ShantanuT01/DACTYL-Pretraining huggingface dataset:
We present high resolution radio continuum observations with the Karl G. Jansky Very Large Array at 6, 8.5, 11.5 and 15 GHz of the double-peaked emission-line galaxy 2MASXJ12032061+1319316. The radio emission has a prominent S-shaped morphology with highly symmetric radio jets that extend over a distance of $\sim1.5^{\prime\prime}$ (1.74~kpc) on either side of the core of size $\sim0.1^{\prime\prime}$(116~pc). The radio jets have a helical structure resembling the precessing jets in the galaxy NGC~326 which has confirmed dual active galactic nuclei (AGN). The nuclear bulge velocity dispersion gives an upper limit of $(1.56\pm$0.26$)\times$10$^8$~M$_{\odot}$ for the total mass of nuclear black hole(s). We present a simple model of precessing jets in 2MASXJ1203 and find that the precession timescale is around 10$^5$ years: this matches the source lifetime estimate via spectral aging. We find that the expected super massive black hole (SMBH) separation corresponding to this timescale is 0.02 pc. We used the double peaked emission lines in 2MASXJ1203 to determine an orbital speed for a dual AGN system and the associated jet precession timescale, which turns out to be more than the Hubble time, making it unfeasible. We conclude that the S-shaped radio jets are due to jet precession caused either by a binary/dual SMBH system, a single SMBH with a tilted accretion disk or a dual AGN system where a close pass of the secondary SMBH in the past has given rise to jet precession.
We hope to be able (in the future) to carefully analyze this structure and to tie the Jacobian Conjecture in dimension two to certain Zeta functions, thereby invoking a powerful arithmetic machinery to handle the two dimensional Jacobian Conjecture. Let us denote by ${\rm et}(\mathbb{C}^2)$ the semigroup of two dimensional Keller mappings. We would like to prove something like the following: a) That there exists an infinite index set $I$, and a family of mappings indexed by $I$, $\{F_i\,|\,i\in I\} \subset {\rm et}(\mathbb{C}^2)$ such that $$ {\rm et}(\mathbb{C}^2)={\rm Aut}(\mathbb{C}^2)\cup\bigcup_{i\in I} R_{F_i}({\rm et}(\mathbb{C}^2)), $$ where if $i\ne j$ then $R_{F_i}({\rm et}(\mathbb{C}^2))\cap R_{F_j}({\rm et}(\mathbb{C}^2))=\emptyset$. b) That the parallel representation to the representation described in (a) above holds true, this time with respect to the left composition operators $L_{G_j}$.   These two claims will be the basis for a fractal structure on ${\rm et}(\mathbb{C}^2)$ because the pieces $R_{F_i}({\rm et}(\mathbb{C}^2))$ are similar to each other in the sense that they are homeomorphic, and we further have the scaling property of self-similarity, namely $R_F({\rm et}(\mathbb{C}^2))$ is homeomorphic to its proper subspace $R_{G\circ F}({\rm et}(\mathbb{C}^2))$ that is homeomorphic to its proper subspace $R_{H\circ G\circ F}({\rm et}(\mathbb{C}^2))$ etc . This is the right place to remark that the purpose of the current paper is to start and develop the parallel theory for entire functions in one complex variable. Results in this setting will hint that there are hopes to accomplish the above objective.
We investigate the conductance of normal-conductor/graphene/normal-conductor (NGN) junctions for arbitrary on-site potentials in the normal and graphitic parts of the system. We find that a ballistic NGN junction can display insulating behavior even when the charge-carrier density in the graphene part is finite. This effect originates in the different k intervals supporting propagating modes in graphene and a normal conductor, and persists for moderate levels of bulk, edge, or interface disorder. The ensuing conductance thresholds could be used as an electronic tool to map out details of the graphene band structure in absolute k space.
We elucidate the asymptotics of the L^s-quantization error induced by a sequence of L^r-optimal n-quantizers of a probability distribution P on R^d when s>r. In particular we show that under natural assumptions, the optimal rate is preserved as long as s<r+d (and for every s in the case of a compactly supported distribution). We derive some applications of these results to the error bounds for quantization based quadrature formulae in numerical integration on R^d and on the Wiener space.
We give two general transformations that allows certain quite general basic hypergeometric multi-sums of arbitrary depth (sums that involve an arbitrary sequence $\{g(k)\}$), to be reduced to an infinite $q$-product times a single basic hypergeometric sum. Various applications are given, including summation formulae for some $q$ orthogonal polynomials, and various multi-sums that are expressible as infinite products.
We observe a disappearance of the 1/3 magnetization plateau and a striking change of the magnetic configuration under a moderate doping of the model triangular antiferromagnet RbFe(MoO4)2. The reason is an effective lifting of degeneracy of mean-field ground states by a random potential of impurities, which compensates, in the low temperature limit, the fluctuation contribution to free energy. These results provide a direct experimental confirmation of the fluctuation origin of the ground state in a real frustrated system. The change of the ground state to a least collinear configuration reveals an effective positive biquadratic exchange provided by the structural disorder. On heating, doped samples regain the structure of a pure compound thus allowing for an investigation of the remarkable competition between thermal and structural disorder.
We investigate one-dimensional families of diagonal forms, considering the evolution of the asymptotic formula and error term. We then discuss properties of the average asymptotic formula obtained. The subsequent second moment analysis precipitates an effective means of computing $p$-adic densities of zeros for large primes $p$.
We determine the spectrum of scalar masses in a supersymmetric vacuum of a general N=1 supergravity theory, with the Kahler potential and superpotential taken to be random functions of N complex scalar fields. We derive a random matrix model for the Hessian matrix and compute the eigenvalue spectrum. Tachyons consistent with the Breitenlohner-Freedman bound are generically present, and although these tachyons cannot destabilize the supersymmetric vacuum, they do influence the likelihood of the existence of an `uplift' to a metastable vacuum with positive cosmological constant. We show that the probability that a supersymmetric AdS vacuum has no tachyons is formally equivalent to the probability of a large fluctuation of the smallest eigenvalue of a certain real Wishart matrix. For normally-distributed matrix entries and any N, this probability is given exactly by P = exp(-2N^2|W|^2/m_{susy}^2), with W denoting the superpotential and m_{susy} the supersymmetric mass scale; for more general distributions of the entries, our result is accurate when N >> 1. We conclude that for |W| \gtrsim m_{susy}/N, tachyonic instabilities are ubiquitous in configurations obtained by uplifting supersymmetric vacua.
A robust prediction of $\Lambda{\rm CDM}$ cosmology is the halo circular velocity function (CVF), a dynamical cousin of the halo mass function. The correspondence between theoretical and observed CVFs is uncertain, however: cluster galaxies are reported to exhibit a power-law CVF consistent with $N$-body simulations, but that of the field is distinctly Schechter-like, flattened relative to $\Lambda{\rm CDM}$ expectations at circular velocities $v_c \lesssim 200\, {\rm km\, s^{-1}}$. Groups offer a powerful probe of the role environment plays in this discrepancy as they bridge the field and clusters. Here, we construct the CVF for a large, mass- and multiplicity-complete sample of group galaxies from the Sloan Digital Sky Survey. Using independent photometric $v_c$ estimators, we find no transition from a field- to $\Lambda{\rm CDM}$-shaped CVF above $v_c = 50\, {\rm km\, s^{-1}}$ as a function of group halo mass. All groups with $12.4 \lesssim \log M_{\rm halo} / M_{\odot} \lesssim 15.1$ (Local Group analogs to rich clusters) display similar Schechter-like CVFs marginally suppressed at low-$v_c$ compared to that of the field. Conversely, some agreement with $N$-body results emerges for samples saturated with late-type galaxies, with isolated late-types displaying a CVF similar in shape to $\Lambda{\rm CDM}$ predictions. We conclude that the flattening of the low-$v_c$ slope in groups is due to their depressed late-type fractions -- environment affecting the CVF only to the extent that it correlates with this quantity -- and that previous cluster analyses may suffer from interloper contamination. These results serve as useful benchmarks for cosmological simulations of galaxy formation.
We present deep Hubble Space Telescope near-infrared (NIR) observations of the magnetar SGR 1935+2154 from June 2021, approximately 6 years after the first HST observations, a year after the discovery of fast radio burst like emission from the source, and in a period of exceptional high frequency activity. Although not directly taken during a bursting period the counterpart is a factor of ~1.5 to 2.5 brighter than seen at previous epochs with F140W(AB) = $24.65\pm0.02$ mag. We do not detect significant variations of the NIR counterpart within the course of any one orbit (i.e. on minutes-hour timescales), and contemporaneous X-ray observations show SGR 1935+2154 to be at the quiescent level. With a time baseline of 6 years from the first identification of the counter-part we place stringent limits on the proper motion of the source, with a measured proper motion of ${\mu} = 3.1\pm1.5$ mas/yr. The direction of proper motion indicates an origin of SGR 1935+2154 very close to the geometric centre of SNR G57.2+08, further strengthening their association. At an adopted distance of $6.6\pm0.7$ kpc, the corresponding tangential space velocity is ${\nu_T} = 97\pm48$ km/s (corrected for differential Galactic rotation and peculiar Solar motion), although its formal statistical determination may be compromised owing to few epochs of observation. The current velocity estimate places it at the low end of the kick distribution for pulsars, and makes it among the lowest known magnetar kicks. When collating the few-magnetar kick constraints available, we find full consistency between the magnetar kick distribution and the much larger pulsar kick sample
On the basis of a recently derived color-metallicity relation and stellar parameters from the Sloan Digtal Sky Survey Data Release 7 spectroscopic survey, a large sample of red horizontal branch candidates have been selected to serve as standard candles. The metallicity and kinematic distributions of these stars indicate that they mainly originate from the thick-disk and the halo populations. The typical thick disk is characterized by the first group peaking at [Fe/H] ~ -0.6, Vrot ~ 170 km/s with a vertical scale height around |Z| ~ 1.2 kpc, while stars with [Fe/H] < -0.9 are dominated by the halo population. Two sub-populations of the halo are suggested by the RHB stars peaking at [Fe/H] ~-1.3: one component with Vrot > 0 km/s (Halo I) shows a sign of metallicity gradient in the [Fe/H] versus |Z| diagram, while the other with Vrot < 0 km/s (Halo II) does not. The Halo I mainly clumps at the inner halo with R < 10 kpc and the Halo II comes both from the inner halo with R < 10 kpc and the outer halo with R > 10 kpc based on the star distribution in the R versus |Z| diagram.
The Vista Variables in the Via Lactea (VVV) survey has performed a multi-epoch near-infrared imaging of the inner Galactic plane. High-fidelity photometric catalogs are needed to utilize the data. We aim at producing a deep, point-spread-function (PSF) photometric catalog for the VVV survey J, H, and Ks band data. Specifically, we aim at taking advantage of all the epochs of the survey to reach high limiting magnitudes. We develop an automatic PSF-fitting pipeline based on the DaoPHOT algorithm and perform photometry on the stacked VVV images in J, H, and Ks bands. We present a PSF photometric catalog in the Vega system that contains about 926 million sources in the J, H, and Ks filters. About 10% of the sources are flagged as possible spurious detections. The 5 sigma limiting magnitudes of the sources with high reliability are about 20.8, 19.5, and 18.7 mag in the J, H, and Ks band, respectively, depending on the local crowding condition. Our photometric catalog reaches on average about one magnitude deeper than the previously released PSF DoPHOT photometric catalog. It also includes less spurious detections. There are significant differences in the brightnesses of faint sources between our catalog and the previously released one. The likely origin of these differences is in the different photometric algorithms that are utilized; it is not straightforward to assess which catalog is more accurate in which situations. Our new catalog is beneficial especially for science goals that require high limiting magnitudes; our catalog reaches such in fields that have a relatively uniform source number density. Overall, the limiting magnitudes and completeness are different in the fields with different crowding conditions.
Using the linear sigma model, we study the evolutions of the quark condensate and of the nucleon mass in the nuclear medium. Our formulation of the model allows the inclusion of both pion and scalar-isoscalar degrees of freedom. It guarantees that the low energy theorems and the constrains of chiral perturbation theory are respected. We show how this formalism incorporates quantum hadro-dynamics improved by the pion loops effects.
Black holes found in binaries move at very high velocities relative to our own reference frame and can accelerate due to the emission of gravitational radiation. Here, we investigate the numerical stability and late-time behavior of linear scalar perturbations in accelerating black holes described by the $C-$metric. We identify a family of quasinormal modes associated with the photon surface and a brand new family of purely imaginary modes associated with the boost parameter of the accelerating black hole spacetime. When the accelerating black hole is charged, we find a third family of modes which dominates the ringdown waveform near extremality. Our frequency and time domain analysis indicate that such spacetimes are stable under scalar fluctuations, while the late-time behavior follows an exponential decay law, dominated by quasinormal modes. This result is in contrast with the common belief that such perturbations, for black holes without a cosmological constant, always have a power-law cutoff. In this sense, our results suggest that the asymptotic structure of black hole backgrounds does not always dictate how radiative fields behave at late times.
We present first results from the quantitative spectroscopic analysis of 266 Galactic O-type stars targeted by the IACOB and OWN surveys (implying the largest sample of stars of this type analyzed homogeneously). We also evaluate what is the present situation regarding available information about distances, as provided by the Hipparcos and Gaia missions.
We theoretically study an optomechanical system, which consists of a two-sided cavity and a mechanical membrane that is placed outside of it. The membrane is positioned close to one of its mirrors, and the cavity is coupled to the external light field through the other mirror. Our study is focused on the regime where the dispersive optomechanical coupling in the system vanishes. Such a regime is found to be possible if the membrane is less reflecting than the adjacent mirror, yielding a potentially very strong dissipative optomechanical coupling. Specifically, if the absolute values of amplitude transmission coefficients of the membrane and the mirror, $t$ and $t_m$ respectively, obey the condition $ t_m^2< t\ll t_m\ll 1$, the dissipative coupling constant of the setup exceeds the dispersive coupling constant for an optomechanical cavity of the same length. The dissipative coupling constant and the corresponding optomechanical cooperativity of the proposed system are also compared with those of the Michelson-Sagnac interferometer and the so-called "membrane-at-the-edge" system, which are known for a strong optomechanical dissipative interaction. It is shown that under the above condition, the system proposed here is advantageous in both aspects. It also enables an efficient realization of the two-port configuration, which was recently proposed as a promising optomechanical system, providing, among other benefits, a possibility of quantum limited optomechanical measurements in a system, which does not suffer from any optomechanical instability.
The evidence in favor of a dark energy component dominating the Universe, and driving its presently accelerated expansion, has progressively grown during the last decade of cosmological observations. If this dark energy is given by a dynamic scalar field, it may also have a direct interaction with other matter fields in the Universe, in particular with cold dark matter. Such interaction would imprint new features on the cosmological background evolution as well as on the growth of cosmic structure, like an additional long-range fifth-force between massive particles, or a variation in time of the dark matter particle mass. We review here the implementation of these new physical effects in the N-body code GADGET-2, and we discuss the outcomes of a series of high-resolution N-body simulations for a selected family of interacting dark energy models, as already presented in Baldi et al. [20]. We interestingly find, in contrast with previous claims, that the inner overdensity of dark matter halos decreases in these models with respect to LCDM, and consistently halo concentrations show a progressive reduction for increasing couplings. Furthermore, the coupling induces a bias in the overdensities of cold dark matter and baryons that determines a decrease of the halo baryon fraction below its cosmological value. These results go in the direction of alleviating tensions between astrophysical observations and the predictions of the LCDM model on small scales, thereby opening new room for coupled dark energy models as an alternative to the cosmological constant.
First I emphasize the magnetospheric loop current system induced by the wind activity. Next, I address the formation of the field-aligned electric field. An interesting aspect is the reaction of the inner magnetosphere to an induced current. In the traditional outer gap, the current running through the gap is all carried by the particles created in the gap. However, if external current-carrying particles are added, the gap moves inward or outward; it can even appear near the star. It is suggested that the gaps appear at various altitudes, depending on the current distribution on field lines, the field line geometry, and the source of the current-carrying particles.   For definiteness of sign of charge and current direction, $\vec{\Omega} \cdot \vec{\mu} >0$ is assumed throughout.
The black hole spacetime is described by general relativity and characterized by two quantities: the black hole mass and spin. Black hole spin measurement requires information from the vicinity of the event horizon, which is spatially resolved for the Galactic center SagittariusA* (SgrA*) and nearby radio galaxy M87 by means of very long baseline interferometry (VLBI) observations with the Event Horizon Telescope (EHT). In this paper, we simulate EHT observations for a gas cloud intermittently falling onto a black hole, and construct a method for spin measurement based on its relativistic flux variation. The light curve of the infalling gas cloud is composed of peaks formed by photons which directly reach a distant observer and by secondary ones reaching the observer after more than one rotation around the black hole. The time interval between the peaks is determined by a period of photon rotation near the photon circular orbit which uniquely depends on the spin. We perform synthetic EHT observations for SgrA* under a more realistic situation that a number of gas clouds intermittently fall towards the black hole with various initial parameters. Even for this case, the black hole spin dependence is detectable in correlated flux densities which are accurately calibrated by baselines between sites with redundant stations. The synthetic observations indicate that our methodology can be applied to EHT observations of Sgr A* since April 2017.
In this paper, we prove that the inverse of Malliavin matrix is p integrable for a kind of degenerate stochastic differential equation under some conditions, which like to Hormander condition, but don't need all the coefficients of the SDE are smooth. Furthermore, we obtain a uniform estimation for Malliavin matrix, a gradient estimate, and prove that the semigroup generated by the SDE is strong Feller. Also some examples are given.
We present in detail a theoretical model for fragmentation reactions of three--body halo nuclei. The different reaction mechanisms corresponding to the different processes are described and discussed. Coulomb and nuclear interactions are simultaneously included and the method is therefore applicable for any target, light, intermediate and heavy. Absolute values of many differential cross sections are then available as function of beam energy and target. We apply the method to fragmentation of $^6$He and $^{11}$Li on C, Cu and Pb. A large variety of observables, cross sections and momentum distributions, are computed. In almost all cases we obtain good agreement with the available experimental data.
A number of techniques for interpretability have been presented for deep learning in computer vision, typically with the goal of understanding what the networks have based their classification on. However, interpretability for deep video architectures is still in its infancy and we do not yet have a clear concept of how to decode spatiotemporal features. In this paper, we present a study comparing how 3D convolutional networks and convolutional LSTM networks learn features across temporally dependent frames. This is the first comparison of two video models that both convolve to learn spatial features but have principally different methods of modeling time. Additionally, we extend the concept of meaningful perturbation introduced by \cite{MeaningFulPert} to the temporal dimension, to identify the temporal part of a sequence most meaningful to the network for a classification decision. Our findings indicate that the 3D convolutional model concentrates on shorter events in the input sequence, and places its spatial focus on fewer, contiguous areas.
We study the sub-Keplerian rotation and dust content of the circumstellar material around the asymptotic giant branch (AGB) star L$_2$ Puppis. We find that the thermal pressure gradient alone cannot explain the observed rotation profile. We find that there is a family of possible dust populations for which radiation pressure can drive the observed sub-Keplerian rotation. This set of solutions is further constrained by the spectral energy distribution (SED) of the system, and we find that a dust-to-gas mass ratio of $\sim10^{-3}$ and a maximum grain size that decreases radially outwards can satisfy both the rotation curve and SED. These dust populations are dynamically tightly coupled to the gas azimuthally. However grains larger than $\sim0.5\mu$m are driven outward radially by radiation pressure at velocities $\sim5$kms$^{-1}$, which implies a dust replenishment rate of $\sim3\times10^{-9}$M$_\odot$yr$^{-1}$. This replenishment rate is consistent with observational estimates to within uncertainties. Coupling between the radial motion of the dust and gas is weak and hence the gas does not share in this rapid outward motion. Overall we conclude that radiation pressure is a capable and necessary mechanism to explain the observed rotation profile of L$_2$ Pup, and offers other additional constraints on the dust properties.