ShantanuT01/DACTYL-Pretraining huggingface dataset:
The star formation history of nearby early-type galaxies is investigated via numerical modelling. Idealized hydrodynamical N-body simulations with a star formation prescription are used to study the minor merger process between a giant galaxy (host) and a less massive spiral galaxy (satellite) with reasonable assumptions for the ages and metallicities of the merger progenitors. We find that the evolution of the star formation rate is extended over several dynamical times and shows peaks which correspond to pericentre passages of the satellite. The newly formed stars are mainly located in the central part of the satellite remnant while the older stars of the initial disk are deposited at larger radii in shell-like structures. After the final plunge of the satellite, star formation in the central part of the remnant can continue for several Gyrs depending on the star formation efficiency. Although the mass fraction in new stars is small, we find that the half-mass radius differs from the half-light radius in the V and H bands. Moreover synthetic 2D images in J, H, NUV, Hb and V bands, using the characteristic filters of the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST), reveal that residual star formation induced by gas-rich minor mergers can be clearly observed during and after the final plunge, especially in the NUV band, for interacting systems at (z<0.023) over moderate numbers of orbits (~2 orbits correspond to typical exposure times of ~3600 sec). This suggests that WFC3 has the potential to resolve these substructures, characterize plausible past merger episodes, and give clues to the formation of early-type galaxies.
The paper investigates the sensitivity of the inverse problem of recovering the velocity field in a bounded domain from the boundary dynamic Dirichlet-to-Neumann map (DDtN) for the wave equation. Three main results are obtained: (1) assuming that two velocity fields are non-trapping and are equal to a constant near the boundary, it is shown that the two induced scattering relations must be identical if their corresponding DDtN maps are sufficiently close; (2) a geodesic X-ray transform operator with matrix-valued weight is introduced by linearizing the operator which associates each velocity field with its induced Hamiltonian flow. A selected set of geodesics whose conormal bundle can cover the cotangent space at an interior point is used to recover the singularity of the X-ray transformed function at the point; a local stability estimate is established for this case. Although fold caustics are allowed along these geodesics, it is required that these caustics contribute to a smoother term in the transform than the point itself. The existence of such a set of geodesics is guaranteed under some natural assumptions in dimension greater than or equal to three by the classification result on caustics and regularity theory of Fourier Integral Operators. The interior point with the above required set of geodesics is called "fold-regular"; (3) assuming that a background velocity field with every interior point fold-regular is fixed and another velocity field is sufficiently close to it and satisfies a certain orthogonality condition, it is shown that if the two corresponding DDtN maps are sufficiently close then they must be equal.
We study a mod $p^c$ analog of the notion of transfer for automorphic forms. Instead of existence of eigenforms, such transfers yield congruences between eigenforms but, like transfers, we show that they can be established by a comparison of trace formulas. This rests on the properties of mod $p^c$ reduced multiplicities which count congruences between eigenforms. As an application we construct finite slope $p$-adic {\it continuous} families of Siegel eigenforms using a comparison of trace formulas.
In order to study the nucleon-nucleon pairing effects in clustering nuclei, we formulate a superposed Tohsaki-Horiuchi-Schuck-Roepke (THSR) wave function, which includes both molecular-orbit and pairing configurations explicitly. With this new wave function, we investigate the abnormal deuteron-like pn-pairing effect in 10B with T=0 and S=1 (isoscalar) by comparing with isovector NN pairs (T=1, S=1) in 10Be and 10C. Energies are calculated for the ground states of 10Be, 10B and 10C nuclei, and the 1+ excited state of 10B. These energies are essentially improved comparing with studies using previous version of THSR wave function. Further more, overlaps between the total wave function and the pairing component indicate that the NN pairing effect is more visible in 10B than in 10Be and 10C. By analyzing the energies and the overlaps between wave function components, we observe two different mechanisms enhancing the formation of deuteron-like pairs in 10B. We also discuss the pairing effect by showing average distances between components in each nucleus and density distributions of valance nucleons.
Fix a smooth, complete algebraic curve $X$ over an algebraically closed field $k$ of characteristic zero. To a reductive group $G$ over $k$, we associate an algebraic stack $\operatorname{Par}_G$ of quantum parameters for the geometric Langlands theory. Then we construct a family of (quasi-)twistings parametrized by $\operatorname{Par}_G$, whose module categories give rise to twisted $\mathcal D$-modules on $\operatorname{Bun}_G$ as well as quasi-coherent sheaves on the DG stack $\operatorname{LocSys}_G$.
We introduce a new class of Josephson arrays which have non-trivial topology and exhibit a novel state at low temperatures. This state is characterized by long range order in a two Cooper pair condensate and by a discrete topological order parameter. These arrays have degenerate ground states with this degeneracy 'protected' from the external perturbations (and noise) by the topological order parameter. We show that in ideal conditions the low order effect of the external perturbations on this degeneracy is exactly zero and that deviations from ideality lead to only exponentially small effects of perturbations. We argue that this system provides a physical implementation of an ideal quantum computer with a built in error correction and show that even a small array exhibits interesting physical properties such as superconductivity with double charge, 4e, and extremely long decoherence times.
Properties of semi-convection and core convective overshooting of stars with 15 $M_{\odot}$ and 30 $M_{\odot}$ are calculated in the present paper. New methods are used to deal with semi-convection. Different entropy gradient is used when adopting the Schwarzschild method and the Ledoux method which are used to confine the convective boundary and to calculate the turbulent quantities: $\frac{\partial \overline{s}}{\partial r}=-\frac{c_{p}}{H_P}(\nabla-\nabla_{\rm ad})$ when the Schwarzschild method is adopted and $\frac{\partial \overline{s}}{\partial r}=-\frac{c_{p}}{H_P}(\nabla-\nabla_{\rm ad}-\nabla_{\mu})$ when the Ledoux method is adopted. Core convective overshooting and semi-convection are treated as a whole part and the development of them are found to present nearly opposite tendency, more intensive core convective overshooting lead to weaker semi-convection. The influences of different parameters and the convection processing methods on the turbulent quantities are analyzed in this paper. Increasing the mixing-length parameter $\alpha$ leads to more turbulent dynamic energy in the convective core and prolonging the overshooting distance but depressing the development of semi-convection. The Ledoux method adopted leads to overshooting extending further and semi-convection developing suppressed.
The mass assembly and star formation histories of massive galaxies identified at low redshift z in different cosmological hydrodynamical simulations, have been studied through a detailed follow-up backwards in time of their constituent mass elements (sampled by particles) of different types. Then, the configurations they depict at progressively higher zs have been analysed.   The analyses show that these histories share common generic patterns, irrespective of particular circumstances. In any case, the results we have found are different depending on the particle type. The most outstanding differences follow. We have found that by z ~ 3.5 - 6, mass elements identified as stellar particles at z=0 exhibit a gaseous cosmic-web-like morphology with scales of ~ 1 physical Mpc, where the densest mass elements have already turned into stars by z ~ 6. These settings are in fact the densest pieces of the cosmic web, where no hot particles show up, and dynamically organized as a hierarchy of flow convergence regions, that is, attraction basins for mass flows. On the other hand, mass elements identified at the diffuse hot coronae surrounding massive galaxies at z = 0, do not display a clear web-like morphology at any z. Diffuse gas is heated when flow convergence regions go through contractive deformations, and most of it keeps hot and with low density along the evolution.   To shed light on the physical foundations of the behaviour our analyses show up, as well as on their possible observational implications, these patterns have been confronted with some generic properties of singular flows as described by the adhesion model. We have found that these common patterns simulations show can be interpreted as a consequence of flow properties, that, moreover, could explain different generic observational results on massive galaxies or their samples. We briefly discuss some of them.[Abridged]
The next generation of proposed galaxy surveys will increase the number of galaxies with photometric redshifts by two orders of magnitude, drastically expanding both redshift range and detection threshold from the current state of the art. Obtaining spectra for a fair sub-sample of this new data could be cumbersome and expensive. However, adequate calibration of the true redshift distribution of galaxies is vital to tapping the potential of these surveys. We examine a promising alternative to direct spectroscopic follow up: calibration of the redshift distribution of photometric galaxies via cross-correlation with an overlapping spectroscopic survey whose members trace the same density field. We review the theory, develop a pipeline, apply it to mock data from N-body simulations, and examine the properties of this redshift distribution estimator. We demonstrate that the method is effective, but the estimator is weakened by two factors. 1) The correlation function of the spectroscopic sample must be measured in many bins along the line of sight, rendering it noisy and interfering with high quality reconstruction of the photometric redshift distribution. 2) The method is not able to disentangle the photometric redshift distribution from evolution in the bias of the photometric sample. We establish the impact of these factors using our mock catalogs. Although it may still be necessary to spectroscopically follow up a fair subsample of the photometric survey data, further refinement may appreciably decrease the number of spectra that will be needed to calibrate future surveys.
We have measured the times of onset of recent fadings in four R CrB stars -- V854 Cen, RY Sgr, R CrB, and S Aps. These times continue to be locked to the stars' pulsation periods, though with some scatter. In RY Sgr, the onsets of fading tend to occur at or a few days after pulsation maximum. We have studied the pulsation properties of RY Sgr through its recent long maximum using (O-C) analysis and wavelet analysis. The period "wanders" by a few percent. This wandering can be modelled by random cycle-to-cycle period fluctuations, as in some other types of pulsating stars. The pulsation amplitude varies between 0.05 and 0.25 in visual light, non-periodically but on a time scale of about 20 pulsation periods.
We analyze temporal evolution of the number of accreting white dwarfs with shell hydrogen burning in semidetached and detached binaries. We consider a stellar system in which star formation lasts for 10 Gyr with a constant rate, as well as a system in which the same amount of stars is formed in a single burst lasting for 1 Gyr. Evolution of the number of white dwarfs is confronted to the evolution of occurrence rate of events that usually are identified with SN Ia or accretion-induced collapses, i.e. with accumulation of Chandrasekhar mass by a white dwarf or a merger of a pair of CO white dwarfs with total mass not lower than the Chandrasekhar one. In the systems with a burst of star formation, at $t=$10 Gyr observed supersoft X-ray sources, most probably, are not precursors of SN Ia. The same is true for an overwhelming majority of the sources in the systems with constant star formation rate. In the systems of both kinds mergers of white dwarfs is the dominant SN Ia scenario. In symbiotic binaries, accreting CO-dwarfs do not accumulate enough mass for SN Ia explosion, while ONeMg-dwarfs finish their evolution by an accretion-induced collapse with formation of a neutron star.
Recently, we pointed out that on a class on non exactly decimable fractals two different parameters are required to describe diffusive and vibrational dynamics. This phenomenon we call dynamical dimension splitting is related to the lack of exact decimation invariance for these structures, which turn out to be invariant under a more complex cutting-decimation transform. In this paper we study in details the dynamical dimension splitting on these fractals analyzing the mathematical properties of the cutting-decimation transform. Our results clarify how the splitting arises from the cutting transform and show that the dynamical dimension degeneration is a very peculiar consequence of exact decimability.
We used K-band photometry, maximum rotational velocities derived from Fabry-Perot data and HI observed and predicted masses to study, for the first time, the K-band, stellar and baryonic Tully-Fisher relations for galaxies in Hickson compact groups. We compared these relations with the ones defined for galaxies in less dense environments from the GHASP survey and from a sample of gas-rich galaxies. We find that most of the Hickson compact group galaxies lie on the K-band Tully-Fisher relation defined by field galaxies with a few low-mass outliers, namely HCG 49b and HCG 96c, which appear to have had strong recent burst of star formation. The stellar Tully-Fisher relation for compact group galaxies presents a similar dispersion to that of the K-band relation, and it has no significant outliers when a proper computation of the stellar mass is done for the strongly star-forming galaxies. The scatter in these relations can be reduced if the gaseous component is taken into account, i.e., if a baryonic Tully-Fisher relation is considered. In order to explain the positions of the galaxies off the K-band Tully-Fisher relation we favour a scenario in which their luminosities are brightened due to strong star formation or AGN activity. We argue that strong bursts of star formation can affect the B and K-band luminosities of HCG 49b and HCG 96c and in the case of the latter also AGN activity may affect the K-band magnitude considerably, without affecting their total masses.
This paper does not suppose a priori that the evolution of the price of a financial asset is a semimartingale. Since possible strategies of investors are self-financing, previous prices are forced to be finite quadratic variation processes. The non-arbitrage property is not excluded if the class ${\cal A}$ of admissible strategies is restricted. The classical notion of martingale is replaced with the notion of ${\cal A}$-martingale. A calculus related to ${\cal A}$-martingales with some examples is developed. Some applications to the maximization of the utility of an insider are expanded.
The presence of excess scatter in the Ly-$\alpha$ forest at $z\sim 5.5$, together with the existence of sporadic extended opaque Gunn-Peterson troughs, has started to provide robust evidence for a late end of hydrogen reionisation. However, low data quality and systematic uncertainties complicate the use of Ly-$\alpha$ transmission as a precision probe of reionisation's end stages. In this paper, we assemble a sample of 67 quasar sightlines at $z>5.5$ with high signal-to-noise ratios of $>10$ per $\leq 15$ km s$^{-1}$ spectral pixel, relying largely on the new XQR-30 quasar sample. XQR-30 is a large program on VLT/X-Shooter which obtained deep (SNR $>20$ per pixel) spectra of 30 quasars at $z>5.7$. We carefully account for systematics in continuum reconstruction, instrumentation, and contamination by damped Ly-$\alpha$ systems. We present improved measurements of the mean Ly-$\alpha$ transmission over $4.9<z<6.1$. Using all known systematics in a forward modelling analysis, we find excellent agreement between the observed Ly-$\alpha$ transmission distributions and the homogeneous-UVB simulations Sherwood and Nyx up to $z\leq5.2$ ($<1 \sigma$), and mild tension ($\sim 2.5 \sigma$) at $z=5.3$. Homogeneous UVB models are ruled out by excess Ly-$\alpha$ transmission scatter at $z\geq5.4$ with high confidence ($>3.5 \sigma$). Our results indicate that reionisation-related fluctuations, whether in the UVB, residual neutral hydrogen fraction, and/or IGM temperature, persist in the intergalactic medium until at least $z=5.3$ ($t=1.1$ Gyr after the Big Bang). This is further evidence for a late end to reionisation.
We show the benefits of using Electron-Multiplying CCDs and the shift-and-add technique as a tool to minimise the effects of the atmospheric turbulence such as blending between stars in crowded fields and to avoid saturated stars in the fields observed. We intend to complete, or improve, the census of the variable star population in globular cluster NGC~6715.   Our aim is to obtain high-precision time-series photometry of the very crowded central region of this stellar system via the collection of better angular resolution images than has been previously achieved with conventional CCDs on ground-based telescopes.   Observations were carried out using the Danish 1.54-m Telescope at the ESO La Silla observatory in Chile. The telescope is equipped with an Electron-Multiplying CCD that allowed to obtain short-exposure-time images (ten images per second) that were stacked using the shift-and-add technique to produce the normal-exposure-time images (minutes). The high precision photometry was performed via difference image analysis employing the DanDIA pipeline. We attempted automatic detection of variable stars in the field.   We statistically analysed the light curves of 1405 stars in the crowded central region of NGC~6715 to automatically identify the variable stars present in this cluster. We found light curves for 17 previously known variable stars near the edges of our reference image (16 RR Lyrae and 1 semi-regular) and we discovered 67 new variables (30 RR Lyrae, 21 long-period irregular, 3 semi-regular, 1 W Virginis, 1 eclipsing binary, and 11 unclassified). Photometric measurements for these stars are available in electronic form through the Strasbourg Astronomical Data Centre.
A classical theorem of Dirac from 1952 asserts that every graph on $n$ vertices with minimum degree at least $\lceil n/2 \rceil$ is Hamiltonian. In this paper we extend this result to random graphs. Motivated by the study of resilience of random graph properties we prove that if $p \gg \log n /n$, then a.a.s. every subgraph of $G(n,p)$ with minimum degree at least $(1/2+o(1))np$ is Hamiltonian. Our result improves on previously known bounds, and answers an open problem of Sudakov and Vu. Both, the range of edge probability $p$ and the value of the constant 1/2 are asymptotically best possible.
Trajectories of a Bohmian particle confined in time-dependent cylindrical and spherical traps are computed for both contracting and expanding boxes. Quantum effective force is considered in arbitrary directions. It is seen that in contrast to the problem of a particle in an infinite rectangular box with one wall in motion, if particle initially is in an energy eigenstate of a tiny box the force is zero in all directions. Trajectories of a two-body system confined in the spherical trap are also computed for different statistics. Computations show that there are situations for which distance between bosons is greater than the fermions. However, results of average separation of the particles confirm our expectation about the statistics.
We briefly review the recent studies of the behavior of composite systems in magnetic field. The hydrogen atom is chosen to demonstrate the new results which may be experimentally tested. Possible applications to physics of antihydrogen are mentioned.
We consider the trapping reaction, $A+B\to B$, where $A$ and $B$ particles have a diffusive dynamics characterized by diffusion constants $D_A$ and $D_B$. The interaction with $B$ particles can be formally incorporated in an effective dynamics for one $A$ particle as was recently shown by Bray {\it et al}. [Phys. Rev. E {\bf 67}, 060102 (2003)]. We use this method to compute, in space dimension $d=1$, the asymptotic behaviour of the spatial fluctuation, $<z^2(t)>^{1/2}$, for a surviving $A$ particle in the perturbative regime, $D_A/D_B\ll 1$, for the case of an initially uniform distribution of $B$ particles. We show that, for $t\gg 1$, $<z^2(t)>^{1/2} \propto t^{\phi}$ with $\phi=1/4$. By contrast, the fluctuations of paths constrained to return to their starting point at time $t$ grow with the larger exponent 1/3. Numerical tests are consistent with these predictions.
This report summarizes four recent papers on the characteristics of the hadronic decays of the Z by the LEP collaborations ALEPH, DELPHI and OPAL.
Jamming and percolation of square objects of size $k \times k$ ($k^2$-mers) isotropically deposited on simple cubic lattices have been studied by numerical simulations complemented with finite-size scaling theory. The $k^2$-mers were irreversibly deposited into the lattice. Jamming coverage $\theta_{j,k}$ was determined for a wide range of $k$ ($2 \leq k \leq 200$). $\theta_{j,k}$ exhibits a decreasing behavior with increasing $k$, being $\theta_{j,k\rightarrow\infty}=0.4285(6)$ the limit value for large $k^2$-mer sizes. On the other hand, the obtained results shows that percolation threshold, $\theta_{c,k}$, has a strong dependence on $k$. It is a decreasing function in the range $2 \leq k \leq 18$ with a minimum around $k=18$ and, for $k \geq 18$, it increases smoothly towards a saturation value. Finally, a complete analysis of critical exponents and universality has been done, showing that the percolation phase transition involved in the system has the same universality class as the 3D random percolation, regardless of the size $k$ considered.
The aim of this paper is to investigate the intersection problem between two linear sets in the projective line over a finite field. In particular, we analyze the intersection between two clubs with eventually different maximum fields of linearity. Also, we analyze the intersection between the linear set defined by the polynomial $\alpha x^{q^k}+\beta x$ and other linear sets having the same rank; this family contains the linear set of pseudoregulus type defined by $x^q$. The strategy relies on the study of certain algebraic curves whose rational points describe the intersection of the two linear sets. Among other geometric and algebraic tools, function field theory and the Hasse-Weil bound play a crucial role. As an application, we give asymptotic results on semifields of BEL-rank two.