RAS_WEB (Page 4,570)

Atomic source selection in space-borne gravitational wave detection. (arXiv:1812.11348v1 [physics.atom-ph]) <a href="http://arxiv.org/find/physics/1/au:+Loriani_S/0/1/0/all/0/1">S Loriani</a>, <a href="http://arxiv.org/find/physics/1/au:+Schlippert_D/0/1/0/all/0/1">D Schlippert</a>, <a href="http://arxiv.org/find/physics/1/au:+Schubert_C/0/1/0/all/0/1">C Schubert</a>, <a href="http://arxiv.org/find/physics/1/au:+Abend_S/0/1/0/all/0/1">S Abend</a>, <a href="http://arxiv.org/find/physics/1/au:+Ahlers_H/0/1/0/all/0/1">H Ahlers</a>, <a href="http://arxiv.org/find/physics/1/au:+Ertmer_W/0/1/0/all/0/1">W Ertmer</a>, <a href="http://arxiv.org/find/physics/1/au:+Rudolph_J/0/1/0/all/0/1">J Rudolph</a>, <a href="http://arxiv.org/find/physics/1/au:+Hogan_J/0/1/0/all/0/1">J M Hogan</a>, <a href="http://arxiv.org/find/physics/1/au:+Kasevich_M/0/1/0/all/0/1">M A Kasevich</a>, <a href="http://arxiv.org/find/physics/1/au:+Rasel_E/0/1/0/all/0/1">E M Rasel</a>, <a href="http://arxiv.org/find/physics/1/au:+Gaaloul_N/0/1/0/all/0/1">N Gaaloul</a> Recent proposals for space-borne gravitational wave detectors based on atom interferometry rely on extremely narrow single-photon transition lines as featured by alkaline-earth metals or atomic species with similar electronic configuration. Despite their similarity, these species differ in key parameters such as abundance of isotopes, atomic flux, density and temperature regimes, achievable expansion rates, density limitations set by interactions, asRead More →

JVLA overview of the bursting H$_2$O maser source G25.65+1.05. (arXiv:1812.11353v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Bayandina_O/0/1/0/all/0/1">O. S. Bayandina</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Burns_R/0/1/0/all/0/1">R. A. Burns</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kurtz_S/0/1/0/all/0/1">S. E. Kurtz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shakhvorostova_N/0/1/0/all/0/1">N. N. Shakhvorostova</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Valtts_I/0/1/0/all/0/1">I. E. Val&#x27;tts</a> The source G25.65+1.05 (RAFGL7009S, IRAS 18316-0602) is the least studied of the three regions of massive star formation known to show exceptionally powerful H$_2$O maser bursts. We report spectral line observations of the H$_2$O maser at 22 GHz, the methanol maser transitions at 6.7, 12.2 and 44 GHz, and the continuum in these same frequency bands with The Karl G. Jansky Very Large Array (JVLA) at the post-burst epoch of 2017. For the firstRead More →

On the Possibility of Generating Harmonics of the Electron Plasma Frequency in the Solar Atmosphere due to Explosive Instability in a System of Interpenetrating Electron and Ion Flows. (arXiv:1812.11397v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Fomichev_V/0/1/0/all/0/1">V. V. Fomichev</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fainshtein_S/0/1/0/all/0/1">S. M. Fainshtein</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chernov_G/0/1/0/all/0/1">G. P. Chernov</a> An alternative mechanism is proposed for the generation of harmonics of the electron plasma frequency due to the development of explosive instability in a system of interpenetrating electron and proton flows in the solar atmosphere. The efficiency of the new mechanism in comparison with the earlier discussed mechanisms involving multistage processes of nonlinear interaction of waves in plasma is determined. It is shownRead More →

A wide-area photometric and astrometric (Gaia DR2) study of the young cluster NGC 6530. (arXiv:1812.11402v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Damiani_F/0/1/0/all/0/1">F.Damiani</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Prisinzano_L/0/1/0/all/0/1">L.Prisinzano</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Micela_G/0/1/0/all/0/1">G.Micela</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sciortino_S/0/1/0/all/0/1">S.Sciortino</a> (abridged) NGC6530 is a young cluster with a complex morphology and star-formation history. We present a statistical study of its global properties using a new large list of candidate members down to masses of 0.2-0.4 Msun and Gaia DR2 astrometry. We consider a wider sky region compared to previous studies, to investigate the whole cluster and its neighborhood. We study the distribution of extinction and age across the different regions, and obtain constraints on the star-formation history. Cluster membership is determinedRead More →

The effect of adiabatic losses on spectra of stationary jets and the origin of soft radio spectra of accreting black-hole sources. (arXiv:1812.11410v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Zdziarski_A/0/1/0/all/0/1">Andrzej A. Zdziarski</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Stawarz_L/0/1/0/all/0/1">Lukasz Stawarz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sikora_M/0/1/0/all/0/1">Marek Sikora</a> It has been suggested that adiabatic energy losses are not effective in stationary jets, where the jet expansion is not associated with net work. Here, we study jet solutions without them, assuming that adiabatic losses are balanced by electron reacceleration. The absence of effective adiabatic losses makes electron advection along the jet an important process, and we solve the electron kinetic equation including that process. We find analytical solutions for the caseRead More →

Boosting Assisted Annihilation for a Cosmologically Safe MeV Scale Dark Matter. (arXiv:1812.11418v1 [hep-ph]) <a href="http://arxiv.org/find/hep-ph/1/au:+Dey_U/0/1/0/all/0/1">Ujjal Kumar Dey</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Maity_T/0/1/0/all/0/1">Tarak Nath Maity</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Ray_T/0/1/0/all/0/1">Tirtha Sankar Ray</a> Assisted annihilation generates thermal sub-GeV dark matter through a novel annihilation between a pair of dark matter and one or more SM-like states, called the textit{assisters}. We show that depending on the mass hierarchy between the assister and dark matter there can be either a suppression or a boost from the Boltzmann factor in the effective cross section. This augmentation enables the possibility of MeV scale thermal dark matter with perturbative coupling that saturate the relic density estimates while beingRead More →

Condensation of SiC Stardust in CO Nova Outbursts. (arXiv:1812.11432v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Bose_M/0/1/0/all/0/1">Maitrayee Bose</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Starrfield_S/0/1/0/all/0/1">Sumner Starrfield</a> This study on presolar grains compares high-precision isotopic compositions of individual SiC grains with low 12C/13C ratios, low 14N/15N ratios, large 30Si excesses and high 26Al/27Al ratios, available in the presolar grain database, to new CO nova models with white dwarf (WD) masses from 0.6-1.35M_sol. The models were designed to match the Large Binocular Telescope (LBT) high dispersion spectra acquired for nova V5668 Sgr (Starrfield et al. 2018). These CO nova models provide elemental abundances up to calcium and include mixing of WD material into the accreted material inRead More →

Examining MAVEN NGIMS Neutral Data Response to Solar Wind Drivers. (arXiv:1812.11434v1 [astro-ph.EP]) <a href="http://arxiv.org/find/astro-ph/1/au:+Williamson_H/0/1/0/all/0/1">H.N. Williamson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Elrod_M/0/1/0/all/0/1">M.K. Elrod</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Curry_S/0/1/0/all/0/1">S.M. Curry</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Johnson_R/0/1/0/all/0/1">R.E. Johnson</a> The Martian upper atmosphere is known to vary diurnally and seasonally due to changing amounts of solar radiation. However, in the upper thermosphere and exosphere, the neutrals are also subject to ion precipitation. This can increase the temperature in the region of precipitation, resulting in density changes that might be seen in in situ data (Fang et al. 2013). Therefore, we examine neutral density data from the MAVEN Neutral Gas and Ion Mass Spectrometer (NGIMS) in Mars-Solar-Electric (MSE) coordinates, where locationRead More →

On the magnetisation and the radiative efficiency of BL Lac jets. (arXiv:1812.11435v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Sobacchi_E/0/1/0/all/0/1">E. Sobacchi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lyubarsky_Y/0/1/0/all/0/1">Y.E. Lyubarsky</a> Theoretical modelling and observations of AGN jets suggest that the non-thermal electrons emitting the observed radiation should (i) carry an amount of energy comparable to the magnetic fields ($U_esim U_B$), which is likely the case if the magnetic fields play a dynamically important role in the jet’s acceleration process; (ii) cool efficiently in a dynamical time ($t_{rm cool}lesssim t_{rm dyn}$), which is suggested by the fact that a large fraction of the jet’s kinetic energy is promptly converted into radiation. These expectations are at odds withRead More →

Time Evolution of 3D Disk Formation with Misaligned Magnetic Field and Rotation Axes. (arXiv:1812.11471v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Vaisala_M/0/1/0/all/0/1">Miikka S. V&#xe4;is&#xe4;l&#xe4;</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shang_H/0/1/0/all/0/1">Hsien Shang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Krasnopolsky_R/0/1/0/all/0/1">Ruben Krasnopolsky</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Liu_S/0/1/0/all/0/1">Sheng-Yuan Liu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lam_K/0/1/0/all/0/1">Ka Ho Lam</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Li_Z/0/1/0/all/0/1">Zhi-Yun Li</a> Distinguishing diagnostic observational signatures produced by MHD models is essential in understanding the physics for the formation of protostellar disks in the ALMA era. Developing suitable tools along with time evolution will facilitate better identification of diagnostic features. With a ray-tracing based radiative transfer code Perspective, we explore time evolution of MHD models carried out in Li, Krasnopolsky & Shang (2013) – most of which have $90^circ$ misalignment between theRead More →

Constraining the magnetic field on white dwarf surfaces; Zeeman effects and fine structure constant variation. (arXiv:1812.11480v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Hu_J/0/1/0/all/0/1">J. Hu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Webb_J/0/1/0/all/0/1">J. K. Webb</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ayres_T/0/1/0/all/0/1">T. R. Ayres</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bainbridge_M/0/1/0/all/0/1">M. B. Bainbridge</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Barrow_J/0/1/0/all/0/1">J. D. Barrow</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Barstow_M/0/1/0/all/0/1">M. A. Barstow</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Berengut_J/0/1/0/all/0/1">J. C. Berengut</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Carswell_R/0/1/0/all/0/1">R.F. Carswell</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dzuba_V/0/1/0/all/0/1">V. A. Dzuba</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Flambaum_V/0/1/0/all/0/1">V. V. Flambaum</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Holberg_J/0/1/0/all/0/1">J. B. Holberg</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lee_C/0/1/0/all/0/1">C. C. Lee</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Preval_S/0/1/0/all/0/1">S. P. Preval</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Reindl_N/0/1/0/all/0/1">N. Reindl</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tchang_Brillet_W/0/1/0/all/0/1">W.-&#xdc; L. Tchang-Brillet</a> White dwarf atmospheres are subjected to gravitational potentials around $10^5$ times larger than occur on Earth. They provide a unique environment in which to search for any possible variation in fundamentalRead More →

Probing the Running of Primordial Bispectrum and Trispectrum using CMB Spectral Distortions. (arXiv:1812.11486v1 [astro-ph.CO]) <a href="http://arxiv.org/find/astro-ph/1/au:+Emami_R/0/1/0/all/0/1">Razieh Emami</a> (Harvard University) We compute the impact of the running of higher order density correlation functions on the two point functions of CMB spectral distortions (SD). We show that having some levels of running enhances all of the SDs by few orders of magnitude which might make them easier to detect. Taking a reasonable range for $ |n_{f_{NL}}|< 1.5$ and with $f_{NL} = 5$ we show that for PIXIE like experiment, the signal to noise ratio, $(S/N)_{i}$, enhances to $lesssim 10^4$ and $lesssim 30$ for $mu T$ and $yT$Read More →

Cancellation of Small-Scale Magnetic Features. (arXiv:1812.11496v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Kaithakkal_A/0/1/0/all/0/1">Anjali J. Kaithakkal</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Solanki_S/0/1/0/all/0/1">Sami K. Solanki</a> We investigate small-scale flux cancellations in a young active region observed with the high-resolution imaging magnetograph IMaX on the Sunrise balloon-borne solar observatory. We identified 11 opposite-polarity cancelling pairs using an automatic detection code, and derived their statistical properties.We classified the cancellations into two groups. Class I events are those for which cancellation happens between a pre-existing large magnetic feature of one polarity and a smaller feature of the other polarity that emerged/appeared nearby. For Class II events cancellations occur between two pre-existing, previously unconnected features that converge toward eachRead More →

A Model-Independent Mass and Moderate Eccentricity for $beta$ Pic b. (arXiv:1812.11530v1 [astro-ph.EP]) <a href="http://arxiv.org/find/astro-ph/1/au:+Dupuy_T/0/1/0/all/0/1">Trent J. Dupuy</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brandt_T/0/1/0/all/0/1">Timothy D. Brandt</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kratter_K/0/1/0/all/0/1">Kaitlin M. Kratter</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bowler_B/0/1/0/all/0/1">Brendan P. Bowler</a> We use a cross-calibration of Hipparcos and Gaia DR2 astrometry for $beta$ Pic to measure the mass of the giant planet $beta$ Pic b $(13pm3$ $M_{rm Jup})$ in a comprehensive joint orbit analysis that includes published relative astrometry and radial velocities. Our mass uncertainty is somewhat higher than previous work because our astrometry from the Hipparcos-Gaia Catalog of Accelerations accounts for the error inflation and systematic terms that are required to bring the two data sets ontoRead More →

Weak field limit and gravitational waves in higher-order gravity. (arXiv:1812.11557v1 [gr-qc]) <a href="http://arxiv.org/find/gr-qc/1/au:+Capozziello_S/0/1/0/all/0/1">Salvatore Capozziello</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Capriolo_M/0/1/0/all/0/1">Maurizio Capriolo</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Caso_L/0/1/0/all/0/1">Loredana Caso</a> We derive the weak field limit for a gravitational Lagrangian density $L_{g}=(R+a_{0}R^{2}+sum_{k=1}^{p} a_{k}RBox^{k}R)sqrt{-g}$ where higher-order derivative terms in the Ricci scalar $R$ are taken into account. The interest for this kind of effective theories comes out from the consideration of the infrared and ultraviolet behaviors of gravitational field and, in general, from the formulation of quantum field theory in curved spacetimes. Here, we obtain solutions in weak field regime both in vacuum and in the presence of matter and derive gravitational waves considering the contributionRead More →

Space Telescope and Optical Reverberation Mapping Project. X. The Hidden Life of “the Obscurer” in NGC 5548 and Understanding the Absorption-Line Holiday. (arXiv:1812.11578v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Dehghanian_M/0/1/0/all/0/1">M. Dehghanian</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ferland_G/0/1/0/all/0/1">G. J. Ferland</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kriss_G/0/1/0/all/0/1">G. A. Kriss</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Peterson_B/0/1/0/all/0/1">B. M. Peterson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mathur_S/0/1/0/all/0/1">S. Mathur</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mehdipour_M/0/1/0/all/0/1">M. Mehdipour</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Guzman_F/0/1/0/all/0/1">F. Guzman</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chatzikos_M/0/1/0/all/0/1">M. Chatzikos</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hoof_P/0/1/0/all/0/1">P. A. M. Van Hoof</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Williams_R/0/1/0/all/0/1">R. J. R. Williams</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Arav_N/0/1/0/all/0/1">N. Arav</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Barth_A/0/1/0/all/0/1">A. J. Barth</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bentz_M/0/1/0/all/0/1">M. C. Bentz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bisogni_S/0/1/0/all/0/1">S. Bisogni</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brandt_W/0/1/0/all/0/1">W. N. Brandt</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Crenshaw_D/0/1/0/all/0/1">D. M. Crenshaw</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bonta_E/0/1/0/all/0/1">E. Dalla Bonta</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rosa_G/0/1/0/all/0/1">G. De Rosa</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fausnaugh_M/0/1/0/all/0/1">M. M. Fausnaugh</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gelbord_J/0/1/0/all/0/1">J. M. Gelbord</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Goad_M/0/1/0/all/0/1">M. R. Goad</a>, <aRead More →

The NANOGrav 11-Year Data Set: Limits on Gravitational Waves from Individual Supermassive Black Hole Binaries. (arXiv:1812.11585v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Aggarwal_K/0/1/0/all/0/1">K. Aggarwal</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Arzoumanian_Z/0/1/0/all/0/1">Z. Arzoumanian</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Baker_P/0/1/0/all/0/1">P. T. Baker</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brazier_A/0/1/0/all/0/1">A. Brazier</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brinson_M/0/1/0/all/0/1">M. R. Brinson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brook_P/0/1/0/all/0/1">P. R. Brook</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Burke_Spolaor_S/0/1/0/all/0/1">S. Burke-Spolaor</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chatterjee_S/0/1/0/all/0/1">S. Chatterjee</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cordes_J/0/1/0/all/0/1">J. M. Cordes</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cornish_N/0/1/0/all/0/1">N. J. Cornish</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Crawford_F/0/1/0/all/0/1">F. Crawford</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Crowter_K/0/1/0/all/0/1">K. Crowter</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cromartie_T/0/1/0/all/0/1">T. Cromartie</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+DeCesar_M/0/1/0/all/0/1">M. DeCesar</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Demorest_P/0/1/0/all/0/1">P. B. Demorest</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dolch_T/0/1/0/all/0/1">T. Dolch</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ellis_J/0/1/0/all/0/1">J. A. Ellis</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ferdman_R/0/1/0/all/0/1">R. D. Ferdman</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ferrara_E/0/1/0/all/0/1">E. Ferrara</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fonseca_E/0/1/0/all/0/1">E. Fonseca</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Garver_Daniels_N/0/1/0/all/0/1">N. Garver-Daniels</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gentile_P/0/1/0/all/0/1">P. Gentile</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hazboun_J/0/1/0/all/0/1">J. S. Hazboun</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Holgado_A/0/1/0/all/0/1">A. M. Holgado</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Huerta_E/0/1/0/all/0/1">E. A. Huerta</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Islo_K/0/1/0/all/0/1">K.Read More →

Relatively complicated? Using models to teach general relativity at different levels. (arXiv:1812.11589v1 [gr-qc]) <a href="http://arxiv.org/find/gr-qc/1/au:+Possel_M/0/1/0/all/0/1">Markus P&#xf6;ssel</a> This review presents an overview of various kinds of models — physical, abstract, mathematical, visual — that can be used to present the concepts and applications of Einstein’s general theory of relativity at the level of undergraduate and even high-school teaching. After a general introduction dealing with various kinds of models and their properties, specific areas of general relativity are addressed: the elastic sheet model and other models for the fundamental geometric properties of gravity, models for black holes including the river model, cosmological models for an expanding universe,Read More →

Relaxation of structures resulting from head-on mergers of ultralight bosonic dark matter cores. (arXiv:1812.11608v1 [astro-ph.CO]) <a href="http://arxiv.org/find/astro-ph/1/au:+Avilez_Lopez_A/0/1/0/all/0/1">Ana Avilez-Lopez</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Guzman_F/0/1/0/all/0/1">F. S. Guzman</a> In this work we study some features of head-on mergers of equilibrium solutions of the Gross-Pitaevskii-Poisson system that rules the dynamics of the ultralight bosonic dark matter model. The importance of equilibrium solutions is that they play the role of halo cores in structure formation simulations. We consider a given range of initial conditions in order to sample the parameter space in terms of mass ratio and head-on momentum. In each case we analyze the relaxation process induced by gravitational cooling in theRead More →