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ICRANet Newsletter

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2019
February/March - April/May


ICRANet Newsletter
April - May 2019






1. ICRANet receives Awards for Essay for the Gravity Research Foundation Award Competition 2019

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Fig. 1. Theoretical RAR rotation curves from 10-7 pc all the way to 105 pc, for three representative fermion masses in the mc2 keV region: 0.6 keV (dotted yellow curve), 48 keV (long-dashed-gray curve) and 345 keV (solid black curve).


The article "Can Fermionic Dark Matter Mimic Supermassive Black Holes?" by C. R. Argüelles, A. Krut, J. A. Rueda and R. Ruffini receives the Third Award by the Gravity Research Foundation www.gravityresearchfoundation.org in the Award Competition 2019. The paper analyzes the intriguing possibility to explain both dark mass components in a galaxy: the dark matter (DM) halo and the supermassive dark compact object lying at the center, by a unified approach in terms of a quasi-relaxed system of massive, neutral fermions in general relativity. The solutions to the mass distribution of such a model that fulfill realistic halo boundary conditions inferred from observations, develop a highly-density core supported by the fermion degeneracy pressure able to mimic massive black holes at the center of galaxies. Remarkably, these dense core-dilutedhaloconfigurations can explain the dynamics of the closest stars around Milky Way's center (SgrA*) all the way to the halo rotation curve, without spoiling the baryonic bulge-disk components, for a narrow particle mass range mc2 ∼10-102 keV.
The paper can be downloaded here: https://arxiv.org/abs/1905.09776
For details see: https://www.gravityresearchfoundation.org/s/2019abstracts.pdf



2. Renewal of the collaboration agreement ICRANet - UFRGS, April 5, 2019

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On April 5, 2019, the agreement between ICRANet and UFRGS (Universidade Federal do Rio Grande do Sul) has been renewed. This new agreement was signed by Prof. Dr. Rui Vincente Oppermann (Rector of UFRGS), Prof. Naira Maria Balzaretti (Director of UFRGS Department of Physics), Prof. Dr. Dimiter Hadjimichef (UFRGS Department of Physics) and by Prof. Remo Ruffini (Director of ICRANet).
This agreement will be valid for 5 years and the main joint activities to be developed under its framework include: the promotion of theoretical and observational activities within the field of Relativistic Astrophysics; the joint collaboration of faculty members, researchers, post-doctorate fellows and students; the organization of training and teaching courses, seminars, conferences, workshops or short courses, and the joint work on scientific publications.
For the text of the agreement, see here.




3. Armenian-Italian Science Day, Yerevan, April 15, 2019

On April 15, 2019, ICRANet organized the Armenian-Italian Science Day event "Joint ICRANet activities in Relativistic Astrophysics. Information Event for Cooperation in the field of Relativistic Astrophysics", a one day conference which took place in Yerevan on April 15, 2019. This event has been organized thanks to the collaboration among ICRANet, the National Academy of Sciences of Armenia (NASRA) and the Italian Embassy in Yerevan. The morning session was held at the National Academy of Sciences, whereas the afternoon session was held at the Italian Embassy in Yerevan.

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Institutional representatives from Armenia and from several other countries were present and addressed the opening session in the morning, namely: Ambassador Ashot Kocharian (Ministry of Foreign Affairs of the Republic of Armenia), Artak Apitonian (Deputy Minister of Foreign Affairs of Armenia), Radik Martirosyan (President of the NASRA), Samvel Haroutiunian (Chairman of the RA MES Science Committee), Vardan Sahakyan (Deputy Chairman of the RA MES Science Committee), Vincenzo Del Monaco (Ambassador of Italy to Armenia), Matthias Kiesler (Ambassador of Germany to Armenia) and Remo Ruffini (Director of ICRANet). During the day, the most recent scientific developments on which ICRANet is working on, were presented by eminent Professors and researchers, namely by Prof. Narek Sahakyan (ICRANet Armenia), Prof. Razmik Mirzoyan (Max Planck Institute of Physics, Germany), Dr Wang Yu (ICRANet), Rahim Moradi (ICRANet), Prof. Remo Ruffini (ICRANet), Dr Li Liang (ICRANet), Prof. Gregory Vereshchagin – video conference (ICRANet), Prof. Paolo Giommi (ICRANet-ASI), Ashot Chilingaryan (Cosmic Ray Division) and Leonid Bezrukov (vice Director of the Institute for Nuclear Research in Moscow).
In the same afternoon, Professor Remo Ruffini (Director of ICRANet), met the President of the Republic of Armenia, H.E. Armen Sarkissian at his residence in Yerevan, leading an ICRANet delegation composed by Ambassador Ashot Kocharian, President Radik Martirosyan, Prof. Narek Sahakyan, Prof. Razmik Mirzoyan, Prof. Paolo Giommi and Prof. Massimo Della Valle. President Sarkissian stressed the importance of the ICRANet activities in Armenia, pushing for a strong development of education and science in the country. Prof. Ruffini hailed cooperation with Armenia and noted that there is an intention to implement new programs with the countries of Central Asia via Armenia. All the interlocutors discussed possibilities of the implementation of joint programs and further deepening of cooperation with the world’s leading centers, organizations, and universities, such as ICRANet.

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The Armenian-Italian Science day ended with the Concert "Primavera Italiana", held at the Komitas Chamber Music Hall in Yerevan and offered by the Italian Embassy. The concert honored several Italian opera composers, such as Arcangelo Corelli, Giovanni Pergolesi, Antonio Vivaldi and Niccolò Paganini.

For more information about the event:
http://www.icranet.org/Armenian-ItalianScienceDay
For photos and videos:
http://www.icranet.org/index.php?option=com_content&task=view&id=1240
For the press releases on the event:
http://www.icranet.org/index.php?option=com_content&task=view&id=1239




4. ICRANet press release "Professor Roy Kerr elected as Royal Society Fellow", April 18, 2019

The New-Zealander Professor Roy Kerr, mathematician and physicist, holding the Yevgeny Lifshitz Chair at ICRANet and Crafoord Prize in Astronomy 2016 "for his fundamental work on rotating blacks holes and their astrophysical consequences", has been nominated Fellow of the Royal Society (UK) for his exceptional contributions to science, placing him among the world’s most eminent scientists. He will be officially nominated in a formal admission ceremony, which will be held on July 12, 2019 in London.

The Royal Society awarded Professor Kerr this high and prestigious title "for the solution of Einstein's equations of General Relativity for rotating black holes, an epochal result now known as the Kerr metric, describing Kerr black holes. Other major contributions include prescient work on algebraically special solutions of reduced holonomy."

In fact, Prof. Roy Kerr discovered in 1963 an exact solution to the Albert Einstein's equations on General Relativity of a rotating object: "This mathematic solution – recalls the ICRANet Director Prof. Remo Ruffini – has allowed fundamental unprecedented advances in the applications in the fields of Physics, Astronomy and Relativistic Astrophysics: the applications extend to the field of the micro-physics of the elementary particles, such as the structure of the electron, to the astrophysics of Black Holes, which arise at the end of a star evolution, up to the most energetic processes in the universe, such as GRBs and the active galactic nuclei, where Black Holes and maxi-Black Holes, up to billions of times greater than our sun, dominate." It was indeed Remo Ruffini with John Archibald Wheeler who used the Kerr mathematic solution, introducing it in the description of the fundamental physics processes, giving them the name of "Black Hole", which has been then translated in all languages worldwide (Physics Today, 30, 1971). These topics have been further investigated by Blandford and Znajek (MNRAS, 179, 433, 1977) following an article by Ruffini and Wilson (Phys. Rev. D 12, 2959,1975).

Kerr's discovery sparked a revolution in physics and, since then, his work proved of great importance and all subsequent detailed work on black holes has depended fundamentally on it.

In 2006 Prof. Roy Kerr got the Marcel Grossmann Award on the occasion of the institutional international meeting for Relativistic Astrophysics, which takes place every three years in a different country. Prof. Roy Kerr has been teaching at ICRANet within the IRAP PhD program, the first International joint Doctorate, founded by ICRANet and internationally coordinated by the University of Nice "Sophia Antipolis".

Professor Kerr has also been in the news this month after astronomers captured the first image of a black hole, attentively interpreted within ICRANet.




5. Visit of the Erasmus students from the High School ITIS Alessandro Volta, May 7, 2019


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On May 7, 2019 a delegation of Erasmus students and Italian students from the High School ITIS Alessandro Volta of Pescara, visited ICRANet center in Pescara. Under the supervision of Gregory Vereshchagin, ICRANet Faculty Professor, the students had the possibility to visit the center and its library and that was for them a unique opportunity to take part in science activities aiming to showcase both the fascination of research as a career and its significant societal impact.
After the opening remarks of Professor Vereshchagin, Prof. She-Sheng Xue (ICRANet), Dr Wang Yu (ICRANet), Dr Liang Li (ICRANet), Rahim Moradi (ICRANet) and Yen-Chen Chen (ICRANet) presented the most recent scientific developments on which ICRANet is working on.

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6. Mission of Professor Ruffini to China, May 10 - 22, 2019


From 11 to 18 May 2019, Professor Ruffini visited China, together with Dr Yu Wang and Dr Li Liang. During that visit, they were invited to participate and deliver a talk to the “Gamma-Ray Bursts and Related Astrophysics in Multi-Messenger Era”, a conference held in Nanjing University Center from 13 to 17 May 2019.

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Professor Ruffini delivered a talk titled “Self-similar structure of the ultra-relativistic prompt emission of GRB 190114C”, Dr Wang Yu delivered a talk titled “GRB 190114C: most comprehensive portrait of gamma-ray burst” and Dr Liang Li delivered a talk titled “Shock breakout in BdHN I and BdHN II, the case of GRB 13027A, 180728A and 190114C”.

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During his visit, Prof. Ruffini also visited some Chinese researchers in Shanghai at Jiaotong University and was invited by Professor Shing-Tung Yau, Director of the Yau Mathematical Science Center, to visit Tsinghua University in Beijing, one of the most important Chinese universities. On that occasion, Prof. Ruffini had a fruitful meeting both with Prof. Yau and with Prof. Shude Mao, Director of the Department of Astronomy at Tsinghua University. After that, Prof. Ruffini flew to Hefei in order to meet Porf. Ye-Fei Yuan from the Department of Astronomy of the University of Science and Technology of China (USTC).

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During his visit, Prof. Ruffini had the possibility to present the most recent scientific developments on which ICRANet is working on and to have fruitful exchange of ideas with other researchers from all over the world.

On Friday 17 May 2019, Prof. Remo Ruffini, Director of ICRANet, sent an important message from China, on the occasion of the 40° anniversary of his first visit to China:

"When I introduced in Princeton the concept of "Black Hole" with John Archibald Wheeler, our omen was to open a new era thanks to the study of Relativistic Astrophysics. Daily phone conversations between me (who was in Princeton) and Riccardo Giacconi (who was in Harvard), tying to interpret data from the satellite UHURU ("freedom" in Swahili, launched by Luigi Broglio from the space station San Marco in Kenia), made this omen a reality. In 1973, I received the Cressy Morrison Award from the New York Academy of Sciences for the discovery of the first "Black Hole" in the galaxy and, in 2002, Riccardo Giacconi received the Nobel Prize in Physics.
This progresses have also been marked in 1973 by another event destined to become memorable: the discovery of Gamma Ray Bursts (GRBs). To achieve their understanding/comprehension, it took more than 40 years marked by everyday theoretical studies, accompanied by a "multimessanger" technological and optical development without precedent in the history of humanity. Recently, there have been announcements of a Black Hole at the center of the galaxy, of binary Black Holes, a photo of a Black Hole with enormous multi-media clamor: very interesting if true, using an euphemism by Wigner.
Thanks to GRB 190114C observed on January 14, 2019, we have identified for the first time, the birth/origin of a "Black Hole", which manifested its existence through the emission of the biggest energy source in the Universe. A "new" energy source, 1030 bigger than the one of the atomic bomb of Los Alamos, with a particle flux 1042 and energies 1012 bigger than those of CERN and those planned in China at the CEPC. Fermi led the way: with his research in nuclear physics begun a new age economic, political and military development. Those who will control the science and technology based on this new enormous cosmic energy source, will decide the economic, political and military future of the planet".




7. Upcoming meetings


The Open Universe International Doctoral School, June 11 - 14, 2019
It gives us great pleasure to announce the Open Universe International Doctoral School on "Magnetized Black Holes, GRBs, AGNs and the most violent Universe: from observation on data acquisition to the theory and model-building of GRB 190114C", a 3 days conference which will be held from June 11 - 14, 2019 in the ICRANet Seat at Villa Ratti (Nice - France). It has been organized thanks to the collaboration among ICRANet, LAPP (Laboratoire d'Annecy de Physique des particules) and the Max Planck Institute for Physics. The scientific program is under preparation, and more details about the event will be published soon on our webpage: http://www.icranet.org/index.php?option=com_content&task=view&id=1241


16th Italian-Korean Symposium on Relativistic Astrophysics
It gives us great pleasure to announce the 16th Italian-Korean Symposium on Relativistic Astrophysics, that will be held at ICRANet center in Pescara from July 1 - 5, 2019. The Italian-Korean Symposia on Relativistic Astrophysics is a series of biannual meetings, alternatively organized in Italy and in Korea since 1987. The symposia discussions cover topics in astrophysics and cosmology, such as gamma-ray bursts and compact stars, high energy cosmic rays, dark energy and dark matter, general relativity, black holes, and new physics related to cosmology. The scientific program is under preparation, and more details about the event will be published soon on our webpage: http://www.icranet.org/index.php?option=com_content&task=view&id=1234




8. Recent publications


Glauch, Theo; Padovani, Paolo; Giommi, Paolo; Resconi, Elisa; Arsioli, Bruno; Sahakyan, Narek; Huber, Matthias, Dissecting the region around IceCube-170922A: the blazar TXS 0506+056 as the first cosmic neutrino source, published online on Mai 10, 2019 in EPJ Web of Conferences 207, 02003 (2019).
On MJD 58018 the IceCube neutrino observatory detected a highlyenergetic, well-reconstructed neutrino, IceCube-170922A, at a distance of 0:1° to a γ-ray flaring blazar, TXS 0506+056. Follow-up searches in archival data additionally revealed a larger flare of neutrinos from the same direction. In order to complete the picture we present here a full multi-wavelength study of the region around IceCube-170922A. While we identify also other non-thermal counterpart candidates, we show that all the evidence points to TXS 0506+056 as the dominant neutrino emitter. Additionally, an analysis of all the available Fermi-LAT data indicates a hard spectrum/low flux of TXS 0506+056 during the neutrino flare in contrast to a soft spectrum/high flux at the arrival time of IceCube-170922A. Putting all the pieces together we conclude that the SED of TXS 0506+056 can be energetically reconnected for both neutrino observations.
Link:
https://www.epj-conferences.org/articles/epjconf/abs/2019/12/epjconf_vlvnt2018_02003/epjconf_vlvnt2018_02003.html


V. A. Acciari, S. Ansoldi, L.A. Antonelli, A. Arbet Engels, D. Baack, A. Babić, B. Banerjee, U. Barres de Almeida, J. A. Barrio, J. Becerra González, W. Bednarek, L. Bellizzi, E. Bernardini, A. Berti, J. Besenrieder, W. Bhattacharyya, C. Bigongiari, A. Biland, O. Blanch, G. Bonnoli, G. Busetto, R. Carosi, G. Ceribella, Y. Chai, S. Cikota, S. M. Colak, U. Colin, E. Colombo, J.L. Contreras, J. Cortina, S. Covino, V. D’Elia, P. Da Vela, F. Dazzi, A. De Angelis, B. De Lotto, M. Delfino, J. Delgado, F. Di Pierro, E. Do Souto Espiñeira, A. Domínguez, D. Dominis Prester, D. Dorner, M. Doro, D. Elsaesser, V. Fallah Ramazani, A. Fattorini, A. Fernández-Barral, G. Ferrara, D. Fidalgo, L. Foffano, M. V. Fonseca, L. Font, C. Fruck, D. Galindo, S. Gallozzi, R. J. García López, M. Garczarczyk, S. Gasparyan, M. Gaug, N. Godinović, D. Green, D. Guberman, D. Hadasch, A. Hahn, T. Hassan, J. Herrera, J. Hoang, D. Hrupec, S. Inoue, K. Ishio, Y. Iwamura, H. Kubo, J. Kushida, A. Lamastra, D. Lelas, F. Leone, E. Lindfors, S. Lombardi, F. Longo, M. López, R. López-Coto, A. López-Oramas, B. Machado de Oliveira Fraga, C. Maggio, P. Majumdar, M. Makariev, M. Mallamaci, G. Maneva, M. Manganaro, K. Mannheim, L. Maraschi, M. Mariotti, M. Martínez, S. Masuda, D. Mazin, S. Mićanović, D. Miceli, M. Minev, J. M. Miranda, R. Mirzoyan, E Molina, A. Moralejo, D. Morcuende, V. Moreno, E. Moretti, P. Munar-Adrover, V. Neustroev, A. Niedzwiecki, M. Nievas Rosillo, C. Nigro, K. Nilsson, D. Ninci, K. Nishijima, K. Noda, L. Nogués, M. Nöthe, S. Paiano, J. Palacio, M. Palatiello, D. Paneque, R. Paoletti, J. M. Paredes, P. Peñil, M. Peresano, M. Persic, P. G. Prada Moroni, E. Prandini, I. Puljak, W. Rhode, M. Ribó, J. Rico, C. Righi, A. Rugliancich, L. Saha, N. Sahakyan, T. Saito, K. Satalecka, T. Schweizer, J. Sitarek, I. Šnidarić, D. Sobczynska, A. Somero, A. Stamerra, D. Strom, M. Strzys, T. Surić, F. Tavecchio, P. Temnikov, T. Terzić, M. Teshima, N. Torres-Albà, S. Tsujimoto, J. van Scherpenberg, G. Vanzo, M. Vázquez Acosta, I. Vovk, M. Will, D. Zarić, Measurement of the extragalactic background light using MAGIC and Fermi-LAT gamma-ray observations of blazars up to z = 1, published on 4 April 2019 on Monthly Notices of the Royal Astronomical Society, Volume 486, Issue 3, July 2019, Pages 4233–4251.
We present a measurement of the extragalactic background light (EBL) based on a joint likelihood analysis of 32 gamma-ray spectra for 12 blazars in the redshift range z = 0.03–0.944, obtained by the MAGIC telescopes and Fermi-LAT. The EBL is the part of the diffuse extragalactic radiation spanning the ultraviolet, visible, and infrared bands. Major contributors to the EBL are the light emitted by stars through the history of the Universe, and the fraction of it that was absorbed by dust in galaxies and re-emitted at longer wavelengths. The EBL can be studied indirectly through its effect on very high energy photons that are emitted by cosmic sources and absorbed via γγ interactions during their propagation across cosmological distances. We obtain estimates of the EBL density in good agreement with state-of-the-art models of the EBL production and evolution. The 1σ upper bounds, including systematic uncertainties, are between 13 per cent and 23 per cent above the nominal EBL density in the models. No anomaly in the expected transparency of the Universe to gamma-rays is observed in any range of optical depth. We also perform a wavelength-resolved EBL determination, which results in a hint of an excess of EBL in the 0.18–0.62 μmμm range relative to the studied models, yet compatible with them within systematic.
Link: https://doi.org/10.1093/mnras/stz943


Gallego Cadavid, Alexander; Romano, Antonio Enea, One spectrum to rule them all?, to be published on Physics Letters B, Volume 793, p. 1-7 on June 2019.
We show that in absence of entropy or effective anisotropic stress the freedom in the choice of the initial energy scale of inflation implies the existence of an infinite family of dual slow-roll parameters histories which can produce the same spectrum of comoving curvature perturbations. This implies that in general there is no one-to-one correspondence between the spectrum and higher order correlation functions. We give some numerical examples of expansion histories corresponding to different initial energy scales, with the same spectrum of curvature perturbations, the same squeezed limit bispectrum, in agreement with the squeezed limit consistency condition, but with different bispectra in other configurations and different spectra of primordial gravitational waves. The combined analysis of data from future CMB and gravitational wave experiments could allow to distinguish between dual models.
Link:
https://www.sciencedirect.com/science/article/pii/S0370269319302497?via%3Dihub


Yen-Chen Chen, Chorng-Yuan Hwang, Emission line luminosity distributions of Seyfert 2 galaxies, published on March 8, 2019 on Monthly Notices of the Royal Astronomical Society, Volume 485, Issue 3, May 2019, Pages 3402–3408.
We probed the relation between line activities of Seyfert 2 galaxies and their host galaxies. We selected Seyfert 2 galaxies from the Sloan Digital Sky Survey Data Release 10 with redshifts less than 0.2. We used the luminosity of the emission lines as indicators of AGN power. We found that the Seyfert 2 galaxies seem to have two populations in the emission line luminosity distributions. We considered the L[OIII]/Lbulge ratio as an accretion rate indicator and found that the two Seyfert 2 distributions seem to have different accretion rates. We found that these two Seyfert 2 populations, although classified by their emission line distributions, turned out to have different morphology distributions. These results indicate that these different populations of the Seyfert 2 galaxies might be significantly different in their physical conditions.
Link: https://doi.org/10.1093/mnras/stz677


T. Maiolino, P. Laurent, L. Titarchuk, M. Orlandini and F. Frontera, Red-skewed Kα iron lines in GX 13+1, published on April 30, 2019 on A&A, Volume 625, May 2019.
Context. Broad, asymmetric, and red-skewed Fe Kα emission lines have been observed in the spectra of low-mass X-ray binaries hosting neutron stars (NSs) as a compact object. Because more than one model is able to describe these features, the explanation of where and how the red-skewed Fe lines are produced is still a matter of discussion. It is broadly accepted that the shape of the Fe Kα line is strongly determined by the special and general relativistic effects occurring in the innermost part of the accretion disk. In this relativistic framework, the Fe fluorescent lines are produced in the innermost part of the accretion disk by reflection of hard X-ray photons coming from the central source (corona and/or NS surface). We developed an alternative and nonrelativistic model, called the WINDLINE model, that is capable to describe the Fe line features. In this nonrelativistic framework, the line photons are produced at the bottom of a partly ionized outflow (wind) shell as a result of illumination by the continuum photons coming from the central source. In this model the red-skewness of the line profile is explained by repeated electron scattering of the photons in a diverging outflow.
Aims. Examining the asymmetry of the fluorescent Fe K emission line evident in the XMM-Newton EPIC-pn spectra of the NS source GX 13+1, we aim to distinguish between the two line models. Because GX 13+1 is a well-known disk-wind source, it is a perfect target for testing the WINDLINE model and compare the spectral fits between the relativistic and nonrelativistic line models.
Methods. We used two XMM-Newton EPIC-pn observations in which the Fe line profiles were previously reported in the literature. These observations are not strongly affected by pile-up, and the Fe emission lines appear very strong and red-skewed. In order to access the goodness of the fit and distinguish between the two line models, we used the run-test statistical method in addition to the canonical χ2 statistical method. Results. The DISKLINE and WINDLINE models both fit the asymmetric Fe line well that is present in the XMM-Newton energy spectra of GX 13+1. From a statistical point of view, for the two observations we analyzed, the run-test was not able to distinguish between the two Fe line models, at 5% significance level.
Link: https://doi.org/10.1051/0004-6361/201833163


Loppini, Alessandro, Filippi, Simonetta; Stanley, H. Eugene, Critical transitions in heterogeneous networks: Loss of low-degree nodes as an early warning signal, published on April 2, 2019 in Phys. Rev. E 99, 040301(R).
A large number of real networks show abrupt phase transition phenomena in response to environmental changes. In this case, cascading phenomena can induce drastic and discontinuous changes in the system state and lead to collapse. Although complex network theory has been used to investigate these drastic events, we are still unable to predict them effectively. We here analyze collapse phenomena by proposing a minimal two-state dynamic on a complex network and introducing the effect of local connectivities on the evolution of network nodes. We find that a heterogeneous system of interconnected components presents a mixed response to stress and can serve as a control indicator. In particular, before the critical transition point is reached a severe loss of low-degree nodes is observed, masked by the minimal failure of higher-degree nodes. Accordingly, we suggest that a significant reduction in less connected nodes can indicate impending global failure.
Link: https://journals.aps.org/pre/abstract/10.1103/PhysRevE.99.040301


MAGIC Collaboration; Acciari, V. A.; Ansoldi, S.; Antonelli, L. A.; Arbet Engels, A.; Baack, D.; Babić, A.; Banerjee, B.; Barres de Almeida, U.; Barrio, J. A.; Becerra González, J.; Bednarek, W.; Bernardini, E.; Berti, A.; Besenrieder, J.; Bhattacharyya, W.; Bigongiari, C.; Biland, A.; Blanch, O.; Bonnoli, G. Busetto, G.; Carosi, R.; Ceribella, G.; Cikota, S.; Colak, S. M.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; D'Elia, V.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Lotto, B.; Delfino, M.; Delgado, J.; Di Pierro, F.; Do Souto Espiñera, E.; Domínguez, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Einecke, S.; Elsaesser, D.; Fallah Ramazani, V.; Fattorini, A.; Fernández-Barral, A.; Ferrara, G.; Fidalgo, D.; Foffano, L.; Fonseca, M. V.; Font, L.; Fruck, C.; Galindo, D.; Gallozzi, S.; García López, R. J.; Garczarczyk, M.; Gasparyan, S.; Gaug, M.; Giammaria, P.; Godinović, N.; Green, D.; Guberman, D.; Hadasch, D.; Hahn, A.; Herrera, J.; Hoang, J.; Hrupec, D.; Inoue, S.; Ishio, K.; Iwamura, Y.; Kubo, H.; Kushida, J.; Kuveždić, D.; Lamastra, A.; Lelas, D.; Leone, F.; Lindfors, E.; Lombardi, S.; Longo, F.; López, M.; López-Oramas, A.; Machado de Oliveira Fraga, B.; Maggio, C.; Majumdar, P.; Makariev, M.; Mallamaci, M.; Maneva, G.; Manganaro, M.; Mannheim, K.; Maraschi, L.; Mariotti, M.; Martínez, M.; Masuda, S.; Mazin, D.; Minev, M.; Miranda, J. M.; Mirzoyan, R.; Molina, E.; Moralejo, A.; Moreno, V.; Moretti, E.; Munar-Adrover, P.; Neustroev, V.; Niedzwiecki, A.; Nievas Rosillo, M.; Nigro, C.; Nilsson, K.; Ninci, D.; Nishijima, K.; Noda, K.; Nogués, L.; Nöthe, M.; Paiano, S.; Palacio, J.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Pedaletti, G.; Peñil, P.; Peresano, M.; Persic, M.; Prada Moroni, P. G.; Prandini, E.; Puljak, I.; Garcia, J. R.; Rhode, W.; Ribó, M.; Rico, J.; Righi, C.; Rugliancich, A.; Saha, L.; Sahakyan, N.; Saito, T.; Satalecka, K.; Schweizer, T.; Sitarek, J.; Šnidarić, I.; Sobczynska, D.; Somero, A.; Stamerra, A.; Strzys, M.; Surić, T.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Teshima, M.; Torres-Albà, N.; Tsujimoto, S.; van Scherpenberg, J.; Vanzo, G.; Vazquez Acosta, M.; Vovk, I.; Will, M.; Zarić, D., Deep observations of the globular cluster M15 with the MAGIC telescopes, published on Monthly Notices of the Royal Astronomical Society, Volume 484, Issue 2, April 2019, Pages 2876–2885.
A population of globular clusters (GCs) has been recently established by the Fermi-LAT telescope as a new class of GeV γ-ray sources. Leptons accelerated to TeV energies, in the inner magnetospheres of MSPs or in their wind regions, should produce γ-rays through the inverse Compton scattering in the dense radiation field from the huge population of stars. We have conducted deep observations of the GC M15 with the MAGIC telescopes and used 165 h in order to search for γ-ray emission. A strong upper limit on the TeV γ-ray flux <3.2×10−13cm−2s−1<3.2×10−13cm−2s−1 above 300 GeV (<0.26 per cent of the Crab nebula flux) has been obtained. We interpret this limit as a constraint on the efficiency of the acceleration of leptons in the magnetospheres of the MSPs. We constrain the injection rate of relativistic leptons, ηe, from the MSPs magnetospheres and their surrounding. We conclude that ηe must be lower than expected from the modelling of high-energy processes in MSP inner magnetospheres. For leptons accelerated with the power-law spectrum in the MSP wind regions, ηe is constrained to be much lower than derived for the wind regions around classical pulsars. These constraints are valid for the expected range of magnetic field strengths within the GC and for the range of likely energies of leptons injected from the inner magnetospheres, provided that the leptons are not removed from the GC very efficiently due to advection process. We discuss consequences of these constraints for the models of radiation processes around millisecond pulsars.
Link:
https://academic.oup.com/mnras/article-abstract/484/2/2876/5298496?redirectedFrom=fulltext


L Becerra K. Boshkayev, J. A. Rueda, R. Ruffini, Time evolution of rotating and magnetized white dwarf stars, published on May 20, 2019 in Monthly Notices of the Royal Astronomical Society.
We investigate the evolution of isolated, zero and finite temperature, massive, uniformly rotating and highly magnetized white dwarf stars under angular momentum loss driven by magnetic dipole braking. We consider the structure and thermal evolution of the white dwarf isothermal core taking also into account the nuclear burning and neutrino emission processes. We estimate the white dwarf lifetime before it reaches the condition either for a type Ia supernova explosion or for the gravitational collapse to a neutron star. We study white dwarfs with surface magnetic fields from 106 to 109 G and masses from 1.39 to 1.46 M and analyze the behavior of the WD parameters such as moment of inertia, angular momentum, central temperature and magnetic field intensity as a function of lifetime. The magnetic field is involved only to slow down white dwarfs, without affecting their equation of state and structure. In addition, we compute the characteristic time of nuclear reactions and dynamical time scale. The astrophysical consequences of the results are discussed.
Links: https://doi.org/10.1093/mnras/stz1394; https://arxiv.org/abs/1812.10543


C. R. Argüelles, A. Krut, J. A. Rueda, R. Ruffini, Can Fermionic Dark Matter Mimic Supermassive Black Holes?, Article Winner of the Third Award in the "Gravity Research Foundation 2019 awards for essays on Gravitation", to be published in an special issue of the International Journal of Modern Physics D dedicated to the Essay Competition.
We analyze the intriguing possibility to explain both dark mass components in a galaxy: the dark matter (DM) halo and the supermassive dark compact object lying at the center, by a unified approach in terms of a quasi-relaxed system of massive, neutral fermions in general relativity. The solutions to the mass distribution of such a model that fulfill realistic halo boundary conditions inferred from observations, develop a highly-density core supported by the fermion degeneracy pressure able to mimic massive black holes at the center of galaxies. Remarkably, these dense core-diluted halo configurations can explain the dynamics of the closest stars around Milky Way's center (SgrA*) all the way to the halo rotation curve, without spoiling the baryonic bulge-disk components, for a narrow particle mass range mc2 ∼ 10-102 keV.
Link to the winners announcement:
https://www.gravityresearchfoundation.org/announcement
Link to the article:
https://static1.squarespace.com/static/5852e579be659442a01f27b8/t/5cd46772e4966b1d5dcd2e14/1557423988074/Arguelles%5Bc.a.%5D_Krut_Rueda_Ruffini_2019.pdf


J. A. Rueda, R. Ruffini, Y. Wang, Induced Gravitational Collapse, Binary-Driven Hypernovae, Long Gramma-ray Bursts and Their Connection with Short Gamma-ray Bursts, published on Mai 9, 2019 in Universe: Invited Review for the Special Issue "Accretion Disks, Jets, Gamma-Ray Bursts and Related Gravitational Waves".
Short and long Gamma-ray bursts (GRBs) originate in subclasses with specific energy release, spectra, duration, etc, and have binary progenitors. We review here the binary-driven hypernovae (BdHNe) subclass whose progenitor is a COcore-neutron star (NS). The supernova (SN) explosion of the COcore produces at its center a new NS (νNS) and triggers a hypercritical accretion onto the NS. The NS can become a more massive NS or collapse into a black hole (BH). We summarize this topic from the first analytic estimates in 2012 to the most recent three-dimensional (3D) smoothed-particle-hydrodynamics (SPH) numerical simulations in 2018. Long GRBs are richer and more complex than previously thought. The SN and the accretion explain X-ray precursors. The NS accretion, its collapse and the BH formation produce asymmetries in the SN ejecta, implying a 3D GRB analysis. The newborn BH surrounded by the ejecta and the magnetic field inherited from the NS, are the \emph{inner engine} from which the electron-positron (e+e) plasma and the high-energy emission initiate. The e+e impact on the ejecta converts the SN into a hypernova (HN). The plasma dynamics in the ejecta explains the ultrarelativistic prompt emission in the MeV domain and the mildly-relativistic flares of the early afterglow in the X-ray domain. The feedback of the νNS emission on the HN explains the X-ray late afterglow and its power-law regime. All the above is in contrast with GRB models attempting to explain all the GRB phases with the kinetic energy of anultrarelativistic jet, as traditionally proposed in the "collapsar-fireball" model. In addition, BdHNe in their different flavors lead to νNS-NS or νNS-BH binaries. These binaries merge by gravitational wave emission producing short GRBs, establishing a connection between long and short GRBs and their occurrence rates.
Links: https://www.mdpi.com/2218-1997/5/5/110; https://arxiv.org/abs/1905.06050


Seddigheh Tizchang, Rohoollah Mohammadi, She-Sheng Xue, Probing Lorentz violation effects via a laser beam interacting with a high-energy charged lepton beam, published on The European Physical Journal C, March 2019, 79:224.
In this work, the conversion of linear polarization of a laser beam to circular one through its forward scattering by a TeV order charged lepton beam in the presence of Lorentz violation correction is explored. We calculate the ratio of circular polarization to linear one (Faraday Conversion phase ΔΦFC) of the laser beam interacting with either electron or the muon beam in the framework of the quantum Boltzmann equation. Regarding the experimentally available sensitivity to the Faraday conversion ΔΦFC≃10−3−10−2, we show that the scattering of a linearly polarized laser beam with energy k0∼0.1 eV and an electron/muon beam with flux ∈¯e,μ∼1010/1012 TeV cm−2 s−1 places an upper bound on the combination of lepton sector Lorentz violation coefficients cμνcomponents (cTT+1.4 c(TZ)+0.25(cXX+cYY+2 cZZ)). The obtained bound on the combination for the electron beam is at the 4.35×10−15 level and for the muon beam at the 3.9×10−13 level. It should be mentioned that the laser and charged lepton beams considered here to reach the experimentally measurable ΔΦFC are currently available or will be accessible in the near future. This study provides a valuable supplementary to other theoretical and experimental frameworks for measuring and constraining Lorentz violation coefficients.
Link: https://link.springer.com/article/10.1140%2Fepjc%2Fs10052-019-6716-5
 
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