ShantanuT01/DACTYL-Pretraining huggingface dataset:
Massive black holes in the centers of galaxies today must have grown by several orders of magnitude from seed black holes formed at early times. Detecting a population of intermediate mass black holes (IMBHs) can provide constraints on these elusive BH seeds. Here we use the large volume, cosmological hydrodynamical simulation Astrid, which includes IMBH seeds and dynamical friction to investigate the population of IMBH seeds. Dynamical friction is largely inefficient at sinking and merging seed IMBHs at high-z. This leads to an extensive population (several hundred per galaxy) of wandering IMBHs in large halos at z~2. A small fraction of these IMBHs are detectable as HLXs, Hyper Luminous X-ray sources. Importantly, at z ~ 2, IMBHs mergers produce the peak of GW events. We find close to a million GW events in Astrid between z=2-3 involving seed IMBH mergers. These GW events (almost all detectable by LISA) at cosmic noon should provide strong constraints on IMBH seed models and their formation mechanisms. At the center of massive galaxies, where the number of IMBHs can be as high as 10-100, SMBH-IMBH pairs can form. These Intermediate mass ratio inspirals (IMRIs) and extreme mass ratio inspirals (EMRIs), will require the next generation of milli-muHz space-based GW interferometers to be detected. Large populations of IMBHs around massive black holes will probe their environments and MBH causal structure.
We present a ~ 1" (100 pc) resolution 12CO (3-2) map of the nearby intermediate stage interacting galaxy pair NGC 4038/9 (the Antennae galaxies) obtained with the Submillimeter Array. We find that half the CO (3-2) emission originates in the overlap region where most of the tidally induced star formation had been previously found in shorter wavelength images, with the rest being centered on each of the nuclei. The gross distribution is consistent with lower resolution single dish images, but we show for the first time the detailed distribution of the warm and dense molecular gas across this galaxy pair at resolutions comparable to the size of a typical giant molecular complex. While we find that 58% (33/57) of the spatially resolved Giant Molecular Associations (GMAs; a few x 100 pc) are located in the overlap region, only \leqq 30% spatially coincides with the optically detected star clusters, suggesting that the bulk of the CO (3-2) emission traces the regions with very recent or near future star formation activity. The spatial distribution of the CO (3-2)/CO (1-0) integrated brightness temperature ratios mainly range between 0.3 and 0.8, which suggests that on average the CO (3-2) line in the Antennae is not completely thermalized and similar to the average values of nearby spirals. A higher ratio is seen in both nuclei and the southern complexes in the overlap region. Higher radiation field associated with intense star formation can account for the nucleus of NGC 4038 and the overlap region, but the nuclear region of NGC 4039 show relatively little star formation or AGN activities and cannot be easily explained. We show kinematical evidence that the high line ratio in NGC 4039 is possibly caused by gas inflow into the counter-rotating central disk.
We present a general study on exclusive semileptonic decays of heavy (B, D, B_s) to light (pi, rho, K, K^*) mesons in the framework of effective field theory of heavy quark. Transition matrix elements of these decays can be systematically characterized by a set of wave functions which are independent of the heavy quark mass except for the implicit scale dependence. Form factors for all these decays are calculated consistently within the effective theory framework using the light cone sum rule method at the leading order of 1/m_Q expansion. The branching ratios of these decays are evaluated, and the heavy and light flavor symmetry breaking effects are investigated. We also give comparison of our results and the predictions from other approaches, among which are the relations proposed recently in the framework of large energy effective theory.
In this paper we prove the existence of a solution to a nonlinear Schr{\"o}dinger--Poisson eigenvalue problem in dimension less than $3$. Our proof is based on a global approach to the determination of eigenvalues and eigenfunctions which allows us to characterize the complete sequence of eigenvalues and eigenfunctions at once, via a variational approach, and thus differs from the usual and less general proofs developed for similar problems in the literature. Our approach seems to be new for the determination of the spectrum and eigenfunctions for compact and self-adjoint operators, even in a finite dimensional setting.
We analysed how the active galactic nucleus (AGN) X-ray primary continuum depends on AGN activity in radio, using the data of RXTE Spectral & Timing Database (Rossi X-ray Timing Explorer) and INTEGRAL (INTErnational Gamma-Ray Astrophysics Laboratory). Our aim is to test the relation between spectral shapes of these AGNs and the prediction of the "spin-paradigm" model of the AGN "central engine". We have found that for the major part of radio-quiet (RQ) AGNs the value of high-energy exponential cut-off in primary spectrum appears to be significantly higher than 100 keV and thus follows the "spin-paradigm" predictions. In the same time, near 25% of radio-loud (RL) AGNs demonstrate the high-energy cut-off at the energies above 150 keV, contradicting the "spin paradigm". We have composed a sample of "peculiar" 69 RQ and 10 RL AGNs that seem to contradict to the "spin paradigm" for further individual studies of these objects.
For a given triangle $\triangle ABC$, we define two sequences of points on line $BC$ and provide their generalizations to real functions such that centers of circumscribed circles around $A$ and adjacent points in subsequences generate a pencil of conics touching perpendicular bisectors of $AB$ and $AC$.
The recent discovery of thousands of ultra diffuse galaxies (UDGs) in nearby galaxy clusters has opened a new window into the process of galaxy formation and evolution. Several scenarios have been proposed to explain the formation history of UDGs, and their ability to survive in the harsh cluster environments. A key requirement to distinguish between these scenarios is a measurement of their halo masses which, due to their low surface brightnesses, has proven difficult if one relies on stellar tracers of the potential. We exploit weak gravitational lensing, a technique that does not depend on these baryonic tracers, to measure the average subhalo mass of 784 UDGs selected in 18 clusters at $z\leq0.09$. Our sample of UDGs has a median stellar mass $\langle m_\star\rangle=2\times10^8\,\mathrm{M}_\odot$ and a median effective radius $\langle r_\mathrm{eff}\rangle=2.8$ kpc. We constrain the average mass of subhaloes within 30 kpc to $\log m_\mathrm{UDG}(r<30\,\mathrm{kpc})/\mathrm{M}_\odot\leq10.99$ at 95 per cent credibility, implying an effective virial mass $\log m_{200}/\mathrm{M}_\odot\leq11.80$, and a lower limit on the stellar mass fraction within 10 kpc of 1.0 per cent. Such mass is consistent with a simple extrapolation of the subhalo-to-stellar mass relation of typical satellite galaxies in massive clusters. However, our analysis is not sensitive to scatter about this mean mass; the possibility remains that extreme UDGs reside in haloes as massive as the Milky Way.
We evaluate the ratio of shear viscosity to entropy density in a pion gas employing the Uehling-Uehlenbeck equation and experimental phase-shifts parameterized by means of the SU(2) Inverse Amplitude Method. We find that the ratio for this monocomponent gas stays well above the KSS 1/(4 pi) bound. We find similar results with other sets of phase shifts and conclude the bound is nowhere violated.
Recent work ([18], [1]) has produced a complete list of weighted homogeneous surface singularities admitting smoothings whose Milnor fibre has only trivial rational homology (a "rational homology disk"). Though these special singularities form an unfamiliar class and are rarely even log-canonical, we prove the   Theorem. A rational homology disk smoothing of a weighted homogeneous surface singularity can always be chosen so that the total space is log-terminal. In particular, this smoothing is $\Q$-Gorenstein.   The key idea is to define a finite "graded discrepancy" of a normal graded domain with $\Q$-Cartier canonical divisor, and to study its behavior for a smoothing.
We present a detailed stellar population analysis of 11 bright ($H<26.6$) galaxies at $z=9-11$ (three spectroscopically confirmed) to constrain the chemical enrichment and growth of stellar mass of early galaxies. We use the flexible Bayesian spectral energy distribution (SED) fitting code Prospector with a range of star-formation histories (SFHs), a flexible dust attenuation law and a self-consistent modeling of emission lines. This approach allows us to assess how different priors affect our results, and how well we can break degeneracies between dust attenuation, stellar ages, metallicity and emission lines using data which probe only the rest-frame ultraviolet to optical wavelengths. We measure a median observed ultraviolet spectral slope $\beta=-1.87_{-0.43}^{+0.35}$ for relatively massive star-forming galaxies ($9<\log(M_{\star}/M_{\odot})<10$), consistent with no change from $z=4$ to $z=9-10$ at these stellar masses, implying rapid enrichment. Our SED-fitting results are consistent with a star-forming main sequence with sub-linear slope ($0.7\pm0.2$) and specific star-formation rates of $3-10~\mathrm{Gyr}^{-1}$. However, the stellar ages and SFHs are less well constrained. Using different SFH priors, we cannot distinguish between median mass-weighted ages of $\sim50-150$ Myr, which corresponds to 50\% formation redshifts of $z_{50}\sim10-12$ at $z\sim9$ and is of the order of the dynamical timescales of these systems. Importantly, the models with different SFH priors are able to fit the data equally well. We conclude that the current observational data cannot tightly constrain the mass-buildup timescales of these $z=9-11$ galaxies, with our results consistent with SFHs implying both a shallow and steep increase of the cosmic SFR density with time at $z>10$.
Encompasing a volume of ~1 km^3 of glacial ice at the South Pole, IceCube is currently the worlds largest neutrino detector. It consists of 5160 optical modules on 86 strings in a depth between 1450m and 2450m, as well as 324 optical modules arranged in 81 stations on the surface to detect charged cosmic rays. A large amount of data has already been acquired with smaller configurations throughout the installation period. Using this data the atmospheric neutrino spectrum in the northern hemisphere has been measured up to 100 TeV. No point sources have been identified in a set of more than 10^5 neutrino candidates from both hemispheres. Searches for transient sources have set stringent limits on neutrino emission from gamma-ray bursts, and are now accompanied by an extensive neutrino-triggered follow-up program. A very large statistics of cosmic ray events has revealed an anisotropy in the cosmic ray flux on the 10^-3 level in the 10-100 TeV range. While no sources of extra-terrestrial neutrinos have been found yet, the physics results obtained so far illustrate the very good performance of the detector.
We compute and analyze the gravitational waveform emitted to future null infinity by a system of two black holes in the large mass ratio limit. We consider the transition from the quasi-adiabatic inspiral to plunge, merger, and ringdown. The relative dynamics is driven by a leading order in the mass ratio, 5PN-resummed, effective-one-body (EOB), analytic radiation reaction. To compute the waveforms we solve the Regge-Wheeler-Zerilli equations in the time-domain on a spacelike foliation which coincides with the standard Schwarzschild foliation in the region including the motion of the small black hole, and is globally hyperboloidal, allowing us to include future null infinity in the computational domain by compactification. This method is called the hyperboloidal layer method, and is discussed here for the first time in a study of the gravitational radiation emitted by black hole binaries. We consider binaries characterized by five mass ratios, $\nu=10^{-2,-3,-4,-5,-6}$, that are primary targets of space-based or third-generation gravitational wave detectors. We show significative phase differences between finite-radius and null-infinity waveforms. We test, in our context, the reliability of the extrapolation procedure routinely applied to numerical relativity waveforms. We present an updated calculation of the gravitational recoil imparted to the merger remnant by the gravitational wave emission. As a self consistency test of the method, we show an excellent fractional agreement (even during the plunge) between the 5PN EOB-resummed mechanical angular momentum loss and the gravitational wave angular momentum flux computed at null infinity. New results concerning the radiation emitted from unstable circular orbits are also presented.
We have studied the hole charging spectra of self-assembled InAs quantum dots in perpendicular magnetic fields by capacitance-voltage spectroscopy. From the magnetic field dependence of the individual peaks we conclude that the s-like ground state is completely filled with two holes but that the fourfold degenerate p-shell is only half filled with two holes before the filling of the d-shell starts. The resulting six-hole ground state is highly polarized. This incomplete shell filling can be explained by the large influence of the Coulomb interaction in this system.
We investigated the influence of vacuum annealing on interface properties of silicon carbide (SiC) metal-oxide-semiconductor (MOS) structures. For as-oxidized and nitric oxide (NO)-annealed samples, the interface state density ($D_{\rm it}$) near the conduction band edge ($E_{\rm C}$) of SiC did not increase by subsequent vacuum annealing. For phosphoryl chloride (POCl$_3$)-annealed samples, in contrast, $D_{\rm it}$ at $E_{\rm C}-0.2$ eV increased from $1.3\times10^{10}$ to $2.2\times10^{12}$ cm$^{-2}$eV$^{-1}$ by the vacuum annealing, and the channel mobility of MOS field effect transistors (MOSFETs) decreased from 109 to 44 cm$^2$V$^{-1}$s$^{-1}$. Mechanism of the observed increase in $D_{\rm it}$ was discussed based on the results of secondary ion mass spectrometry measurement.
We consider normal affine T-varieties X endowed with an action of finite abelian group G commuting with the action of T. For such varieties we establish the existence of G-equivariant geometrico-combinatorial presentations in the sense of Altmann and Hausen. As an application, we determine explicit presentations of the Koras-Russell threefolds as bi-cyclic covers of A^3 equipped with a hyperbolic C^*-action.
In this study, we systematically studied the X-ray to GeV gamma-ray spectra of 61 {\it Fermi} Large Area Telescope (LAT) detected radio galaxies. We found an anticorrelation between peak frequency and peak luminosity in the high-energy spectral component of radio galaxies, similar to blazars. With this sample, we also constructed a gamma-ray luminosity function (GLF) of gamma-ray-loud radio galaxies. We found that blazar-like GLF shapes can reproduce their redshift and luminosity distribution, but the log$N$-log$S$ relation prefers models with more low-$z$ radio galaxies. This indicates many low-$z$ gamma-ray-loud radio galaxies. By utilizing our latest GLF, the contribution of radio galaxies to the extragalactic gamma-ray background is found to be 1--10\%. We further investigated the nature of gamma-ray-loud radio galaxies. Compared to radio or X-ray flux-limited radio galaxy samples, the gamma-ray selected sample tends to lack high radio power galaxies like FR-II radio galaxies. We also found that only $\sim$10\% of radio galaxies are GeV gamma-ray loud. Radio galaxies may contribute to the cosmic MeV gamma-ray background comparable to blazars if gamma-ray-quiet radio galaxies have X-ray to gamma-ray spectra like Cen A, with a small gamma-ray to X-ray flux ratio.
Evidence is mounting that the small bodies of our Solar System, such as comets and asteroids, have at least partially inherited their chemical composition from the first phases of the Solar System formation. It then appears that the molecular complexity of these small bodies is most likely related to the earliest stages of star formation. It is therefore important to characterize and to understand how the chemical evolution changes with solar-type protostellar evolution. We present here the Large Program "Astrochemical Surveys At IRAM" (ASAI). Its goal is to carry out unbiased millimeter line surveys between 80 and 272 GHz of a sample of ten template sources, which fully cover the first stages of the formation process of solar-type stars, from prestellar cores to the late protostellar phase. In this article, we present an overview of the surveys and results obtained from the analysis of the 3 mm band observations. The number of detected main isotopic species barely varies with the evolutionary stage and is found to be very similar to that of massive star-forming regions. The molecular content in O- and C- bearing species allows us to define two chemical classes of envelopes, whose composition is dominated by either a) a rich content in O-rich complex organic molecules, associated with hot corino sources, or b) a rich content in hydrocarbons, typical of Warm Carbon Chain Chemistry sources. Overall, a high chemical richness is found to be present already in the initial phases of solar-type star formation.
Multipolar orderings in degenerate orbital systems offer unique opportunities for emergent topological phases. The phase diagram of interacting spinless fermions in a $p$-band diamond lattice at unit filling is first studied to elucidate the essential role of orbital multipolar orderings in the evolution of multifold degenerate band nodes. The free band structure around the Brillouin zone center is described by two quadratic band nodes each with a threefold degeneracy, which are spanned by the bonding and anti-bonding $p$-orbital multiplets, respectively. Upon switching on interactions, the triply degenerate band node is split into a pair of Weyl fermions with opposite chirality due to the onset of orbital multipolar orderings. Further raising interactions ultimately drives the system into an insulating phase with the orbital quadrupolar ordering. Our study is then generalized to spin-$1/2$ fermions, which has direct relevance with solid-state materials. The system develops full spin polarization through a ferromagnetic transition at tiny interactions, leaving the remaining orbital sector activated. The ensuing transitions take place in the orbital sector as a natural consequence, qualitatively recovering the phase diagram of spinless fermions. Our findings shed new light on the realization of emergent novel fermions with a prospect being a frontier at the confluence of topology, orbital physics and strong correlation.
The most important advances achieved recently on the double heavy flavored mesons are reviewed. Some problems and outlooks on them are also outlined.
Recently sparse representation has gained great success in face image super-resolution. The conventional sparsity-based methods enforce sparse coding on face image patches and the representation fidelity is measured by $\ell_{2}$-norm. Such a sparse coding model regularizes all facial patches equally, which however ignores distinct natures of different facial patches for image reconstruction. In this paper, we propose a new weighted-patch super-resolution method based on AdaBoost. Specifically, in each iteration of the AdaBoost operation, each facial patch is weighted automatically according to the performance of the model on it, so as to highlight those patches that are more critical for improving the reconstruction power in next step. In this way, through the AdaBoost training procedure, we can focus more on the patches (face regions) with richer information. Various experimental results on standard face database show that our proposed method outperforms state-of-the-art methods in terms of both objective metrics and visual quality.
The statistics of dark matter halos is an essential component of understanding the nonlinear evolution in modified gravity cosmology. Based on a series of modified gravity N-body simulations, we investigate the halo mass function, concentration and bias. We model the impact of modified gravity by a single parameter \zeta, which determines the enhancement of particle acceleration with respect to GR, given the identical mass distribution (\zeta=1 in GR). We select snapshot redshifts such that the linear matter power spectra of different gravity models are identical, in order to isolate the impact of gravity beyond modifying the linear growth rate. At the baseline redshift corresponding to z_S=1.2 in the standard \Lambda CDM, for a 10% deviation from GR(|\zeta-1|=0.1), the measured halo mass function can differ by about 5-10%, the halo concentration by about 10-20%, while the halo bias differs significantly less. These results demonstrate that the halo mass function and/or the halo concentration are sensitive to the nature of gravity and may be used to make interesting constraints along this line.
The finite temperature phase diagram is obtained for an infinite honeycomb lattice with spin-$1/2$ Ising interaction $J$ by using thermal-state fidelity and von Neumann entropy based on the infinite projected entangled pair state algorithm with ancillas. % The tensor network representation of the fidelity, which is defined as an overlap measurement between two thermal states, is presented for thermal states on the honeycomb lattice. % We show that the fidelity per lattice site and the von Neumann entropy can capture the phase transition temperatures for applied magnetic field, consistent with the transition temperatures obtained via the transverse magnetizations, which indicates that a continuous phase transition occurs in the system. In the temperature-magnetic field plane, the phase boundary is found to have the functional form $(k_BT_c)^2 + h_c^2/2 = a J^2$ with a single numerical fitting coefficient $a = 2.298$, where $T_c$ and $h_c$ are the critical temperature and field with the Boltzmann constant $k_B$. For the quantum state at zero temperature, this phase boundary function gives the critical field estimate $h_c = \sqrt{2a} J \simeq 2.1438 J$, consistent with the known value $h_c = 2.13250(4)\, J$ calculated from a Cluster Monte Carlo approach. The critical temperature in the absence of magnetic field is estimated as $k_BT_c = \sqrt{a}J \simeq 1.5159\, J$, consistent with the exact result $k_BT_c = 1.51865...\, J$.
The degenerate free Fermi gas coupled to a random potential is used to compute a.c. conductivity in various dimensions. We first formally diagonalise the hamiltonian using an appropriate basis that is a functional of the disorder potential. Then we compute the a.c. conductivity at zero temperature using the Kubo formula. This a.c. conductivity is a functional of the disordered potential. The wavefunction of extended states is written as exponential of the logarithm. We use the cumulant expansion to compute the disordered averaged a.c. conductivity for Gaussian disorder. The formula is valid if a certain linearization approximation is valid in the long-wavelength limit.
Some new methods for the extraction of CKM phases $\alpha$ and $\gamma$ using flavor SU(3) symmetry have been suggested through the construction of rigid polygons in the complex plane with sides equal to the decay amplitudes of B mesons into two mesons belonging to the light (charmless) pseudoscalar octet. These rigid polygons incorporate all the possible amplitude triangles and, being overdetermined, also serve as consistency checks and in estimating the rates of some decay modes. The same techniques also lead to numerous useful amplitude triangles when octet-singlet mixing has been taken into account and nearly physical $\eta,\eta'$ are used.