ShantanuT01/DACTYL-Pretraining huggingface dataset:
Assuming the generalized Riemann hypothesis, we prove quantitative estimates for the number of simple zeros on the critical line for the L-functions attached to classical holomorphic newforms.
Based on a large sample of massive ($M_{*}\geq 10^{10} M_{\odot}$) compact galaxies at $1.0 < z < 3.0$ in five 3D-HST/CANDELS fields, we quantify the fractional abundance and comoving number density of massive compact galaxies as a function of redshift. The samples of compact quiescent galaxies (cQGs) and compact star-forming galaxies (cSFGs) are constructed by various selection criteria of compact galaxies in literatures, and the effect of compactness definition on abundance estimate is proved to be remarkable, particularly for the cQGs and cSFGs at high redshifts. Regardless of the compactness criteria adopted, their overall redshift evolutions of fractional abundance and number density are found to be rather similar. Large samples of the cQGs exhibit a sustaining increase in number density from $z \sim 3$ to 2 and a plateau at $1<z<2$. For massive cSFGs, a plateau in the number density at $2<z<3$ can be found, as well as a continuous drop from $z \sim 2$ to 1. The evolutionary trends of the cQG and cSFG abundances support the scenario that the cSFGs at $z \geq 2$ may have been rapidly quenched into quiescent phase via violent dissipational processes such as major merger and disk instabilities. Rarity of the cSFGs at lower redshifts ($z < 1$) can be interpreted by the decrease of gas reservoirs in dark matter halos and the consequent low efficiency of gas-rich dissipation.
We report results of the study of the recently discovered magnetic resonance in the orbitally ordered phase of CeB6 (the orbital ordering resonance) in a wide frequency range 44-360 GHz. It is found that the g-factor for this resonance increases with frequency from g(44 GHz)~1.55 to g(>250 GHz)~1.7. In addition to the orbital ordering resonance for the frequencies exceeding 200 GHz a new magnetic resonance with the g-factor 1.2-1.3 is detected.
Zn in GaN forms an efficient radiative center and acts as a deep acceptor which can make the crystal insulating. Four different Zn-related centers have been by now identified, leading to light emission in the range between 1.8 eV and 2.9 eV. We present a first-principles investigation total energy and electronic structure calculations for Ga-substitutional and hetero-antisite N-substitutional Zn in wurtzite GaN, using ultrasoft pseudopotentials and a conjugate-gradient total energy minimization method. Our results permit the identification of the blue-light emission center as the substitutional acceptor, while contrary to a common belief the Zn_N heteroantisite has a very high formation energy and donor behavior, which seems to exclude it as the origin of the other centers.
The progenitors of type-IIb supernovae (SNe) are believed to have lost their H-rich envelopes almost completely in the direct pre-SN phase. Recently the first 'flash spectrum' of a SN IIb (SN2013cu) has been presented, taken early enough to study its immediate circumstellar medium (CSM). Similar to a previous study by Groh (2014) we analyse the structure and chemical composition of the optically-thick CSM using non-LTE model atmospheres. For the first time we take light-travel time (LTT) effects on the spectrum formation into account, which affect the shapes and strengths of the observable emission lines, as well as the inferred SN luminosity. Based on the new CSM parameters we estimate a lower limit of ~0.3Msun for the CSM mass, which is a factor 10-100 higher than previous estimates. The spectral fit implies a CSM in the form of a homogeneous and spherically symmetric superwind whose mass-loss rate exceeds common expectations by up to two orders of magnitude. The derived chemical composition is in agreement with a progenitor that has just left, or is just about to leave the Red-Supergiant (RSG) stage, confirming the standard picture for the origin of SNe IIb. Due to its extreme mass loss the SN progenitor will likely appear as extreme RSG, Luminous Blue Variable (LBV), or Yellow Hypergiant (YHG). The direct detection of a superwind, and the high inferred CSM mass suggest that stellar wind mass loss may play an important role in the formation of SNe IIb.
We say that a word $w$ of length $kn$ is a $k$-\textit{antipower} if it can be written in the form $w_1 \cdots w_k$, where each $w_i$ is a distinct word of length $n$. We analyze prefixes of the Thue-Morse word $\textbf{t}$ and lengths of antipowers occurring in them. Define $\Gamma(k)$ to be the largest odd $n$ such that the prefix of $\textbf{t}$ of length $kn$ is not a $k$-antipower, and $\gamma(k)$ to be the smallest odd $n$ such that the corresponding prefix is a $k$-antipower. We provide strong bounds on the asymptotic values of $\gamma(k)$ and $\Gamma(k)-\gamma(k)$. Our bounds on $\gamma(k)$ affirmatively answer one conjecture of Defant and make substantial progress towards answering a second conjecture of Defant. It was previously known that $\Gamma(k)$ and $\gamma(k)$ grow linearly in $k$, but our bounds on $\Gamma(k)-\gamma(k)$ prove that $\Gamma(k)-\gamma(k)$ also grows linearly in $k$.
We present the discovery of an extended ring of ultraviolet emission surrounding the AGB star U Hya in archival observations performed by the Galaxy Evolution Explorer (GALEX). This is the third discovery of extended UV emission from a carbon AGB star and the first from an AGB star with a detached shell. From imaging and photometric analysis of the FUV and NUV images, we determined that the ultraviolet ring has a radius of $\sim 110^{\prime\prime}$, thus indicating that the emitting material is likely associated with the detached shell seen in the infrared. We find that scattering of the central point source of NUV and FUV emission by the dust shell is negligible. Moreover, we find that scattering of the interstellar radiation field by the dust shell can contribute at most $\sim10%$ of the FUV flux. Morphological and photometric evidence suggests that shocks caused by the star's motion through space and, possibly, shock-excited H$_2$ molecules are the most likely origins of the UV flux. In contrast to previous examples of extended UV emission from AGB stars, the extended UV emission from U Hya does not show a bow shock-like structure, which is consistent with a lower space velocity and lower interstellar medium density. This suggests the detached dust shell is the source of the UV emitting material and can be used to better understand the formation of detached shells.
Background: Neutron-skin thickness is an excellent indicator of isovector properties of atomic nuclei. As such, it correlates strongly with observables in finite nuclei that depend on neutron-to-proton imbalance and the nuclear symmetry energy that characterizes the equation of state of neutron-rich matter. A rich worldwide experimental program involving studies with rare isotopes, parity violating electron scattering, and astronomical observations is devoted to pinning down the isovector sector of nuclear models. Purpose: We assess the theoretical systematic and statistical uncertainties of neutron-skin thickness and relate them to the equation of state of nuclear matter, and in particular to nuclear symmetry energy parameters. Methods: We use the nuclear superfluid Density Functional Theory with several Skyrme energy density functionals and density dependent pairing. To evaluate statistical errors and their budget, we employ the statistical covariance technique. Results: We find that the errors on neutron skin increase with neutron excess. Statistical errors due to uncertain coupling constants of the density functional are found to be larger than systematic errors, the latter not exceeding 0.06 fm in most neutron-rich nuclei across the nuclear landscape. The single major source of uncertainty is the poorly determined slope L of the symmetry energy that parametrizes its density dependence. Conclusions: To provide essential constraints on the symmetry energy of the nuclear energy density functional, next-generation measurements of neutron skins are required to deliver precision better than 0.06 fm.
Recent experiments on twisted bilayer graphene show an anomalous quantum Hall (AQH) effect at filling of $3$ electrons per moir\`e unit cell. The AQH effect arises in an insulating state with both valley- and ferromagnetic order. We argue, that weak doping of such a system leads to the formation of a novel topological spin texture, a `double-tetarton lattice'. The building block of this lattice, the `double-tetarton', is a spin configuration which covers $1/4$ of the unit-sphere twice. In contrast to skyrmion lattices, the net magnetization of this magnetic texture vanishes. Only at large magnetic fields more conventional skyrmion lattices are recovered. But even for large fields the addition of a single charge to the ferromagnetic AQH state flips hundreds of spins. Our analysis is based on the investigation of an effective non-linear sigma model which includes the effects of long-ranged Coulomb interactions.
As early as the 1930s, P\'al Erd\H{o}s conjectured that: {\em for any multiplicative function $f:\mathbb{N}\to\{-1,1\}$, the partial sums $\sum_{n\leq x}f(n)$ are unbounded.} Considering this conjecture, in this paper we consider multiplicative functions $f$ satisfying $$\sum_{p\leq x}f(p)=c\cdot\frac{x}{\log x}(1+o(1)).$$ We prove that if $c>0$ then the partial sums of $f$ are unbounded, and if $c<0$ then the partial sums of $\mu f$ are unbounded. Extensions of this result are also discussed.
During the last fifteen years, multiferroic (MF) research communities have been searching for an alternative room temperature MF material with large magnetoelectric (ME) coupling for possible applications in high density electronic components, low heat dissipation memory and logic devices. We have studied Pb(Zr0.20Ti0.80)0.70Pd0.30O3-{\delta} (PZTP30) system with an unusually large (30%) palladium occupancy in B site of PZT. This material exhibited a giant ME coupling coefficient ~0.36 mV/cm.Oe. Interestingly, this is the first time any room temperature single phase compound that showed ME trends, and magnitude similar to those in the well established mechanical strain-mediated ferroelectric and ferromagnetic composites; the latter ones are already in the commercial stage as nT/pT magnetic field sensors due to their large ME values. The presence of Pd in PZTP30 has been confirmed by XPS and XRF studies and assigned with related binding energies of Pd+2 and Pd+4 ions as 336.37 eV, 342.9 eV, and 337.53 eV, 343.43 eV, respectively, which may be the origin of room temperature magnetism in Pd substituted PZT ceramics. A sharp first order ferroelectric phase transition was observed at ~569 K (+/-5 K) that is confirmed from dielectric, Raman, and thermal analysis. Both ferromagnetic and ferroelectric orderings with large ME coupling were found above room temperature, a significant step forward in the development of single phase ME material with enhanced functionalities.
We have carried out an H-alpha flux measurement for 52 nearby galaxies as part of a general H-alpha imaging survey for the Local Volume sample of galaxies within 10 Mpc. Most of the objects are probable members of the groups around Maffei 2/IC 342, NGC 672/IC 1727, NGC 784, and the Orion galaxy. The measured H-alpha fluxes corrected for extinction are used to derive the galaxy star formation rate (SFR). We briefly discuss some basic scaling relations between SFR, hydrogen mass and absolute magnitude of the Local Volume galaxies. The total SFR density in the local (z = 0) universe is estimated to be (0.019+/-0.003) M_sun yr/Mpc^3.
The transient Swift J1644+57 is believed to have been produced by an unlucky star wandering too close to a supermassive black hole (BH) leading to a tidal disruption event. This unusual flare displayed highly super-Eddington X-ray emission which likely originated in a relativistic, collimated jet. This presents challenges to modern accretion and jet theory as upper limits of prior BH activity, which we obtain from the radio afterglow of this event, imply that both the pre-disruption BH and stellar magnetic fluxes fall many orders of magnitude short of what is required to power the observed X-ray luminosity. We argue that a pre-existing, "fossil" accretion disc can contain a sufficient reservoir of magnetic flux and that the stellar debris stream is capable of dragging this flux into the BH. To demonstrate this, we perform local, 3D magnetohydrodynamic simulations of the disc--stream interaction and demonstrate that the interface between the two is unstable to mixing. This mixing entrains a sufficient amount of fossil disc magnetic flux into the infalling stellar debris to power the jet. We argue that the interaction with the fossil disc can have a pronounced effect on the structure and dynamics of mass fallback and likely the resulting transient. Finally, we describe possible ramifications of these interactions on unresolved problems in tidal disruption dynamics, in particular, the efficiency of debris circularization, and effects of the disruption on the preexisting black hole system.   Animations online: http://goo.gl/T84tLs
In this work we investigate an optomechanical system consisting of two cavities coupled to the same mechanical resonator. We consider each cavity being weakly pumped as well as a small tunneling rate between the cavities. In such conditions, the system can be studied via quantum Langevin equations and the steady state solution can be found perturbatively. In order to ensure that the approximations and methods used to study the system are suitable, the analytical results were compared to numerical simulations. We study the statistical properties of the cavity radiation fields and we show that depending on the values of the parameters of the system, it is possible to modify the spectrum of the cavities and even enhance the sub-Poissonian character of the cavity field.
Recent studies of the distribution and kinematics of the Milky Way and Andromeda satellite galaxy systems have confirmed the existence of coplanar, corotating structures of galaxies. In addition to the 'missing satellite problem', these structures pose a major challenge to the standard $\Lambda$CDM scenario of structure formation. We complement the efforts made by the dwarf galaxy community to extend these studies to other nearby galaxy groups by systematically searching for faint, unresolved dwarf members with a low surface brightness in the Southern Centaurus group of galaxies. The aim is to determine whether these coplanar, corotating structures are a universal phenomenon. We imaged an area of 60 square degrees (0.3 Mpc$^2$) around the M83 subgroup with the wide-field Dark Energy Camera (DECam) at the CTIO 4 m Blanco telescope in $g$ and $r$ down to a limiting surface brightness of $\mu_r\approx 30$ mag arcsec$^{-2}$. Various image-filtering techniques were applied to the DECam data to enhance the visibility of extremely low-surface brightness objects. We report the discovery of 16 new dwarf galaxy candidates in the direction of the M83 subgroup, roughly doubling the number of known dwarfs in that region. The photometric properties of the candidates, when compared to those of the Local Group, suggest membership in the M83 subgroup. The faintest objects have a central star density of $\approx1.3 L_\odot$ pc$^{-2}$ and a total magnitude of $g = 20.25$, corresponding to $M_g = -9.55$ at the nominal distance of 4.9 Mpc. The sky distribution of the new objects is significantly prolonged toward Cen A, suggesting that many of them belong to the Cen A subgroup or a common halo. We also provide updated surface photometry for the brighter, known dwarf members in the surveyed area.
We present a computation of the O(at*as + at^2) two--loop corrections to the MSSM Higgs masses. An appropriate use of the effective potential approach allows us to obtain simple analytical formulae, valid for arbitrary values of mA and of the mass parameters in the stop sector. In a large region of the parameter space the O(at^2) corrections are comparable to the O(at*as) ones, increasing the prediction for mh by several GeV.
We have obtained HST-NICMOS observations of five of M31's most metal rich globular clusters: G1, G170, G174, G177 & G280. For the two clusters farthest from the nucleus we statistically subtract the field population and estimate metallicities using K-(J-K) color-magnitude diagrams (CMDs). Based on the slopes of their infrared giant branches we estimate [Fe/H]=-1.22+/-0.43 for G1 and -0.15+/-0.37 for G280. We combine our infrared observations of G1 with two epochs of optical HST-WFPC2 V-band data and identify at least one LPV based on color and variability. The location of G1's giant branch in the K-(V-K) CMD is very similar to that of M107, indicating a higher metallicity than our purely infrared CMD: [Fe/H]=-0.9+/-0.2.   For the field surrounding G280, we estimate the metallicity to be -1.3 with a spread of 0.5 from the slope and width of the giant branch. Based on the numbers and luminosities of the brightest giants, we conclude that only a small fraction of the stars in this field could be as young as 2 Gyr, while the majority have ages closer to 10 Gyr.   The K-band luminosity functions (LFs) of the upper few magnitudes of G1 and G280, as well as for the fields surrounding all clusters, are indistinguishable from the LF measured in the bulge of our Galaxy. This indicates that these clusters are very similar to Galactic clusters, and at least in the surrounding fields observed, there are no significant populations of young luminous stars.
We describe the most general treatment of all anomalies both for chiral and massless Dirac fermions, in two-dimensional gravity. It is shown that for this purpose two regularization dependent parameters are present in the effective action. Analogy to the \sc\ model is displayed corresponding to a specific choice of the second parameter, thus showing that the gravitational model contains \a\ relations having no analogy in the \sc\ model.
We present new results of our program to systematically search for strongly lensed galaxies in the Sloan Digital Sky Survey (SDSS) imaging data. In this study six strong lens systems are presented which we have confirmed with follow-up spectroscopy and imaging using the 3.5m telescope at the Apache Point Observatory. Preliminary mass models indicate that the lenses are group-scale systems with velocity dispersions ranging from 466-878 km s^{-1} at z=0.17-0.45 which are strongly lensing source galaxies at z=0.4-1.4. Galaxy groups are a relatively new mass scale just beginning to be probed with strong lensing. Our sample of lenses roughly doubles the confirmed number of group-scale lenses in the SDSS and complements ongoing strong lens searches in other imaging surveys such as the CFHTLS (Cabanac et al 2007). As our arcs were discovered in the SDSS imaging data they are all bright ($r\lesssim22$), making them ideally suited for detailed follow-up studies.
In this article, Temperley's bijection between spanning trees of the square grid on the one hand, and perfect matchings (also known as dimer coverings) of the square grid on the other, is extended to the setting of general planar directed (and undirected) graphs, where edges carry nonnegative weights that induce a weighting on the set of spanning trees. We show that the weighted, directed spanning trees (often called arborescences) of any planar graph G can be put into a one-to-one weight-preserving correspondence with the perfect matchings of a related planar graph H.   One special case of this result is a bijection between perfect matchings of the hexagonal honeycomb lattice and directed spanning trees of a triangular lattice. Another special case gives a correspondence between perfect matchings of the ``square-octagon'' lattice and directed weighted spanning trees on a directed weighted version of the cartesian lattice.   In conjunction with results of Kenyon, our main theorem allows us to compute the measures of all cylinder events for random spanning trees on any (directed, weighted) planar graph. Conversely, in cases where the perfect matching model arises from a tree model, Wilson's algorithm allows us to quickly generate random samples of perfect matchings.
We discuss constraints that the observed brightness temperatures impose on coherent processes in pulsars and Fast Radio Bursts (FRBs), and in particular on the hypothesis of coherent curvature emission by bunches. We estimate the peak brightness temperature that a bunch of charge $Ze$ can produce via synchrotron and/or curvature emission as $k_B T \sim (Z e)^2/\lambda$, where $\lambda$ is the typical emitted wavelength. We demonstrate that the bunch's electrostatic energy required to produce observed brightness temperature is prohibitively high, of the order of the total {\it bulk } energy. We compare corresponding requirements for the Free Electron Laser mechanism (Lyutikov 2021) and find that in that case the constraints are much easier satisfied.
We analyze the structure of the Higgs potential in gauge-Higgs unification with a flat extra dimension. As a concrete model, we first consider the cases where the Standard Model Higgs doublet is embedded into a higher-dimensional $SU(3)_{w}^{}$ gauge multiplet with five-dimensional Lorentz symmetry relaxed. In this $SU(3)_{w}^{}$ model with Lorentz violation, the deviation of the resulting triple Higgs boson coupling from its SM prediction is shown to be less than $10\%$ when the compactification scale is larger than the experimental lower bound, which is around 5 TeV. Next, we examine the Higgs potential in other similar gauge-Higgs unification models with a flat extra dimension. It is pointed out that even in such models the shape of the Higgs potential around the vacuum quickly approaches that of the minimal Higgs potential with one Higgs doublet as the compactification scale of the extra dimension increases. An observable deviation of the triple Higgs boson coupling at planned lepton colliders will necessitate significant extensions of such gauge-Higgs unification models.
The Crab nebula was once considered to be a stable source until strong flares, up to 30 times increase in flux, were observed in the MeV and GeV energy range by the AGILE and Fermi Gamma-ray Observatories. Existing nebula models often assume that the electron population emitting synchrotron radiation at lower energies is responsible for the VHE emission via Inverse Compton (IC) scattering. This suggests that the variability of the synchrotron $\gamma$-ray emission may also become observable in the multi-TeV energy range. Until now, no variability in the Crab Nebula flux has been found in the VHE regime. In 2015, MAGIC started an observational campaign which improved the collection efficiency of $\gamma$-rays above several tens of TeV. These observations are performed under Very Large Zenith Angles (VLZA) and lead to a large increase in the collection area. This allows us to observe the low fluxes at TeV energies in a shorter time compared to standard observations, and to significantly increase the observable energy towards higher energies. We have studied the Crab Nebula light curve obtained from the VLZA data since 2015 in search for the flux variability at the highest TeV energies. The results of this study will be presented.