Papers published in 2021 include:

• B. Zhang, Y.Wang, L. Li; Dissecting the Energy Budget of a Gamma-Ray Burst Fireball; The Astrophysical Journal Letters, 909, L3 (2021)

• L. Li, B. Zhang; Testing the High-latitude Curvature Effect of Gamma-Ray Bursts with Fermi Data: Evidence of Bulk Acceleration in Prompt Emission; The Astrophysical Journal Supplement Series, 253, 43 (2021)

• L. Li, F. Ryde, A. Pe’er, H.-F. Yu, Z. Acuner; The Astrophysical Journal Supplement Series; 254, 35 (2021)

• Y.Wang; Do All Long-duration Gamma-Ray Bursts Emit GeV Photons?;The Astrophysical Journal, 913, 86 (2021)

• L. Li; Searching for Observational Evidence for Binary Star Systems in Gamma-ray Bursts; Astronomy Reports, 65, 973 (2021)

• Y. Wang; Gamma-Ray Burst from Binary Star: Neutron Star and Carbon–Oxygen Core; Astronomy Reports, 65, 1077 (2021)

• R. Ruffini; Discovery of the Moment of Formation of the Black Hole in GRB 190114C; Astronomy Reports, 65, 1030 (2021)

• R. Ruffini, R. Moradi, J.A. Rueda, L. Li, N. Sahakyan, Y.-C. Chen, Y. Wang, Y. Aimuratov, L. Becerra, C.L. Bianco, C. Cherubini, S. Filippi, M. Karlica, G.J. Mathews, M. Muccino, G.B. Pisani, S.-S. Xue; The morphology of the X-ray afterglows and of the jetted GeV emission in long GRBs; Monthly Notices of the Royal Astronomical Society, 504, 5301 (2021)

• R. Moradi, J.?A. Rueda, R. Ruffini, Liang Li, C.L. Bianco, S. Campion, C. Cherubini, S. Filippi, Y. Wang, and S.-S. Xue; Nature of the ultrarelativistic prompt emission phase of GRB 190114C; Phys. Rev. D, 104, 063043 (2021)

• R. Moradi, J.A. Rueda, R. Ruffini and Y.Wang; The newborn black hole in GRB 191014C proves that it is alive; Astronomy & Astrophysics, 649, A75 (2021)

Theoretical Astroparticle Physics (Page 369)

Astroparticle physics is a new field of research emerging at the intersection of particle physics, astrophysics and cosmology. We focused on several topics with three major directions of research: a) electron-positron plasma, b) thermal emission from relativistic plasma and GRBs, c) Relativistic kinetic theory and its applications; and d) ultra high energy particles.

Electron-positron plasma appear relevant for GRBs and also for the Early Universe, in laboratory experiments with ultraintense lasers, etc. Our numerical results indicate that the rates of three-particle interactions become comparable to those of two-particle ones for temperatures exceeding the electron rest-mass energy. Thus three particle interactions such as relativistic bremsstrahlung, double Compton scattering and radiative pair creation become essential not only for establishment of thermal equilibrium, but also for correct evaluation of interaction rates, energy losses etc. We found strong anisotropies in reaction rates in three-particle interactions.

We also obtained new results on propagation of ultra high energy particles, such as photons, neutrinos and protons, at cosmological distances and the limiting distance (cosmic horizon) is obtained as function of particle energy. In addition, new calculations are performed for the cosmic horizon for photons subject to photon-photon scattering.

Papers published in 2021 include:

• M. A. Prakapenia and G. V. Vereshchagin, “Numerical scheme for evaluating the collision integrals for triple interactions in relativistic plasma”, Astronomy Reports, volume 65 (2021), pp. 1011–1014.

• D. Begue, L. Li and G. V. Vereshchagin, “Is magnetically dominated outflow required to explain GRBs?”, arXiv:2201.05062, submitted to MNRAS.

Generalization of the Kerr-Newman solution (Page 389)

The unsolved problem of a physical solution in general relativity of an astrophysical object which must be characterized necessarily by four parameters, mass, charge, angular momentum and quadrupole moment, has also been debated for years and it is yet not satisfactorily solved. The presence in ICRANet of Prof. Quevedo as an Adjunct Professor has shown an important result published by Bini, Geralico, Longo, Quevedo [Class. Quant. Grav., 26 (2009), 225006]. This result has been obtained for the special case of a Mashhoon-Quevedo solution characterized only by mass, angular momentum and quadrupole moment. It has been shown that indeed such a Mashhoon-Quevedo solution can be matched to an internal solution solved in the post-Newtonian approximation by Hartle and Thorne for a rotating star.

The most important metrics in general relativity is the Kerr-Newman solution which describes the gravitational and electromagnetic fields of a rotating charged mass, characterized by its mass M, charge Q and angular momentum L in geometrical units. This solution characterizes the field of a black hole. For astrophysical purposes, however, it is necessary to take into account the effects due to the moment of inertia of the object. To attack this problem, an exact solution of the Einstein-Maxwell equations have been proposed by Mashhoon and Quevedo which posses an infinite set of gravitational and electromagnetic multipole moments. It is not clear, however, how this external solution to an astrophysical object can be matched to a physical internal solution corresponding to a physically acceptable rotating mass.

Papers published in 2021 include:

• Pugliese, Daniela, Quevedo, Hernando; “Extracting information on black hole horizons”; Nuclear Physics B, 972, 115544 (2021).

• Boshkayev, Kuantay, Konysbayev, Talgar, Kurmanov, Ergali, Luongo, Orlando, Malafarina, Daniele, Quevedo, Hernando; “Luminosity of accretion disks in compact objects with a quadrupole”; Physical Review D, 104, 084009 (2021).

• Abishev, Medeu, Beissen, Nurzada, Belissarova, Farida, Boshkayev, Kuantay, Mansurova, Aizhan, Muratkhan, Aray, Quevedo, Hernando, Toktarbay, Saken; “Approximate perfect fluid solutions with quadrupole moment”, International Journal of Modern Physics D, 30, 2150096 (2021).

• Pugliese, Daniela, Quevedo, Hernando; “Repulsive gravity effects in horizon formation”, General Relativity and Gravitation, 53, 89 (2021).

• Escamilla-Rivera, Celia, Quevedo, Hernando; “Quantum signatures from Hoava-Lifshitz cosmography”, Classical and Quantum Gravity, 38, 115009 (2021).

• Pugliese, D., Quevedo, H.; “Kerr metric Killing bundles”, The European Physical Journal C, 81, 258 (2021).

• Pineda-Reyes, V., Escamilla-Herrera, L.F., Gruber, C., Nettel, F., Quevedo, H.; “Reparametrizations and metric structures in thermodynamic phase space”, Physica A: Statistical Mechanics and its Applications, 563, 125464 (2021).

Cosmology Group of Tartu Observatory (Page 481)

Prof. Einasto has been collaborating in the previous years intensively within ICRANet about the large scale structure of the Universe and its possible fractal structure. With Prof. Einasto there is also the collaboration of Prof. G. Hutsi. Prof. Einasto is an Adjunct Professor of ICRANet and an active member of the Faculty of the IRAP PhD. Prof. Einasto has completed a book reviewing the status of the dark matter and the large scale structure of the universe published by World Scientific as Volume 14^th in the Advanced Series in Astrophysics and Cosmology Series edited by L.Z. Fang and R. Ruffini. This book covers the material of the lectures delivered in the IRAP PhD program as well as an historical perspective between the different approaches to the study of the dark matter content of the universe in the west and in the former Soviet union.

Papers published in 2021 include:

• Einasto, J., H¨utsi, G., & Einasto, M. 2021a, Correlation functions in 2D and 3D as descriptors of the cosmic web, A&A, 652, A152

• Einasto, J., H¨utsi, G., Suhhonenko, I., Liivam¨agi, L. J., & Einasto, M. 2021b, Evolution of superclusters and supercluster cocoons in various cosmologies, A&A, 647, A17

• Einasto, J., Klypin, A., H¨utsi, G., Liivam¨agi, L.-J., & Einasto,M. 2021c, Evolution of skewness and kurtosis of cosmic density fields, A&A, 652, A94

• Einasto,M., Kipper, R., Tenjes, P., Lietzen, H., Tempel, E., Liivam¨agi, L. J., Einasto, J., Tamm, A., Hein¨am¨aki, P., & Nurmi, P. 2021d, The Corona Borealis supercluster: connectivity, collapse, and evolution, A&A, 649, A51

Black Holes and Quasars (Page 499)

This report refers to the activity of Prof. Brian Punsly, who is actively participating within ICRANet with the publication of his internationally recognized book on “Black hole gravitohydromagnetics”, the first and second edition (2010) being published with Springer. In addition, Prof. Punsly have been interested in observational properties of quasars such as broad line emission excess in radio loud quasars accentuated for polar line of sight and excess narrow line widths of broad emission lines in broad absorption line quasars, showing that this is best explained by polar lines of sight.

Papers published in 2021 include:

• Punsly, Brian; Nagai, Hiroshi; Savolainen, Tuomas; Orienti, Monica, “Observing the Time Evolution of the Multicomponent Nucleus of 3C 84”, 2021, ApJ, 911, 19

• Punsly, Brian “The Bulk Flow Velocity and Acceleration of the Inner Jet in M87”, 2021, ApJ, 918, 4

• Punsly, Brian and Sina Chen “Did the Event Horizon Telescope Detect the Base of the Sub-milliarcsecond Tubular Jet in M87?”, 2021, ApJ, 921, L38

The electron-positron pairs in physics, astrophysics and cosmology (Page 503)

This problem “The electron-positron pairs in physics and astrophysics: from heavy nuclei to black holes” has been the subject of a physics reports of more than 500 references, which is inserted on page 745, by Ruffini, Vereshchagin and Xue. There, all the different aspects of the field has been reviewed: The fundamental contributions to the electron-positron pair creation and annihilation and the concept of critical electric field; Nonlinear electrodynamics and rate of pair creation; Pair production and annihilation in QED; Semi-classical description of pair production in a general electric field; Phenomenology of electron-positron pair creation and annihilation; The extraction of blackholic energy from a black hole by vacuum polarization processes. Due to the interaction of physics and astrophysics we are witnessing in these years a splendid synthesis of theoretical, experimental and observational results originating from three fundamental physical processes. They were originally proposed by Dirac, by Breit and Wheeler and by Sauter, Heisenberg, Euler and Schwinger. For almost seventy years they have all three been followed by a continued effort of experimental verification on Earth-based experiments. The Dirac process, e⁺e^- →2γ, has been by far the most successful. The Breit-Wheeler process, 2γ → e⁺e^-, although conceptually simple, being the inverse process of the Dirac one, has been by far one of the most difficult to be verified experimentally.

The e⁺e⁻ pairs generated by the vacuum polarization process around a gravitationally collapsing charged core are entangled in the electromagnetic field (R. Ruffini, L. Vitagliano, S.-S. Xue, Phys. Lett. B 573, (2003) 33), and thermalize in an electron–positron–photon plasma on a time scale ~ 10⁴ τ_C (R. Ruffini, L. Vitagliano, S.-S. Xue, Phys. Lett. B 559, (2003) 12). As soon as the thermalization has occurred, the hydrodynamic expansion of this electrically neutral plasma starts (R. Ruffini, J. Salmonson, J. Wilson, S.-S. Xue, A&A Vol. 335 (1999) 334; Vol. 359 (2000) 855). While the temporal evolution of the e⁺e⁻ gravitationally collapsing core moves inwards, giving rise to a further amplified supercritical field, which in turn generates a larger amount of e⁺e⁻ pairs leading to a yet higher temperature in the newly formed e⁺e⁻γ plasma. As a consequence, an enormous amount of pairs is left behind the collapsing core and a Dyadosphere (G. Preparata, R. Ruffini, S.-S. Xue, A&A Vol. 338 (1998) L87) is formed. see also B. Han, R. Ruffini, S.-S. Xue, Physics Review D86, 084004 (2012), R. Ruffini, and S-S. Xue, Physics Letters A377 (2013) 2450.

The Schwinger pair-production and nonlinear QED effects in a curved space time are also studied. Taking into account the Euler-Heisenberg effective Lagrangian of one-loop nonperturbative QED contributions, we formulate the Einstein-Euler-Heisenberg theory and study the solutions of nonrotating black holes with electric and magnetic charges in spherical geometry (R. Ruffini, Y.-B. Wu and S.-S. Xue, Physics Review D88, 085004 (2013)). In addition, the Schwinger pair-production and back reaction are recently studied in de Sitter space time in order to understand their roles in early Universe, some results are published (C. Stahl, E. Strobel, and S.-S. Xue, Phys. Rev. D 93, 025004 (2016); C. Stahl and S.-S. Xue, Phys. Lett B 760, 288-292 (2016); E. Bavarsad, C. Stahl and S.-S. Xue, Phys. Rev. D 94, 104011 (2016)).

An interesting aspect of effective field theories in the strong-field or strong coupling limit has recently been emphasized. We study that pair-production in super-position of static and plane wave fields, and in the strong fields expansion, the leading order behavior of the Euler-Heisenberg effective Lagrangian is logarithmic, and can be formulated as a power law (H. Kleinert, E. Strobel and S-S. Xue, Phys. Rev. D88, 025049 (2013), Annals of Physics Vol. 333 (2013) 104). We have also investigated the fundamental processes relevant to the issues of intense laser physics, pair-production (E. Strobel and S-S. Xue , Nucl. Phys B 886, (2014) 1153); two laser beams colliding with a high-energy photon (Y.-B. Wu and S-S. Xue, Phys. Rev. D 90, 013009 (2014))，as well as pair-oscillation leading to electromagnetic and gravitational radiation (W.-B. Han and S.-S. Xue, Phys. Rev. D89 (2014) 024008). We study the photon circular-polarization produced by two-laser beams collision (R. Mohammadi, I. Motie, and S.-S. Xue, Phys. Rev. A 89, 062111 (2014)), and by laser and neutrino beams collisions (Phys. Lett. B 731 (2014) 272; Phys. Rev. D 90, 091301(R) (2014)).

In order to account for future observations of GRBs photon polarizations, the possible microscopic origins and preliminary values of GRBs photon polarizations are theoretically calculated (S. Batebi, R. Mohammadi, R. Ruffini, S. Tizchang, and S.-S. Xue, Phys. Rev. D 94, 065033 (2016)). Similarly, by considering possible microscopic interactions and processes, we study the polarization of CMB in cosmology, compared with recent observations (R. Mohammadi, J. Khodagholizadeh, M. Sadegh, and S.-S. Xue, Phys. Rev. D93, 125029 (2016)). All these fundamental processes of microscopic and macroscopic physics are relevant to high-energy phenomena in relativistic astrophysics, black hole physics and laser physics, as early Universe and modern Cosmology.

The Diadotorus

Papers published in 2021 include:

• She-Sheng Xue “Gravo-thermal catastrophe in gravitational collapse and energy progenitor of Gamma-Ray Bursts”, JCAP07 (2021) 044

• S. Campion, J. A.Rueda, S. S. Xue, R. Ruffini “Magnetic field screening process in a Kerr Black Hole”, Physics Letters B Volume 820 (2021), 136562.

• Mian Zhu, Amara Ilyas, Yunlong Zheng, Yi-Fu Cai, Emmanuel N. Saridakis “Scalar and Tensor Perturbations in DHOST Bounce Cosmology ”, JCAP11 (2021) 045

• Mian Zhu, Yunlong Zheng “Improved DHOST Genesis”, JHEP11 (2021) 163

• Li-Yang Gao, Ze-Wei Zhao, She-Sheng Xue, Xin Zhang “Relieving the H0 tension with a new interacting dark energy model”, JCAP 07 (2021) 005

From nuclei to compact stars (Page 1091)

The study of compact objects such as white dwarfs, neutron stars and black holes requires the interplay between nuclear and atomic physics together with relativistic field theories, e.g., general relativity, quantum electrodynamics, quantum chromodynamics, as well as particle physics. In addition to the theoretical physics aspects, the study of astrophysical scenarios characterized by the presence of a compact object has also started to be focus of extensive research within our group. The research which has been done and is currently being developed within our group can be divided into the following topics: nuclear and atomic astrophysics, compact stars (white dwarfs and neutron stars) physics and astrophysics including radiation mechanisms, exact solutions of the Einstein and Einstein-Maxwell equations applied to astrophysical systems and critical fields and non-linear electrodynamics effects in astrophysics.

Also this year we have made progress in all the above fields of research. It is worth to mention that in the recent years it has been established a strong collaboration between the research on the observational and theoretical aspects of GRBs and the one on the physics and astrophysics aspects of white dwarfs and neutron stars. In particular, this collaboration has focused on the problem of establishing the possible progenitors of both short and long GRBs, together with the further development of the model for the explanation of the experimental data of GRBs from the radio all the way to the gamma-rays.

In this line I would like to recall the work by Becerra et al. “On the induced gravitational collapse scenario of gamma-ray bursts associated with supernovae”, ApJ 833, 107 (2016), in which we have, following our induced gravitational collapse (IGC) paradigm of long GRBs, presented numerical simulations of the explosion of a carbon–oxygen core in a binary system with a neutron-star companion. In this work we have presented simulations that follow the hypercritical accretion process triggered onto the neutron star by the supernova explosion, the associated copious neutrino emission near the NS accreting surface, as well as all relevant hydrodynamic aspects within the accretion flow including the trapping of photons. We have shown that indeed the NS can reach the critical mass and collapse to a black hole producing a GRB. Interesting new lines of research has been opened thanks to this work: we have shown that the presence of the neutron star companion near the carbon-oxygen core causes strong asymmetries in the supernova ejecta and that the GRB emission can also interact with the supernova ejecta. Both phenomena cause specific observable signatures which we are currently examining and probing in GRB data.

We have also gone further in probing neutron star binaries as progenitors of short GRBs. Especial mention has to be given in this line to the work of R. Ruffini et al., “GRB 090510: a genuine short-GRB from a binary neutron star coalescing into a Kerr-Newman black hole”, ApJ 831, 178 (2016). We are starting a new era in which, from GRB data, we can extract information on the neutron star parameters leading to black hole formation after the binary coalescence. This kind of research is also of paramount importance to put constraints on the matter content and equation of state at supranuclear densities in neutron stars.

It is also important to mention that we are performing new research on the gravitational wave emission from compact object binaries leading to GRBs, which not only is important by itself but it is relevant to establish the capabilities of current second generation gravitational wave detectors such as Advanded LIGO to detect the gravitational waves associated with GRB events. We have to mention here the work by R. Ruffini et al., “On the classification of GRBs and their occurrence rates”, ApJ 832, 136 (2016), in which we have established a novel classification of short and long GRBs, their binary progenitors, as well as their occurence rate, being the latter necessary to predict a detection rate of the gravitational wave emission from GRBs.

We have also made progress in the understanding of soft gamma ray repeaters (SGRs) and anomalous X-ray pulsars (AXPs). The most used model for the explanation of SGRs/AXPs is based on “magnetars”, ultramagnetized neutron stars. Since there is so far no experimental evidence of such extreme, B > 100 TG, surface magnetic fields in neutron stars, we have focus our effort in analyzing the data of SGRs and AXPs and check whether these objects could be explained by canonical, well tested and experimentally confirmed stars. This was the main idea of a pioneering work of Malheiro, Rueda and Ruffini, “Soft-Gamma-Ray Repeaters (SGRs) and Anomalous X-Ray Pulsars (AXPs) as rotation powered white dwarfs”, PASJ 64, 56 (2012). It was there shown that, indeed, massive (masses of 1 solar mass), fast rotating (rotation periods 1-10 second), highly magnetized (magnetic fields of 1 giga gauss) white dwarfs could explain the observational properties of SGRs/AXPs. In addition, it was there shown that some sources (at the time four) could actually be ordinary, rotation-powered neutron stars. That work opened a new field of research which led in the recent years to several ICRANet publications on the properties of such magnetized white dwarfs, including their radiation emission which has been compared and contrasted with observations. It is particularly important to recall that this area of research has been very active and prolific thanks to an intense collaboration with Brazilian colleagues, including professors and postdoc former students at ICRANet. In the 2016 we have made two important contributions within this collaboration. First, in the work by D. L. Cáceres, et al., “Thermal X-ray emission from massive, fast rotating, highly magnetized white dwarfs”, MNRAS 465, 4434 (2016), it has been shown that such white dwarfs can behave in a similar way as the well-known pulsars, with a specific emission in the X-rays which can explain the soft X-ray emission observed in SGRs and AXPs. Second, in the work by J. G. Coelho et al., “On the nature of some SGRs and AXPs as rotation-powered neutron stars”, A&A 599, A87 (2017), it has been shown that up to 11 out of the total 23 SGRs/AXPs known to date, could be described as rotation-powered neutron stars.

Papers published in 2021 include:

• Moradi, R. ; Rueda, J. A. ; Ruffini, R. ; Li, Liang ; Bianco, C. L. ; Campion, S. ; Cherubini, C. ; Filippi, S. ; Wang, Y. ; Xue, S. S., Nature of the ultrarelativistic prompt emission phase of GRB 190114C, Physical Review D 104, 063043, 2021.

• Campion, S.; Rueda, J. A.; Ruffini, R.; Xue, S. S., Magnetic field screening in strong crossed electromagnetic fields, Physics Letters B 820, 136562, 2021.

• Ruffini, R. ; Moradi, R. ; Rueda, J. A.; Li, L., Sahakyan, N. ; Chen, Y. -C.; Wang, Y. ; Aimuratov, Y., Becerra, L., Bianco, C. L. ; Cherubini, C. ; Filippi, S. ; Karlica, M. ; Mathews, G. J. ; Muccino, M. ; Pisani, G. B. ; Xue, S.-S., The morphology of the X-ray afterglows and of the jetted GeV emission in long GRBs, Monthly Notices of the Royal Astronomical Society 504, 5301, 2021.

• Rueda, J. A. ; Ruffini, R., The quantum emission of an alive black hole, IJMPD 30, 2141003, 2021.

• Moradi, R. ; Rueda, J. A. ; Ruffini, R. ;Wang, Y., The newborn black hole in GRB 191014C proves that it is alive, Astronomy & Astrophysics 649, A75, 2021.

• Uribe, J. D.; Becerra-Vergara, E. A.; Rueda, J. A., Neutrino Oscillations in Neutrino-Dominated Accretion Around Rotating Black Holes, Universe 7, 7, 2021.

• Campion, S. ; Rueda, J. A. ; Xue, S. S. ; Ruffini, R., On the Magnetic Field Screening in Strong Crossed Electromagnetic Fields, Astronomy Reports 65, 911, 2021.

• Rueda, J. A., An Update of the Binary-Driven Hypernovae Scenario of Long Gamma-Ray Bursts, Astronomy Reports 65, 1026, 2021.

• Jorge A. Rueda, Remo Ruffini, Rahim Moradi, Yu Wang, A brief review of binary-driven hypernova, IJMPD 30, 2130007, 2021.

   

Self-gravitating Systems of Dark Matter Particles (Page 1255)

In 2020 major results have been obtained in the field of dark matter, which therefore became a main line of research independent from “Theoretical Astroparticle Physics”.

We have given strong evidence on the nature of the massive compact source at the center of our Galaxy to be a concentration of dark matter made of fermions instead of a supermassive black hole. It is worth to say a few words on this important issue. The closest stars to the Galactic center have been extensively and continuously monitored over decades, leading to high-quality data of their positions and velocities. The explanation of these data, especially the S2 star motion, requires the presence of a compact source, Sagittarius A* (Sgr~A*), and its mass must be of the order of 4 million solar masses. This result has been protagonist of the awarded Nobel Prize in Physics 2020 to Reinhard Genzel and Andrea Ghez “for the discovery of a supermassive compact object at the centre of our galaxy”. Traditionally, the Sgr A* compact source has been assumed to be a supermassive black hole. However, a proof of its existence is still absent. A further challenge to this scenario has come from the G2 cloud motion data whose post-peripassage velocity is much lower than the prediction of the supermasive black hole scenario. An attempt to overcome this difficulty has introduced a friction force produced by an accretion flow, however, such a flow is also observationally unconfirmed. In a series of articles, published from 2015 to 2019, we have introduced the Ruffini-Argüelles-Rueda (RAR) model of dark matter. The RAR model proposed dark matter is made of massive fermions, herafter “darkinos”, and their distribution in galaxies is calculated assuming they are at finite temperatures, in thermodynamic equilibrium, and using general relativity. It was already clear from those works that the darkinos form a core-halo density profile, and that the dense core could produce effects on orbiting matter similar to the ones of a supermassive black hole of similar mass. In the year 2020, we moved forward by performing a detailed observational test of the theoretically predicted existence of the dense core of dark matter the Galactic center using the RAR model. Namely, we test whether the dark matter dense core could work as an alternative to the central black hole scenario for SgrA*. The outstanding result has been that the solely dark matter gravitational potential of darkinos of 56 kiloelectronvolt rest mass-energy (about one ninth of the electron mass), can explain all existing data of the motion of the star S2 as well as of the cloud G2, without the presence of a central black hole, and even with better accuracy. Our result that the center of our Galaxy could harbor a concentration of DM instead of a supermassive black hole has attracted worldwide attention. A Press Release of this result has been published in the Astronomy & Astrophysics journal: https://www.aanda.org/2020-press-releases/1880. It is also worth to mention the award Premio Estímulo en Astronomía “Dr. Jorge Sahade” received by Dr. Carlos R. Argüelles in Argentina, delivered by the National Academy of Physical and Natural Sciences, recognizing the relevance of these works as an advance in the field of dark matter: https://laplata.conicet.gov.ar/la-academia-nacional-de-ciencias-exactas-fisicas-y-naturales-distingue-a-un-investigador-del-conicet-la-plata/. The not-scientific audience has been also attracted by these novelties; indeed the major newspaper in Colombia, “El Tiempo”, dedicated a special article on September 9, 2020, to our results: https://www.eltiempo.com/vida/ciencia/que-hay-en-el-centro-de-la-galaxia-investigadores-aseguran-que-podria-ser-materia-oscura-536640. In 2021 our group published a new paper that extended this work by analyzing all the existing observational data of the S-cluster stars, namely the orbit and velocity data of 17 stars.

Our group has published three additional papers devoted to fermionic dark matter within the RAR model theoretical framework. We have performed a new analysis of NuSTAR mission X-ray data of the center of our Galaxy to constraint possible self-interactions of the darkinos, assuming they could be the sterile neutrinos of the minimal extension of the standard model of particles, and that they can radiatively decay emitting X-rays. We obtained new bounds on the self-interaction strength complementary to previous bounds we have presented in 2016 using the Milky Way rotation curves.

Two additional articles focus on cosmological consequences of fermions of keV mass-energy as predicted in our research. The first paves the way to the possibility of performing numerical simulations on the formation of dark matter halos of these darkinos in cosmological evolution and structure formation models. Boltzmann hierarchies (time-evolution equations of a Boltzmann gas) including particle self-interactions are there obtained. The second work obtained a major result on the cosmological stability of these core-halo configurations, demonstrating they could naturally arise in the cosmological evolution being the ones that maximize the entropy and being stable over timescales of the order of the Hubble time. This gives certainly a great cosmological support to the fermionic dark matter hypothesis proposed by our group.

Papers published in 2021 include:

• Becerra-Vergara, E. A.; Arguelles, C. R.; Krut, A.; Rueda, J. A.; Ruffini, R., “Hinting a dark matter nature of Sgr A* via the S-stars”, Monthly Notices of the Royal Astronomical Society 505 (2021), issue 1, pp L64-L68.

• Arguelles, Carlos R.; Dıaz, Manuel I.; Krut, Andreas; Yunis, Rafael, “On the formation and stability of fermionic dark matter halos in a cosmological framework”, Monthly Notices of the Royal Astronomical Society 502 (2021), issue 3, pp 4227-4246.

• Yunis, R. I; Arguelles, C. R., Scoccola, C. G.; Nacir, D. L.; Giordano, G.“Self Interactions in Warm Dark Matter: A View from Cosmological Perturbation Theory”, Astronomy Reports 65 (2021) issue 10, pp 1068-1073

   

Supernovae (Page 1285)

GRBs have broaden the existing problematic of the study of Supernovae. In some models, e.g. the “collapsar” one, all GRBs are assumed to originate from supernovae. Within our approach, we assume that core-collapse supernovae can only lead to neutron stars, and we also assume that GRBs are exclusively generated in the collapse to a black hole. Within this framework, supernovae and GRBs do necessarily originate in a binary system composed by an evolved main sequence star and a neutron star. The concept of induced gravitational collapse leads to the temporal coincidence between the transition from the neutron star to the black hole and the concurrent transition of the late evolved star into a supernova. This very wide topic has been promoted by the collaboration with Prof. Massimo Della Valle, who is an Adjunct Professor at ICRANet and who is currently Co-PI of a VLT proposal “A spectroscopic study of the supernova/GRB connection”. This kind of research is particularly important for trying to find a coincidence between electromagnetic radiation, high-energy particles, ultra high-energy cosmic rays, neutrinos and gravitational radiation, possible observable for existing or future detectors. A short summary of the internationally well-known activities of Prof. Della Valle is given in the report, which contains the many publications in international journals. A new stimulus has come from the recent understanding of the IGC paradigm, which allows a completely new understanding of the relation between the supernovae and the GRBs.

Papers published in 2021 include:

• Molero, Marta; Simonetti, Paolo; Matteucci, Francesca and 1 more; “Predicted rates of merging neutron stars in galaxies”, 2021MNRAS.500.1071M

• Muccino, M.; Izzo, L.; Luongo, O. and 5 more; “Tracing Dark Energy History with Gamma-Ray Bursts”; 2021ApJ...908..181M

• Barna, Barnabás; Szalai, Tamás; Jha, Saurabh W. and 38 more; “SN 2019muj - a well-observed Type Iax supernova that bridges the luminosity gap of the class”; 2021MNRAS.501.1078B

• Khetan, Nandita; Izzo, Luca; Branchesi, Marica and 15 more; “A new measurement of the Hubble constant using Type Ia supernovae calibrated with surface brightness fluctuations”; 2021A&A...647A..72K

• Harms, Jan; Ambrosino, Filippo; Angelini, Lorella and 55 more; “Lunar Gravitational-wave Antenna”; 2021ApJ...910....1H

• DarkSide-20k Collaboration; Agnes, P.; Albergo, S. and 274 more; “Sensitivity of future liquid argon dark matter search experiments to core-collapse supernova neutrinos”; 2021JCAP...03..043D

• Agnes, P.; Albergo, S.; Albuquerque, I. F. M. and 307 more; “Separating 39Ar from 40Ar by cryogenic distillation with Aria for dark-matter searches”; 2021EPJC...81..359A

• Thöne, C. C.; Izzo, L.; Flores, H. and 12 more; “Outflows from GRB hosts are ubiquitous: Kinematics of z < 0.3 GRB-SN hosts resolved with FLAMES”; 2021A&A...656A.136T

   

Symmetries in General Relativity (Page 1291)

We have studied (Bini, Esposito, Geralico) cosmological models, involving non-ideal fluids as sources of the gravitational field, with equation of state typical for fluids undergoing phase transitions as a possible mechanism to generate the content of dark matter in the present Universe.

We have continued our works on perturbations of black hole spacetimes (Bini, Damour, Geralico), with transcription of the associated results into the effective-one-body model, i.e. the model which encompasses all other approximation techniques for the description of a two-body system. In particular, we have studied the backreaction due to particles moving on eccentric orbits in Schwarzschild and Kerr spacetimes. Moreover, we have started the inclusion of second order perturbation effects into the effective-one-body model and considered gravitational self-force effects (Bini, Carvalho, Geralico) on a scalar charge orbiting a Reissner-Nordstrom spacetime.

We have continued our studies (Bini, Geralico) on drag and friction forces around black hole spacetimes, motivated by the necessity of a deeper understanding of effects like the well known Poynting-Robertson effect.

We have considered (Bini, Jantzen, Geralico) gyroscope precession effects along eccentric orbits (either bound or elliptic-like and unbound or hyperbolic-like) around a Kerr spacetime.

Finally (Bini, Mashhoon) we have studied tidal forces around a Kerr black hole, with applications in gravitational gradiometry as well as some novel applications of nonlocal gravity to conformally flat spacetimes.

Papers published in 2021 include:

• Bini D. , Damour T., Geralico A., Laporta S. and Mastrolia P.; “Gravitational scattering at the seventh order in G: nonlocal contribution at the sixth post-Newtonian accuracy”, Phys. Rev. D, Vol. 103, No. 4, 044038 (2021)

• Bini D. , Esposito G., “Investigating new forms of gravity-matter couplings in the gravitational field equations”, Phys. Rev. D, vol. 103, 064030 (2021)

• Bini D. , Damour T., Geralico A. “Radiative contributions to gravitational scattering”, Phys. Rev. D 104, no.8, 084031 (2021)

• Bini D., Geralico A. “Frequency domain analysis of the gravitational wave energy loss in hyperbolic encounters”, Phys. Rev. D, vol. 104, 104019 (2021)

• Bini D., Geralico A. “Higher-order tail contributions to the energy and angular momentum fluxes in a two-body scattering process”, Phys. Rev. D, 104, 104020 (2021)

Self Gravitating Systems, Galactic Structures and Galactic Dynamics (Page 1403)

The work on classical rotating self-gravitating configurations characterized by a multi-parametric rotation law, written in collaboration with Dr F. Cipolletta, Dr J. Rueda and Prof. R. Ruffini, has been published. In the manuscript a detailed and elegant graphical analysis regarding the stability of the configurations (in particular against mass shedding) in the velocity field’s parameters’s space has been presented. In the general relativistic context, an article regarding the last stable orbit around neutron stars has been published. An interesting comparison between numerical simulations and analytical estimates in this case led the authors to find simple, accurate and especially analytical formulas of great interest for astrophysical applications. The study has been performed by using three different equations of state (EOS) based on nuclear relativistic mean field theory models but it is expected that the formulas found will be still valid also for other equations of state. Finally a “compare and contrast” procedure of these results with Kerr metric quantities has been performed too.

Papers published in 2021 include:

• R. Moradi, J. A. Rueda, R. Ruffini, Liang Li, C. L. Bianco, S. Campion, C. Cherubini, S. Filippi,, Y. Wang, and S. S. Xue, Phys Rev D 104, 063043 (2021).

• R. Ruffini, R. Moradi, J. A. Rueda , L. Li, N. Sahakyan, Y.-C. Chen, Y. Wang, Y. Aimuratov, L. Becerra, C. L. Bianco, C. Cherubini, S. Filippi, M. Karlica, G. J. Mathews, M. Muccino, G. B. Pisani and S. S. Xue, MNRAS 504, 5301-5326 (2021).

Interdisciplinary Complex Systems (Page 1445)

These researches have been focused in fluid-structure problems in hemodynamics in arbitrary Lagrangian-Eulerian formulation, a mathematically involved theory which describes systems of partial differential equations with free boundary conditions. Specifically the nonlinear equations’ set which describes the fluid and the elastic wall within which the fluid flows have been numerically integrated and the previously introduced TDB risk indicator has been applied to this more involved case in order to perform a risk assessment. On the other hand, a numerical analysis of the same mathematical problem, but focused on the case of different biomedical prostheses applied to real patients’ geometries has been carried out in order to perform a quantitative comparison of the mechanical behavior of the different scenarios, having in mind as ultimate target the best outcomes for patients’ health.

Left: Electrical activity map of an electro-elastic deformed patch of cardiac-type tissue. Right: Turbulent flow structure (specifically the velocity amplitude) in a deformed vessel, obtained by numerical integration through finite elements of the incompressible Navier-Stokes equations.

Papers published in 2021 include:

• Loppini A., Barone A., Gizzi A., Cherubini C., Fenton F.H., Filippi S., ”Thermal effects on cardiac alternans onset and development: A spatiotemporal correlation analysis”, Phys. Rev. E vol. 103, L040201 (2021)

5. The 2021 ICRANet activities through the ICRANet Newsletter

We turn now (see Enclosure 9) to review the ICRANet activities of 2021 though the issues of the ICRANet Newsletter bimonthly published in 2021 simultaneously in Armenian, Chinese, English, Italian, Portuguese, and Russian (see http://www.icranet.org/news).

Acknowledgements

I would like to express, also on behalf of all Members of ICRANet, our gratitude to the Ministers of Foreign Affairs and to the Ministers of Economy and Finance of Italy, of Armenia, including also the State Committee of Science of Armenia, for their support.

I would also express the gratitude to the Vatican Secretary of State, to the Presidents of the Universities of Tucson and Stanford as well as to the President of ICRA for their support to the ICRANet activities.

We would like to express our gratitude to the new elected representatives of the Republic of Albania in ICRANet Scientific Committee (Prof. Mimoza Hafizi) and in ICRANet Steering Committee (Prof. Dr. Elida Bylyku), who are collaborating with the President of the Albanian Academy of Sciences and with the Albanian Ministry of Foreign Affairs in order to finalize the entrance of the Republic of Albania in ICRANet as a Member State. Particular important, in this regard, is the decision taken by the President of the Albanian Academy of Sciences to offer us a Seat in Tirana. Equally important, we are especially thankful to the President of the National Academy of Sciences of Belarus, Academician Vladimir Gusakov, for the support to scientists and for offering us an ICRANet Seat in the Academy of Sciences in Minsk. We are particularly grateful to Senatrice Claudia Schilling (Senator for Science and Ports of Bremen – Germany), to H.E. Armando Varricchio, Ambassador of Italy in Berlin, as well as to Dr Marco Fuchs, Honorary Consul of Italy in Bremen, in order to propose the entrance of the Federative Republic of Germany in ICRANet as a Member State, opening an ICRANet center in the City-State of Bremen. Particularly committed for fostering this scientific collaboration goes to Prof. Claus Lämmerzahl, Director of Space Science ZARM. We are also very thankful to H.E. Mohammad Ali Zolfigol, Minister of Science, Research and Technology of the Islamic Republic of Iran, to have initiated the process of adhesion of the Islamic Republic of Iran to ICRANet, as well as to have sponsored the “ICRANet - Isfahan Astronomy Meeting. From the Ancient Persian Astronomy to Recent Developments in Theoretical and Experimental Physics, Astrophysics and General Relativity”, first ICRANet international meeting in Iran held at the Isfahan University of Technology (IUT) and online November 3 to 5, 2021. We would like to express our gratitude also to Prof. S. M. Abtahi, President of IUT, to Prof. Yousef Sobouti (founder of IASBS) as well as to Prof. Soroush Shakeri (IUT and ICRANet).

Particular recognition goes to Italian Foreign Minister for having supported ongoing ICRANet activities in Belarus, Iran, and Kazakhstan which, coordinated by Armenia, are opening new opportunities of Research in Central Asia. Particular relevance is acquiring the support by the University of Sciences and Technology of China (USTC) to ICRA and ICRANet activities. In particular, I would like to mention the direct support of a visitor and postdoc exchange program in ICRA and the International Joint PhD in Relativistic Astrophysics (JIRA PhD) between USTC and the University of Ferrara (UNIFE) with the participation of ICRANet and ICRA. Equally important the support by local organizations to the traditional activities in China (Mainland) and China (Taiwan) and in Korea. I like as well to recall the further extensions of activities within Mexico, Colombia and Argentina, whose Universities and Research organizations have generously contributed trough the financial support of students and postdoc to the further expansion of ICRANet activities. For all this, a particular gratitude goes to Min. Fabrizio Nicoletti, to Cons. Enrico Padula and to Prof. Immacolata Pannone, as well as to Min. Plen. Andrea Orizio, to Cons. Raffaella Di Fabio and to Dr Rebecca Scano of the Italian Ministry of Foreign Affairs and International Cooperation for their attention and constant support and advice.

A special recognition goes to the activities of the many Ambassadors and Consuls who have greatly helped in the intense series of activities carried out by ICRANet in Belarus, Brazil, China, Colombia, Italy, Mexico.

I also express the plaudit for the support of ongoing activities of the IRAP-PhD to the President of Université Côte d'Azur Prof. Jeanick Brisswalter, as well as to the Director of the Observatoire de la Côte D’Azur Prof. Stéphane Mazevet. We are grateful to the Mayor of Pescara, Carlo Masci, to the Mayor of Nice Christian Estrosi, to the President of PACA, Renaud Muselier, to the Cons. Agnès Rampal of PACA, to the President of the National Academy of Science of Armenia, Prof. Ashot S. Saghyan, and to Prof. Ulisses Barres De Almeida (CBPF), to keep his generous support in granting to ICRANet the logistics of the Centers in their respective townships.

Clearly, a special mention of satisfaction goes to all the Scientific Institutions and Research Centers which have signed with ICRANet a collaboration agreement, namely:
Alzahra University (Iran), Al-Farabi Kazakh National University (Kazakhstan), ASI - Agenzia Spaziale Italiana (Italy), BRFFR - Belarusian Republican Foundation For Fundamental Research (Belarus), BSU - Belarusian State University (Belarus), CBPF - Centro Brasileiro de Pesquisas Fisicas (Brazil), CIMPA - Centre International de Mathématiques Pures et Appliquées (France), CNR - Consiglio Nazionale delle Ricerche (Italy), Damghan University (Iran), ENU - Eurasian National University (Kazakhstan), GARR - Municipality of Pescara - University of Pescara "D'Annunzio" (Italy), Government of the State of Ceará (Brazil), IAIC (International Agreement on Interuniversity Cooperation), IASBS - Institute For Advanced Studies In Basic Sciences (Iran), ICTP - International Centre for Theoretical Physics (Italy), IHEP - Institute of High Energy Physics, Chinese Academy of Science (China), INAF - Istituto Nazionale di Astrofisica (Italy), IPM - Institute for Research in Fundamental Sciences (Iran), ITA - Instituto Tecnológico de Aeronáutica (Brazil), IUT - Isfahan University of Technology (Iran), JSC - National Center of Space Research and Technology (Kazakhstan), KPS - Kazakh Physical Society (Kazakhstan), LeCosPa - Leung Centre for Cosmology and Particle Astrophysics (Taiwan), NASB - National Academy of Sciences of Belarus (Belarus), RUDN - Peoples' Friendship University of Russia (Russia), SCSA (State Committee of Science of Armenia) - NAS RA (National Academy of Sciences of the Republic of Armenia) – Armenia, Silesian University in Opava (Czech Republic), Sharif University of Technology (Iran), Sun Yat-Sen University (China), TSU - Ivane Javakhishvili Tbilisi State University (Georgia), UAM - Universidad Autónoma Metropolitana (Mexico), UCGWP - United Center for Gravitational Wave Physics (China), UDEA - Universidad de Antioquia (Colombia), UDESC - Universidade do Estado de Santa Catarina (Brazil), UFPB - Universidade Federal da Paraíba (Brazil), UFRGS - IFUFRGS (Brazil), UIS - Universidad Industrial de Santander (Colombia), UBAI - Ulugh Beg Astronomical Institute of Uzbekistan Academy of Sciences (Uzbekistan), UnB - Universidade de Brasília (Brazil), UNICAMP - Universidade Estadual de Campinas (Brazil), UNIFE - University of Ferrara (Italy), Universidad del Valle (Colombia), UNLP - Universidad Nacional de La Plata (Argentina), Università Campus Bio-Medico (Italy), University of Belgrade (Serbia), University of L'Aquila (Italy), University of Ljubljana (Slovenia), University of Mazandaran (Iran), University of Novi Sad (Serbia), University of Sharjah (United Arab Emirates), University of Tirana (Albania), University of Tuzla (Bosnia and Herzegovina), UNS - Universidad Nacional del Sur (Argentina), USTC - University of Science and Technology of China (China), UTFPR - Universidade Tecnológica Federal do Paraná (Brazil), WIGNER (Hungary), Shiraz University (Iran), UNAM - Universidad Nacional Autonoma de Mexico (Mexico). The complete list can be found at http://www.icranet.org/ScientificAgreements
A special mention of gratitude, of course, goes to the Administrative, Secretarial and Technical staff of ICRANet and ICRA for their essential and efficient daily support and to all Faculty for their dedication to fostering, opening and teaching new scientific horizons in our knowledge of the Universe.