Untangling cosmic magnetic fields: Faraday tomography at metre wavelengths with LOFAR. (arXiv:1811.12732v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+OSullivan_S/0/1/0/all/0/1">Shane P. O&#x27;Sullivan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bruggen_M/0/1/0/all/0/1">M. Br&#xfc;ggen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Eck_C/0/1/0/all/0/1">C. L. Van Eck</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hardcastle_M/0/1/0/all/0/1">M. J. Hardcastle</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Haverkorn_M/0/1/0/all/0/1">M. Haverkorn</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shimwell_T/0/1/0/all/0/1">T. W. Shimwell</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tasse_C/0/1/0/all/0/1">C. Tasse</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vacca_V/0/1/0/all/0/1">V. Vacca</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Horellou_C/0/1/0/all/0/1">C. Horellou</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Heald_G/0/1/0/all/0/1">G. Heald</a> The technique of Faraday tomography is a key tool for the study of magnetised plasmas in the new era of broadband radio polarisation observations. In particular, observations at metre-wavelengths provide significantly better Faraday depth accuracies compared to traditional cm-wavelength observations. However, the effect of Faraday depolarisation makes the polarised signal very challenging to detect at metre wavelengthsRead More →

Numerical Simulation of Coronal Waves Interacting with Coronal Holes: III. Dependence on Initial Amplitude of the Incoming Wave. (arXiv:1811.12735v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Piantschitsch_I/0/1/0/all/0/1">Isabell Piantschitsch</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vrsnak_B/0/1/0/all/0/1">Bojan Vrsnak</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hanslmeier_A/0/1/0/all/0/1">Arnold Hanslmeier</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lemmerer_B/0/1/0/all/0/1">Birgit Lemmerer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Veronig_A/0/1/0/all/0/1">Astrid Veronig</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hernandez_Perez_A/0/1/0/all/0/1">Aaron Hernandez-Perez</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Calogovic_J/0/1/0/all/0/1">Jasa Calogovic</a> We performed 2.5D magnetohydrodynamic (MHD) simulations showing the propagation of fast-mode MHD waves of different initial amplitudes and their interaction with a coronal hole (CH), using our newly developed numerical code. We find that this interaction results in, first, the formation of reflected, traversing and transmitted waves (collectively, secondary waves) and, second, in the appearance of stationary features at the CH boundary. Moreover, weRead More →

Primordial gravitational waves in Horndeski gravity. (arXiv:1811.12760v1 [gr-qc]) <a href="http://arxiv.org/find/gr-qc/1/au:+Nunes_R/0/1/0/all/0/1">Rafael C. Nunes</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Alves_M/0/1/0/all/0/1">Marcio E. S. Alves</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Araujo_J/0/1/0/all/0/1">Jose C. N. de Araujo</a> We investigate the propagation of primordial gravitational waves within the context of the Horndeski theories, for this, we present a generalized transfer function quantifying the sub-horizon evolution of gravitational waves modes after they enter the horizon. We compare the theoretical prediction of the primordial gravitational waves spectral density with the aLIGO, Einstein telescope, LISA, gLISA and DECIGO sensitivity curves. Assuming reasonable and different values for the free parameters of the theory (in agreement with the event GW170817), we note that the gravitationalRead More →

Dark matter and the early Universe. (arXiv:1811.12764v1 [hep-ph]) <a href="http://arxiv.org/find/hep-ph/1/au:+Arbey_A/0/1/0/all/0/1">A. Arbey</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Ellis_J/0/1/0/all/0/1">J. Ellis</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Mahmoudi_F/0/1/0/all/0/1">F. Mahmoudi</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Robbins_G/0/1/0/all/0/1">G. Robbins</a> Big-Bang nucleosynthesis (BBN) represents one of the earliest phenomena that can lead to observational constraints on the early Universe properties. It is well-known that many important mechanisms and phase transitions occurred before BBN. We discuss the possibility of gaining insight into the primordial Universe through studies of dark matter in cosmology, astroparticle physics and colliders. For this purpose, we assume that dark matter is a thermal relic, and show that combining collider searches with dark matter observables can lead to strong constraints on the periodRead More →

X-ray and optical monitoring of the December 2017 outburst of the Be/X-ray binary AX J0049.4-7323. (arXiv:1811.12795v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Ducci_L/0/1/0/all/0/1">L. Ducci</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Malacaria_C/0/1/0/all/0/1">C. Malacaria</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Romano_P/0/1/0/all/0/1">P. Romano</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ji_L/0/1/0/all/0/1">L. Ji</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bozzo_E/0/1/0/all/0/1">E. Bozzo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Saathoff_I/0/1/0/all/0/1">I. Saathoff</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Santangelo_A/0/1/0/all/0/1">A. Santangelo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Udalski_A/0/1/0/all/0/1">A. Udalski</a> AX J0049.4-7323 is a Be/X-ray binary that shows an unusual and poorly understood optical variability that consists of periodic and bright optical outbursts, simultaneous with X-ray outbursts, characterised by a highly asymmetric profile. The periodicity of the outbursts is thought to correspond to the orbital period of the neutron star. To understand the behaviour shown by this source, we performed the first multi-wavelength monitoringRead More →

Gas phase detection and rotational spectroscopy of ethynethiol, HCCSH. (arXiv:1811.12798v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Lee_K/0/1/0/all/0/1">Kin Long Kelvin Lee</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Martin_Drumel_M/0/1/0/all/0/1">Marine-Aline Martin-Drumel</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lattanzi_V/0/1/0/all/0/1">Valerio Lattanzi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+McGuire_B/0/1/0/all/0/1">Brett A. McGuire</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Caselli_P/0/1/0/all/0/1">Paola Caselli</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+McCarthy_M/0/1/0/all/0/1">Michael McCarthy</a> We report the gas-phase detection and spectroscopic characterization of ethynethiol ($mathrm{HCCSH}$), a metastable isomer of thioketene ($mathrm{H_2C_2S}$) using a combination of Fourier-transform microwave and submillimeter-wave spectroscopies. Several $a$-type transitions of the normal species were initially detected below 40 GHz using a supersonic expansion-electrical discharge source, and subsequent measurement of higher-frequency, $b$-type lines using double resonance provided accurate predictions in the submillimeter region. With these, searches using a millimeter-wave absorption spectrometer equipped with aRead More →

Praesepe white dwarfs in Gaia DR2. (arXiv:1811.12825v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Salaris_M/0/1/0/all/0/1">M. Salaris</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Bedin_L/0/1/0/all/0/1">L. R. Bedin</a> (2). ((1) J.M.Univ.Liverpool, (2) INAF-OAPD) We have exploited Gaia Data Release 2 to study white dwarf members of the Praesepe star cluster. We recovered eleven known white dwarf members (all DA spectral type) plus a new cluster WD never identified before. Two of the eleven known DA objects did not satisfy all quality indicators available in the data release. The remaining nine objects of known spectral type have then been employed to determine their masses (average error of 3-5%) and cooling times (average uncertainty of 5-7%), by fitting coolingRead More →

Evidence for magnetospheric effects on the radiation of radio pulsars. (arXiv:1811.12831v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Ilie_C/0/1/0/all/0/1">Cristina-Diana Ilie</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Johnston_S/0/1/0/all/0/1">Simon Johnston</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Weltevrede_P/0/1/0/all/0/1">Patrick Weltevrede</a> We have conducted the largest investigation to date into the origin of phase resolved, apparent RM variations in the polarized signals of radio pulsars. From a sample of 98 pulsars based on observations at 1.4 GHz with the Parkes radio telescope, we carefully quantified systematic and statistical errors on the measured RMs. A total of 42 pulsars showed significant phase resolved RM variations. We show that both magnetospheric and scattering effects can cause these apparent variations. There is a clear correlation between complex profilesRead More →

No evidence for enhanced [OIII] 88um emission in a z~6 quasar compared to its companion starbursting galaxy. (arXiv:1811.12836v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Walter_F/0/1/0/all/0/1">Fabian Walter</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Riechers_D/0/1/0/all/0/1">Dominik Riechers</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Novak_M/0/1/0/all/0/1">Mladen Novak</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Decarli_R/0/1/0/all/0/1">Roberto Decarli</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ferkinhoff_C/0/1/0/all/0/1">Carl Ferkinhoff</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Venemans_B/0/1/0/all/0/1">Bram Venemans</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Banados_E/0/1/0/all/0/1">Eduardo Banados</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bertoldi_F/0/1/0/all/0/1">Frank Bertoldi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Carilli_C/0/1/0/all/0/1">Chris Carilli</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fan_X/0/1/0/all/0/1">Xiaohui Fan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Farina_E/0/1/0/all/0/1">Emanuele Farina</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mazzucchelli_C/0/1/0/all/0/1">Chiara Mazzucchelli</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Neeleman_M/0/1/0/all/0/1">Marcel Neeleman</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rix_H/0/1/0/all/0/1">Hans-Walter Rix</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Strauss_M/0/1/0/all/0/1">Michael Strauss</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Uzgil_B/0/1/0/all/0/1">Bade Uzgil</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wang_R/0/1/0/all/0/1">Ran Wang</a> We present ALMA band 8 observations of the [OIII] 88um line and the underlying thermal infrared continuum emission in the z=6.08 quasar CFHQS J2100-1715 and its dust-obscured starburst companion galaxy (projected distance: ~60 kpc). EachRead More →

A Tiny Asteroid Will Pass Very Close to Earth on Saturday A very small asteroid discovered on Nov. 29 is on a path which will bring it very close to Earth on the evening of Dec. 1, but there is no chance that the asteroid could impact our planet. Only about 3 meters (15 feet) in size, the object is predicted to pass so close to Earth that it will be well within the so-called geosynchronous orbit of communications and weather satellites, about 36,000 kilometers (22,000 miles) above the equator. NASA CNEOS Go to SourceRead More →

A New Atomic Clock has been Built that Would be off by Less than a Second Since the Big Bang Physicists have developed an atomic clock so accurate that it would be off by less than a single second in 14 billion years. That kind of accuracy and precision makes it more than just a timepiece. It’s a powerful scientific instrument that could measure gravitational waves, take the measure of the Earth’s gravitational shape, and … Continue reading “A New Atomic Clock has been Built that Would be off by Less than a Second Since the Big Bang” The post A New Atomic Clock hasRead More →

#78 Part 1 December 2018 The Discussion: Arthur Eddington, the Caldwell catalogue and a round-up of emails to the show. The News: Rounding up the space and astronomy news this month we have: Waiting for a Gamma Ray Burst Watching the Milky Way’s supermassive black hole feeding Finding a massive meteorite under 1km of ice in Greenland The discovery that the Milky Way has another satellite galaxy The Hyades is bigger than we thought – much bigger! Silica dust from supernovae discovered Main news story: The discovery of an exoplanet around Barnard’s Star just 6 light year away. The Sky Guide: Covering the solar systemRead More →

Prehistoric Cave Paintings Show That Ancient People Had Pretty Advanced Knowledge of Astronomy According to a new study that examined ancient cave paintings and archaeological sites, it appears that prehistoric humans had a greater understanding of astronomy than we thought. The post Prehistoric Cave Paintings Show That Ancient People Had Pretty Advanced Knowledge of Astronomy appeared first on Universe Today. Universe Today Go to SourceRead More →

Antibiotic Resistant Bacteria has been Found on the Space Station’s Toilet NASA keeps a close eye on the bacteria inhabiting the International Space Station with a program called the Microbial Observatory (M.O.) The ISS is home to a variety of microbes, some of which pose a threat to the health of astronauts. As part of their monitoring, the M.O. has discovered antibiotic resistant bacteria on the … Continue reading “Antibiotic Resistant Bacteria has been Found on the Space Station’s Toilet” The post Antibiotic Resistant Bacteria has been Found on the Space Station’s Toilet appeared first on Universe Today. Universe Today Go to SourceRead More →

A study of almost 2600 IAU members shows that astronomers have a remarkable drive for public engagement Because of the ubiquitous nature of its questions and the stunning insights into the nature of the Universe, astronomy has often been thought of as appealing and the natural science with the most far-reaching popularisation efforts. A recently published study of the outreach activities of IAU members, Bustling public communication by astronomers around the world driven by personal and contextual factors, has shown that professional astronomers may be engaging with the public more than scientists in any other field. phys.org Go to SourceRead More →

Fabrication of powerful telescope begins Fabrication of the Cerro Chajnantor Atacama Telescope-prime (CCAT-p), a powerful telescope capable of mapping the sky at submillimeter and millimeter wavelengths, has now begun, marking a major milestone in the project. phys.org Go to SourceRead More →

First high-resolution look at the quiet Sun with ALMA at 3 mm Observations of the radio continuum at millimeter (mm) wavelengths provide a unique chromospheric diagnostic. The quiet sun mm-wavelength emission mechanism is free-free and electrons are almost always in local thermodynamic equilibrium (e.g. Shibasaki et al. 2011 and Wedemeyer et al. 2016). The availability of mm-wavelength solar observations with ALMA can advance our knowledge on the chromosphere because of the instrument’s unique spatial resolution and sensitivity. In a previous study, the researchers used ALMA full-disk (FD) commissioning data to study the quiet sun under low resolution. However, publications of results from ALMA high-resolution quietRead More →

Magnetic fields found in a jet from a baby star An international research team led by Chin-Fei Lee in the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA) has made a breakthrough observation with the Atacama Large Millimeter/submillimeter Array (ALMA), confirming the presence of magnetic fields in a jet from a protostar. Jets are believed to play an important role in star formation, enabling the protostar to accrete mass from an accretion disk by removing angular momentum from the disk. It is highly supersonic and collimated, and predicted in theory to be launched and collimated by magnetic fields. The finding supports the theoretical prediction andRead More →

Black hole ‘donuts’ are actually ‘fountains’ Based on computer simulations and new observations from the Atacama Large Millimeter/submillimeter Array (ALMA), researchers have found that the rings of gas surrounding active supermassive black holes are not simple donut shapes. Instead, gas expelled from the center interacts with infalling gas to create a dynamic circulation pattern, similar to a water fountain in a city park. phys.org Go to SourceRead More →