ShantanuT01/DACTYL-Pretraining huggingface dataset:
Measurements of time delays between multiple quasar images produced by strong lensing are reaching a sensitivity that makes them a promising cosmological probe. Future surveys will provide significantly more measurements, reaching unprecedented depth in redshift, making strong lensing time delay (SLTD) observations competitive with other background probes. We forecast constraints on the nature of dark energy from upcoming SLTD surveys, simulating future catalogues with different numbers of lenses distributed up to redshift $z\sim 1$ and focusing on cosmological parameters such as the Hubble constant $H_0$ and parametrisations of the dark energy equation of state. We also explore the impact of our ability to precisely model the lens mass profile and its environment, on the forecasted constraints. We find that in the most optimistic cases, SLTD will constrain $H_0$ at the level of $\sim 0.1\%$, while the CPL equation of state parameters, $w_0$ and $w_a$, can be determined with errors $\sigma_{w_0}\sim 0.05$ and $\sigma_{w_a}\sim 0.3$, respectively. Furthermore, we investigate the bias introduced when a wrong cosmological model is assumed for the analysis. We find that the value of $H_0$ could be biased up to $10 \sigma$, assuming a perfect knowledge of the lens profile, when a $\Lambda$CDM model is used to analyse data that really belong to a $w$CDM cosmology with $w=-0.9$. Based on these findings, we identify a consistency check of the assumed cosmological model in future SLTD surveys, by splitting the dataset in several redshift bins. Depending on the characteristics of the survey, this could provide a smoking gun for dark energy.
We report the first half-year monitoring of the new Galactic black hole candidate MAXI J1348-630, discovered on 2019 January 26 with the Gas Slit Camera (GSC) on-board MAXI. During the monitoring period, the source exhibited two outburst peaks, where the first peak flux (at T=14 day from the discovery of T =0) was ~4 Crab (2-20 keV) and the second one (at T =132 day) was ~0.4 Crab (2-20 keV). The source exhibited distinct spectral transitions between the high/soft and low/hard states and an apparent "q"-shape curve on the hardness-intensity diagram, both of which are well-known characteristics of black hole binaries. Compared to other bright black hole transients, MAXI J1348-630 is characterized by its low disk-temperature (~0.75 keV at the maximum) and high peak flux in the high/soft state. The low peak-temperature leads to a large innermost radius that is identified as the Innermost Stable Circular Orbit (ISCO), determined by the black hole mass and spin. Assuming the empirical relation between the soft-to-hard transition luminosity (Ltrans) and the Eddington luminosity (LEdd), Ltrans/LEdd ~ 0.02, and a face-on disk around a non-spinning black hole, the source distance and the black hole mass are estimated to be D ~ 4 kpc and ~7 (D/4 kpc) Mo, respectively. The black hole is more massive if the disk is inclined and the black hole is spinning. These results suggest that MAXI J1348-630 may host a relatively massive black hole among the known black hole binaries in our Galaxy.
We studied temperature and magnetic field dependence of magnetization, $M(T)$ and $M(B)$, on thiospinel FeCr$_{2}$S$_{4}$. We observed a step-like anomaly at $T_{OO} \sim$ 9 K for $M$($T$) attributed to an orbital order transition in magnetic field 0 $< B \leq$ 7 T. Furthermore, also for $M$($B$), an step-like anomaly appears at $B_{c} \sim$ 5.5 T below $T_{OO}$. This suggests an existence of a magnetic phase boundary at $B_{c}$ in $T < T_{OO}$. Because the anomaly at $B_{c}$ of $M(B)$ exists in the orbital ordered phase, the spin structure of FeCr$_{2}$S$_{4}$ in $T\ <\ T_{OO}$ is strongly coupled with the lattice of the system.
Although the planetary nebula NGC 6781 appears to possess an elliptical morphology, its kinematic and emission characteristics are in many ways unusual, and it is possible that it may represent a bipolar source oriented close to the line of sight. We shall present deep imaging of this nebula in [O III], Ha and [N II], and using broad-band (F555W and F814W) filters. These were taken with the 2.56-m Nordic Optical Telescope and Hubble Space Telescope. This is combined with mid-infrared (MIR) imaging and spectroscopy acquired with the Spitzer Space Telescope (Spitzer), and near-infrared spectroscopy deriving from the Infrared Space Observatory (ISO). These reveal details of the complex [N II] structure associated with extended shell emission, perhaps associated with highly inclined bipolar lobes. We also note the presence of narrow absorbing filaments and clumps projected against the surface of the envelope, components which may be responsible for much of the molecular emission. We point out that such clumps may be responsible for complex source structure in the MIR, and give rise to asymmetries in emission along the major axis of the source.
The integral of the Wigner function over a subregion of the phase-space of a quantum system may be less than zero or greater than one. It is shown that for systems with one degree of freedom, the problem of determining the best possible upper and lower bounds on such an integral, over all possible states, reduces to the problem of finding the greatest and least eigenvalues of an hermitian operator corresponding to the subregion. The problem is solved exactly in the case of an arbitrary elliptical region. These bounds provide checks on experimentally measured quasiprobability distributions.
We obtain static selfgravitating solitonic 3-brane solutions in the Einstein-Skyrme model in 7D. These solitons correspond to a smooth version of the previously discussed cosmic p-brane solutions. We show how the energy momentum tensor of the Skyrme field is able to smooth out the singularities found in the thin wall approximation and falls fast enough with the distance from the core of the object so that asymptotically approaches the flat cosmic p-brane metric.
We investigate in this paper an alternative method to simulation based recursive importance sampling procedure to estimate the optimal change of measure for Monte Carlo simulations. We propose an algorithm which combines (vector and functional) optimal quantization with Newton-Raphson zero search procedure. Our approach can be seen as a robust and automatic deterministic counterpart of recursive importance sampling by means of stochastic approximation algorithm which, in practice, may require tuning and a good knowledge of the payoff function in practice. Moreover, unlike recursive importance sampling procedures, the proposed methodology does not rely on simulations so it is quite generic and can come along on the top of Monte Carlo simulations. We first emphasize on the consistency of quantization for designing an importance sampling algorithm for both multi-dimensional distributions and diffusion processes. We show that the induced error on the optimal change of measure is controlled by the mean quantization error. We illustrate the effectiveness of our algorithm by pricing several options in a multi-dimensional and infinite dimensional framework.
We show that cold clumps in the intra--cluster medium (ICM) efficiently lose their angular momentum as they fall in, such that they can rapidly feed the central AGN and maintain a heating feedback process. Such cold clumps are predicted by the cold feedback model, a model for maintaining the ICM in cooling flows hot by a feedback process. The clumps very effectively lose their angular momentum in two channels: the drag force exerted by the ICM and the random collisions between clumps when they are close to the central black hole. We conclude that the angular momentum cannot prevent the accretion of the cold clumps, and the cold feedback mechanism is a viable model for a feedback mechanism in cooling flows. Cold feedback does not suffer from the severe problems of models that are based on the Bondi accretion.
We give a product formula for the number of shifted plane partitions of shifted double staircase shape with bounded entries. This is the first new example of a family of shapes with a plane partition product formula in many years. The proof is based on the theory of lozenge tilings; specifically, we apply the "free boundary" Kuo condensation due to Ciucu.
We introduce the combinatorial notion of posetted trees and we use it in order to write an explicit expression of the Baker-Campbell-Hausdorff formula.
We construct spectra of supernovae interacting strongly with a circumstellar medium (CSM) by adding SN templates, a black-body continuum and an emission-line spectrum. In a Monte Carlo simulation we generate more than 800 spectra, distribute them to 10 different classifiers and study how the different simulation parameters affect the appearance of the spectra. SNe IIn showing some structure over the continuum were characterized as SNe IInS. We demonstrate that the flux ratio of the underlying SN to the continuum fv is the most important parameter determining the spectral classification. Thermonuclear SNe get progressively classified as Ia-CSM, IInS and IIn as fv decreases. The transition between Ia-CSM and IInS occurs at fv~0.2-0.3. It shown that SNe Ia-CSM are found at the magnitude range -19.5> M >-21.6, in good agreement with observations, and that the faintest SN IIn that can hide a SN Ia has M = -20.1. The sample of SNe Ia-CSM shows an association with 91T-like SNe Ia. Our experiment does not support that this association is due to a luminosity bias (91T-like being brighter than normal Ia). We therefore conclude that this association has real physical origins and we propose that 91T-like explosions result from single degenerate progenitors. Despite the similarities between SNe Ibc and SNe Ia, the number of misclassifications between these types was small and mostly at low S/N. Combined with the luminosity function needed to reproduce the observed SN Ia-CSM luminosities, it is unlikely that SNe Ibc constitute an important contaminant within this sample. We show how Type II spectra transition to IIn and how the Ha profiles vary with fv. SNe IIn fainter than M = -17.2 are unable to mask SNe IIP brighter than M = -15. A simulation including radiative transfer shows that our simplified model is a good first order approximation. The spectra obtained are in good agreement with real data.
One of the scientific objectives of NASA's Fermi Gamma-ray Space Telescope is the study of Gamma-Ray Bursts (GRBs). The Fermi Gamma-Ray Burst Monitor (GBM) was designed to detect and localize bursts for the Fermi mission. By means of an array of 12 NaI(Tl) (8 keV to 1 MeV) and two BGO (0.2 to 40 MeV) scintillation detectors, GBM extends the energy range (20 MeV to > 300 GeV) of Fermi's main instrument, the Large Area Telescope, into the traditional range of current GRB databases. The physical detector response of the GBM instrument to GRBs is determined with the help of Monte Carlo simulations, which are supported and verified by on-ground individual detector calibration measurements. We present the principal instrument properties, which have been determined as a function of energy and angle, including the channel-energy relation, the energy resolution, the effective area and the spatial homogeneity.
Star formation depends strongly both on the local environment of galaxies, and on the internal dynamics of the interstellar medium. To disentangle the two effects, we obtained, in the framework of the AMIGA project, Ha and Gunn r photometric data for more than 200 spiral galaxies lying in very low-density regions of the local Universe. We characterise the Ha emission, tracing current star formation, of the 45 largest and less inclined galaxies observed for which we estimate the torques between the gas and the bulk of the optical matter. We could subsequently study the Ha morphological aspect of these isolated spiral galaxies. Using Fourier analysis, we focus on the modes of the spiral arms and also on the strength of the bars, computing the torques between the gas and newly formed stars (Ha) and the bulk of the optical matter (Gunn r). We interpret the various bar/spiral morphologies observed in terms of the secular evolution experienced by galaxies in isolation. We also classify the different spatial distributions of star forming regions in barred galaxies. The observed frequency of particular patterns brings constraints on the lifetime of the various evolution phases. We propose an evolutive sequence accounting for the transitions between the different phases we could observe. Isolated galaxies appear not to be preferentially barred or unbarred. Through numerical simulations, trying to fit the Ha distributions yields constraints on the star formation law, which is likely to differ from a genuine Schmidt law. In particular, it is probable that the relative velocity of the gas in the bar also needs to be taken into account.
We present near-infrared and optical observations of the nova V496 Scuti 2009 covering various phases - pre-maximum, early decline and nebular - during the first 10 months of its discovery followed by limited observations in early part of 2011 April. The spectra follow the evolution of the nova when the lines had strong P Cygni profiles to a phase dominated by prominent emission lines. The notable feature of the near-IR spectra in the early decline phase is the rare presence of first overtone bands of carbon monoxide in emission. Later about 150 days after the peak brightness the IR spectra show clear dust formation in the expanding ejecta. Dust formation in V496 Sct is consistent with the presence of lines of elements with low ionization potentials like Na and Mg in the early spectra and the detection of CO bands in emission. The light curve shows a slow rise to the maximum and a slow decline indicating a prolonged mass loss. This is corroborated by the strengthening of P Cygni profiles during the first 30 days. In the spectra taken close to the optical maximum brightness, the broad and single absorption component seen at the time of discovery is replaced by two sharper components. During the early decline phase two sharp dips that show increasing outflow velocities are seen in the P Cygni absorption components of Fe II and H I lines. The spectra in 2010 March showed the onset of the nebular phase. Several emission lines display saddle-like profiles during the nebular phase. In the nebular stage the observed fluxes of [O III] and H-beta lines are used to estimate the electron number densities and the mass of the ejecta. The optical spectra show that the nova evolved in the P_fe A_o spectral sequence. The physical conditions in the ejecta are estimated. The absolute magnitude and the distance to the nova are estimated to be M_V = -7.0 +/- 0.2 and d = 2.9 +/- 0.3 kpc respectively.
The two-phase free boundary problem with surface tension and downforce gravity for the Navier-Stokes system is considered in a situation where the initial interface is close to equilibrium. The boundary symbol of this problem admits zeros in the unstable halfplane in case the heavy fluid is on top of the light one, which leads to the well-known Rayleigh-Taylor instability. Instability is proved rigorously in an $L_p$-setting by means of an abstract instability result due to Henry.
The phenomenon of ferromagnetic resonance (FMR) provides fundamental information on the physics of magnetic materials and lies at the heart of a variety of signal processing microwave devices. Here we demonstrate theoretically that substrate-induced lattice strains may change the FMR frequency of an epitaxial ferromagnetic film dramatically, leading to ultralow and ultrahigh resonance frequencies at room temperature. Remarkably, the FMR frequency varies with the epitaxial strain nonmonotonically, reaching minimum at a critical strain corresponding to the strain-induced spin reorientation transition. Furthermore, by coupling the ferromagnetic film to a ferroelectric substrate, it becomes possible to achieve an efficient voltage control of FMR parameters. In contrast to previous studies, we found that the tunability of FMR frequency varies with the applied electric field and strongly increases at critical field intensity. The revealed features open up wide opportunities for the development of advanced tunable magnetoelectric devices based on strained nanomagnets.
In this paper, we present some geometric properties of the maximum entropy (MaxEnt) Tsallis- distributions under energy constraint. In the case q > 1, these distributions are proved to be marginals of uniform distributions on the sphere; in the case q < 1, they can be constructed as conditional distribu- tions of a Cauchy law built from the same uniform distribution on the sphere using a gnomonic projection. As such, these distributions reveal the relevance of using Tsallis distributions in the microcanonical setup: an example of such application is given in the case of the ideal gas.
The possibility of using charm meson physics to test the Standard Model (SM) is reviewed. In the case of $D^0-\bar{D}^0$ mixing, the SM contributions are carefully considered and the existence of a window for the observation of new physics is discussed. Some examples of extensions of the SM giving large mixing signals are presented. Finally, some distinctive aspects of CP violation and rare decays in charm mesons are discussed.
We discuss large non-universality in the Higgs sector at high scale in supersymmetric theories, in the context of the Large Hadron Collider (LHC). In particular, we note that if ${m_{H_u}}^2-{m_{H_d}}^2$ is large and negative ($\simeq 10^6 {\rm ~GeV^2}$) at high scale, the lighter slepton mass eigenstates at the electroweak scale are mostly left chiral, in contrast to a minimal supergravity (mSUGRA) scenario. We use this feature to distinguish between non-universal Higgs masses (NUHM) and mSUGRA by two methods. First, we study final states with same-sign ditaus. We find that an asymmetry parameter reflecting the polarization of the taus provides a notable distinction. In addition, we study a charge asymmetry in the jet-lepton invariant mass distribution, arising from decay chains of left-chiral squarks leading to leptons of the first two families, which sets apart an NUHM scenario of the above kind.
We present an innovative approach to the methodology of dynamical modelling, allowing practical reconstruction of the underlying dark matter mass without assuming both the density and anisotropy functions. With this, the mass-anisotropy degeneracy is reduced to simple model inference, incorporating the uncertainties inherent with observational data, statistically circumventing the mass-anisotropy degeneracy in spherical collisionless systems. We also tackle the inadequacy that the Jeans method of moments has on small datasets, with the aid of Generative Adversarial Networks: we leverage the power of artificial intelligence to reconstruct non-parametrically the projected line-of-sight velocity distribution. We show with realistic numerical simulations of dwarf spheroidal galaxies that we can distinguish between competing dark matter distributions and recover the anisotropy and mass profile of the system.
Let V be a symplectic vector space and LG be the Lagrangian Grassmannian which parametrizes maximal isotropic subspaces in V. We give a presentation for the (small) quantum cohomology ring QH^*(LG) and show that its multiplicative structure is determined by the ring of (Q^~)-polynomials. We formulate a "quantum Schubert calculus" which includes quantum Pieri and Giambelli formulas, as well as algorithms for computing the structure constants appearing in the quantum product of Schubert classes.
We construct versal and equimultiple versal deformations of the parametrization of a Legendrian curve.
We study the quasilinear wave equation $\Box_{g}\phi=0$ where the metric $g = g(\phi,t,x)$ is close to and asymptotically approaches $g(0,t,x)$, which equals the Schwarzschild metric or a Kerr metric with small angular momentum, as time tends to infinity. Under only weak assumptions on the metric coefficients, we prove an improved pointwise decay rate for the solution $\phi$. One consequence of this rate is that for bounded $|x|$, we have the integrable decay rate $|\phi(t,x)| \le Ct^{-1-\min(\delta,1)}$ where $\delta>0$ is a parameter governing the decay, near the light cone, of the coefficient of the slowest-decaying term in the quasilinearity. We also obtain the same aforementioned pointwise decay rates for the quasilinear wave equation $(\Box_{\tilde g} + B^{\alpha}(t,x)\partial_\alpha + V(t,x))\phi=0$ with a more general asymptotically flat metric $\tilde g = \tilde g(\phi,t,x)$ and with other time-dependent asymptotically flat lower order terms.
The gas-phase metallicity of low-mass galaxies increases with increasing stellar mass ($M_\ast$) and is nearly constant for high-mass galaxies. Theory suggests that this tight mass-metallicity relationship is shaped by galactic outflows removing metal-enriched gas from galaxies. Here, we observationally model the outflow metallicities of the warm outflowing phase from a sample of seven local star-forming galaxies with stellar masses between 10$^{7}$-10$^{11}$ M$_\odot$. We estimate the outflow metallicities using four weak rest-frame ultraviolet absorption lines, the observed stellar continua, and photoionization models. The outflow metallicity is flat with $M_\ast$, with a median metallicity of $1.0\pm0.6$ Z$_\odot$. The observed outflows are metal-enriched: low and high-mass galaxies have outflow metallicities 10-50 and 2.6 times larger than their ISM metallicities, respectively. The observed outflows are mainly composed of entrained ISM gas with at most 22% of the metals directly coming from recent supernovae enrichment. The metal outflow rate shallowly increases with $M_\ast$, as $M_\ast^{0.2 \pm 0.1}$, because the mass outflow rate shallow increases with $M_\ast$. Finally, we normalize the metal outflow rate by the rate at which star formation retains metals to calculate the metal-loading factor. The metal-loading factor inversely scales with $M_\ast$. The normalization and scaling of the metal-loading factor agree with analytic expressions that reproduce observed mass-metallicity relations. Galactic outflows fundamentally shape the observed mass-metallicity relationship.
Resonant x-ray scattering at the Dy $M_5$ and Ni $L_3$ absorption edges was used to probe the temperature and magnetic field dependence of magnetic order in epitaxial LaNiO$_3$-DyScO$_3$ superlattices. For superlattices with 2 unit cell thick LaNiO$_3$ layers, a commensurate spiral state develops in the Ni spin system below 100 K. Upon cooling below $T_{ind} = 18$ K, Dy-Ni exchange interactions across the LaNiO$_3$-DyScO$_3$ interfaces induce collinear magnetic order of interfacial Dy moments as well as a reorientation of the Ni spins to a direction dictated by the strong magneto-crystalline anisotropy of Dy. This transition is reversible by an external magnetic field of 3 T. Tailored exchange interactions between rare-earth and transition-metal ions thus open up new perspectives for the manipulation of spin structures in metal-oxide heterostructures and devices.