- Editorial
1 Citations
2,145 Views
2 Pages
Seyfert Galaxies Astrophysics
- Luigi Foschini
Looking back in time, it is somehow surprising to see the enormous advancement made by astrophysics in just about one century [...]
- 2.6Impact Factor
- 5.2CiteScore
- 23 daysTime to First Decision
Universe, Volume 6, Issue 8
August 2020 - 28 articles
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Cover Story: The cold dark matter (CDM) model along with the cosmological constant is successful in explaining the large-scale structures of the Universe. However, in the scale of galaxies, it encounters several long-standing issues such as the disk-halo conspiracy, cusp-core problem, missing satellite problem, too-big-to-fail problem, and planes of satellite galaxies problem. In this review, we discuss the aforementioned problems and their solutions within the CDM framework. Prospects of alternative dark matter candidates in the context of small-scale problems are reviewed, which include warm dark matter, self-interacting dark matter, QCD axion, and fuzzy dark matter. We also describe several proposed modifications to the standard theory of gravity such as modified Newtonian dynamics (MOND), modified gravity (MOG), and f(R) gravity. View this paper.
Articles (28)
- Review
5 Citations
2,189 Views
23 Pages
Analogous Hawking Effect in Dielectric Media and Solitonic Solutions
- Francesco Belgiorno and
- Sergio L. Cacciatori
We review some aspects of our longstanding research concerning the analogous Hawking effect in dispersive dielectric media. We introduce nonlinear contributions in the polarization field in the relativistically covariant version of the Hopfield model...
- Review
48 Citations
4,915 Views
27 Pages
Black-Hole Models in Loop Quantum Gravity
- Martin Bojowald
Dynamical black-hole scenarios have been developed in loop quantum gravity in various ways, combining results from mini and midisuperspace models. In the past, the underlying geometry of space-time has often been expressed in terms of line elements w...
- Article
40 Citations
2,923 Views
15 Pages
Quark Stars in Massive Brans–Dicke Gravity with Tolman–Kuchowicz Spacetime
- Amal Majid and
- M. Sharif
In this paper, we construct anisotropic model representing salient features of strange stars in the framework of massive Brans–Dicke gravity. We formulate the field equations for Tolman–Kuchowicz ansatz by incorporating the MIT bag model....
- Article
7 Citations
3,620 Views
40 Pages
Dark Side of Weyl Gravity
- Petr Jizba,
- Lesław Rachwał,
- Stefano G. Giaccari and
- Jaroslav Kňap
We address the issue of a dynamical breakdown of scale invariance in quantum Weyl gravity together with related cosmological implications. In the first part, we build on our previous work [Phys. Rev. D2020, 101, 044050], where we found a non-trivial...
- Communication
4 Citations
2,247 Views
6 Pages
Possible Wormhole Candidates in Active Galactic Nuclei
- Mikhail Piotrovich,
- Serguei Krasnikov,
- Stanislava Buliga and
- Tinatin Natsvlishvili
The hypothesis is considered that the active galactic nuclei (AGNs) are wormhole (WH) mouths rather than supermassive black holes (SMBHs). We study the difference in the physical properties of such objects from those of AGNs with SMBH, as well as the...
- Article
9 Citations
2,732 Views
15 Pages
We discuss the consequences of the charge, parity, time, and mass (CPTM) extended reversal symmetry for the problems of the vacuum energy density and value of the cosmological constant. The results obtained are based on the framework with the separat...
- Communication
3 Citations
2,717 Views
8 Pages
Ionospheric Behavior of foF2 over Chinese EIA Region and Its Comparison with IRI-2016
- Peng Zhu,
- Cong Xie,
- Chunhua Jiang,
- Guobin Yang,
- Jing Liu,
- Zhengqiang Li and
- Zhengyu Zhao
The ionograms, which were recorded by the ionosonde located at Pu’er station (PUR, 22.7° N, 101.05° E, Dip Latitude 12.9° N) in the Southwest of China in the year of 2016, were used to study the ionospheric behavior of the ordinary...
- Article
2 Citations
2,134 Views
9 Pages
Intensity and Polarization of Radiation Emerging from Rotating Accretion Disc with Increasing Height
- Nikolai Silant’ev,
- Galina Alekseeva,
- Yulia Ananjevskaja and
- Viktor Novikov
We consider the radiation emission in continuum and spectral lines from rotating accretion disc with the progressive increasing height. It is known that for the plane accretion disc with homogeneous atmosphere the wave electric field E is perpendicul...
- Article
43 Citations
3,124 Views
16 Pages
Paradigms and Scenarios for the Dark Matter Phenomenon
- Paolo Salucci,
- Nicola Turini and
- Chiara di Paolo
Well known scaling laws among the structural properties of the dark and the luminous matter in disc systems are too complex to be arisen by two inert components that just share the same gravitational field. This brings us to critically focus on the 3...
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