ICRANet Newsletter
October - November 2017
1. Early X-ray Flares in GRBs - a fundamental discovery by the ICRA/ICRANet group
The article "Early X-ray Flares in GRBs" by R. Ruffini, Y. Wang, Y. Aimuratov et al., is accepted for publication in the Astrophysical Journal on 23 of November 2017.
The milestone of understanding the nature of Gamma Ray Bursts (GRBs), presented today in the most prestigious Astrophysical Journal by scientists of ICRA/ICRANet at the University "Sapienza" (see: https://arxiv.org/pdf/1704.03821.pdf), show how GRBs originates in the most complex system ever studied in physics and astrophysics and energetically the most powerful in the Universe. "In only 100s a supernova (SN) is observed to explode and hypercritically accrete at a rate ~1 Msun/s on a tightly bound binary neutron star (NS) companion. In sequence, the NS, after reaching its critical mass, gravitationally collapse to a Black Hole (BH) emitting a GRB. The GRB impacts on the SN ejecta, it originates an X-ray and gamma Flare and transforms the SN in a hypernova. This "cosmic matrix", named Binary-driven-hypernova (BdHN), is the most energetic of seven GRB subclasses". GRBs are the most luminous objects in the Universe and can consequently be observed at 10 billions light year of distance in our past light cone: their luminosities equal the summed luminosities of all the stars of our Universe, the luminosity of 100 billions of billions of Suns! A GRB occurs every 100 million years in a galaxy and is visible in all the billions of galaxies of our Universe: the product gives a GRB rate of circa "one a day", an ideal rate for unveiling their nature on the ground of Einstein theory, see Figure 1.
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Figure 1: Left to right A. Einstein, H. Yukawa, J.A. Wheeler.
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Figure 2: R. Ruffini discussing with J.A. Wheeler in Princeton (1971).
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Essential has been the observational effort in the X and gamma rays, with space missions (e.g. BeppoSAX, SWIFT, FERMI) with vigorous European presence and with the European ESO VLT and the US KECK optical observatories. Crucial has been the ICRANet theoretical effort in attributing the astrophysical meaning to the observed photons received by these observatories from systems which preceded by 8 billion years the birth of our planetary system! This effort is well summarized in 25 additional papers by the same authors, quoted in the above article. Professor Ruffini has been for many years on the forefront of this research: from "introducing the Black hole" with J. A. Wheeler (see Figure 2) to the discovery of the first BH with R. Giacconi (see Figure 3), to the first announcement of the GRB discovery with H. Gursky, to the developments in the recent years of the BdHNe with Profs. C.L. Bianco, J. Rueda and C. Fryer and the many students of the joint European Ph.D. Program, the IRAP PhD, at the University of Rome (see Figure 4).
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Figure 3: From left to right H. Gursky, R. Giacconi, R. Ruffini. Naval Research Laboratory, Washington D.C., 1984.
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Figure 4: Picture of Prof. Ruffini with young researchers who partecipated in this discovery.
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2. The "China-Italy Science, Technology & Innovation Week", Beijing, China, 13-17 November 2017
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Figure 5. The meeting “China-Italy Science, Technology & Innovation Week” in Beijing. From right to left: Prof. Remo Ruffini, Director of ICRANet, the Chinese Minister of Science and Technology, Wan Gang, Italian Minister of Education, University and Research, Valeria Fedeli. Fifth from right: Prof. Wen Biao Han, from the Shanghai Astronomical Observatory.
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From the 13 th to 17 th of November the "China-Italy Science, Technology & Innovation Week" 2017 Edition has been held in three different cities across China: Beijing, Chengdu and Guiyang, see: http://www.cittadellascienza.it/cina/. The initiative, dedicated to the science and technology cooperation activities between the two countries with the aim of creating scientific, technological and commercial partnerships in the innovative research-entrepreneurial system, is promoted by the Ministry of Science and Technology of China and from the Italian side by the Ministry of Education, University and Research - MIUR in cooperation with the Ministry of Foreign Affairs and International Cooperation - MAECI and it is coordinated by Città della Scienza of Naples. It is realized in synergy with the Ministry of Economic Development, the Ministry of Health and the Ministry of Environment and Land and Sea Protection and in cooperation with the National Research Council, Confindustria (the Italian association of Italian entrepreneurs) and the main Italian Universities and Research Centers, together with the Campania Region for the Sino-Italian Exchange Event.
Professor Remo Ruffini, Director of ICRANet, has participated at the opening institutional ceremony of the event, launched in Beijing on November 14 th in presence of the Italian Minister of Education, University and Research, Valeria Fedeli, and the Chinese Minister of Science and Technology, Wan Gang. In this occasion, Prof. Ruffini and Prof. Wen Biao Han, from the Shanghai Astronomical Observatory (SHAO) signed the "Agreement on joint Chinese-Italian activities in the field of relativistic astrophysics".
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Figure 6. The signature of collaboration agreements by Chinese and Italian partners. Standing: the Chinese Minister of Science and Technology, Wan Gang and Italian Minister of Education, University and Research, Valeria Fedeli. Third and forth from left: Prof. Remo Ruffini from ICRANet, and Prof. Wen Biao Han, from the Shanghai Astronomical Observatory.
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3. The "Serbian-Italian Astronomical Workshop", Belgrade, Serbia, 31 October 2017
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Figure 7-8. Ceremony of signing of the cooperation agreement between ICRANet and the University of Belgrade.
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On October 31 2017 Professor Ruffini, Director of ICRANet, participated in the Serbian-Italian Astronomical Workshop in Belgrade, organized by the Astronomical Observatory of Belgrade in collaboration with the Embassy of Italy. The purpose of the workshop was to discuss, in collaboration with the prominent scientist from Italy, the future observing projects, as well as to share the experiences related to various astronomical observations, and other astronomical and technical and computational possibilities which include the usage of astronomical instruments, reductions, storage and analysis of the observing material. Prof. Ruffini delivered the talk "Specific examples of separatrix between the collapsar and the BdHN models of GRBs".
4. Lecture at the University of Tuzla in Bosnia and Herzegovina by Prof. Remo Ruffini in occasion of the signature of collaboration agreement between the University of Tuzla and ICRANet, 27 November 2017
On the 27 th of November Prof. Remo Ruffini, Director of ICRANet, visited University of Tuzla in Bosnia and Herzegovina and delivered a talk "The Puzzle of GRB 090510, GRB 130603B and GRB 170817A", see: here.
After the lecture, in the presence of H.E. the Ambassador of the Republic of Italy, Nicola Minasi, the Scientific Attache Dr. Paolo Battinelli, the university and faculty management, numerous academics as well as students and representatives of the government of Tuzla and Tuzla Canton, an Agreement of collaboration between the University of Tuzla and ICRANet was signed.
Prof. Ruffini said: "This corresponds to my dream, which is to promote the joint study of the Universe, based on the ideas of Einstein, in collaboration with scientists from all the countries of the Western Balkan region, promoting joint scientific endeavors in the region, which is very important to ICRANet, Italy and Europe as a whole. We have already recently signed the corresponding Agreement with the universities in Belgrade and Novi Sad, with plans on signing more agreements with other scientific institutions in the Western Balkans". Prof. Dr. Vedad Pašić, the Dean of the Faculty of natural Sciences and Mathematics at the University of Tuzla added: "We sincerely believe that this represents a whole new chapter of scientific research between our two friendly countries, as well as the first step of Bosnia and Herzegovina joining the broader family of ICRANet member States and Institutions". The Rector of the University of Tuzla, Prof. Dr. Nermina Hadžigrahić expressed her sincere hope that Bosnia and Herzegovina will become the first member State of ICRANet from the Western Balkans. Ambassador Minasi stated his full support to the activities of the University of Tuzla and ICRANet and after the signing ceremony further discussed the various possibilities of academic, cultural as well as economic collaborations between Bosnia and Herzegovina and Italy with the representatives of the University of Tuzla.
5. New collaboration agreements: University of Belgrade; Agreement on joint Chinese-Italian activities in the field of relativistic astrophysics; University of Tuzla
| Cooperation Agreement ICRANet - University of Belgrade |
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During the Serbian-Italian Astronomical Workshop in Belgrade Prof. Remo Ruffini and Prof. Dr. Vladimir Bumbasirevic, Rector of the Belgrade University, signed the agreement of cooperation between the University of Belgrade and ICRANet, in the presence of Dr. Paolo Battinelli, Science Attaché of the Embassy of Italy in Belgrade.
The agreement consist of joint actions including: the promotion of theoretical and observational research activities within the field of Relativistic Astrophysics; the institutional exchange of faculty members, researchers, post-doctoral fellows and students; the promotion of technological developments; the development of Data Centers for Astrophysical data in all wavebands; the organization of training and teaching courses, and the development of inter-institutional research areas associated to local graduate programs; the organization of seminars, conferences, workshops or short courses; joint publications.
For the text of the Agreement, see: here. |
| Agreement on joint Chinese-Italian activities in the field of relativistic astrophysics |
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In this agreement SHAO, ASI, ASI – Centro Geodesia Spaziale G. Colombo Matera, ICRA/ICRANet, INFN, University Campus Biomedico in Rome, University "l'Orientale" in Naples, University of Rome "Sapienza, agree to collaborate on joint activities in the period 2018 - 2019, including seminars and workshops such as: the Fifteenth Marcel Grossman Meeting to be held in Rome from 1 to 7 July 2018 MGXV (http://www.icra.it/mg/mg15), the Sixth Galileo-Xu Guangqi Meeting - GX6 (http://www.icranet.org/GXMeetings) to be held in Pescara and Rome (Italy) at ICRA/ICRANet, in Naples at the University "L'Orientale", and in Matera at the "Centro di Geodesia Spaziale Giuseppe Colombo" in 2019. In addition, it was agreed that ASI, ICRA/ICRANet, INFN researchers will visit Chinese Institutions and, analogously, Chinese researchers will visit ASI, ICRA/ICRANet, INFN. The research topics, in the field of Relativistic Astrophysics, to be covered by these joint activities, include: Gamma-Ray Bursts, Gravitational waves, Neutron Stars, Active Galactic Nuclei, Quasars, Neutrino astrophysics, Black Hole physics and astrophysics, Dark Matter, Quantum Gravity and Curved Space Quantum Field Theory as well as Nuclear Astrophysics.
For the text of the Agreement, see: here. |
| Cooperation Agreement ICRANet - University of Tuzla |
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On 27 of November 2017 Prof. Remo Ruffini, Director of ICRANet and Prof. Nermina Hadzigrahic, Rector of the University of Tuzla signed a collaboration agreement on scientific cooperation between their institutes. This agreement will be valid for 5 years and the joint activities will consist in: promotion of theoretical and observational research activities within the field of Relativistic Astrophysics; institutional exchange of faculty members, researchers, post- doctoral fellows and students; development of teaching and/or research activities; support of technical-scientific and cultural events and activities open to the public; organization of seminars, conferences, workshops or short courses; joint publications.
For articles, photos and videos of the signing ceremony see here.
The text of the agreement can be found here.
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6. Fourteenth Marcel Grossmann meeting proceedings published online and in hard copy
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It is our pleasure to announce the publication of the Proceedings of the Fourteenth Marcel Grossman Meeting on General Relativity edited by Massimo Bianchi, Robert T Jantzen, Remo Ruffini, World Scientific, Singapore, 2017.
The open source e-book, allowing its content to be viewed by a wide international audience free of charge, is now available at the following link: http://www.worldscientific.com/worldscibooks/10.1142/10614#t=toc
The four volume paper edition of some 4400 pages of the proceedings of MG14 is published in December 2017. |
7. Recent publications
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V.Belinski and M.Henneaux, "The Cosmological Singularity" (Cambridge University Press). The book (in hard copy) has been published on 26 October 2017.
Available here: https://www.cambridge.org/core/books/cosmological-singularity/652DFD197ED573BAC18EBB0778BD0886
Written for researchers focusing on general relativity, supergravity, and cosmology, this is a self-contained exposition of the structure of the cosmological singularity in generic solutions of the Einstein equations, and an up-to-date mathematical derivation of the theory underlying the Belinski-Khalatnikov-Lifshitz (BKL) conjecture on this field. Part I provides a comprehensive review of the theory underlying the BKL conjecture. |
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The generic asymptotic behavior near the cosmological singularity of the gravitational field, and fields describing other kinds of matter, is explained in detail. Part II focuses on the billiard reformulation of the BKL behavior. Taking a general approach, this section does not assume any simplifying symmetry conditions and applies to theories involving a range of matter fields and space-time dimensions, including supergravities. Overall, this book will equip theoretical and mathematical physicists with the theoretical fundamentals of the Big Bang, Big Crunch, Black Hole singularities, the billiard description, and emergent mathematical structures. |
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Gabriel L. Gómez, and Jorge A. Rueda, "Dark matter dynamical friction versus gravitational wave emission in the evolution of compact-star binaries", Physical Review D, Volume 96, Issue 6, id.063001 (2017), published on 6 September 2017 and available here: http://adsabs.harvard.edu/abs/2017PhRvD..96f3001G
The measured orbital period decay of relativistic compact-star binaries, with characteristic orbital periods ˜0.1 days, is explained with very high precision by the gravitational wave (GW) emission of an inspiraling binary in a vacuum predicted by general relativity. However, the binary gravitational binding energy is also affected by an usually neglected phenomenon, namely the dark matter dynamical friction (DMDF) produced by the interaction of the binary components with their respective DM gravitational wakes. Therefore, the inclusion of the DMDF might lead to a binary evolution which is different from a purely GW-driven one. The entity of this effect depends on the orbital period and on the local value of the DM density, hence on the position of the binary in the Galaxy. We evaluate the DMDF produced by three different DM profiles: the Navarro-Frenk-White (NFW) profile, the nonsingular-isothermal-sphere (NSIS) and the Ruffini-Argüelles-Rueda (RAR) DM profile based on self-gravitating keV fermions. We first show that indeed, due to their Galactic position, the GW emission dominates over the DMDF in the Neutron star (NS)-NS, NS-(White Dwarf) WD and WD-WD binaries for which measurements of the orbital decay exist. Then, we evaluate the conditions (i.e. orbital period and Galactic location) under which the effect of DMDF on the binary evolution becomes comparable to, or overcomes, the one of the GW emission. We find that, for instance for 1.3 - 0.2 M⊙ NS-WD, 1.3 - 1.3 M⊙ NS-NS, and 0.25 - 0.50 M⊙ WD-WD, located at 0.1 kpc, this occurs at orbital periods around 20-30 days in a NFW profile while, in a RAR profile, it occurs at about 100 days. For closer distances to the Galactic center, the DMDF effect increases and the above critical orbital periods become interestingly shorter. Finally, we also analyze the system parameters (for all the DM profiles) for which DMDF leads to an orbital widening instead of orbital decay. All the above imply that a direct/indirect observational verification of this effect in compact-star binaries might put strong constraints on the nature of DM and its Galactic distribution.
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F. Cipolletta, C. Cherubini, S. Filippi, J.A. Rueda and R. Ruffini, "Equilibrium Configurations of Classical Polytropic Stars with a Multi-Parametric Differential Rotation Law: A Numerical Analysis", Communications in Computational Physics, vol. 22, issue 03, pp. 863-888 (2017), published on 21 September 2017 and available here: http://adsabs.harvard.edu/abs/2017CCoPh..22..863C
In this paper we analyze in detail the equilibrium configurations of classical polytropic stars with a multi-parametric differential rotation law of the literature using the standard numerical method introduced by Eriguchi and Mueller. Specifically we numerically investigate the parameters' space associated with the velocity field characterizing both equilibrium and non-equilibrium configurations for which the stability condition is violated or the mass-shedding criterion is verified.
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Soroush Shakeri, Mansour Haghighat, She-Sheng Xue, "Nonlinear QED effects in X-ray emission of pulsars", JCAP (2017) no.10,014, and available here: http://adsabs.harvard.edu/abs/2017JCAP...10..014S
In the presence of strong magnetic fields near pulsars, the QED vacuum becomes a birefringent medium due to nonlinear QED interactions. Here, we explore the impact of the effective photon-photon interaction on the polarization evolution of photons propagating through the magnetized QED vacuum of a pulsar. We solve the quantum Boltzmann equation within the framework of the Euler-Heisenberg Lagrangian to find the evolution of the Stokes parameters. We find that linearly polarized X-ray photons propagating outward in the magnetosphere of a rotating neutron star can acquire high values for the circular polarization parameter. Meanwhile, it is shown that the polarization characteristics of photons besides photon energy depend strongly on parameters of the pulsars such as magnetic field strength, inclination angle and rotational period. Our results are clear predictions of QED vacuum polarization effects in the near vicinity of magnetic stars which can be tested with the upcoming X-ray polarimetric observations.
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B. Eslam Panah, G. H. Bordbar, S. H. Hendi, R. Ruffini, Z. Rezaei and R. Moradi, "Expansion of Magnetic Neutron Stars in an Energy (in)Dependent Spacetime", The Astrophysical Journal, Volume 848, Issue 1, article id. 24, 11 pp. (2017), published on 6 October 2017 and available here: http://adsabs.harvard.edu/abs/2017ApJ...848...24E
Regarding the strong magnetic field of neutron stars and the high-energy regime scenario that is based on the high-curvature region near the compact objects, one is motivated to study magnetic neutron stars in an energy-dependent spacetime. In this paper, we show that such a strong magnetic field and energy dependency of spacetime have considerable effects on the properties of neutron stars. We examine the variations of maximum mass and related radius, Schwarzschild radius, average density, gravitational redshift, Kretschmann scalar, and Buchdahl theorem due to the magnetic field and energy dependency of the metric. First, it will be shown that the maximum mass and radius of neutron stars are increasing functions of the magnetic field, while average density, redshift, strength of gravity, and Kretschmann scalar are decreasing functions of it. These results are due to a repulsive-like force behavior for the magnetic field. Next, the effects of gravity's rainbow will be studied, and it will be shown that by increasing the rainbow function, the neutron stars could enjoy an expansion in their structures. Then, we obtain a new relation for the upper mass limit of a static spherical neutron star with uniform density in gravity's rainbow (Buchdahl limit) in which such an upper limit is modified as Meff < 4c2R/9G. In addition, stability and energy conditions for the equation of state of neutron star matter are investigated, and a comparison with empirical results is done. It is notable that the numerical study in this paper is conducted by using the lowest-order constrained variational approach in the presence of a magnetic field employing AV18 potential.
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S.H.Hendi, B.Eslam Panah, S.Panahiyan M.Momennia, "Three dimensional magnetic solutions in massive gravity with (non)linear field", Physics Letters B 775 (2017) 251–261, available online at: http://www.sciencedirect.com/science/article/pii/S0370269317308651
The Noble Prize in physics 2016 motivates one to study different aspects of topological properties and topological defects as their related objects. Considering the significant role of the topological defects (especially magnetic strings) in cosmology, here, we will investigate three dimensional horizonless magnetic solutions in the presence of two generalizations: massive gravity and nonlinear electromagnetic field. The effects of these two generalizations on properties of the solutions and their geometrical structure are investigated. The differences between de Sitter and anti de Sitter solutions are highlighted and conditions regarding the existence of phase transition in geometrical structure of the solutions are studied.
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S. H. Hendi, B. Eslam Panah, S. Panahiyan, M. Momennia, "Dilatonic black holes in gravity's rainbow with a nonlinear source: the effects of thermal fluctuations", Eur. Phys. J. C (2017) 77:647, available online at: http://adsabs.harvard.edu/abs/2017EPJC...77..647H
This paper is devoted to an investigation of nonlinearly charged dilatonic black holes in the context of gravity's rainbow with two cases: (1) by considering the usual entropy, (2) in the presence of first order logarithmic correction of the entropy. First, exact black hole solutions of dilatonic Born-Infeld gravity with an energy dependent Liouville-type potential are obtained. Then, thermodynamic properties of the mentioned cases are studied, separately. It will be shown that although mass, entropy and the heat capacity are modified due to the presence of a first order correction, the temperature remains independent of it. Furthermore, it will be shown that divergences of the heat capacity, hence phase transition points are also independent of a first order correction, whereas the stability conditions are highly sensitive to variation of the correction parameter. Except for the effects of a first order correction, we will also present a limit on the values of the dilatonic parameter and show that it is possible to recognize AdS and dS thermodynamical behaviors for two specific branches of the dilatonic parameter. In addition, the effects of nonlinear electromagnetic field and energy functions on the thermodynamical behavior of the solutions will be highlighted and dependency of critical behavior, on these generalizations will be investigated.
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D. Bini, A. Geralico, J. Vines, "Hyperbolic scattering of spinning particles by a Kerr black hole", Physical Review D, Volume 96, Issue 8, id.084044 (2017), available online at: http://adsabs.harvard.edu/abs/2017PhRvD..96h4044B
We investigate the scattering of a spinning test particle by a Kerr black hole within the Mathisson-Papapetrou-Dixon model to linear order in spin. The particle's spin and orbital angular momentum are taken to be aligned with the black hole's spin. Both the particle's mass and spin length are assumed to be small in comparison with the characteristic length scale of the background curvature, in order to avoid backreaction effects. We analytically compute the modifications due to the particle's spin to the scattering angle, the periastron shift, and the condition for capture by the black hole, extending previous results valid for the nonrotating Schwarzschild background. Finally, we discuss how to generalize the present analysis beyond the linear approximation in spin, including spin-squared corrections in the case of a black-hole-like quadrupolar structure for the extended test body.
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B. Punsly, "A Jet Source of Event Horizon Telescope Correlated Flux in M87", accepted for publication in Astrophysical Journal, available online: https://arxiv.org/abs/1710.08355
Event Horizon Telescope (EHT) observations at 230 GHz are combined with Very Long Baseline Interferometry (VLBI) observations at 86 GHz and high resolution Hubble Space Telescope optical observations in order to constrain the broadband spectrum of the emission from the base of the jet in M87. The recent VLBI observations of Hada et al provide much stricter limits on the 86 GHz luminosity and component acceleration in the jet base than was available to previous modelers. They reveal an almost hollow jet on sub-mas scales. Thus, tubular models of the jet base emanating from the innermost accretion disk are considered within the region responsible for the EHT correlated flux. There is substantial synchrotron self absorbed opacity at 86 GHz. A parametric analysis indicates that the jet dimensions and power depend strongly on the 86 GHz flux density and the black hole spin, but weakly on other parameters such as jet speed, 230 GHz flux density and optical flux. The entire power budget of the M87 jet, ≲1044ergs/sec, can be accommodated by the tubular jet. No invisible, powerful spine is required. Even though this analysis never employs the resolution of the EHT, the spectral shape implies a dimension transverse to the jet direction of 12-21 µas (~24-27µas) for 0.99>a/M>0.95 (a/M~0.7) where M is the mass and a is the angular momentum per unit mass of the central black hole.
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8. Congratulation to Ronald Cintra Shellard for his nomination to the Brazilian Academy of Sciences
On May 9, 2017, Prof. Ronald Cintra Shellard, Director of CBPF, has been nominated full member of the Brazilian Academy of Sciences (Academia Brasileira de Ciências - ABC) in the field of Physical Sciences. The ceremony was held at Escola Naval, in the city of Rio de Janeiro and included the presence of the Minister of Science, Technology, Innovation and Communication of Brazil, Min. Gilberto Kassab.
ABC mission is to promote Science, Technology and Innovation in Brazil through the recognition of merit of top Brazilian researchers, as well as through the enhancement of scientific activities in all the fields of knowledge.
Prof. Shellard has been actively promoting the collaboration between ICRANet and CBPF.
See: http://www.abc.org.br/centenario/?Ronald-Cintra-Shellard
SBF website (in portuguese): http://www.sbfisica.org.br/v1/home/index.php/pt/acontece/364-fisicos-tomam-posse-como-membros-da-academia-brasileira-de-ciencias
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