Refining MOND interpolating function and TeVeS Lagrangian

The phenomena customly called Dark Matter or Modified Newtonian Dynamics (MOND) have been argued by Bekenstein (2004) to be the consequences of a covariant scalar field, controlled by a free function (related to the MOND interpolating function) in its Lagrangian density. In the context of this relativistic MOND theory (TeVeS), we examine critically the interpolating function in the transition zone between weak and strong gravity. Bekenstein's toy model produces too gradually varying functions and fits rotation curves less well than the standard MOND interpolating function. However, the latter varies too sharply and implies an implausible external field effect (EFE). These constraints on opposite sides have not yet excluded TeVeS, but made the zone of acceptable interpolating functions narrower. An acceptable "toy" Lagrangian density function with simple analytical properties is singled out for future studies of TeVeS in galaxies. We also suggest how to extend the model to solar system dynamics and cosmology, and compare with strong lensing data (see also astro-ph/0509590).Comment: accepted for publication in ApJ Letter

Cyclosporin A in skin samples from in vitro penetration studies may be assayed by a simple HPLC method

Neste estudo foi desenvolvido um método simples utilizando Cromatografia Líquida de Alta Eficiência (CLAE) com detecção no UV para quantificação de Ciclosporina A (CysA) em amostras de pele após estudos de penetração cutânea in vitro. O peptídeo foi extraído do estrato córneo e da epiderme sem estrato córneo + derme ([E+D]) através de agitação em vórtex e sonicação utilizando um solvente extrator (metanol). A recuperação da CysA de ambas as camadas da pele foi de 85%, conforme estimado por CLAE utilizando coluna RP-18, detecção em 210 nm e fase móvel composta de acetonitrila e água (67:33, v/v). O limite de quantificação do peptídeo utilizando este método cromatográfico foi de 150 ng/mL. O método mostrou-se linear na faixa de 0,15-500 mig/mL. A precisão e exatidão intra e inter-ensaio foram avaliadas utilizando três concentrações distintas (1, 10 e 20 mig/mL). Os valores de coeficiente de variação e o desvio do valor teórico foram inferiores a 5%. O método descrito pode ser utilizado para determinação da CysA após estudos de penetração cutânea in vitro utilizando pele de porco como modelo de membranaA simple High Performance Liquid Chromatographic method with UV detection was developed for quantification of Cyclosporin A (CysA) in skin samples after in vitro penetration studies. The peptide was recovered from two different layers of skin, the stratum corneum and the epidermis plus dermis ([E+D]), by vortex homogenization and bath sonication in an organic solvent (methanol). Recovery of CysA from skin was about 85%, and CysA was estimated by HPLC using a RP-18 column, UV detection at 210 nm and acetonitrile:water (67:33 v/v) as the mobile phase. The quantification limit was 150ng/mL. The assay was linear from 0.15-500 mg/muL. The within-day and between-day assay precision and accuracy were studied at three concentration levels (1, 10 and 20 mug/mL). The coefficients of variation and deviation from the theoretical values were lower than 5%. The method described has a potential application to in vitro penetration studies of CysA using porcine skin as a biological membrane model

The canonical 8-form on manifolds with holonomy group Spin(9)

An explicit expression of the canonical 8-form on a Riemannian manifold with a Spin(9)-structure, in terms of the nine local symmetric involutions involved, is given. The list of explicit expressions of all the canonical forms related to Berger's list of holonomy groups is thus completed. Moreover, some results on Spin(9)-structures as G-structures defined by a tensor and on the curvature tensor of the Cayley planes, are obtained

First Results from the KMOS Lens-Amplified Spectroscopic Survey (KLASS): Kinematics of Lensed Galaxies at Cosmic Noon

We present the first results of the KMOS Lens-Amplified Spectroscopic Survey (KLASS), a new ESO Very Large Telescope (VLT) large program, doing multi-object integral field spectroscopy of galaxies gravitationally lensed behind seven galaxy clusters selected from the HST Grism Lens-Amplified Survey from Space (GLASS). Using the power of the cluster magnification we are able to reveal the kinematic structure of 25 galaxies at $0.7 \lesssim z \lesssim 2.3$, in four cluster fields, with stellar masses $8 \lesssim \log{(M_\star/M_\odot)} \lesssim 11$. This sample includes 5 sources at $z>1$ with lower stellar masses than in any previous kinematic IFU surveys. Our sample displays a diversity in kinematic structure over this mass and redshift range. The majority of our kinematically resolved sample is rotationally supported, but with a lower ratio of rotational velocity to velocity dispersion than in the local universe, indicating the fraction of dynamically hot disks changes with cosmic time. We find no galaxies with stellar mass $<3 \times 10^9 M_\odot$ in our sample display regular ordered rotation. Using the enhanced spatial resolution from lensing, we resolve a lower number of dispersion dominated systems compared to field surveys, competitive with findings from surveys using adaptive optics. We find that the KMOS IFUs recover emission line flux from HST grism-selected objects more faithfully than slit spectrographs. With artificial slits we estimate slit spectrographs miss on average 60% of the total flux of emission lines, which decreases rapidly if the emission line is spatially offset from the continuum.Comment: Accepted for publication in Ap

A QUMOND galactic N-body code I: Poisson solver and rotation curve fitting

Here we present a new particle-mesh galactic N-body code that uses the full multigrid algorithm for solving the modified Poisson equation of the Quasi Linear formulation of Modified Newtonian Dynamics (QUMOND). A novel approach for handling the boundary conditions using a refinement strategy is implemented and the accuracy of the code is compared with analytical solutions of Kuzmin disks. We then employ the code to compute the predicted rotation curves for a sample of five spiral galaxies from the THINGS sample. We generated static N-body realisations of the galaxies according to their stellar and gaseous surface densities and allowed their distances, mass-to-light ratios (M/L) and both the stellar and gas scale-heights to vary in order to estimate the best fit parameters. We found that NGC 3621, NGC 3521 and DDO 154 are well fit by MOND using expected values of the distance and M/L. NGC 2403 required a moderately larger $M/L$ than expected and NGC 2903 required a substantially larger value. The surprising result was that the scale-height of the dominant baryonic component was well constrained by the rotation curves: the gas scale-height for DDO 154 and the stellar scale-height for the others. In fact, if the suggested stellar scale-height (one-fifth the stellar scale-length) was used in the case of NGC 3621 and NGC 3521 it would not be possible to produce a good fit to the inner rotation curve. For each of the four stellar dominated galaxies, we calculated the vertical velocity dispersions which we found to be, on the whole, quite typical compared with observed stellar vertical velocity dispersions of face on spirals. We conclude that modelling the gas scale-heights of the gas rich dwarf spiral galaxies will be vital in order to make precise conclusions about MOND.Comment: 14 pages, 11 figures, MNRAS in pres

Can MOND take a bullet? Analytical comparisons of three versions of MOND beyond spherical symmetry

A proper test of Modified Newtonian Dynamics (MOND) in systems of non-trivial geometries depends on modelling subtle differences in several versions of its postulated theories. This is especially important for lensing and dynamics of barely virialised galaxy clusters with typical gravity of scale $\sim a_0 \sim 1\AA{\rm s}^{-2}$. The original MOND formula, the classical single field modification of the Poisson equation, and the multi-field general relativistic theory of Bekenstein (TeVeS) all lead to different predictions as we stray from spherical symmetry. In this paper, we study a class of analytical MONDian models for a system with a semi-Hernquist baryonic profile. After presenting the analytical distribution function of the baryons in spherical limits, we develop orbits and gravitational lensing of the models in non-spherical geometries. In particular, we can generate a multi-centred baryonic system with a weak lensing signal resembling that of the merging galaxy cluster 1E 0657-56 with a bullet-like light distribution. We finally present analytical scale-free highly non-spherical models to show the subtle differences between the single field classical MOND theory and the multi-field TeVeS theory.Comment: 14 pages, 9 figures, accepted for publication in MNRA

Milky Way Mass Models and MOND

Using the Tuorla-Heidelberg model for the mass distribution of the Milky Way, I determine the rotation curve predicted by MOND. The result is in good agreement with the observed terminal velocities interior to the solar radius and with estimates of the Galaxy's rotation curve exterior thereto. There are no fit parameters: given the mass distribution, MOND provides a good match to the rotation curve. The Tuorla-Heidelberg model does allow for a variety of exponential scale lengths; MOND prefers short scale lengths in the range 2.0 to 2.5 kpc. The favored value of scale length depends somewhat on the choice of interpolation function. There is some preference for the `simple' interpolation function as found by Famaey & Binney. I introduce an interpolation function that shares the advantages of the simple function on galaxy scales while having a much smaller impact in the solar system. I also solve the inverse problem, inferring the surface mass density distribution of the Milky Way from the terminal velocities. The result is a Galaxy with `bumps and wiggles' in both its luminosity profile and rotation curve that are reminiscent of those frequently observed in external galaxies.Comment: Accepted for publication in the Astrophysical Journal. 31 pages including 8 figures and 3 table

MOND and the Universal Rotation Curve: similar phenomenologies

The Modified Newtonian Dynamics (MOND) and the Universal Rotation Curve (URC) are two ways to describe the general properties of rotation curves, with very different approaches concerning dark matter and gravity. Phenomenological similarities between the two approaches are studied by looking for properties predicted in one framework that are also reproducible in the other one. First, we looked for the analogous of the URC within the MOND framework. Modifying in an observationally-based way the baryonic contribution Vbar to the rotation curve predicted by the URC, and applying the MOND formulas to this Vbar, leads to a "MOND URC" whose properties are remarkably similar to the URC. Second, it is shown that the URC predicts a tight mass discrepancy - acceleration relation, which is a natural outcome of MOND. With the choice of Vbar that minimises the differences between the URC and the "MOND URC" the relation is almost identical to the observational one. This similarity between the observational properties of MOND and the URC has no implications about the validity of MOND as a theory of gravity, but it shows that it can reproduce in detail the phenomenology of disk galaxies' rotation curves, as described by the URC. MOND and the URC, even though they are based on totally different assumptions, are found to have very similar behaviours and to be able to reproduce each other's properties fairly well, even with the simple assumptions made on the luminosity dependence of the baryonic contribution to the rotation curve.Comment: Accepted for publication in ApJ. 8 pages, 5 figure

Constraining Lyman-alpha spatial offsets at 3<z<5.53<z<5.5 from VANDELS slit spectroscopy

We constrain the distribution of spatially offset Lyman-alpha emission (Ly$\alpha$) relative to rest-frame ultraviolet emission in $\sim300$ high redshift ($3<z<5.5$) Lyman-break galaxies (LBGs) exhibiting Ly$\alpha$ emission from VANDELS, a VLT/VIMOS slit-spectroscopic survey of the CANDELS Ultra Deep Survey and Chandra Deep Field South fields (${\simeq0.2}~\mathrm{deg}^2$ total). Because slit spectroscopy compresses two-dimensional spatial information into one spatial dimension, we use Bayesian inference to recover the underlying Ly$\alpha$ spatial offset distribution. We model the distribution using a 2D circular Gaussian, defined by a single parameter $\sigma_{r,\mathrm{Ly}\alpha}$, the standard deviation expressed in polar coordinates. Over the entire redshift range of our sample ($3<z<5.5$), we find $\sigma_{r,\mathrm{Ly}\alpha}=1.70^{+0.09}_{-0.08}$ kpc ($68\%$ conf.), corresponding to $\sim0.25$ arcsec at $\langle z\rangle=4.5$. We also find that $\sigma_{r,\mathrm{Ly}\alpha}$ decreases significantly with redshift. Because Ly$\alpha$ spatial offsets can cause slit-losses, the decrease in $\sigma_{r,\mathrm{Ly}\alpha}$ with redshift can partially explain the increase in the fraction of Ly$\alpha$ emitters observed in the literature over this same interval, although uncertainties are still too large to reach a strong conclusion. If $\sigma_{r,\mathrm{Ly}\alpha}$ continues to decrease into the reionization epoch, then the decrease in Ly$\alpha$ transmission from galaxies observed during this epoch might require an even higher neutral hydrogen fraction than what is currently inferred. Conversely, if spatial offsets increase with the increasing opacity of the IGM, slit losses may explain some of the drop in Ly$\alpha$ transmission observed at $z>6$. Spatially resolved observations of Ly$\alpha$ and UV continuum at $6<z<8$ are needed to settle the issue.Comment: Submitted to MNRA