2021-$H_0$ Odyssey: Closed, Phantom and Interacting Dark Energy Cosmologies. (arXiv:2101.03129v1 [astro-ph.CO]) <a href="http://arxiv.org/find/astro-ph/1/au:+Yang_W/0/1/0/all/0/1">Weiqiang Yang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pan_S/0/1/0/all/0/1">Supriya Pan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Valentino_E/0/1/0/all/0/1">Eleonora Di Valentino</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mena_O/0/1/0/all/0/1">Olga Mena</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Melchiorri_A/0/1/0/all/0/1">Alessandro Melchiorri</a> Up-to-date cosmological data analyses have shown that textit{(a)} a closed universe is preferred by the Planck data at more than $99%$ CL, and textit{(b)} interacting scenarios offer a very compelling solution to the Hubble constant tension. In light of these two recent appealing scenarios, we consider here an interacting dark matter-dark energy model with a non-zero spatial curvature component and a freely varying dark energy equation of state in both the quintessential and phantom regimes. When considering CosmicRead More →

Cosmological Tension of Ultralight Axion Dark Matter and its Solutions. (arXiv:2008.02279v2 [hep-ph] UPDATED) <a href="http://arxiv.org/find/hep-ph/1/au:+Dror_J/0/1/0/all/0/1">Jeff A. Dror</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Leedom_J/0/1/0/all/0/1">Jacob M. Leedom</a> A number of proposed and ongoing experiments search for axion dark matter with a mass nearing the limit set by small scale structure (${cal O} ( 10 ^{ – 21 } {rm eV} ) $). We consider the late universe cosmology of these models, showing that requiring the axion to have a matter-power spectrum that matches that of cold dark matter constrains the magnitude of the axion couplings to the visible sector. Comparing these limits to current and future experimental efforts, we find thatRead More →

Finite System-Size Effects in Self-Organized Criticality Systems. (arXiv:2101.03124v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Aschwanden_M/0/1/0/all/0/1">Markus J. Aschwanden</a> We explore upper limits for the largest avalanches or catastrophes in nonlinear energy dissipation systems governed by self-organized criticality (SOC). We generalize the idealized “straight” power low size distribution and Pareto distribution functions in order to accomodate for incomplete sampling, limited instrumental sensitivity, finite system-size effects, “Black-Swan” and “Dragon-King” extreme events. Our findings are: (i) Solar flares show no finite system-size limits up to L < 200 Mm, but solar flare durations reveal an upper flare duration limit of < 6 hrs; (ii) Stellar flares observed with KEPLER exhibit inertial ranges ofRead More →

Solar wind energy flux observations in the inner heliosphere: First results from Parker Solar Probe. (arXiv:2101.03121v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Liu_M/0/1/0/all/0/1">M. Liu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Issautier_K/0/1/0/all/0/1">K. Issautier</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Meyer_Vernet_N/0/1/0/all/0/1">N. Meyer-Vernet</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Moncuquet_M/0/1/0/all/0/1">M. Moncuquet</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Maksimovic_M/0/1/0/all/0/1">M. Maksimovic</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Halekas_J/0/1/0/all/0/1">J. S. Halekas</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Huang_J/0/1/0/all/0/1">J. Huang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Griton_L/0/1/0/all/0/1">L. Griton</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bale_S/0/1/0/all/0/1">S. Bale</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bonnell_J/0/1/0/all/0/1">J. W. Bonnell</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Case_A/0/1/0/all/0/1">A. W. Case</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Goetz_K/0/1/0/all/0/1">K. Goetz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Harvey_P/0/1/0/all/0/1">P. R. Harvey</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kasper_J/0/1/0/all/0/1">J. C. Kasper</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+MacDowall_R/0/1/0/all/0/1">R. J. MacDowall</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Malaspina_D/0/1/0/all/0/1">D. M. Malaspina</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pulupa_M/0/1/0/all/0/1">M. Pulupa</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Stevens_M/0/1/0/all/0/1">M. L. Stevens</a> We investigate the solar wind energy flux in the inner heliosphere using 12-day observations around each perihelion of Encounter One (E01), Two (E02), Four (E04), andRead More →

AMEGO: Exploring the Extreme Multimessenger Universe. (arXiv:2101.03105v1 [astro-ph.IM]) <a href="http://arxiv.org/find/astro-ph/1/au:+Kierans_C/0/1/0/all/0/1">Carolyn A. Kierans</a>, the <a href="http://arxiv.org/find/astro-ph/1/au:+Team_AMEGO/0/1/0/all/0/1">AMEGO Team</a> The All-sky Medium Energy Gamma-ray Observatory (AMEGO) is a Probe-class mission concept that will provide essential contributions to multimessenger astrophysics in the next decade. AMEGO operates both as a Compton and pair telescope to achieve unprecedented sensitivity between 200 keV and $>$5 GeV. The instrument consists of four subsystems. A double-sided strip silicon Tracker gives a precise measure of the first Compton scatter interaction and tracks of pair-conversion products. A novel CdZnTe Low Energy Calorimeter with excellent position and energy resolution surrounds the bottom and sides of the TrackerRead More →

A Comparison of Trapped Particle Models in Low Earth Orbit. (arXiv:2101.03090v1 [astro-ph.IM]) <a href="http://arxiv.org/find/astro-ph/1/au:+Ripa_J/0/1/0/all/0/1">J. Ripa</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dilillo_G/0/1/0/all/0/1">G. Dilillo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Campana_R/0/1/0/all/0/1">R. Campana</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Galgoczi_G/0/1/0/all/0/1">G. Galgoczi</a> Space radiation is well-known to pose serious issues to solid-state high-energy sensors. Therefore, radiation models play a key role in the preventive assessment of the radiation damage, duty cycles, performance and lifetimes of detectors. In the context of HERMES-SP mission we present our investigation of AE8/AP8 and AE9/AP9 specifications of near-Earth trapped radiation environment. We consider different circular Low-Earth orbits. Trapped particles fluxes are obtained, from which maps of the radiation regions are computed, estimating duty cycles at different flux thresholds.Read More →

POLAR-2: a large scale gamma-ray polarimeter for GRBs. (arXiv:2101.03084v1 [astro-ph.IM]) <a href="http://arxiv.org/find/astro-ph/1/au:+Hulsman_J/0/1/0/all/0/1">J. Hulsman</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Angelis_N/0/1/0/all/0/1">N. de Angelis</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Burgess_J/0/1/0/all/0/1">J. M. Burgess</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cadoux_F/0/1/0/all/0/1">F. Cadoux</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Greinerd_J/0/1/0/all/0/1">J. Greinerd</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kole_M/0/1/0/all/0/1">M. Kole</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Li_H/0/1/0/all/0/1">H. Li</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mianowski_S/0/1/0/all/0/1">S.Mianowski</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pollo_A/0/1/0/all/0/1">A. Pollo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Produit_N/0/1/0/all/0/1">N. Produit</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rybka_D/0/1/0/all/0/1">D. Rybka</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Stauffer_J/0/1/0/all/0/1">J. Stauffer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wu_X/0/1/0/all/0/1">X. Wu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zadrozny_A/0/1/0/all/0/1">A. Zadrozny</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhang_S/0/1/0/all/0/1">S.N.Zhang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sun_J/0/1/0/all/0/1">J. Sun</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wu_B/0/1/0/all/0/1">B. Wu</a> The prompt emission of GRBs has been investigated for more than 50 years but remains poorly understood. Commonly, spectral and temporal profiles of {gamma}-ray emission are analysed. However, they are insufficient for a complete picture on GRB-related physics. The addition of polarization measurements providesRead More →

Radio Emission by Soliton Formation in Hot Streaming Pair Pulsar Plasmas. (arXiv:2101.03083v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Benacek_J/0/1/0/all/0/1">Jan Ben&#xe1;&#x10d;ek</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Munoz_P/0/1/0/all/0/1">Patricio A. Mu&#xf1;oz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Manthei_A/0/1/0/all/0/1">Alina C. Manthei</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Buchner_J/0/1/0/all/0/1">J&#xf6;rg B&#xfc;chner</a> A number of possible pulsar radio emission mechanisms is based on instabilities of the relative streaming and beams in their relativistic electron-positron pair plasma. At saturation the unstable waves can form, in principle, stable solitary waves which could emit the observed intense radio signals. We searched for the proper plasma parameters which would lead to the formation of solitons, investigated their properties and dynamics as well as the resulting oscillations of electrons and positrons possibly leading to radioRead More →

SpaceX’s Next Idea: to Catch Super Heavy Boosters With the Launch Tower A new animation shows how SpaceX will “catch” the first stage boosters of their Starship, allowing for faster turnaround and more flights to space. The post SpaceX’s Next Idea: to Catch Super Heavy Boosters With the Launch Tower appeared first on Universe Today. Universe Today Go to SourceRead More →

This is the Fireworks Galaxy. It’s had ten Supernovae in the Last Century Alone Say hello to NGC 6946, otherwise known as the Fireworks Galaxy. This little galaxy is the most prolific producer of supernovae in the known universe, popping off those incredible explosions roughly once a decade. It’s secret? An incredibly high rate of star formation. NGC 6946 sits about 25 million light-years away, close enough that it … Continue reading “This is the Fireworks Galaxy. It’s had ten Supernovae in the Last Century Alone” The post This is the Fireworks Galaxy. It’s had ten Supernovae in the Last Century Alone appeared first onRead More →

Solar wind shock wave arrived at Earth A slow shock wave arrived today around 08:25 UTC at DSCOVR. The source is unclear but it could have come from a filament eruption back on 6 January or one that took place on 8 January. The resulting coronal mass ejections were not expected to arrive at Earth but one of these two eruptions likely grazed our planet today. Space Weather Live Go to SourceRead More →

Measurements of pulsar acceleration reveal Milky Way’s dark side It is well known that the expansion of the universe is accelerating due to a mysterious dark energy. Within galaxies, stars also experience an acceleration, though this is due to some combination of dark matter and the stellar density. In a new study to be published in Astrophysical Journal Letters researchers have now obtained the first direct measurement of the average acceleration taking place within our home galaxy, the Milky Way. Led by Sukanya Chakrabarti at the Institute for Advanced Study with collaborators from Rochester Institute of Technology, University of Rochester, and University of Wisconsin-Milwaukee, theRead More →

Unveiling the double origin of cosmic dust in the distant Universe Two billion years after the Big Bang, the Universe was still very young. However, thousands of huge galaxies, rich in stars and dust, were already formed. An international study, led by SISSA—Scuola Internazionale Superiore di Studi Avanzati, now explains how this was possible. Scientists combined observational and theoretical methods to identify the physical processes behind their evolution and, for the first time, found evidence for a rapid growth of dust due to a high concentration of metals in the distant Universe. The study, published in Astronomy & Astrophysics, offers a new approach to investigateRead More →

ALMA captures distant colliding galaxy dying out as it loses the ability to form stars Galaxies begin to “die” when they stop forming stars, but until now astronomers had never clearly glimpsed the start of this process in a far-away galaxy. Using the Atacama Large Millimeter/submillimeter Array (ALMA), in which the European Southern Observatory (ESO) is a partner, astronomers have seen a galaxy ejecting nearly half of its star-forming gas. This ejection is happening at a startling rate, equivalent to 10 000 Suns-worth of gas a year — the galaxy is rapidly losing its fuel to make new stars. The team believes that this spectacularRead More →

Researchers perform largest-ever supersonic turbulence simulation Early astronomers painstakingly studied the subtle movements of stars in the night sky to try and determine how our planet moves in relation to other celestial bodies. As technology has increased, so has the understanding of how the universe works and our relative position within it. phys.org Go to SourceRead More →

Image: Cosmic neon lights This image shows a new type of star that has never been seen before in X-ray light. This strange star formed after two white dwarfs—remnants of stars like our sun—collided and merged. But instead of destroying each other in the event, the white dwarfs formed a new object that shines bright in X-ray light. phys.org Go to SourceRead More →

Eight binary millisecond pulsars examined by researchers Using the Arecibo 305-m radio telescope, an international team of astronomers has investigated eight binary millisecond pulsars (MSPs). Results of this study, presented in a paper published December 30 on the arXiv pre-print server, provide important information about the properties of these sources. phys.org Go to SourceRead More →

Image: Hubble views a dazzling ‘fireworks galaxy’ The galaxy NGC 6946 is nothing short of spectacular. In the last century alone, NGC 6946 has experienced 10 observed supernovae, earning its nickname as the Fireworks Galaxy. In comparison, our Milky Way averages just one to two supernova events per century. This NASA/ESA Hubble Space Telescope image shows the stars, spiral arms, and various stellar environments of NGC 6946 in phenomenal detail. phys.org Go to SourceRead More →