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We consider a principal problem, that of the possible dominating role of self-consistent gravitational interaction in the formation of cosmic structures: voids and their walls in the local Universe. It is in the context of the Hubble tension as a possible indication of the difference in the descriptions of the late (local) and early (global) Universe. The kinetic Vlasov treatment enables us to consider the evolution of gravitating structures where the fundamental role has the modified gravitational potential with a cosmological constant, leading to the prediction of a local flow with a Hubble parameter that is nonidentical to that of the global Hubble flow. The Poisson equation for a potential with an additional repulsive term, including an integral equation formulation, is analyzed, and we predict the appearance of multiply connected two-dimensional gravitating structures and voids in the local Universe. The obvious consequence of the developed mechanism is that the cosmological constant poses a natural scaling for the voids, along with the physical parameters of their local environment, which can be traced in observational surveys., 8 pages, A&A, in press

The tidal disruption of stars in the vicinity of massive black holes is discussed in the context of $\Lambda$-gravity. The latter provides an explanation to the Hubble tension as a possible consequence of two Hubble flows, the local and global ones. The bunch of notions which play role for the considered tidal effect are obtained, along with the rate of the disrupted stars. The role of pulsars is emphasized due to their ability to penetrate up to the horizon of the massive black hole as for them the tidal radius can reach the horizon. Tidal disruption mechanism also can lead to segregation of stars by their mean density vs the distance from the black hole, the denser stars surviving at shorter distances. The interplay of the central gravity field and the repulsive $\Lambda$-term increasing with radius and its certain observational consequences are discussed., Comment: 6 pages, 3 figures; Eur.Phys.J.Plus (in press)

The property of adiabatic invariance is studied for the generalized potential satisfying the condition of identity of sphere's and point mass's gravity. That function contains a second term corresponding to the cosmological constant as weak-field General Relativity and enables to describe the dynamics of groups and clusters of galaxies and the Hubble tension as a result of two flows, local and global ones. Using the adiabatic invariance approach we derive the orbital parameters via Weierstrass functions, including the formula for the eccentricity which explicitly reveals the differences from the Kepler problem., 6 pages, 2 figures; Eur. Phys. J. Plus (in press)

The emergence of one and two-dimensional configurations -- Zeldovich pancakes -- progenitors of the observed filaments and clusters and groups of galaxies, is predicted by means of a developed kinetic approach in analyzing the evolution of initial density perturbations. The self-consistent gravitational interaction described by Vlasov-Poisson set of equations with branching conditions is shown to predict two-dimensional structures as of layers of increased density and voids between them, i.e. the cellular macro-structure of the Universe. The modified potential of weak-field General Relativity is involved, which enables one to explain the Hubble tension, revealing the conceptual discrepancy in the local galactic flows and the cosmological expansion. This demonstrates the possible essential role of self-consistent gravity in the formation of the cosmic web., Comment: 8 pages, 1 fig., Eur.Phys.J.Plus (in press), to match the published version

Frame dragging, one of the outstanding phenomena predicted by General Relativity, is efficiently studied by means of the laser-ranged satellites LARES, LAGEOS and LAGEOS 2. The accurate analysis of the orbital perturbations of Earth's solid and ocean tides has been relevant for increasing the accuracy in the test of frame-dragging using these three satellites. The Earth's tidal perturbations acting on the LARES satellite are obtained for the 110 significant modes of corresponding Doodson number and are exhibited to enable the comparison to those of the LAGEOS and LAGEOS-2 satellites. For LARES we represent 29 perturbation modes for l=2,3,4 for ocean tides., Comment: 14 pages, 9 figures, to appear in Eur Phys J Plus (subm. Sept 20, 2017)

Planck's data acquired during the first 15.4 months of observations towards both the disk and halo of the M31 galaxy are analyzed. We confirm the existence of a temperature asymmetry, previously detected by using the 7-year WMAP data, along the direction of the M31 rotation, therefore indicative of a Doppler-induced effect. The asymmetry extends up to about 10 degrees (about 130 kpc) from the M31 center. We also investigate the recent issue raised in Rubin and Loeb (2014) about the kinetic Sunyaev-Zeldovich effect from the diffuse hot gas in the Local Group, predicted to generate a hot spot of a few degrees size in the CMB maps in the direction of M31, where the free electron optical depth gets the maximum value. We also consider the issue whether in the opposite direction with respect to the M31 galaxy the same effect induces a minimum in temperature in the Planck's maps of the sky. We find that the Planck's data at 100 GHz show an effect even larger than that expected., 4 pages, 1 table, 2 figures, in press as a Letter in A&A

This list of 10 problems and their subsequent discussion by prominent scholars at the workshop in Geneva Observatory, 1993, were published in Lecture Notes in Physics, 1994, not too reachable now. The problems cover Theory, Computer Simulations (including regarding Lyapunov exponents and the search of codes radically differing from standard N-body ones) and Observations. The elapsed 20 year period enables to reveal the occurred developments, if any, on each problem and the validity of predictions made by experts., Comment: 12 pages, 2 figures

According to General Relativity, as distinct from Newtonian gravity, motion under gravity is treated by a theory that deals, initially, only with test particles. At the same time, satellite measurements deal with extended bodies. We discuss the correspondence between geodesic motion in General Relativity and the motion of an extended body by means of the Ehlers-Geroch theorem, and in the context of the recently launched LAser RElativity Satellite (LARES). Being possibly the highest mean density orbiting body in the Solar system, this satellite provides the best realization of a test particle ever reached experimentally and provides a unique possibility for testing the predictions of General Relativity., Comment: 4 pages, 1 image

The rareness of nearby supernovae ensures particular value to the historic records for determination of their light curves. We provide the translation of 13th century Armenian chronicle of Hetum, which by its unexpected association to Cronaca Rampona and other chronicles can influence the debates whether there are reliable European records of the supernova of 1054 AD, as well as the analysis of the records vs the conjunction with the Moon and their role in assigning of the Type I or II to that supernova., to appear in The Observatory (UK), 3 pages, 1 photo of the ancient manuscript

In arxiv:1108.5354 the Kolmogorov-Smirnov (K-S) test and Kolmogorov stochasticity parameter (KSP) is applied to CMB data. Their interpretation of the KSP method, however, lacks essential elements. In addition, their main result on the Gaussianity of CMB was not a matter of debate in previous KSP-CMB studies which also included predictions on cold spots, point sources., 3 pages

New analysis confirms our earlier claim [1], [7] of circles of notably low temperature variance, often in concentric sets, in the cosmic microwave background (CMB), discernable in WMAP data. Their reality can be interpreted as evidence of supermassive black-hole encounters in a previous aeon, as predicted by conformal cyclic cosmology (CCC) [2]. Counter arguments [4-6] pointed out that such circles arise, at similar frequency, also in simulated data using WMAP's CMB power spectrum, plus random input. We responded [7] that if such circles contribute to CMB, this influences the power spectrum, enhancing such circles in simulations. We confirm this here, but show that if the theoretical LCDM power spectrum is used instead, then the low-variance circles disappear. This is evidence that the LCDM model gives an incomplete explanation of the CMB, missing crucial information, which is provided by incorporating low-variance circles of CCC. The excellent agreement between theoretical LCDM and observed power spectrum, even for fairly large l-values, does not reveal this discrepancy, of relevance only at larger l-values where agreement is weak. We point out various non-random aspects of the circles, seen both in the true data and in simulations with WMAP power spectrum, but not with the theoretical LCDM spectrum. We also show the spatial distribution of concentric circle sets to be very non-random in the true WMAP data (perhaps owing to large-scale mass inhomogeneities distorting CCC's circle shapes), in complete contrast with simulations with WMAP power spectrum, where such circle sets are much sparser and closer to average temperature. These features are fully consistent with CCC (and with an earlier analysis [8] that the random Gaussian component in the CMB is only around 0.2 in the total CMB signal) but do not readily fit in with the random initial fluctuations of standard inflation., 8 pages, 5 figures

Two groups [3,4] have confirmed the results of our paper concerning the actual existence of low variance circles in the cosmic microwave background (CMB) sky. They also point out that the effect does not contradict the LCDM model - a matter which is not in dispute. We point out two discrepancies between their treatment and ours, however, one technical, the other having to do with the very understanding of what constitutes a Gaussian random signal. Both groups simulate maps using the CMB power spectrum for LCDM, while we simulate a pure Gaussian sky plus the WMAP's noise, which points out the contradiction with a common statement [3] that "CMB signal is random noise of Gaussian nature". For as it was shown in [5], the random component is a minor one in the CMB signal, namely, about 0.2. Accordingly, the circles we saw are a real structure of the CMB sky and they are not of a random Gaussian nature. Although the structures studied certainly cannot contradict the power spectrum, which is well fitted by LCDM model, we particularly emphasize that the low variance circles occur in concentric families, and this key fact cannot be explained as a purely random effect. It is, however a clear prediction of conformal cyclic cosmology., 2 pages

We briefly report on a crater on the western slope of Mt.Ararat . It is located in an area closed to foreigners at an altitude around 2100m with geographic coordinates 39\deg 47' 30"N, 44\deg 14' 40"E. The diameter of the crater is around 60-70m, the depth is up to 15m. The origin of the crater, either of meteorite impact or volcanic, including the evaluation of its age, will need detailed studies., Comment: 2 pages, 1 color image, to appear in The Observatory (February 2011)

Conformal cyclic cosmology (CCC) posits the existence of an aeon preceding our Big Bang 'B', whose conformal infinity 'I' is identified, conformally, with 'B', now regarded as a spacelike 3-surface. Black-hole encounters, within bound galactic clusters in that previous aeon, would have the observable effect, in our CMB sky, of families of concentric circles over which the temperature variance is anomalously low, the centre of each such family representing the point of 'I' at which the cluster converges. These centres appear as fairly randomly distributed fixed points in our CMB sky. The analysis of Wilkinson Microwave Background Probe's (WMAP) cosmic microwave background 7-year maps does indeed reveal such concentric circles, of up to 6{\sigma} significance. This is confirmed when the same analysis is applied to BOOMERanG98 data, eliminating the possibility of an instrumental cause for the effects. These observational predictions of CCC would not be easily explained within standard inflationary cosmology., Comment: 8 pages, 6 figs

The recently shown two premises (Gurzadyan 2000), i.e. the absence of 56/64 year Venus cycle constraints, at the importance of the 8-year cycle in the Venus Tablet, stimulated new studies on the Chronology of the Ancient Near East (2nd millennium BC). The analysis by B.Banjevic using both premises, however, did not provide anchors of strenght similar to those of Ur III eclipses, while available solar eclipses lack unambiguous links to historical events. The Ultra-Low chronology (Gasche et al 1998), therefore, has to be considered as currently the one most reliably based on ancient astronomical records.

The introduction of the three interpretational paradigms for Gamma-Ray Bursts (GRBs) and recent progress in understanding the X- and gamma ray luminosity in the afterglow allow us to make assessments about the astrophysical settings of GRBs. In particular, we evidence the distinct possibility that some GRBs occur in a binary system. This subclass of GRBs manifests itself in a "tryptich": one component formed by the collapse of a massive star to a black hole, which originates the GRB; a second component by a supernova and a third one by a young neutron star born in the supernova event. Similarly, the understanding of the physics of quantum relativistic processes during the gravitational collapse makes possible precise predictions about the structure of short GRBs., 8 pages, 2 figures, to appear in the Proceedings of "Gamma-Ray Burst in the Afterglow Era: 4th Workshop", held in Rome, October 18-22, 2004, L. Piro, L. Amati, S. Covino, B. Gendre (eds.), Il Nuovo Cimento C, in press

The formula for the dark energy, derived by Padmanabhan in a recent Letter to Editor (Class.Quantum Grav. September 2005, the formula given in its Abstract), was actually derived 4 years earlier ourselves in astro-ph/0105245; Mod.Phys.Lett. A18, 561, 2003. Among dozens of references in that Letter, no quotation to our paper. Based on the same Zeldovich idea on vacuum fluctuations, Padmanabhan derives it from scaling considerations, while we had gone into more details and shown that the formula fits the observed value of the cosmological constant if l=0 modes are relevant., Comment: missing factor 2 added; refs added

The ellipticity of the anisotropy spots of the Cosmic Microwave Background measured by the Wilkinson Microwave Anisotropy Probe (WMAP) has been studied. We find an average ellipticity of about 2, confirming with a far larger statistics similar results found first for the COBE-DMR CMB maps, and then for the BOOMERanG CMB maps. There are no preferred directions for the obliquity of the anisotropy spots. The average ellipticity is independent of temperature threshold and is present on scales both smaller and larger than the horizon at the last scattering. The measured ellipticity characteristics are consistent with being the effect of geodesics mixing occurring in an hyperbolic Universe, and can mark the emergence of CMB ellipticity as a new observable constant describing the Universe. There is no way of simulating this effect. Therefore we cannot exclude that the observed behavior of the measured ellipticity can result from a trivial topology in the popular flat $��$-CDM model, or from a non-trivial topology., 10 pages, 5 figures, the version to appear in Mod.Phys.Lett. A

Bit strings rather than byte files can be a mode of transmission both for intelligent signals and for travels of extraterrestrial life. Kolmogorov complexity, i.e. the minimal length of a binary coded string completely defining a system, can then, due to its universality, become a key concept in the strategy of the search of extraterrestrials. Evaluating, for illustration, the Kolmogorov complexity of the human genome, one comes to an unexpected conclusion that a low complexity compressed string - analog of Noah's ark - will enable the recovery of the totality of terrestrial life. The recognition of bit strings of various complexity up to incompressible Martin-L\"{o}f random sequences, will require a different strategy for the analysis of the cosmic signals. The Fermi paradox "Where is Everybody?" can be viewed under in the light of such information panspermia, i.e. a Universe full of traveling life streams., Comment: Refs added. To appear in The Observatory

In the summer of 1929 Andrei Kolmogorov and Pavel Aleksandrov visited lake Sevan in Armenia and lived in a cell in the monastery on the island. During about a month they not only enjoyed the beauties of the lake, but actively continued their research, Alexandrov working on "Aleksandrov-Hopf" (P.Alexandroff, H.Hopf, Topologie, Berlin, 1935), Kolmogorov on the paper "On analytic methods in the theory of probability". Both mathematicians mentioned Sevan in their memoirs many decades later. They visited also other sites of Armenia and climbed Mt.Aragatz.

This illustrated article represents a popular account of the study of the Babylonian astronomical records of Enuma Anu Enlil tablet series i.e. of the Venus Tablet of Ammisaduqa and of two lunar eclipses linked with the IIIrd dynasty of Ur, having resulted in the proposal of Ultra-Low chronology of the Near East in II millennium B.C. The emerged Ultra-Low chronology is by 96 years shorter than the conventional Middle chronology and by now is supported by various independent studies. Tables of relative chronologies of principal kingdoms of Mesopotamia are given, along with some dates associated with the fall of Babylon in II millennium B.C. The technical details are given in the book by H.Gasche, J.A.Armstrong, S.W.Cole and V.G.Gurzadyan, "Dating the Fall of Babylon" (Mesopotamian History and Environment, Series II, University of Ghent and Chicago Press, 1998) and in subsequent articles.

The graph-theoretical S-tree technique developed for the study of the nonlinear N-body systems, is used for the study for the first time of the substructure of a high redshift cluster of galaxies, namely of MS 1054-03, z\simeq 0.8. Nearby galaxy clusters studied via the same S-tree code reveal several clearly distinguished subgroups with significant bulk velocities. Therefore the study of distant clusters can enable to trace the evolution of their dynamics over cosmological time scales. The study of the MS 1054-03 showed a different structure, i.e. no evidence of merging subgroups but only of a core of galaxies with velocity dispersion about 700 km s^{-1} while the velocity dispersion of the main cluster 1870 km s^{-1}. Further study of samples of high redshift clusters will enable to conclude whether this discrepancy in the structure and dynamics between nearby and distant galaxy clusters is a genuine evolutionary effect., to appear in NUovo Cimento B

The recent study of BOOMERanG 150 GHz Cosmic Microwave Background (CMB) radiation maps have detected ellipticity of the temperature anisotropy spots independent on the temperature threshold. The effect has been found for spots up to several degrees in size, where the biases of the ellipticity estimator and of the noise are small. To check the effect, now we have studied, with the same algorithm and in the same sky region, the WMAP maps. We find ellipticity of the same average value also in WMAP maps, despite of the different sensitivity of the two experiments to low multipoles. Large spot elongations had been detected also for the COBE-DMR maps. If this effect is due to geodesic mixing and hence due to non precisely zero curvature of the hyperbolic Universe, it can be linked to the origin of WMAP low multipoles anomaly., More explanations and two references added

We outline the priority of high quality data of astronomical content as our strategy for the analysis of the ancient astronomical records in the search of the absolute chronology of the Near East in II millennium BC. The correspondingly defined set of data for two lunar eclipses of EAE 20 and 21 tablets linked to Ur III period enables us the choice of eclipses of 27 June 1954 BC and 17 March 1912 BC; here the information on the exit position of the darkening of the lunar disk acts as a crucial informator survived in the records. We then discuss why the 56/64 year Venus cycle cannot be traced in the Venus Tablet and therefore cannot serve as an anchor for the search of chronologies. The month length method is discussed as well. In sum the available data support the Ultra-Low Chronology proposed in the book by H.Gasche, J.A.Armstrong, S.W.Cole and V.G.Gurzadyan, "Dating the Fall of Babylon" (1998) and, particularly, leave no astronomical background for the High Chronology. Ultra-Low Chronology is supported also by archaeological, dendrochronological, Assyrian king lists and other data as summarized at the Intern. Colloquium on Ancient Near Eastern Chronology (Ghent, July, 2000).

I argue that the widely adopted framework of stellar dynamics survived since 1940s, is not fitting the current knowledge on non-linear systems. Borrowed from plasma physics when several fundamental features of perturbed non-linear systems were unknown, that framework ignores the difference in the role of perturbations in two different classes of systems, in plasma with Debye screening and gravitating systems with no screening. Now, when the revolutionary role of chaotic effects is revealed even in planetary dynamics i.e. for nearly integrable systems, one would expect that for stellar systems, i.e. non-integrable systems, their role have to be far more crucial. Indeed, ergodic theory tools already enabled to prove that spherical stellar systems are exponentially instable due to N-body interactions, while the two-body encounters, contrary to existing belief, are not the dominating mechanism of their relaxation. Chaotic effects distinguish morphological and other properties of galaxies. Using the Ricci curvature criterion, one can also show that a central massive object (nucleus) makes the N-body gravitating system more instable (chaotic), while systems with double nuclei are even more instable than those with a single one., Comment: Talk delivered at Joint Discussion 11, IAU XXVth General Assembly, Sydney, July,2003, to appear in Highlights of Astronomy, vol.13

It is shown that the refraction near the horizon is introducing an additional bias into the Venus Tablet of Ammisaduqa, which is able to influence the interpretation of the data. We then discuss the attempts to link certain solar eclipses to the birth of Shamshi-Adad and conclude that a record of a single solar eclipse without description of details and/or unambiguous historical links, can hardly act as a reliable anchor.

We have measured the ellipticity of several degree scale anisotropies in the BOOMERanG maps of the Cosmic Microwave Background (CMB) at 150 GHz. The average ellipticity is around 2.6-2.7. The biases of the estimator of the ellipticity and for the noise are small in this case. Large spot elongation had been detected also for COBE-DMR maps. If this effect is due to geodesic mixing, it would indicate a non precisely zero curvature of the Universe which is among the discussed reasons of the WMAP low multipole anomaly. Both effects are related to the diameter of the Universe: the geodesics mixing through hyperbolic geometry, low multipoles through boundary conditions.This common reason can also be related with the origin of the the cosmological constant: the modes of vacuum fluctuations conditioned by the boundary conditions lead to a value of the cosmological constant being in remarkable agreement with the supernovae observations., Comment: Added: two co-authors and a comment on the possible relation of the discussed CMB properties with the origin of the observed value of the cosmological constant

The major problem posed by the Fermi-Pasta-Ulam work was the relaxation (thermalization) of a many-body system. We review two approaches to this problem, the ergodic theory and Langevin (stochastic) equation ones, which have been applied for the description of statistical mechanics of stellar systems. Among the particular problems that we consider, are 1-dimensional long-range interacting systems and iterated maps and 3-dimensional N-body gravitating systems., To appear in "Fermi and Astrophysics" (Proceed. of ICRA Workshop dedicated to 100th birthday of E.Fermi, Rome-Pescara, 2001), World Scientific. New version in WS macros

Some points related to the exponential instability of N-body gravitating systems and which are misinterpreted in various papers are clarified. Exponential instability is a phenomenon essentially responsible for the relaxation, evolutionary, morphological and other properties of certain type of galaxies and star clusters., in "The Chaotic Universe", (V.G.Gurzadyan and R.Ruffini, eds.), p.245, World Sci. 2000; the paper by M.Valluri and D.Merritt in the same volume, p.229; astro-ph/9909403

The information theory approach is suggested to the Cosmic Microwave Background (CMB) problem for negatively curved homogeneous and isotropic Universe. Namely, the Kolmogorov complexity of anisotropy of spots in CMB sky maps is proposed as a new descriptor for revealing crucial cosmological information, particularly on the curvature of the Universe. Such profound descriptor can be especially valuable while analyzing the data of forthcoming space and ground based experiments MAP, Planck surveyor, CAT, etc., Comment: to appear in Europhysics Letters

The properties of the Cosmic Microwave Background (CMB) radiation must be different in flat, positively and negatively curved universes. This fact leads to a direct way of determining the geometry of the universe. The signature of the predicted effect of geodesic mixing, i.e., of the `chaotic' behavior of photon beams in negatively curved spaces peculiar to Anosov systems with strong statistical properties, has been detected while studying the COBE-DMR 4-year data \cite{GT}. This possible observation of the negative curvature of the universe suggests the need to search for more effective ways to analyze the CMB data expected from forthcoming high precision experiments. Information theory offers such a descriptor for the CMB sky maps - the Kolmogorov complexity - as well as provides novel insight into the problem of the loss of information and time asymmetry in a hyperbolic universe., Comment: to appear in: V.G.Gurzadyan and R.Ruffini (Eds.) "The Chaotic Universe", World Sci

The relation between the thermodynamical and cosmological arrows of time is usually viewed in the context of the initial conditions of the Universe. It is a necessary but not sufficient condition for ensuring the thermodynamical arrow. We point out that in the Friedmann-Robertson-Walker Universe with negative curvature, k=-1, there is the second necessary ingredient. It is based on the geodesic mixing - the dynamical instability of motion along null geodesics in hyperbolic space. Kolmogorov (algorithmic) complexity as a universal and experimentally measurable concept can be very useful in description of this chaotic behavior using the data on Cosmic Microwave Background radiation. The formulated {\it curvature anthropic principle} states the negative curvature as a necessary condition for the time asymmetric Universe with an observer., Comment: Revtex, to appear in the proceedings of the workshop THE CHAOTIC UNIVERSE, Eds.V.G.Gurzadyan, R.Ruffini, World Sci

The S-tree method is used to estimate the redshift of the core of Coma cluster - $cz = 6953$ km s$^{-1}$ and dispersion $\sigma=949$ km s$^{-1}$. The existence of three subgroups of galaxies is revealed, one of them is associated with the cD galaxy NGC 4874, another - with NGC 4889. It is argued that these subgroups are 'galaxy associations', i.e. galactic dynamical entities moving through the main cluster. The non-stationarity of the dynamical processes ongoing in the Coma core is concluded., Comment: to appear in the proceedings of Coma Cluster meeting (Marseille, June, 1997)

The geodesics followed by cosmic microwave background (CMB) photons show different behaviours depending on the geometry of space. Namely, the effect of `mixing geodesics' predicts a distinct signature in CMB maps: threshold-independent elongated anisotropy spots in negatively curved geometries. We have found statistically significant sign for spot elongation in the COBE four year maps. This can be a direct indication for the negative curvature of the Universe., Comment: Talk given at VIII Marcel Grossmann Meeting (Jerusalem, 1997); to appear in proceedings; Latex 4 pages

The existence of period-doubling bifurcations is shown for the Konishi-Kaneko map. The value of the control parameter $k_{\infty}$ corresponding to the transition to the chaotic phase is estimated, along with the Feigenbaum universal number. This type of facts can be crucial in diagnosis of chaos in stellar dynamics., Comment: Latex file 4 pages; Il Nuovo Cimento, vol.112B, 1997

We report the results of an analysis of the hierarchical properties of the cluster of galaxies Abell 119. Observational data from the ESO Nearby Abell Cluster Survey (ENACS) are used, complemented by data from previous studies, while the analysis is performed with the S-tree method. The main physical system and its three subgroups with truncated Gaussian velocity distributions are identified; due to their remarkable physical features and possible cosmogonical mission we call these subgroups ``galaxy associations''. The mass centre of the core of main system is shown to coincide with the X-ray centre of the cluster. An alignment of the mass centres of the 3 galaxy associations is also shown., Latex file, 7 pages, 2 figures, .ps files can be obtained from the authors. To appear in The Observatory, vol.116, No.1134, 1996

Results of precise measurements of the periods of pulsars discovered in the central regions of globular clusters are shown to be approaching the capabilities of testing the existence of a central black hole. For example, in the case of M 15 the available data on two pulsars PSR 2129+1210A and PSR 2129+1209D seem to exclude the existence of a black hole, the presence of which was instead supported by recent Hubble Space Telescope data on surface brightness profile (Yanny et al. 1994). The fluctuations of the gravitational field caused by the stars of the system are enough to explain the acceleration observed for both pulsars. In the case of the Galactic center, additional data are needed for similar definite conclusions., Comment: laa-style Latex 4 pages; to appear in Astronomy and Astrophysics

When considering the statistical properties of a bundle of cosmic microwave background (CMB) photons propagating through space, the effect of `mixing geodesics' appears with a distinct signature that depends on the geometry of space. In a Universe with negative curvature this effect is expected to produce elongated anisotropy spots on CMB maps. We used COBE-DMR data to look for such effect. Based on the analysis of a measure of eccentricity of hot spots it appears that there is a clear indication of an excess eccentricity of hot spots with respect to that expected from noise alone. This result must be interpreted with caution as this effect can be due in part to galactic emission. If the detected eccentricity of anisotropy spots can be attributed to the effect of mixing it implies the negative curvature of the Universe and a value of $\Omega < 1$., Comment: Text 5 pages, AA Latex style file, with 2 postscript figures. To appear in Astronomy and Astrophysics

As was shown before (Gurzadyan and Kocharyan, 1992, 1993ab) the statistical properties (exponential mixing) of motion of CMB photon beams in Friedmann Universe with negative curvature can have definite observable consequences including the decrease of the CMB anisotropy amplitude after the last scattering, distortion of images on CMB sky maps. Here we consider one more consequence concerning the behaviour of temperature autocorrelation function C(\theta,\beta), where \theta is the modulation (separation) angle, and \beta the observing beam effective angle. We prove that in the Universe with negative curvature any spectrum of perturbations at last scattering epoch becomes a scale-invariant by present time. It is also predicted that the temperature autocorrelation function should increase while obtained from measurements with small beam sizes within some mixing beam angle., Comment: 6 pages, plain LaTeX, IC/93/419

In two previous papers we presented the LARES 2 space experiment aimed at a very accurate test of frame-dragging and at other tests of fundamental physics and measurements of space geodesy and geodynamics. We presented the error sources of the LARES 2 experiment, its error budget and Monte Carlo simulations and covariance analyses confirming an accuracy of a few parts in one thousand in the test of frame-dragging. Here we discuss the impact of the orbital perturbation known as the de Sitter effect, or geodetic precession, in the error budget of the LARES 2 frame-dragging experiment. We show that the uncertainty in the de Sitter effect has a negligible impact in the final error budget because of the very accurate results now available for the test of the de Sitter precession and because of its very nature. The total error budget in the LARES 2 test of frame-dragging remains at a level of the order of 0.2%, as determined in the first two papers of this series., 9 pages

Galactic halos are of great importance for our understanding of both the dark matter nature and primordial non-Gaussianity in the perturbation spectrum, a powerful discriminant of the physical mechanisms that generated the cosmological fluctuations observed today. In this paper we analyze {\it Planck} data towards the galaxy M104 (Sombrero) and find an asymmetry in the microwave temperature which extends up to about $1 \degr$ from the galactic center. This frequency-independent asymmetry is consistent with that induced by the Doppler effect due to the galactic rotation and we find a probability of less than about $0.2\%$ that it is due to a random fluctuation of the microwave background. In addition, {\it Planck} data indicate the relatively complex dynamics of the M104 galactic halo, and this appears to be in agreement with previous studies. In view of our previous analysis of the dark halos of nearby galaxies, this finding confirms the efficiency of the method used in revealing and mapping the dark halos around relatively nearby edge-on galaxies., Comment: 6 pages, 5 Figures, in press on Astronomy and Astrophyiscs

Satellite laser-ranging is successfully used in space geodesy, geodynamics and Earth sciences; and to test fundamental physics and specific features of General Relativity. We present a confirmation to approximately one part in a billion of the fundamental weak equivalence principle (uniqueness of free fall) in the Earth's gravitational field, obtained with three laser-ranged satellites, at previously untested range and with previously untested materials. The weak equivalence principle is at the foundation of General Relativity and of most gravitational theories., Comment: 24 pages, 3 figures

We report the improved test of frame-dragging, an intriguing phenomenon predicted by Einstein's General Relativity, obtained using 7 years of Satellite Laser Ranging (SLR) data of the satellite LARES (ASI, 2012) and 26 years of SLR data of LAGEOS (NASA, 1976) and LAGEOS 2 (ASI and NASA, 1992). We used the static part and temporal variations of the Earth gravity field obtained by the space geodesy mission GRACE (NASA and DLR) and in particular the static Earth's gravity field model GGM05S augmented by a model for the 7-day temporal variations of the lowest degree Earth spherical harmonics. We used the orbital estimator GEODYN (NASA). We measured frame-dragging to be equal to 0.9910 +/- 0.02, where 1 is the theoretical prediction of General Relativity normalized to its frame-dragging value and +/- 0.02 is the estimated systematic error due to modelling errors in the orbital perturbations, mainly due to the errors in the Earth's gravity field determination. Therefore, our measurement confirms the prediction of General Relativity for frame-dragging with a few percent uncertainty., Comment: Submitted on September 27, 2019; accepted for publication on October 8, 2019 and published on October 23, 2019 in The European Physical Journal C: Eur. Phys. J. C (2019) 79:872 https://doi.org/10.1140/epjc/s10052-019-7386-z

In 2016, we published "A test of general relativity using the LARES and LAGEOS satellites and a GRACE Earth gravity model. Measurement of Earth's dragging of inertial frames [1]", a measurement of frame-dragging, a fundamental prediction of Einstein's theory of General Relativity, using the laser-ranged satellites LARES, LAGEOS and LAGEOS 2. The formal error, or precision, of our test was about 0.2% of frame-dragging, whereas the systematic error was estimated to be about 5%. In the 2017 paper "A comment on "A test of general relativity using the LARES and LAGEOS satellites and a GRACE Earth gravity model by I. Ciufolini et al." "by L. Iorio [2] (called I2017 in the following), it was incorrectly claimed that, when comparing different Earth gravity field models, the systematic error in our test due to the Earth's even zonal harmonics of degree 6, 8, 10 could be aslarge as 15%, 6% and 36%, respectively. Furthermore, I2017 contains other, also incorrect, claims about the number of necessary significant decimal digits of the coefficients used in our test (claimed to be nine), in order to eliminate the largest uncertainties in the even zonals of degree 2 and 4, and about the non-repeatability of our test. Here we analyze and rebut those claims in I2017., Comment: Published on The European Physical Journal C 78, no. 11 (2018): 880

This paper is a follow-up of a previous paper about the M82 galaxy and its halo based on Planck observations. As in the case of M82, so also for the M81 galaxy a substantial North-South and East-West temperature asymmetry is found, extending up to galactocentric distances of about $1.5^\circ$. The temperature asymmetry is almost frequency independent and can be interpreted as a Doppler-induced effect related to the M81 halo rotation and/or triggered by the gravitational interaction of the galaxies within the M81 Group. Along with the analogous study of several nearby edge-on spiral galaxies, the CMB temperature asymmetry method thus is shown to act as a direct tool to map the galactic haloes and/or the intergalactic bridges, invisible in other bands or by other methods., 5 pages, 3 figures, in press in Astronomy and Astrophysics, Main Journal

Laser ranging satellites have proved their efficiency for high precision testing of the effect of frame-dragging, one of remarkable predictions of the General Relativity. The analysis of the randomness properties of the residuals of LAGEOS and LAGEOS 2 satellites reveals the role of the thermal thrust -- Yarkovsky effect -- on the satellite which was in the orbit for longer period (LAGEOS). We also compute Earth's tidal modes affecting the satellite LARES. The recently obtained 5\% accuracy limit reached for the frame dragging effect based on the 3.5 year data of LARES analysed together with those of LAGEOS satellites and using the Earth gravity model of GRACE satellite, is also represented., 7 pages 3 figures

We introduce the LARES 2 space experiment recently approved by the Italian Space Agency (ASI). The LARES 2 satellite is planned for launch in 2019 with the new VEGA C launch vehicle of ASI, ESA and ELV. The orbital analysis of LARES 2 experiment will be carried out by our international science team of experts in General Relativity, theoretical physics, space geodesy and aerospace engineering. The main objectives of the LARES 2 experiment are gravitational and fundamental physics, including accurate measurements of General Relativity, in particular a test of frame-dragging aimed at achieving an accuracy of a few parts in a thousand, i.e., aimed at improving by about an order of magnitude the present state-of-the-art and forthcoming tests of this general relativistic phenomenon. LARES 2 will also achieve determinations in space geodesy. LARES 2 is an improved version of the LAGEOS 3 experiment, proposed in 1984 to measure frame-dragging and analyzed in 1989 by a joint ASI and NASA study., 16 pages

We used Planck data to study the M33 galaxy and find a substantial temperature asymmetry with respect to its minor axis projected onto the sky plane. This temperature asymmetry correlates well with the HI velocity field at 21 cm, at least within a galactocentric distance of 0.5 degree, and it is found to extend up to about 3 degrees from the galaxy center. We conclude that the revealed effect, that is, the temperature asymmetry and its extension, implies that we detected the differential rotation of the M33 galaxy and of its extended baryonic halo., 8 pages, 8 figures, in press on Astronomy and Astrophysics, main journal

We summarize a laser-ranged satellite test of frame-dragging, a prediction of General Relativity, and then concentrate on the estimate of thermal thrust, an important perturbation affecting the accuracy of the test. The frame dragging study analysed 3.5 years of data from the LARES satellite and a longer period of time for the two LAGEOS satellites. Using the gravity field GGM05S obtained via the Grace mission, which measures the Earth's gravitational field, the prediction of General Relativity is confirmed with a 1-$\sigma$ formal error of 0.002, and a systematic error of 0.05. The result for the value of the frame dragging around the Earth is $\mu$ = 0.994, compared to $\mu$ = 1 predicted by General Relativity. The thermal force model assumes heat flow from the sun (visual) and from Earth (IR) to the satellite core and to the fused silica reflectors on the satellite, and reradiation into space. For a roughly current epoch (days 1460 - 1580 after launch) we calculate an average along-track drag of -0.50 $pm/s^{2}$., Comment: 6 pages, multiple figures in Proceedings of Metrology for Aerospace (MetroAeroSpace), 2016 IEEE

Planck data towards the galaxy M82 are analyzed in the 70, 100 and 143 GHz bands. A substantial north-south and East-West temperature asymmetry is found, extending up to 1 degree from the galactic center. Being almost frequency-independent, these temperature asymmetries are indicative of a Doppler-induced effect regarding the line-of-sight dynamics on the halo scale, the ejections from the galactic center and, possibly, even the tidal interaction with M81 galaxy. The temperature asymmetry thus acts as a model-independent tool to reveal the bulk dynamics in nearby edge-on spiral galaxies, like the Sunyaev-Zeldovich effect for clusters of galaxies., 4 pages, 3 figures, in press on A&A