolometric luminosities of the accretion disks $L_{\rm bol}$, and the black hole masses; we also derive the minimum jet kinetic luminosities, $P_{\rm j}$. With such, we investigate the distribution of our sample in the three-dimensional space of the accretion rate $\lambda_{\rm Edd} \equiv L_{\rm bol}/L_{\rm Edd}$, the nuclear X-ray luminosity $L_{\rm X}$ considered here as a limit for the emission of the disk coronae, and $P_{\rm j}$, expressing the latter two parameters either in the Eddington units, or in the units of the disk luminosity. We find that (i) the accretion rate $\lambda_{\rm Edd}$ in our sample is distributed within a narrow range $\lambda_{\rm Edd} \sim 0.01 - 0.2$; (ii) the normalized jet power $P_{\rm j}/L_{\rm Edd}$ formally correlates with the accretion rate $\lambda_{\rm Edd}$, with some saturation at the largest values $\lambda_{\rm Edd}> 0.05$; (iii) the jet production efficiency $\eta_{\rm jet} \equiv P_{\rm j}/\dot{M}_{\rm acc} c^2$ spans a range from $\eta_{\rm jet} \lesssim 10^{-3}$ up to $\sim 0.2$ at maximum, which is below the level expected for magnetically arrested disks around maximally spinning black holes; and (iv) there is a diversification in $\eta_{\rm jet}$ on the hardness--intensity diagram $L_{\rm X}/L_{\rm bol} - \lambda_{\rm Edd}$, with the jets being produced most efficiently during the high/hard states, and suppressed during the soft states.
A method for non-destructive characterization of a dipole trapped atomic sample is presented. It relies on a measurement of the phase-shift imposed by cold atoms on an optical pulse that propagates through a free space Mach-Zehnder interferometer. Using this technique we are able to determine, with very good accuracy, relevant trap parameters such as the atomic sample temperature, trap oscillation frequencies and loss rates. Another important feature is that our method is faster than conventional absorption or fluorescence techniques, allowing the combination of high-dynamical range measurements and a reduced number of spontaneous emission events per atom.
We describe various properties of continued fraction expansions of complex numbers in terms of Gaussian integers. Numerous distinct such expansions are possible for a complex number. They can be arrived at through various algorithms, as also in a more general way from what we call "iteration sequences". We consider in this broader context the analogues of the Lagrange theorem characterizing quadratic surds, the growth properties of the denominators of the convergents, and the overall relation between sequences satisfying certain conditions, in terms of nonoccurrence of certain finite blocks, and the sequences involved in continued fraction expansions. The results are also applied to describe a class of binary quadratic forms with complex coefficients whose values over the set of pairs of Gaussian integers form a dense set of complex numbers.
We consider a free boundary problem of compressible-incompressible two-phase flows with phase transitions in general domains of $N$-dimensional Euclidean space (e.g. whole space; half-spaces; bounded domains; exterior domains). The compressible fluid and the incompressible fluid are separated by either compact or non-compact sharp moving interface, and the surface tension is taken into account. In our model, the compressible fluid and incompressible fluid are occupied by the Navier-Stokes-Korteweg equations and the Navier-Stokes equations, respectively. This paper shows that for given $T > 0$ the problem admits a unique strong solution on $(0,T)$ in the maximal $L_p - L_q$ regularity class provided the initial data are small in their natural norms.
We review the current status of the exotic pentaquark baryons. After a brief look at experiments of both positive and negative results, we discuss theoretical methods to study the structure and reactions for the pentaquarks. First we introduce the quark model and the chiral soliton model, where we discuss the relation of mass spectrum and parity with some emphasis on the role of chiral symmetry. It is always useful to picture the structure of the pentaquarks in terms of quarks. As for other methods, we discuss a model independent method, and briefly mention the results from the lattice and QCD sum rule. Decay properties are then studied in some detail, which is one of the important properties of Theta+. We investigate the relation between the decay width and the quark structure having certain spin-parity quantum numbers. Through these analyses, we consider as plausible quantum numbers of Theta+, JP = 3/2-. In the last part of this note, we discuss production reactions of Theta+ which provide links between the theoretical models and experimental information. We discuss photoproductions and hadron-induced reactions which are useful to explore the nature of Theta+
For systems close to equilibrium, the relaxation properties of measurable physical quantities are described by the linear response theory and the fluctuation-dissipation theorem (FDT). Accordingly, the response or the generalized susceptibility, which is a function of the unperturbed equilibrium system, can be related to the correlation between spontaneous fluctuations of a given conjugate variable. There have been several attempts to extend the FDT far from equilibrium, introducing new terms or using effective temperatures. Recently, Prost, Joanny, and Parrondo [Phys. Rev. Lett. 103, 090601 (2009)] have shown that the FDT can be restored far from equilibrium by choosing the appropriate variables conjugate to the external perturbations. Here, we apply the generalized FDT to a system perturbed by time-dependent deterministic forces and acting under the influence of white alpha-stable noises.
Magnetar giant flares are rare and highly energetic phenomena observed in the transient sky whose emission mechanisms are still not fully understood. Depending on the nature of the excited modes of the magnetar, they are also expected to emit gravitational waves, which may bring unique information about the dynamics of the excitation. A few magnetar giant flares have been proposed to be associated to short gamma-ray bursts. In this paper we revisit, with a new gravitational-wave search algorithm, the possible emission of gravitational waves from four magnetar giant flares within 5 Mpc. While no gravitational-wave signals were observed, we discuss the future prospects of detecting signals with more sensitive gravitational-wave detectors. We in particular show that galactic magnetar giant flares that emit at least 1% of their electromagnetic energy as gravitational waves could be detected during the planned observing run of the LIGO and Virgo detectors at design sensitivity, with even better prospects for third generation detectors.
Broadband tomography statistically extracts the redshift distribution of frequency dependent emission from the cross correlation of intensity maps with a reference catalog of galaxy tracers. We make forecasts for the performance of future all-sky UV experiments doing broadband tomography. We consider the Cosmological Advanced Survey Telescope for Optical-UV Research (CASTOR) and the Spectro-Photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer (SPHEREx). We show that under reasonable error models, CASTOR measures the UV background SED 2-10 times better than existing data. It will also expand the applicable redshift range from the current z < 1 to z~0-3 with CASTOR and z=5-9 with SPHEREx. We show that CASTOR can provide competitive constraints on the EBL monopole to those available from galaxy number counts and direct measurement techniques. At high redshift especially, these results will help understand galaxy formation and reionization. Our modelling code and chains are publicly available.
Formation of GMCs is one of the most crucial issues in galaxy evolution. I will compare CO and HI in the LMC in 3 dimensional space for the first time aiming at revealing the physical connection between GMCs and associated HI gas at a ~40 pc scale. The present major findings are 1) [total CO intensity] [total HI intensity]0.8 for the 110 GMCs, and 2) the HI intensity tends to increase with the evolution of GMCs. I argue that these findings are consistent with the growth of GMCs via HI accretion over a time scale of a few x 10 Myrs. I will also discuss the role of the background stellar gravity and the dynamical compression by supershells in formation of GMCs.
The basic hypothesis of a post-Copernican Cosmological theory is that {\em all the points} of the Universe have to be essentially equivalent: this hypothesis is required in order to avoid any privileged {\em observer}. This assumption has been implemented by Einstein in the so-called Cosmological Principles (CP): {\em all the positions} in the Universe have to be essentially equivalent, so that the Universe is homogeneous. This situation implies also the condition of spherical symmetry about every point, so that the Universe in also Isotropic. There is a hidden assumption in the formulation of the CP in regard to the hypothesis that all the points are equivalent In fact, the condition that all the occupied points are statistically equivalent with respect to their environment correspond to the property of of Local Isotropy. It is generally believed that the Universe cannot be isotropic about every point without being also homogeneous [1]. Actually Local Isotropy does not necessarily implies homogeneity; in fact a topology theorem states that homogeneity is implied by the condition of local isotropy together with {\em the assumption of the analyticity or regularity} for the distribution of matter. Up to the seventies analyticity was an obvious implicit assumption in any physical problem. Recently however we have learned about intrinsically irregular structures for which analyticity should be considered as a property to be tested with appropriate analysis of experiment.
Nuclear magnetic resonance (NMR) study of the high magnetic field (H) part of the Bose-Einstein condensed (BEC) phase of the quasi-onedimensional (quasi-1D) antiferromagnetic quantum spin-chain compound NiCl2-4SC(NH2)2 (DTN) was performed. We precisely determined the phase boundary, Tc(H), down to 40 mK; the critical boson density, n_c(Tc); and the absolute value of the BEC order parameter S_perp at very low temperature (T = 0.12 K). All results are accurately reproduced by numerical quantum Monte Carlo simulations of a realistic three-dimensional (3D) model Hamiltonian. Approximate analytical predictions based on the 1D Tomonaga-Luttinger liquid description are found to be precise for Tc(H), but less so for S_perp(H), which is more sensitive to the strength of 3D couplings, in particular close to the critical field. A mean-field treatment, based on the Hartree-Fock-Popov description, is found to be valid only up to n_c = 4% (T < 0.3 K), while for higher n_c boson interactions appear to modify the density of states.