Hubble watches cosmic light bend This extraordinary image from the NASA/ESA Hubble Space Telescope of the galaxy cluster Abell 2813 (also known as ACO 2813) has an almost delicate beauty, which also illustrates the remarkable physics at work within it. The image spectacularly demonstrates the concept of gravitational lensing. phys.org Go to SourceRead More →
SpaceX has Given up Trying to Catch Rocket Fairings. Fishing Them out of the Ocean is Fine If there is one driving force in the commercial space industry it is economics. The whole concept of reusable booster rocket emphasizes the importance of getting launch costs down. SpaceX, the company leading the charge in trying to bring launch costs down, doesn’t just recover booster rockets however. It also recovers the rocket fairings that hold the payload during launch. SpaceX’s original plan was to capture the fairings as they fell back to Earth using specially equipped ships with nets to catch them before they landed in theRead More →
When Stars Get Too Close to Each Other, They Cast Out Interstellar Comets and Asteroids In October 2017, humanity caught its first-ever glimpse of an interstellar object – a visitor from beyond our solar system – passing nearby the Sun. We named it Oumuamua, and its unusual properties fascinated and confounded astronomers. Less than two years later, amateur astronomer Gennady Borisov found a second interstellar object: a comet-like body that began to disintegrate as it passed within 2 AU of the Sun (1 AU equals the distance from Earth to the Sun). Where do these interstellar objects come from? How common are they? With aRead More →
You Thought Black Hole Event Horizons Looked Strange. Check out Binary Black Hole Event Horizons One of the strangest predictions of general relativity is that gravity can deflect the path of light. The effect was first observed by Arthur Eddington in 1919. While the bending effect of the Sun is small, near a black hole light deflection can be significant. So significant that you need a powerful supercomputer to calculate how light will behave. Recently the NASA Goddard Media Studios released a few videos showing us how a binary black hole system might look under gravitational lensing. The simulation traces the paths of light comingRead More →
Astronauts Will Soon be Getting a Space Fridge, Keeping Everything Cold in Zero-G One of the least known of NASA’s funding mechanisms is the Small Business Innovation Research (SBIR) program. This program, required by the Baye-Doyle Act of 1980, earmarks a piece of every US Federal agency’s budget (including NASA) for the development of small businesses to commercialize new technologies. NASA’s SBIR program usually focus on commercializing technologies that are useable in space, and many times fund a university doing some work in addition to the small business that received the grant. A company called Air Squared Inc, based in Broomfield, Colorado, recently received oneRead More →
LAMOST J0140355+392651: An evolved cataclysmic variable donor transitioning to become an extremely low mass white dwarf. (arXiv:2104.07033v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+El_Badry_K/0/1/0/all/0/1">Kareem El-Badry</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Quataert_E/0/1/0/all/0/1">Eliot Quataert</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:+Weisz_D/0/1/0/all/0/1">Daniel R. Weisz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kupfer_T/0/1/0/all/0/1">Thomas Kupfer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shen_K/0/1/0/all/0/1">Ken Shen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Xiang_M/0/1/0/all/0/1">Maosheng Xiang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yang_Y/0/1/0/all/0/1">Yong Yang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Liu_X/0/1/0/all/0/1">Xiaowei Liu</a> We present LAMOST J0140355+392651 (hereafter J0140), a close ($P_{rm orb} = 3.81$ hours) binary containing a bloated, low-mass ($M approx 0.15 M_{odot}$) proto-white dwarf (WD) and a massive ($Mapprox 0.95,M_{odot}$) WD companion. The system’s optical light curve is dominated by large-amplitude ellipsoidal variability but also exhibits additional scatter, likely driven by pulsations. The proto-WD is cooler ($T_{rm eff} =Read More →
Forever young white dwarfs: when stellar ageing stops. (arXiv:2008.03028v2 [astro-ph.SR] UPDATED) <a href="http://arxiv.org/find/astro-ph/1/au:+Camisassa_M/0/1/0/all/0/1">María E. Camisassa</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Althaus_L/0/1/0/all/0/1">Leandro G. Althaus</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Torres_S/0/1/0/all/0/1">Santiago Torres</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Corsico_A/0/1/0/all/0/1">Alejandro H. Córsico</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rebassa_Mansergas_A/0/1/0/all/0/1">Alberto Rebassa-Mansergas</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tremblay_P/0/1/0/all/0/1">Pier-Emmanuel Tremblay</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cheng_S/0/1/0/all/0/1">Sihao Cheng</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Raddi_R/0/1/0/all/0/1">Roberto Raddi</a> White dwarf stars are the most common end point of stellar evolution. Of special interest are the ultramassive white dwarfs, as they are related to type Ia Supernovae explosions, merger events, and Fast Radio Bursts. Ultramassive white dwarfs are expected to harbour oxygen-neon (ONe) cores as a result of single standard stellar evolution. However, a fraction of them could have carbon-oxygen (CO) cores. Recent studies, based onRead More →
A New Window into Planet Formation and Migration: Refractory-to-Volatile Elemental Ratios in Ultra-hot Jupiters. (arXiv:2011.10626v2 [astro-ph.EP] UPDATED) <a href="http://arxiv.org/find/astro-ph/1/au:+Lothringer_J/0/1/0/all/0/1">Joshua D. Lothringer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rustamkulov_Z/0/1/0/all/0/1">Zafar Rustamkulov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sing_D/0/1/0/all/0/1">David K. Sing</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gibson_N/0/1/0/all/0/1">Neale P. Gibson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wilson_J/0/1/0/all/0/1">Jamie Wilson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Schlaufman_K/0/1/0/all/0/1">Kevin C. Schlaufman</a> A primary goal of exoplanet characterization is to use a planet’s current composition to understand how that planet formed. For example, the C/O ratio has long been recognized as carrying important information on the chemistry of volatile species. Refractory elements, like Fe, Mg, and Si, are usually not considered in this conversation because they condense into solids like Fe(s) or MgSiO$_3$ and would be removed fromRead More →
Losing the trace to find dynamical Newton or Planck constants. (arXiv:2011.07055v2 [gr-qc] UPDATED) <a href="http://arxiv.org/find/gr-qc/1/au:+Jirousek_P/0/1/0/all/0/1">Pavel Jiroušek</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Shimada_K/0/1/0/all/0/1">Keigo Shimada</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Vikman_A/0/1/0/all/0/1">Alexander Vikman</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Yamaguchi_M/0/1/0/all/0/1">Masahide Yamaguchi</a> We show that promoting the trace part of the Einstein equations to a trivial identity results in the Newton constant being an integration constant. Thus, in this formulation the Newton constant is a global dynamical degree of freedom which is also a subject to quantization and quantum fluctuations. This is similar to what happens to the cosmological constant in the unimodular gravity where the trace part of the Einstein equations is lost in a different way. We introduce a constrainedRead More →
Bayesian search for gravitational wave bursts in pulsar timing array data. (arXiv:2011.01942v2 [gr-qc] UPDATED) <a href="http://arxiv.org/find/gr-qc/1/au:+Becsy_B/0/1/0/all/0/1">Bence Bécsy</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Cornish_N/0/1/0/all/0/1">Neil J. Cornish</a> The nanohertz frequency band explored by pulsar timing arrays provides a unique discovery space for gravitational wave signals. In addition to signals from anticipated sources, such as those from supermassive black hole binaries, some previously unimagined sources may emit transient gravitational waves (a.k.a. bursts) with unknown morphology. Unmodeled transients are not currently searched for in this frequency band, and they require different techniques from those currently employed. Possible sources of such gravitational wave bursts in the nanohertz regime are parabolic encounters of supermassive blackRead More →
The circumstellar matter of type II intermediate luminosity optical transients (ILOTs). (arXiv:2010.14490v3 [astro-ph.HE] UPDATED) <a href="http://arxiv.org/find/astro-ph/1/au:+Soker_N/0/1/0/all/0/1">Noam Soker</a> (Technion, Israel) I find that a 0.1-1Mo outflowing equatorial dusty disk (torus) that the binary system progenitor of an intermediate luminosity optical transient (ILOT) ejects several years to several months before and during the outburst can reduce the total emission to an equatorial observer by two orders of magnitude and shifts the emission to wavelengths of mainly >10mum. This is termed a type II ILOT (ILOT II). To reach this conclusion I use calculations of type II active galactic nuclei and apply them to the equatorial ejecta (disk/torus)Read More →
Towards a self-consistent analysis of the anisotropic galaxy two- and three-point correlation functions on large scales: application to mock galaxy catalogues. (arXiv:2010.06179v3 [astro-ph.CO] UPDATED) <a href="http://arxiv.org/find/astro-ph/1/au:+Sugiyama_N/0/1/0/all/0/1">Naonori S. Sugiyama</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Saito_S/0/1/0/all/0/1">Shun Saito</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Beutler_F/0/1/0/all/0/1">Florian Beutler</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Seo_H/0/1/0/all/0/1">Hee-Jong Seo</a> We establish a practical method for the joint analysis of anisotropic galaxy two- and three-point correlation functions (2PCF and 3PCF) on the basis of the decomposition formalism of the 3PCF using tri-polar spherical harmonics. We perform such an analysis with MultiDark Patchy mock catalogues to demonstrate and understand the benefit of the anisotropic 3PCF. We focus on scales above $80 h^{-1},{rm Mpc}$, and use information from the shapeRead More →
Static response and Love numbers of Schwarzschild black holes. (arXiv:2010.00593v2 [hep-th] UPDATED) <a href="http://arxiv.org/find/hep-th/1/au:+Hui_L/0/1/0/all/0/1">Lam Hui</a>, <a href="http://arxiv.org/find/hep-th/1/au:+Joyce_A/0/1/0/all/0/1">Austin Joyce</a>, <a href="http://arxiv.org/find/hep-th/1/au:+Penco_R/0/1/0/all/0/1">Riccardo Penco</a>, <a href="http://arxiv.org/find/hep-th/1/au:+Santoni_L/0/1/0/all/0/1">Luca Santoni</a>, <a href="http://arxiv.org/find/hep-th/1/au:+Solomon_A/0/1/0/all/0/1">Adam R. Solomon</a> We derive the quadratic action for the physical degrees of freedom of massless spin-0, spin-1, and spin-2 perturbations on a Schwarzschild–(A)dS background in arbitrary dimensions. We then use these results to compute the static response of asymptotically flat Schwarzschild black holes to external fields. Our analysis reproduces known facts about black hole Love numbers, in particular that they vanish for all types of perturbation in four spacetime dimensions, but also leads to new results. For instance, weRead More →
HI intensity mapping with the MIGHTEE survey: power spectrum estimates. (arXiv:2009.13550v2 [astro-ph.CO] UPDATED) <a href="http://arxiv.org/find/astro-ph/1/au:+Paul_S/0/1/0/all/0/1">Sourabh Paul</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Santos_M/0/1/0/all/0/1">Mario G. Santos</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Townsend_J/0/1/0/all/0/1">Junaid Townsend</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jarvis_M/0/1/0/all/0/1">Matt J. Jarvis</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Maddox_N/0/1/0/all/0/1">Natasha Maddox</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Collier_J/0/1/0/all/0/1">Jordan D. Collier</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Frank_B/0/1/0/all/0/1">Bradley S. Frank</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Taylor_R/0/1/0/all/0/1">Russ Taylor</a> Intensity mapping (IM) with neutral hydrogen is a promising avenue to probe the large scale structure of the Universe. In this paper, we demonstrate that using the 64-dish MeerKAT radio telescope as a connected interferometer, it is possible to make a statistical detection of HI in the post-reionization Universe. With the MIGHTEE (MeerKAT International GHz Tiered Extragalactic Exploration) survey project observing in the L-bandRead More →
Association of IceCube neutrinos with radio sources observed at Owens Valley and Mets”ahovi Radio Observatories. (arXiv:2009.10523v3 [astro-ph.HE] UPDATED) <a href="http://arxiv.org/find/astro-ph/1/au:+Hovatta_T/0/1/0/all/0/1">T. Hovatta</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lindfors_E/0/1/0/all/0/1">E. Lindfors</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kiehlmann_S/0/1/0/all/0/1">S. Kiehlmann</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Max_Moerbeck_W/0/1/0/all/0/1">W. Max-Moerbeck</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hodges_M/0/1/0/all/0/1">M. Hodges</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Liodakis_I/0/1/0/all/0/1">I. Liodakis</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lahteenmaki_A/0/1/0/all/0/1">A. Lahteenmaki</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pearson_T/0/1/0/all/0/1">T. J. Pearson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Readhead_A/0/1/0/all/0/1">A. C. S. Readhead</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Reeves_R/0/1/0/all/0/1">R. A. Reeves</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Suutarinen_S/0/1/0/all/0/1">S. Suutarinen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tammi_J/0/1/0/all/0/1">J. Tammi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tornikoski_M/0/1/0/all/0/1">M. Tornikoski</a> Identifying the most likely sources for high-energy neutrino emission has been one of the main topics in high-energy astrophysics ever since the first observation of high-energy neutrinos by the IceCube Neutrino Observatory. Active galactic nuclei with relativistic jets, also known as blazars, have beenRead More →
Milky Way Accelerometry via Millisecond Pulsar Timing. (arXiv:2008.13052v2 [astro-ph.GA] UPDATED) <a href="http://arxiv.org/find/astro-ph/1/au:+Phillips_D/0/1/0/all/0/1">David F. Phillips</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ravi_A/0/1/0/all/0/1">Aakash Ravi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ebadi_R/0/1/0/all/0/1">Reza Ebadi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Walsworth_R/0/1/0/all/0/1">Ronald L. Walsworth</a> The temporal stability of millisecond pulsars is remarkable, rivaling even some terrestrial atomic clocks at long timescales. Using this property, we show that millisecond pulsars distributed in the galactic neighborhood form an ensemble of accelerometers from which we can directly extract the local galactic acceleration. From pulsar spin period measurements, we demonstrate acceleration sensitivity with about 1$sigma$ precision using 117 pulsars. We also present results from a complementary analysis using orbital periods of 13 binary pulsar systems that eliminates systematics associatedRead More →
Constraining Primordial Black Holes with Dwarf Galaxy Heating. (arXiv:2007.02213v2 [astro-ph.CO] UPDATED) <a href="http://arxiv.org/find/astro-ph/1/au:+Lu_P/0/1/0/all/0/1">Philip Lu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Takhistov_V/0/1/0/all/0/1">Volodymyr Takhistov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gelmini_G/0/1/0/all/0/1">Graciela B. Gelmini</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hayashi_K/0/1/0/all/0/1">Kohei Hayashi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Inoue_Y/0/1/0/all/0/1">Yoshiyuki Inoue</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kusenko_A/0/1/0/all/0/1">Alexander Kusenko</a> Black holes formed in the early universe, prior to the formation of stars, can exist as dark matter and also contribute to the black hole merger events observed in gravitational waves. We set a new limit on the abundance of primordial black holes (PBHs) by considering interactions of PBHs with the interstellar medium, which result in the heating of gas. We examine generic heating mechanisms, including emission from the accretion disk, dynamical friction, and diskRead More →
Redshift space power spectrum beyond Einstein-de Sitter kernels. (arXiv:2012.05077v2 [astro-ph.CO] UPDATED) <a href="http://arxiv.org/find/astro-ph/1/au:+Aviles_A/0/1/0/all/0/1">Alejandro Aviles</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Valogiannis_G/0/1/0/all/0/1">Georgios Valogiannis</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rodriguez_Meza_M/0/1/0/all/0/1">Mario A.Rodriguez-Meza</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cervantes_Cota_J/0/1/0/all/0/1">Jorge L. Cervantes-Cota</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Li_B/0/1/0/all/0/1">Baojiu Li</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bean_R/0/1/0/all/0/1">Rachel Bean</a> We develop a framework to compute the redshift space power spectrum (PS), with kernels beyond Einstein-de Sitter (EdS), that can be applied to a wide variety of generalized cosmologies. We build upon a formalism that was recently employed for standard cosmology in Chen, Vlah & White (2020), and utilize an expansion of the density-weighted velocity moment generating function that explicitly separates the magnitude of the $k$-modes and their angle to the line-of-sight direction dependencies. WeRead More →
Implications of a possible TeV break in the cosmic-ray electron and positron flux. (arXiv:2007.00703v2 [astro-ph.HE] UPDATED) <a href="http://arxiv.org/find/astro-ph/1/au:+Ding_Y/0/1/0/all/0/1">Yu-Chen Ding</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Li_N/0/1/0/all/0/1">Nan Li</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wei_C/0/1/0/all/0/1">Chun-Cheng Wei</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wu_Y/0/1/0/all/0/1">Yue-Liang Wu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhou_Y/0/1/0/all/0/1">Yu-Feng Zhou</a> A TeV spectral break in the total flux of cosmic-ray electrons and positrons (CREs) at which the spectral power index softens from $sim 3$ to $sim 4$ has been observed by H.E.S.S. and recently confirmed by DAMPE with a high significance of $6.6~sigma$. Such an observation is apparently inconsistent with the data from other experiments such as Fermi-LAT, AMS-02 and CALET. We perform a global analysis to the latest CRE data including Fermi-LAT, AMS-02,Read More →
Likelihood-free Cosmological Constraints with Artificial Neural Networks: An Application on Hubble Parameters and SNe Ia. (arXiv:2005.10628v2 [astro-ph.CO] UPDATED) <a href="http://arxiv.org/find/astro-ph/1/au:+Wang_Y/0/1/0/all/0/1">Yu-Chen Wang</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Xie_Y/0/1/0/all/0/1">Yuan-Bo Xie</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Zhang_T/0/1/0/all/0/1">Tong-Jie Zhang</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Huang_H/0/1/0/all/0/1">Hui-Chao Huang</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Zhang_T/0/1/0/all/0/1">Tingting Zhang</a> (3), <a href="http://arxiv.org/find/astro-ph/1/au:+Liu_K/0/1/0/all/0/1">Kun Liu</a> (3) ((1) Department of Physics, Beijing Normal University, Beijing, China, (2) Department of Astronomy, Beijing Normal University, Beijing, China, (3) College of Command and Control Engineering, PLA Army Engineering University, Nanjing, China) The errors of cosmological data generated from complex processes, such as the observational Hubble parameter data (OHD) and the Type Ia supernova (SN Ia) data, cannot be accurately modeled by simple analyticalRead More →
