ALMA Detection of Extended Millimeter Halos in the HD 32297 and HD 61005 Debris Disks. (arXiv:1812.05610v1 [astro-ph.EP]) <a href="">Meredith A. MacGregor</a>, <a href="">Alycia J. Weinberger</a>, <a href="">A. Meredith Hughes</a>, <a href="">D. J. Wilner</a>, <a href="">Thayne Currie</a>, <a href="">John H. Debes</a>, <a href="">Jessica K. Donaldson</a>, <a href="">Seth Redfield</a>, <a href="">Aki Roberge</a>, <a href="">Glenn Schneider</a> We present ALMA 1.3 mm (230 GHz) observations of the HD 32297 and HD 61005 debris disks, two of the most iconic debris disks due to their dramatic swept-back wings seen in scattered light images. These observations achieve sensitivities of 14 and 13 $mu$Jy beam$^{-1}$ for HD 32297 and HD 61005, respectively,Read More →

Galaxy cluster mergers as triggers for the formation of jellyfish galaxies: case study of the A901/2 system. (arXiv:1812.05611v1 [astro-ph.GA]) <a href="">Rafael Ruggiero</a>, <a href="">Rubens E. G. Machado</a>, <a href="">Fernanda V. Roman-Oliveira</a>, <a href="">Ana L. Chies-Santos</a>, <a href="">Gast&#xe3;o B. Lima Neto</a>, <a href="">Lia Doubrawa</a>, <a href="">Bruno Rodr&#xed;guez del Pino</a> The A901/2 system is a rare case of galaxy cluster interaction, in which two galaxy clusters and two smaller groups are seen in route of collision with each other simultaneously. Within each of the four substructures, several galaxies with features indicative of jellyfish morphologies have been observed. In this paper, we propose a hydrodynamic model for theRead More →

A Brief History of the Co-evolution of Supernova Theory with Neutrino Physics. (arXiv:1812.05612v1 [astro-ph.SR]) <a href="">Adam Burrows</a> The histories of core-collapse supernova theory and of neutrino physics have paralleled one another for more than seventy years. Almost every development in neutrino physics necessitated modifications in supernova models. What has emerged is a complex and rich dynamical scenario for stellar death that is being progressively better tested by increasingly sophisiticated computer simulations. Though there is still much to learn about the agency and details of supernova explosions, whatever final theory emerges will have the neutrino at its core. I summarize in this brief contribution some ofRead More →

A conclusive test for star formation prescriptions in cosmological hydrodynamical simulations. (arXiv:1812.05613v1 [astro-ph.GA]) <a href="">Tobias Buck</a> (1,2), <a href="">Aaron A. Dutton</a> (3), <a href="">Andrea V. Macci&#xf2;</a> (3,1) ((1) MPIA, (2) AIP, (3) NYUAD) State-of-the-art cosmological hydrodynamical simulations of galaxy formation have reached the point at which their outcomes result in galaxies with ever more realism. Still, the employed sub-grid models include several free parameters such as the density threshold, $n$, to localize the star-forming gas. In this work, we investigate the possibilities to utilize the observed clustered nature of star formation (SF) in order to refine SF prescriptions and constrain the density threshold parameter. ToRead More →

Detections and Constraints on White Dwarf Variability from Time-Series GALEX Observations. (arXiv:1812.05614v1 [astro-ph.SR]) <a href="">Dominick M. Rowan</a>, <a href="">Michael A. Tucker</a>, <a href="">Benjamin J. Shappee</a>, <a href="">J.J. Hermes</a> We search for photometric variability in more than 23,000 known and candidate white dwarfs, the largest ultraviolet survey compiled for a single study of white dwarfs. We use gPhoton, a publicly available calibration/reduction pipeline, to generate time-series photometry of white dwarfs observed by GALEX. By implementing a system of weighted metrics, we select sources with variability due to pulsations and eclipses. Although GALEX observations have short baselines (< 30 min), we identify intrinsic variability in sources asRead More →

Chaotic Tides in Migrating Gas Giants: Forming Hot and Transient Warm Jupiters via High-Eccentricity Migration. (arXiv:1812.05618v1 [astro-ph.EP]) <a href="">Michelle Vick</a>, <a href="">Dong Lai</a>, <a href="">Kassandra R. Anderson</a> High-eccentricity migration is an important channel for the formation of hot Jupiters (HJs). In particular, Lidov-Kozai (LK) oscillations of orbital eccentricity/inclination induced by a distant planetary or stellar companion, combined with tidal friction, have been shown to produce HJs on Gyr timescales, provided that efficient tidal dissipation operates in the planet. We re-examine this scenario with the inclusion of dynamical tides. When the planet’s orbit is in a high-eccentricity phase, the tidal force from the star excites oscillatoryRead More →

An analytic model for mass transfer in orbits with arbitrary eccentricity, with applications to triple star systems. (arXiv:1812.05624v1 [astro-ph.SR]) <a href="">Adrian S. Hamers</a>, <a href="">Fani Dosopoulou</a> Most studies of mass transfer in binary systems assume circular orbits at the onset of Roche-lobe overflow. However, there are theoretical and observational indications that mass transfer could occur in eccentric orbits. In particular, eccentricity could be produced via sudden mass loss and velocity kicks during supernova explosions, or Lidov-Kozai (LK) oscillations in hierarchical triple systems, or, more generally, secular evolution in multiple-star systems. However, current analytic models of eccentric mass transfer are faced with the problem that theyRead More →

A method to analyse velocity structure. (arXiv:1812.05628v1 [astro-ph.SR]) <a href="">Becky Arnold</a>, <a href="">Simon Goodwin</a> We present a new method of analysing and quantifying velocity structure in star forming regions suitable for the rapidly increasing quantity and quality of stellar position-velocity data. The method can be applied to data in any number of dimensions, does not require the centre or characteristic size (e.g. radius) of the region to be determined, and can be applied to regions with any underlying density and velocity structure. We test the method on a variety of example datasets and show it is robust with realistic observational uncertainties and selection effects. ThisRead More →

OMEGA — OSIRIS Mapping of Emission-line Galaxies in A901/2 — V. The rich population of jellyfish galaxies in the multi-cluster system Abell 901/2. (arXiv:1812.05629v1 [astro-ph.GA]) <a href="">Fernanda V. Roman-Oliveira</a>, <a href="">Ana L. Chies-Santos</a>, <a href="">Bruno Rodr&#xed;guez del Pino</a>, <a href="">A. Arag&#xf3;n-Salamanca</a>, <a href="">Meghan E. Gray</a>, <a href="">Steven P. Bamford</a> We present the results of a systematic search and characterisation of jellyfish galaxy candidates in the multi-cluster system A901/2, at z ~ 0.165, as part of the OMEGA survey. By visual inspecting ACS/HST F606W images looking for morphological signatures of ram-pressure stripping events in Halpha-emitting galaxies, we identify a total of 70 candidates. Out of these,Read More →

Systematic Differences in Spectroscopic Analysis of Red Giants. (arXiv:1812.05630v1 [astro-ph.SR]) <a href="">Ditte Slumstrup</a>, <a href="">Frank Grundahl</a>, <a href="">Victor Silva Aguirre</a>, <a href="">Karsten Brogaard</a> A spectroscopic analysis of stellar spectra can be carried out using different approaches; different methods, line lists, atomic parameters, solar abundances etc. The resulting atmospheric parameters from these choices can vary beyond quoted uncertainties in the literature. Here we characterize these differences by systematically comparing some of the commonly adopted ingredients; line lists, equivalent width measurements and atomic parameters. High resolution and high signal-to-noise spectroscopic data of one helium-core-burning red giant star in each of the three open clusters, NGC6819, M67 andRead More →

A semiclassical path to cosmic large-scale structure. (arXiv:1812.05633v1 [astro-ph.CO]) <a href="">Cora Uhlemann</a>, <a href="">Cornelius Rampf</a>, <a href="">Mateja Gosenca</a>, <a href="">Oliver Hahn</a> We chart a path towards solving for the nonlinear gravitational dynamics of cold dark matter by relying on a semiclassical description using the propagator. The evolution of the propagator is given by a Schr”odinger equation, where the small parameter $hbar$ acts as a softening scale that regulates singularities at shell-crossing. The leading-order propagator, called free propagator, is the semiclassical equivalent of the Zel’dovich approximation (ZA), that describes inertial particle motion along straight trajectories. At next-to-leading order, we solve for the propagator perturbatively and obtainRead More →

Polarized backgrounds of relic gravitons. (arXiv:1812.05635v1 [gr-qc]) <a href="">Massimo Giovannini</a> The polarizations of the tensor modes of the geometry evolving in cosmological backgrounds are treated as the components of a bispinor whose dynamics follows from an appropriate gauge-invariant action. This novel framework bears a close analogy with the (optical) Jones calculus and leads to a compact classification of the various interactions able to polarize the relic gravitons. The polarizations of the tensor modes of the geometry evolving in cosmological backgrounds are treated as the components of a bispinor whose dynamics follows from an appropriate gauge-invariant action. This novel framework bears a close analogy with theRead More →

Accretion Disk Size Measurement and Time Delays in the Lensed Quasar WFI 2033-4723. (arXiv:1812.05639v1 [astro-ph.GA]) <a href="">Christopher W. Morgan</a>, <a href="">Gregory E. Hyer</a>, <a href="">Vivien Bonvin</a>, <a href="">Ana M. Mosquera</a>, <a href="">Matthew Cornachione</a>, <a href="">Frederic Courbin</a>, <a href="">Christopher S. Kochanek</a>, <a href="">Emilio E. Falco</a> We present 13 seasons of $R$-band photometry of the quadruply-lensed quasar WFI 2033-4723 from the 1.3m SMARTS telescope at CTIO and the 1.2m Euler Swiss Telescope at La Silla, in which we detect microlensing variability of $sim0.2$ mags on a timescale of $sim$6 years. Using a Bayesian Monte Carlo technique, we analyze the microlensing signal to obtain a measurement of theRead More →

Characterizing gravito-turbulence in 3D: turbulent properties and stability against fragmentation. (arXiv:1812.05644v1 [astro-ph.EP]) <a href="">Richard A. Booth</a>, <a href="">Cathie J. Clarke</a> We have investigated the properties of gravito-turbulent discs in 3D using high-resolution shearing-box simulations. For large enough domain sizes, $L_y gtrsim 60H$, the disc settles down into a quasi-steady state, showing no long term trends in properties or variation with box size. For smaller boxes, we find that the azimuthal wavelength of the dominant spiral modes are limited to the domain size. This is associated with a bursty behaviour that differs from the quasi-steady dynamics at larger sizes. We point out that a similar transitionRead More →

Hair loss in parity violating gravity. (arXiv:1812.05646v1 [gr-qc]) <a href="">Pratik Wagle</a>, <a href="">Nicolas Yunes</a>, <a href="">David Garfinkle</a>, <a href="">Lydia Bieri</a> The recent detection of gravitational waves by the LIGO/VIRGO collaboration has allowed for the first tests of Einstein’s theory in the extreme gravity regime, where the gravitational interaction is simultaneously strong, non-linear and dynamical. One such test concerns the rate at which the binaries inspiral, or equivalently the rate at which the gravitational wave frequency increases, which can constrain the existence of hairy black holes. This is because black holes with scalar hair typically excite dipole radiation, which in turn leads to a faster decayRead More →

Cascading Constraints from Neutrino Emitting Blazars: The case of TXS 0506+056. (arXiv:1812.05654v1 [astro-ph.HE]) <a href="">Anita Reimer</a>, <a href="">Markus Boettcher</a>, <a href="">Sara Buson</a> We present a procedure to generally constrain the environments of neutrino-producing sites in photomeson production models of jetted Active Galactic Nuclei (AGN) where any origin of the dominant target photon field can be accommodated. For this purpose we reconstruct the minimum target photon spectrum required to produce the (observed) neutrino spectrum, and derive all corresponding secondary particles. These initiate electromagnetic cascades with an efficiency that is linked to the neutrino production rate. The derived photon spectra represent the minimum radiation emerging from theRead More →

The star formation histories of dwarf galaxies in Local Group cosmological simulations. (arXiv:1812.05669v1 [astro-ph.GA]) <a href="">Ruth Digby</a>, <a href="">Julio F. Navarro</a>, <a href="">Azadeh Fattahi</a>, <a href="">Christine M. Simpson</a>, <a href="">Kyle A. Oman</a>, <a href="">Facundo A. Gomez</a>, <a href="">Carlos S. Frenk</a>, <a href="">Robert J. J. Grand</a>, <a href="">Ruediger Pakmor</a> We use the APOSTLE and Auriga cosmological simulations to study the star formation histories (SFHs) of field and satellite dwarf galaxies. Despite sizeable galaxy-to-galaxy scatter, the SFHs of APOSTLE and Auriga dwarfs exhibit robust average trends with galaxy stellar mass: faint field dwarfs ($10^5Read More →

Neutrino damping in a fermion and scalar background. (arXiv:1812.05672v1 [hep-ph]) <a href="">Jos&#xe9; F. Nieves</a>, <a href="">Sarira Sahu</a> We consider the propagation of a neutrino in a background composed of a scalar particle and a fermion using a simple model for the coupling of the form $lambdabar f_Rnu_Lphi$. In the presence of these interactions there can be damping terms in the neutrino effective potential and index of refraction. We calculate the imaginary part of the neutrino self-energy in this case, from which the damping terms are determined. The results are useful in the context of Dark Matter-neutrino interaction models in which the scalar and/or fermion constituteRead More →

KIC 10001893: A pulsating sdB star with multiple trapped modes. (arXiv:1812.05675v1 [astro-ph.SR]) <a href="">M. Uzundag</a>, <a href="">A.S. Baran</a>, <a href="">R.H. &#xd8;stensen</a>, <a href="">M.D. Reed</a>, <a href="">J.H. Telting</a>, <a href="">B.K. Quick</a> KIC 10001893 is a V1093 Her type pulsating subdwarf-B star, which was observed extensively by the Kepler spacecraft. It was a part of the survey searching for compact pulsators in the Kepler field of view. An amplitude spectrum of the star demonstrates a rich content of g-modes between 102 and 496 {mu}Hz as well as a few p-modes above 2000 {mu}Hz. In total, we found 110 frequencies. The g-mode region contains 104 frequencies, while theRead More →

Just discovered! “Farout”, the Farthest Object Ever Seen in the Solar System Astronomers have discovered a distant body that’s more than 100 times farther from the Sun than Earth is. Its provisional designation is 2018 VG18, but they’ve nicknamed the planet “Farout.” Farout is the most distant body ever observed in our Solar System, at 120 astronomical units (AU) away. The International Astronomical Union’s Minor Planet Center … Continue reading “Just discovered! “Farout”, the Farthest Object Ever Seen in the Solar System” The post Just discovered! “Farout”, the Farthest Object Ever Seen in the Solar System appeared first on Universe Today. Universe Today Go toRead More →