ShantanuT01/DACTYL-Pretraining huggingface dataset:
In this note we show how the main conjecture of the Iwasawa theory over Q has a natural place in the context of the Galois representation of the Galois group $Gal(\bar Q/Q)$ on the etale pro-p fundamental group of the projective line minus three points. However we still need to assume the Vandiver conjecture to get a proof of the main conjecture in this context.
We perform microscopic calculations of the inelastic cross sections for the double and triple excitation of giant resonances induced by heavy ion probes within a semicalssical coupled channels formalism. The channels are defined as eigenstates of a bosonic quartic Hamiltonian constructed in terms of collective RPA phonons. Therefore, they are superpositions of several multiphonon states, also with different numbers of phonons and the spectrum is anharmonic. The inclusion of (n+1) phonon configurations affects the states whose main component is a n-phonon one and leads to an appreacible lowering of their energies. We check the effects of such further anharmonicities on the previous published results for the cross section for the double excitation of Giant Resonances. We find that the only effect is a shift of the peaks towards lower energies, the double GR cross section being not modified by the explicity inclusion of the three-phonon channels in the dynamical calculations. The latters give an important contribution to the cross section in the triple GR energy region which however is still smaller than the experimental available data. The inclusion of four phonon configurations in the structure calculations does not modify the results.
The Seebeck coefficient plays a fundamental role in identifying the efficiency of a thermoelectric device. Its theoretical evaluation for atomistic models is routinely based on Density Functional Theory calculations combined with the Landauer-B\"uttiker approach to quantum transport. This combination, however, suffers from serious drawbacks for devices in the Coulomb blockade regime. We show how to cure the theory through a simple correction in terms of the {\em temperature derivative} of the exchange correlation potential. Our results compare well with both rate equations and experimental findings on carbon nanotubes.
We report on an observation of SGR 1627-41 made with the Chandra X-ray Observatory on 2011 June 16. Approximately three years after its outburst activity in 2008, the source's flux has been declining, as it approaches its quiescent state. For an assumed power-law spectrum, we find that the absorbed 2--10 keV flux for the source is $1.0^{+0.3}_{-0.2} \times 10^{-13} erg cm^{-2} s^{-1}$ with a photon index of $2.9 \pm 0.8$ ($N_H=1.0\times10^{23}$ cm^{-2}). This flux is approximately consistent with that measured at the same time after the source's outburst in 1998. With measurements spanning 3 years after the 2008 outburst, we analyze the long-term flux and spectral evolution of the source. The flux evolution is well described by a double exponential with decay times of 0.5 $\pm$ 0.1 and 59 $\pm$ 6 days, and a thermal cooling model fit suggests that SGR 1627-41 may have a hot core ($T_c ~ 2\times 10^8$ K). We find no clear correlation between flux and spectral hardness as found in other magnetars. We consider the quiescent X-ray luminosities of magnetars and the subset of rotation-powered pulsars with high magnetic fields ($B >~ 10^{13}$ G) in relation to their spin-inferred surface magnetic-field strength, and find a possible trend between the two quantities.
Elliptic Dedekind sums were introduced by R. Sczech as generalizations of classical Dedekind sums to complex lattices. We show that for any lattice with real $j$-invariant, the values of suitably normalized elliptic Dedekind sums are dense in the real numbers. This extends an earlier result of Ito for Euclidean imaginary quadratic rings. Our proof is an adaptation of the recent work of Kohnen, which gives a new proof of the density of values of classical Dedekind sums.
Chandra observations of the core of the nearby starburst galaxy NGC 253 reveal a heavily absorbed source of hard X-rays embedded within the nuclear starburst region. The source has an unabsorbed, 2 to 10 keV luminosity of >=10^39 erg/s and photoionizes the surrounding gas. We observe this source through a dusty torus with a neutral absorbing column density of NH ~ 2x10^23 cm^-2. The torus is hundreds of pc across and collimates the starburst-driven nuclear outflow. We suggest that the ionizing source is an intermediate-mass black hole or a weakly accreting supermassive black hole, which may signal the beginnings or endings of AGN activity.
We briefly review a fruitful approach to compute a variety of radiation signatures of General Relativity (GR) originating from accretion disks in strong gravity. A set of transfer functions can be pre-computed and then employed to accelerate the ray-traycing computations, generate a series of model spectra, and to fit the model predictions to actual data sets in X-rays. We have been developing this method to examine spectra and light curves and to model the expected polarimetric properties; in particular, to analyse the properties of the "corona--disk-line" geometry with GR effects taken into account. New impetus to this activity is emerging in the anticipation of upcoming missions equipped with the sensitivity to polarimetric properties in X-rays: IXPE (Imaging X-Ray Polarimetry Explorer) and eXTP (enhanced X-ray Timing and Polarimetry mission).
New BVRI light curves of the eclipsing binary system 1SWASP J160156.04+202821.6 have been obtained with the 1.88-m telescope of Kottamia Astronomical Observatory (KAO), Egypt on June, 2013. New twenty times of minima of the system J1601 and new ephemeris have been reduced and derived from the present photometry. A preliminary determination of the geometric and photometric element parameters of the system J1601 has been derived.
We report the detection of an infrared burst lagging a thermonuclear Type I X-ray burst from the accreting neutron star 4U 1728-34 (GX 354-0). Observations were performed simultaneously with XMM-Newton (0.7-12 keV), NuSTAR (3-79 keV) and HAWK-I@VLT (2.2$\mu$m). We measure a lag of $4.75 \pm 0.5$ s between the peaks of the emission in the two bands. Due to the length of the lag and the shape of the IR burst, we found that the most plausible cause for such a large delay is reprocessing of the Type I burst X-rays by the companion star. The inferred distance between the neutron star and the companion can be used to constrain the orbital period of the system, which we find to be larger than $\sim$ 66 minutes (or even $\gtrsim$ 2 hours, for a realistic inclination $< 75^\circ$). This is much larger than the current tentatively estimated period of $\sim 11$ minutes. We discuss the physical implications on the nature of the binary and conclude that most likely the companion of 4U 1728-34 is a helium star.
We consider scalar-tensor theories of gravity defined in Weyl integrable space-time and show that in the ADM formalism Weyl transformations corresponding to change of frames induce canonical transformations between different representations of the phase space. In this context, we discuss the physical equivalence of two distinct Weyl frames at the classical level.
We present a warped extra dimension model with the custodial symmetry $SU(2)_L\times SU(2)_R\times U(1)_X\times P_{LR}$ based on the flavor symmetry $S_4\times Z_2\times Z'_2$, and the neutrinos are taken to be Dirac particles. At leading order, the democratic lepton mixing is derived exactly, and the high dimensional operators introduce corrections of order $\lambda_c$ to all the three lepton mixing angles such that agreement with the experimental data can be achieved. The neutrino mass spectrum is predicted to be of the inverted hierarchy and the second octant of $\theta_{23}$ is preferred. We suggest the modified democratic mixing, which is obtained by permuting the second and the third rows of the democratic mixing matrix, should be a good first order approximation to understanding sizable $\theta_{13}$ and the first octant of $\theta_{23}$. The constraints on the model from the electroweak precision measurements are discussed. Furthermore, we investigate the lepton mixing patterns for all the possible residual symmetries $G_{\nu}$ and $G_{l}$ in the neutrino and charged lepton sectors, respectively.
By the m-spectrum of a real number q>1 we mean the set Y^m(q) of values p(q) where p runs over the height m polynomials with integer coefficients. These sets have been extensively investigated during the last fifty years because of their intimate connections with infinite Bernoulli convolutions, spectral properties of substitutive point sets and expansions in noninteger bases. We prove that Y^m(q) has an accumulation point if and only if q<m+1 and q is not a Pisot number. Consequently a number of related results on the distribution of points of this form are improved.
Let A be a finite subset of the naturals and let n be a natural. Let NIM(A;n) be the two player game in which players alternate removing $a\in A$ stones from a pile with $n$ stones; the first player who cannot move loses. This game has been researched thoroughly. We discuss a variant of NIM in which Player 1 and Player 2 start with d and e dollars, respectively. When a player removes a stones from the pile, he loses a dollars. The first player who cannot move loses, but this can now happen for two reasons: (1) The number of stones remaining is less than min(A), (2) The player has less than min(A) dollars. This game leads to much more interesting win conditions than regular NIM. We investigate general properties of this game. We then obtain and prove win conditions for the sets A={1,L} and $A={1,L,L+1}.
We investigate the strong coupling constants of $D D A$, $D^{*}D^{*}A$ and $D^{*} D A$ vertices in the framework of the light-cone QCD sum rules, where $A$ is an axial vector meson such as $a_1, b_1, K_{1A}, K_{1B}, K_1(1270)$ and $K_1(1400)$. Using the strong coupling constants of $D_s D K_1$, $D_s^* D K_1$ and $D_s^* D^* K_1$ vertices for $K_1(1270)$ and $K_1(1400)$ mesons, we evaluated the branching ratios of the non-leptonic decays $B^0\to {K}_{1}^{+}(1270,1400) \pi^-$. Our results for the branching ratios of these decays are a good agreement with the experimental values.
A topological insulating phase has theoretically been predicted for the thermodynamically unstable perovskite phase of YBiO$_{3}$. Here, it is shown that the crystal structure of the Y-Bi-O system can be controlled by using a BaBiO$_{3}$ buffer layer. The BaBiO$_{3}$ film overcomes the large lattice mismatch of 12% with the SrTiO$_{3}$ substrate by forming a rocksalt structure in between the two perovskite structures. Depositing an YBiO$_{3}$ film directly on a SrTiO$_{3}$ substrate gives a fluorite structure. However, when the Y-Bi-O system is deposited on top of the buffer layer with the correct crystal phase and comparable lattice constant, a single oriented perovskite structure with the expected lattice constants is observed.
Testing theories of hierarchical structure formation requires estimating the distribution of galaxy morphologies and its change with redshift. One aspect of this investigation involves identifying galaxies with disturbed morphologies (e.g., merging galaxies). This is often done by summarizing galaxy images using, e.g., the CAS and Gini-M20 statistics of Conselice (2003) and Lotz et al. (2004), respectively, and associating particular statistic values with disturbance. We introduce three statistics that enhance detection of disturbed morphologies at high-redshift (z ~ 2): the multi-mode (M), intensity (I), and deviation (D) statistics. We show their effectiveness by training a machine-learning classifier, random forest, using 1,639 galaxies observed in the H band by the Hubble Space Telescope WFC3, galaxies that had been previously classified by eye by the CANDELS collaboration (Grogin et al. 2011, Koekemoer et al. 2011). We find that the MID statistics (and the A statistic of Conselice 2003) are the most useful for identifying disturbed morphologies.   We also explore whether human annotators are useful for identifying disturbed morphologies. We demonstrate that they show limited ability to detect disturbance at high redshift, and that increasing their number beyond approximately 10 does not provably yield better classification performance. We propose a simulation-based model-fitting algorithm that mitigates these issues by bypassing annotation.
We study CP asymmetries in penguin-induced b -> s\bar{s}s decays in general left-right models without imposing manifest or pseudomanifest left-right symmetry. Using the effective Hamiltonian approach, we evaluate CP asymmetries in B^\pm -> \phi K^{(\ast)\pm} decays as well as mixing induced B meson decays B -> J/\psi K_s and B -> \phi K_s decays. Based on recent measurements revealing large CP violation, we show that nonmanifest type model is more favored than manifest or pseudomanifest type.
This letter utilizes composite spectral energy distributions (SEDs) constructed from NEWFIRM Medium-Band Survey photometry to constrain the dust attenuation curve in 0.5<z<2.0 galaxies. Based on similarities between the full SED shapes (0.3-8 micron), we have divided galaxies in 32 different spectral classes and stacked their photometry. As each class contains galaxies over a range in redshift, the resulting rest-frame SEDs are well-sampled in wavelength and show various spectral features including Halpha and the UV dust bump at 2175 Angstrom. We fit all composite SEDs with flexible stellar population synthesis models, while exploring attenuation curves with varying slopes and UV bump strengths. The Milky Way and Calzetti law provide poor fits at UV wavelengths for nearly all SEDs. Consistent with previous studies, we find that the best-fit attenuation law varies with spectral type. There is a strong correlation between the best-fit dust slope and UV bump strength, with steeper laws having stronger bumps. Moreover, the attenuation curve correlates with specific star formation rate (SFR), with more active galaxies having shallower dust curves and weaker bumps. There is also a weak correlation with inclination. The observed trends can be explained by differences in the dust-to-star geometry, a varying grain size distribution, or a combination of both. Our results have several implications for galaxy evolution studies. First, the assumption of a universal dust model leads to biases in derived galaxy properties. Second, the presence of a dust bump may result in underestimated values for the UV slope, used to correct SFRs of distant galaxies.
Studies of energetic particle acceleration at collisionless shocks by the diffusive shock acceleration process indicate that completely smooth cosmic ray dominated shock structures are possible. The existence of these is discussed and conditions for their existence derived. It is shown that such solutions cannot dominate the evolution of supernova remnants if the particle diffusion coefficient has the expected strong momentum dependence   To appear in Astronomy and Astrophysics, July 1995, vol 299 pp 222-224
Motivated by the spate of recent experimental and theoretical interest in Mott insulating S=1 triangular lattice magnets, we consider a model S=1 Hamiltonian on a triangular lattice interacting with rotationally symmetric biquadratic interactions. We show that the partition function of this model can be expressed in terms of configurations of three colors of tightly-packed, closed loops with {\em non-negative} weights, which allows for efficient quantum Monte Carlo sampling on large lattices. We find the ground state has spin nematic order, i.e. it spontaneously breaks spin rotation symmetry but preserves time reversal symmetry. We present accurate results for the parameters of the low energy field theory, as well as finite-temperature thermodynamic functions.
Initially defined by the IAU in 1958, the galactic coordinate system was thereafter in 1984 transformed from the B1950.0 FK4-based system to the J2000.0 FK5-based system. In 1994, the IAU recommended that the dynamical reference system FK5 be replaced by the ICRS, which is a kinematical non-rotating system defined by a set of remote radio sources. However the definition of the galactic coordinate system was not updated. We consider that the present galactic coordinates may be problematic due to the unrigorous transformation method from the FK4 to the FK5, and due to the non-inertiality of the FK5 system with respect to the ICRS. This has led to some confusions in applications of the galactic coordinates. We tried to find the transformation matrix in the framework of the ICRS after carefully investigating the definition of the galactic coordinate system and transformation procedures, however we could not find a satisfactory galactic coordinate system that is connected steadily to the ICRS. To avoid unnecessary misunderstandings, we suggest to re-consider the definition of the galactic coordinate system which should be directly connected with the ICRS for high precise observation at micro-arcsecond level.
By analyzing the Chandra archival data of the nearby NGC 6338 galaxy group, we identify two X-ray bright clumps (N-clump and S-clump) within the central 100 kpc, and detect an arc-like X-ray brightness discontinuity at the south boundary of the N-clump, which is defined as a cold front with a gas flow Mach number of M<0.8. Furthermore, at the north-east boundary of the S-clump (dominated by galaxy NGC 6338) another X-ray edge is detected that corresponds to a weaker cold front. Therefore, the two clumps are approaching each other approximately from opposite directions, and the group is undergoing a head-on collision that is in a stage of pre-core passage. This merger scenario is also supported by the study of the line-of-sight velocity distribution of the group member galaxies. The merger mass ratio is about 1:1.8 as estimated from the central gas temperature of the two clumps, which suggests the merger is most likely to be a major merger. We also analyze the VLA 1.4 and 4.9 GHz radio data, but we do not detect any extended radio emission that is associated with the merger.
In order to improve the reverberation-mapping based estimate of the mass of the central supermassive black hole in the Seyfert 1 galaxy NGC 4151, we have reanalyzed archival ultraviolet monitoring spectra from two campaigns undertaken with the International Ultraviolet Explorer. We measure emission-line time delays for four lines, C IV 1549, He II 1640, C III] 1909, and Mg II 2798, from both campaigns. We combine these measurements with the dispersion of the variable part of each respective emission line to obtain the mass of the central object. Despite the problematic nature of some of the data, we are able to measure a mass of 41.1 (+/- 7.3) million solar masses, although this, like all reverberation-based masses, is probably systematically uncertain by a factor of 3-4.
We combine Kepler photometry with ground-based spectra to present a comprehensive dynamical model of the double red giant eclipsing binary KIC 9246715. While the two stars are very similar in mass (M1 = 2.171 [+0.006 / -0.008], M2 = 2.149 [+0.006 / -0.008] Msun) and radius (R1 = 8.37 [+0.03 / -0.07], R2 = 8.30 [+0.04 / -0.03] Rsun), an asteroseismic analysis finds one main set of solar-like oscillations with unusually low-amplitude, wide modes. A second set of oscillations from the other star may exist, but this marginal detection is extremely faint. Because the two stars are nearly twins, KIC 9246715 is a difficult target for a precise test of the asteroseismic scaling relations, which yield M = 2.17 +/- 0.14 Msun and R = 8.26 +/- 0.18 Rsun. Both stars are consistent with the inferred asteroseismic properties, but we suspect the main oscillator is Star 2 because it is less active than Star 1. We find evidence for stellar activity and modest tidal forces acting over the 171-day eccentric orbit, which are likely responsible for the essential lack of solar-like oscillations in one star and weak oscillations in the other. Mixed modes indicate the main oscillating star is on the secondary red clump (a core-He-burning star), and stellar evolution modeling supports this with a coeval history for a pair of red clump stars. This system is a useful case study and paves the way for a detailed analysis of more red giants in eclipsing binaries, an important benchmark for asteroseismology.
Using the interaction $Q \cdot Q ~+~ xV_{S.O.}$ where $V_{S.O.}$ is a two-body spin-orbit interaction, we study the effects of varying x on the static electric quadrupole and magnetic dipole moments of the $2^+_1$ and $2^+_2$ states of $^{10}Be$. This is done both in the valence space $s^4p^6$ and in a larger space in which 2 $\hbar \omega$ excitations are allowed. In the former case, for x=0, we have the Wigner Supermultiplet limit in which the $2^+_1$ and $2^+_2$ states are degenerate and correspond to K=0 and K=2 rotational states, with equal and opposite static quadrupole moments. Turning on the spin-orbit interaction with sufficient strength in the valence space gives an energy splitting to the two $2^+$ states in accord with experiment. When higher shell admixtures are allowed, we get quite a different behaviour as a function of x than in the valence space. Of particular interest is a value of x for which $Q(2^+_1)$ and $Q(2^+_2)$ both nearly vanish, and so does (somewhat coincidentally) $\mu(2^+_1)$.
Many X-ray observations of GigaHertz Peaked Spectrum and Compact Steep Spectrum sources have been made with Chandra X-ray Observatory and XMM-Newton Observatory over the last few years. The X-ray spectra contribute the important information to the total energy distribution of the compact radio sources. In addition the spatial resolution of Chandra allows for studies of the X-ray morphology of these sources on arcsec scales and provide a direct view of their environments. This paper gives a review of the current status of the X-ray observations and their contribution to our understanding of the nature of these compact radio sources. It also describes primary physical processes that lead to the observed X-ray emission and summarize X-ray emission properties expected from interactions between an expanding radio source and the intergalactic environment.
We present our results on multiplicity fluctuations in the framework of the string clustering approach. We compare our results --with and without clustering formation-- with CERN SPS NA49 data. We find a non-monotonic behaviour of these fluctuations as a function of the collision centrality, which has the same origin as the observed fluctuations of transverse momentum: the correlations between the produced particles due to the cluster formation.
We analyze with the Bayesian method the solar and KamLAND neutrino data in terms of neutrino oscillations. We show that Bayesian credible regions with a flat prior in the tan^2(theta12)--(Delta m^2)_21 plane strongly support the LMA solution, in agreement with the usual chi-square analysis. Other reasonable priors are considered in order to test the stability of the LMA solution. We show that priors which favor small or large values of the mixing angle lead to minor changes of the allowed LMA region, affecting mainly its large tan^2(theta12) part.