arXiv subjects

Yu. F. Pirogov

Publications and source records attributed to Yu. F. Pirogov.

At least 19 recordsLinked to original sources

arXiv2025

Multiscalar-metric gravity: merging gravity, dark energy and dark matter

The status of a modification of General Relativity (GR) -- Spontaneously Broken Relativity (SBR) -- for merging gravity, dark energy (DE) and dark matter (DM) is presented. The modification is principally grounded on a multiscalar-metric concept of spacetime endowed with two dynamical structures: a basic metric and a set of the reversible multiscalar fields. The latter ones serve geometrically as exceptional dynamical coordinates among arbitrary kinematical/observer's ones and physically as a kind of gravitational Higgs fields producing possible spontaneous breaking of the symmetry (SSB) of relativity. The effective field theory (EFT) of the extended gravity based on the multiscalar-metric spacetime -- the metagravity -- is discussed and some of its particular realizations beyond GR as SBR are explicated. Physically, SBR results in appearance of massive tensor and scalar gravitons. Some of the emerging consequences, problems and prospects for SBR for future deeper unification of gravity with matter in the context of the relativity and internal symmetries breaking are shortly discussed.

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arXiv2025

Quartet-metric gravity and scalar graviton dark holes: supplements

This note includes results of a study of stationary spherically symmetric ``dark holes'', objects merging central black holes and peripheral scalar graviton dark haloes arising in the framework of the modified gravity -- the quartet-metric, or more appropriately, multiscalar-metric gravity with spontaneously broken relativity as a gauge symmetry [1]. An exact solution to be considered as a basic one for the dark holes is presented. This solution may, in principle, be used for a qualitative description of the effect of asymptotically flat rotation curves in galaxies. To convert the basic solution into a more realistic one suitable for astrophysical applications, a family of modified solutions is considered. These solutions are studied numerically for representative set of free parameters. These results were reported in the talk [2] but not included into the proceedings [3] due to article length limitations. The note can be considered as a supplement to this reference.

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arXiv2014

Emergent gravity, violated relativity and dark matter

The nonlinear affine Goldstone model of the emergent gravity, built on the nonlinearly realized/hidden affine symmetry, is concisely revisited. Beyond General Relativity, the explicit violation of general invariance/relativity, under preserving general covariance, is exposed. Dependent on a nondynamical affine connection, a generally covariant second-order effective Lagrangian for metric gravity is worked out, with the general relativity violation and the gravitational dark matter serving as the signatures of emergence.

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arXiv2014

Scalar graviton as dark matter

In the report, the theory of unimodular bimode gravity built on principles of unimodular gauge invariance/relativity and general covariance is exposed. Besides the massless tensor graviton of General Relativity, the theory includes an (almost) massless scalar graviton treated as the gravitational dark matter. A spherically symmetric vacuum solution, describing the coherent scalar-graviton field for the soft-core dark halos with the asymptotically flat rotation curves, is demonstrated.

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arXiv2013

Towards the rotating scalar-vacuum black holes

The problem of merging in black holes the rotation and a massless scalar field is treated. It is argued in the comment that the Kerr-like and Demianski-like metrics in General Relativity with a free massless scalar field or in the free Brans-Dicke theory, claimed so far in the literature as an application of the Newman-Janis algorithm, prove to be invalid. Finding the missing stationary axisymmetric scalar-vacuum solution(s), containing the Kerr one, is still urgent.

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arXiv2012

Unimodular bimode gravity, grand unification and the scalar-graviton dark matter

In prior article of the author, the unimodular bimode gravity/systo-gravity, with the scalar-graviton/systolon dark matter, was worked out. To compile with the anomalous rotation curves of galaxies the scale of the local scale violation in the theory was shown to be about 10^15 GeV. In this letter, to naturally incorporate such a scale the hyper unification framework, merging systo-gravity with grand unification through matter, is constructed. The systolon, as a free propagating compression mode in metric, emerges only below the unification scale, possessing at the same time a modified high-energy behavior to be manifested at the high temperatures.

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arXiv2012

Unimodular bimode gravity and the coherent scalar-graviton field as galaxy dark matter

The explicit violation of the general gauge invariance/relativity is adopted as the origin of dark matter and dark energy of the gravitational nature. The violation of the local scale invariance alone, with the residual unimodular one, is considered. Besides the four-volume preserving deformation mode -- the transverse-tensor graviton -- the metric comprises a compression mode -- the scalar graviton, or the systolon. A unimodular invariant and general covariant metric theory of the bimode/scalar-tensor gravity is consistently worked out. To reduce the primordial ambiguity of the theory a dynamical global symmetry is imposed, with its subsequent spontaneous breaking revealed. The static spherically symmetric case in the empty, but possibly for the origin, space is studied. A three-parameter solution describing a new static space structure -- the dark lacuna -- is constructed. It enjoys the property of gravitational confinement, with the logarithmic potential of gravitational attraction at the periphery, and results in the asymptotically flat rotation curves. Comprising a super-massive dark fracture (a scalar-modified black hole) at the origin surrounded by a cored dark halo, the dark lacunas are proposed as a prototype model of galaxies, implying an ultimate account for the distributed non-gravitational matter and a putative asphericity or rotation.

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arXiv2010

Dark halos built of scalar gravitons: numerical study

In a previous article due to one of the present authors (YFP), an extension to General Relativity, violating general covariance to the residual unimodular one, was proposed. As a manifestation of such a violation, there appears the (massive) scalar graviton in addition to the massless tensor one. The former was proposed as a candidate on the dark matter in the Universe. In a subsequent article (Yu. F. Pirogov, MPLA 24, 3239, 2009;arXiv:0909.3311 [gr-qc]), an application of the extension was developed. Particularly, a regular solution to the static spherically symmetric equations in empty space was studied by means of analytical methods. This solution was proposed as a prototype model for the galaxy soft-core dark halos, with the coherent scalar-graviton field as dark matter. The present report is a supplement to the aforementioned article. The statements of the latter are verified and visualized by means of numerical analysis and symbolic calculations. The nice validity of analytical results is found.

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arXiv2010

Graviscalar dark matter and smooth galaxy halos

In the framework of the unimodular metagravity, with the scalar graviton/graviscalar dark matter, a regular anomalous one-parameter solution to the static spherically symmetric metagravity equations in empty space is found. The solution presents a smooth graviscalar halo, with a finite central density profile, qualitatively reproducing the asymptotically flat rotation curves of galaxies. To refine the description studying the axisymmetric case in the presence of luminous matter is in order.

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arXiv2009

Unimodular metagravity vs. General Relativity with a scalar field

The unimodular metagravity, with the graviscalar as a dark matter, is compared with General Relativity (GR) in the presence of a scalar field. The effect of the graviscalar on the static spherically symmetric metric is studied. An exact limit solution representing a new cosmic object, the (harmonic) graviscalar black hole, is given. The relation with the black hole in the environment of a scalar field in GR is discussed.

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arXiv2008

Scalar graviton and the modified black holes

Under the explicit violation of the general covariance to the unimodular one, the effect of the emerging scalar graviton on the static spherically symmetric metrics is studied. The main results are three-fold. First, there appears the two-parametric family of such metrics, instead of the one-parametric black-hole family in General Relativity (GR). Second, there may exist the one-parametric subfamily describing a pure gravitational object, the ``graviball'', missing in GR. Third, in a simplifying assumption, all the metrics possess the correct Newton's limit as in GR.

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arXiv2008

Minimal metagravity vs. dark matter and/or dark energy

The minimal metagravity theory, explicitly violating the general covariance but preserving the unimodular one, is applied to study the evolution of the isotropic homogeneous Universe. The massive scalar graviton, contained in the theory in addition to the massless tensor one, is treated as a source of the dark matter and/or dark energy. The modified Friedmann equation for the scale factor of the Universe is derived. The question wether the minimal metagravity can emulate the LCDM concordance model, valid in General Relativity, is discussed.

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arXiv2007

Accelerated expansion of the Universe filled up with the scalar gravitons

The concept of the scalar graviton as the source of the dark matter and dark energy of the gravitaional origin is applied to study the evolution of the isotropic homogeneous Universe. A realistic self-consistent solution to the modified pure gravity equations, which correctly describes the accelerated expansion of the spatially flat Universe, is found and investigated. It is argued that the scenario with the scalar gravitons filling up the Universe may emulate the LCDM model, reducing thus the true dark matter to an artefact.

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arXiv2006

Violating general covariance

The explicit violation of the general covariance on the whole and its minimal violation to the unimodular covariance specifically is considered. The proper extension of General Relativity is shown to describe consistently the massive scalar graviton together with the massless tensor one, as the parts of the metric. The bearing of the scalar graviton to the dark matter and dark energy is indicated.

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arXiv2005

General covariance violation and the gravitational dark matter. I. Scalar graviton

The violation of the general covariance is proposed as a resource of the gravitational dark matter. The minimal violation of the covariance to the unimodular one is associated with the massive scalar graviton as the simplest representative of such a matter. The Lagrangian formalism for the continuous medium, the perfect fluid in particular, in the scalar graviton environment is developed. The implications for cosmology are shortly indicated.

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arXiv2005

General covariance violation and the gravitational dark matter. II. Vector graviton

The (four componenet) vector graviton contained in metric, the scalar component incorporated, is attributed to the violation of the general covariance to the residual isoharmonic one. In addition to the previously studied (singlet) scalar graviton, the vector graviton may constitute one more fraction of the gravitational dark matter. The gravity interactions of the vector graviton, as well as its impact on the continuous medium are studied.

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arXiv2005

Gravity as the affine Goldstone phenomenon and beyond

The two-phase structure is imposed on the world continuum, with the graviton emerging as the tensor Goldstone boson during the spontaneous transition from the affinely connected phase to the metric one. The physics principle of metarelativity, extending the respective principle of special relativity, is postulated. The theory of metagravitation as the general nonlinear model GL(4,R)/SO(1,3) in the arbitrary background continuum is built. The concept of Metauniverse as the ensemble of the regions of the metric phase inside the affinely connected phase is introduced, and the possible bearing of the emerging multiple universes to the fine tuning of our Universe is conjectured.

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arXiv2005

Space-time: emerging vs. existing

The concept of the space-time as emerging in the world phase transition, vs. a priori existing, is put forward. The theory of gravity with two basic symmetries, the global affine one and the general covariance, is developed. Implications for the Universe are indicated.

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