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Universe, Volume 5, Issue 6

2019 June - 26 articles

Cover Story: Three zones around a black hole (BH) during accretion of a gas with a frozen magnetic field, homogeneous at infinity. (I) A zone of stationary hydrodynamic flow with a non-stationary magnetic field. (II) A zone of stationary flow where the transition from subsonic to supersonic flow takes place. (Ill) A zone of stationary supersonic flow. Dashed line marks the place where the velocity reaches the sound value. At the plane perpendicular to the magnetic field direction, a thin disk around BH is formed. In zone II, the disk merges with the surrounding flow. Arrows in the direction of the flow velocity have opposite signs in the lower and upper parts, where the magnetic field has the same direction. The ring-like stagnation zone is shown by horizontal strokes. The sizes of two inner zones are slowly increasing with time. View this paper.
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Articles (26)

  • Article
  • Open Access
11 Citations
3,994 Views
34 Pages

How good is our universe at making habitable planets? The answer to this depends on which factors are important for life: Does a planet need to be Earth mass? Does it need to be inside the temperate zone? are systems with hot Jupiters habitable? Here...

  • Article
  • Open Access
41 Citations
3,153 Views
15 Pages

Reflections on the Covariance of Modified Teleparallel Theories of Gravity

  • Cecilia Bejarano,
  • Rafael Ferraro,
  • Franco Fiorini and
  • María José Guzmán

We review the current status of the Lorentz covariance in teleparallel and modified teleparallel theories of gravity, and discuss the controversial features of the different approaches. We also revisit the issue of the remnant Lorentz gauge symmetrie...

  • Article
  • Open Access
19 Citations
3,807 Views
12 Pages

Detecting the Hadron-Quark Phase Transition with Gravitational Waves

  • Matthias Hanauske,
  • Luke Bovard,
  • Elias Most,
  • Jens Papenfort,
  • Jan Steinheimer,
  • Anton Motornenko,
  • Volodymyr Vovchenko,
  • Veronica Dexheimer,
  • Stefan Schramm and
  • Horst Stöcker

The long-awaited detection of a gravitational wave from the merger of a binary neutron star in August 2017 (GW170817) marks the beginning of the new field of multi-messenger gravitational wave astronomy. By exploiting the extracted tidal deformations...

  • Article
  • Open Access
29 Citations
3,124 Views
77 Pages

In this work, we study the key role of generic Effective Field Theory (EFT) framework to quantify the correlation functions in a quasi de Sitter background for an arbitrary initial choice of the quantum vacuum state. We perform the computation in uni...

  • Article
  • Open Access
6 Citations
3,041 Views
12 Pages

We collect the yields of charged pions ( π and π + ), charged kaons ( K and K + ), anti-protons ( p ¯ ), and protons (p) produced in mid-rapidity interval (in most cases) in central gold&nd...

  • Article
  • Open Access
7 Citations
3,009 Views
10 Pages

Recent multi-channel astrophysics observations and the soon-to-be published new measured electromagnetic and gravitation data provide information on the inner structure of the compact stars. These macroscopic observations can significantly increase o...

  • Review
  • Open Access
47 Citations
5,264 Views
23 Pages

Group Field Theory Condensate Cosmology: An Appetizer

  • Andreas G. A. Pithis and
  • Mairi Sakellariadou

This contribution is an appetizer to the relatively young and fast-evolving approach to quantum cosmology based on group field theory condensate states. We summarize the main assumptions and pillars of this approach which has revealed new perspective...

  • Article
  • Open Access
3 Citations
2,893 Views
11 Pages

Averaging and the Shape of the Correlation Function

  • Boris Tomášik,
  • Jakub Cimerman and
  • Christopher Plumberg

A brief pedagogical introduction to correlation femtoscopy is given. We then focus on the shape of the correlation function and discuss the possible reasons for its departure from the Gaussian form and better reproduction with a Lévy stable di...

  • Article
  • Open Access
13 Citations
3,872 Views
26 Pages

In a multiverse setting, we expect to be situated in a universe that is exceptionally good at producing life. Though the conditions for what life needs to arise and thrive are currently unknown, many will be tested in the coming decades. Here we inve...

  • Review
  • Open Access
8 Citations
4,951 Views
11 Pages

The classical evolution of the universe can be seen as a parametrised worldline of the minisuperspace, with the time variable t being the parameter that parametrises the worldline. The time reversal symmetry of the field equations implies that for an...

  • Review
  • Open Access
15 Citations
3,094 Views
14 Pages

Multi-Critical Multi-Field Models: A CFT Approach to the Leading Order

  • Gian Paolo Vacca,
  • Alessandro Codello,
  • Mahmoud Safari and
  • Omar Zanusso

We present some general results for the multi-critical multi-field models in d > 2 recently obtained using conformal field theory (CFT) and Schwinger–Dyson methods at the perturbative level without assuming any symmetry. Results in...

  • Communication
  • Open Access
4 Citations
2,774 Views
7 Pages

Nucleosynthesis and Kilonovae from Strange Star Mergers

  • J. E. Horvath,
  • O. G. Benvenuto,
  • E. Bauer,
  • L. Paulucci,
  • A. Bernardo and
  • H. R. Viturro

In this talk, we summarize the work in progress toward a full characterization of strange star–strange star (SS–SS) mergers related to the GW/GRB/kilonova events. In addition, we show that the a priori probability constructed from the obs...

  • Article
  • Open Access
13 Citations
3,914 Views
19 Pages

By exploring more than sixty thousand quasars from the Sloan Digital Sky Survey Data Release 5, Steinhardt & Elvis discovered a sub-Eddington boundary and a redshift-dependent drop-off at higher black hole mass, possible clues to the growth histo...

  • Review
  • Open Access
12 Citations
4,786 Views
26 Pages

The exact time-dependent solution is obtained for a magnetic field growth during a spherically symmetric accretion into a black hole (BH) with a Schwarzschild metric. Magnetic field is increasing with time, changing from the initially uniform into a...

  • Article
  • Open Access
24 Citations
3,087 Views
13 Pages

Flat Connection for Rotating Vacuum Spacetimes in Extended Teleparallel Gravity Theories

  • Laur Järv,
  • Manuel Hohmann,
  • Martin Krššák and
  • Christian Pfeifer

Teleparallel geometry utilizes Weitzenböck connection which has nontrivial torsion but no curvature and does not directly follow from the metric like Levi–Civita connection. In extended teleparallel theories, for instance in f ( T ) ...

  • Communication
  • Open Access
44 Citations
2,692 Views
7 Pages

The covariant formulation of teleparallel gravity theories must include the spin connection, which has 6 degrees of freedom. One can, however, always choose a gauge such that the spin connection is put to zero. In principle this gauge may affect coun...

  • Article
  • Open Access
31 Citations
4,808 Views
32 Pages

General Relativity Measurements in the Field of Earth with Laser-Ranged Satellites: State of the Art and Perspectives

  • David M. Lucchesi,
  • Luciano Anselmo,
  • Massimo Bassan,
  • Carmelo Magnafico,
  • Carmen Pardini,
  • Roberto Peron,
  • Giuseppe Pucacco and
  • Massimo Visco

Recent results of the LARASE research program in terms of model improvements and relativistic measurements are presented. In particular, the results regarding the development of new models for the non-gravitational perturbations that affect the orbit...

  • Communication
  • Open Access
62 Citations
3,348 Views
8 Pages

Gauge Structure of Teleparallel Gravity

  • José G. Pereira and
  • Yuri N. Obukhov

During the conference Teleparallel Universes in Salamanca, we became aware of a recent paper [M. Fontanini, E. Huguet, and M. Le Delliou, Phys. Rev. D 2019, 99, 064006] in which some criticisms on the interpretation of teleparallel gravity as a gauge...

  • Communication
  • Open Access
3 Citations
2,716 Views
9 Pages

The Structure of the Hadron-Quark Combustion Zone

  • Amir Ouyed,
  • Rachid Ouyed and
  • Prashanth Jaikumar

Hadron-quark combustion in dense matter is a central topic in the study of phases in compact stars and their high-energy astrophysics. We critically reviewed the literature on hadron-quark combustion, dividing them into a “first wave” tha...

  • Review
  • Open Access
11 Citations
3,563 Views
25 Pages

Observing the Dark Sector

  • Valerio Marra,
  • Rogerio Rosenfeld and
  • Riccardo Sturani

Despite the observational success of the standard model of cosmology, present-day observations do not tightly constrain the nature of dark matter and dark energy and modifications to the theory of general relativity. Here, we will discuss some of the...

  • Article
  • Open Access
6 Citations
3,265 Views
16 Pages

We summarize the effective field theory of dark energy construction to explore observable predictions of linear Horndeski theories. We review the diagnostic of these theories on the correlation of the large-scale structure phenomenological functions:...

  • Article
  • Open Access
10 Citations
5,114 Views
20 Pages

By using complex quaternion, which is the system of quaternion representation extended to complex numbers, we show that the laws of electromagnetism can be expressed much more simply and concisely. We also derive the quaternion representation of rota...

  • Communication
  • Open Access
3 Citations
2,525 Views
9 Pages

Multiplicity Dependence in the Non-Extensive Hadronization Model Calculated by the HIJING++ Framework

  • Gábor Bíró,
  • Gergely Gábor Barnaföldi,
  • Gábor Papp and
  • Tamás Sándor Biró

The non-extensive statistical description of the identified final state particles measured in high energy collisions is well-known by its wide range of applicability. However, there are many open questions that need to be answered, including but not...

  • Article
  • Open Access
13 Citations
2,830 Views
11 Pages

Investigation of momentum space correlations of particles produced in high energy reactions requires taking final state interactions into account, a crucial point of any such analysis. Coulomb interaction between charged particles is the most importa...

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Universe - ISSN 2218-1997