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Newsletter Portuguese August/September 2020 Print E-mail

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ICRANet Newsletter

ICRANet Boletim informativo
Agosto - Setembro de 2020

1. Vídeos das últimas palestras proferidas pelos membros do corpo docente da ICRANet
Talk of Prof. Remo Ruffini at IWARA 2020 meeting Talk of Prof. Jorge Rueda at IWARA 2020 meeting
Talk of Prof. Remo Ruffini at The Fourth Zeldovich virtual meeting Talk of Prof. Gregory Vereshchagin at The Fourth Zeldovich virtual meeting
Talk of Prof. Jorge Rueda at The Fourth Zeldovich virtual meeting Talk of Prof. Remo Ruffini at the 14th International Conference on Gravitation, Astrophysics and Cosmology

2. Multiwavelength Study of High-Redshift Blazars

O novo artigo com co-autoria de N. Sahakyan, D. Israyelyan, G. Harutyunyan, M. Khachatryan e S. Gasparyan "Multiwavelength Study of High-Redshift Blazars", foi publicado em Monthly Notices of the Royal Astronomical Society em 17 de agosto de 2020.

Figure 1. Spectra of some blazars.

Blazars harboring supermassive black holes are valuable sources for studying the relativistic outflows and formation and propagation of relativistic jets. In this context, the high redshift blazars (z>2.5) are of particular interest; they are among the most powerful non- explosive astrophysical sources in the Universe. Their study can shed light on the further understanding of the cosmological evolution of blazars and supermassive black holes and also on the evolution of relativistic jets across different cosmic epochs. Motivated by the large number of detected high redshift γ-ray emitting blazars, with the aim to characterize their multiwavelength emission properties, an intense broadband study of all the thirty-three known γ-ray blazars beyond redshift 2.5 is performed. In order to characterize the physical properties of the considered sources, Fermi Large Area Telescope γ-ray data accumulated during 2008-2018, as well as X-ray and optical/UV data from the observations with both Swift X-ray Telescope and Ultraviolet and Optical Telescope in the previous fifteen years are analyzed. This allowed collecting unprecedented data in the optical/UV, X-ray, and γ-ray bands, which is used to constrain the multiwavelength spectral energy distributions (SEDs), see Fig. 1. Then, through modeling of these SEDs within a one-zone leptonic scenario (assuming that the X-ray and γ-ray emissions are produced from inverse Compton scattering of synchrotron and dusty torus photons), the physical parameters characterizing the sources (disc luminosity, black hole mass, etc.) and their jets (e.g., the distribution of underlying electrons, magnetic field, power, etc.) are derived, allowing a quantitative discussion and investigation of the state of plasma in these powerful jets.
Time variability in different energy bands is particularly important. In the X-ray band, only the emission of PKS 0438-43, B2 0743+25 and TXS 0222+185 is found to vary in different Swift XRT observations whereas in the γ-ray band, the emission is variable for fourteen sources: the flux of B3 1343+451 and PKS 0537-286 changes in sub-day scales, that of PKS 0347-211 and PKS 0451-28 in day scales, while the γ-ray variability of the others is in week or month scales. Such rapid variability in high energy band is in agreement with recently proposed model for the inner engine of AGNs by Rueda, J.A., Ruffini, R., "The blackholic quantum", Eur. Phys. J. C 80, 300 (2020), see https://doi.org/10.1140/epjc/s10052-020-7868-z.

O artigo está disponível aqui: https://doi.org/10.1093/mnras/staa2477
ArXiv e-print: https://arxiv.org/abs/2008.09675

3. Geodesic motion of S2 and G2 as a test of the fermionic dark matter nature of our Galactic core

The paper “Geodesic motion of S2 and G2 as a test of the fermionic dark matter nature of our Galactic core”, co-authored by E.A. Becerra-Vergara, C.R. Argüelles, A. Krut, J.A. Rueda, and R. Ruffini has been published by Astronomy & Astrophysics on September 4, 2020. In this paper, the evidence is given on the possibility of different interpretation of observational data of the motion of S2 and G2 objects near the Galactic center. Within this interpretation, which is perfectly consistent with General Relativity, the compact object is not a black hole but a condensation of dark matter.


O artigo está disponível aqui: https://www.aanda.org/articles/aa/abs/2020/09/aa35990-19/aa35990-19.html
Link to ArXiv e-print: https://arxiv.org/abs/2007.11478

4. Novo Acordo de Colaboração entre a Universidade de Mazandaran e ICRANet, 24 de agosto de 2020


No dia 24 de Agosto foi assinado o Acordo de cooperação entre a Universidade da Mazandaran (Irã) e a ICRANet. O acordo foi assinado pelo Prof. Dr. Kourosh Nozari (Presidente da Universidade da Mazandaran), pelo Prof. Mahmoud Azizi (Diretor do Setor de Cooperação Internacional e Científica da Universidade de Mazandaran) e pelo Prof. Remo Ruffini (Diretor da ICRANet). Tal acordo, que terá validade de 5 anos, visa prestar reciprocamente assessoria na promoção de atividade conjuntas de investigação teórica e observacional no campo da Astrofísica Relativística, realizar programas de intercâmbio de docentes, investigadores, estudantes de pós-doutorado e estudantes de doutorado bem como fomentar o desenvolvimento tecnológico, desenvolver os centros de dados para os dados atrofísicos em todas as faixas de frequência, organizar cursos de ensino e formação, seminários, conferências, whorkshops, desenvolver pesquisa inter-institucional nas áreas associadas aos programas de formação locais, e realizar publicações conjuntas.
Para o texto do Acordo, acesse:

5. 14a Conferência Internacional sobre Gravitação, Astrofísica e Cosmologia (ICGAC 14), de 17 a 21 de agosto de 2020

4 A edição de 2020 da 14a Conferência Internacional sobre Gravitação, Astrofísica e Cosmologia (ICGAC 14) foi realizada virtualmente de 17 a 21 de agosto na National Central University, Jhongli, em Taiwan. O Prof. Ruffini apresentou a palestra "The geodesic motion of S2 and G2 as a test of the fermionic dark matter nature of our galactic core", enquanto o Prof. Gregory Vereshchagin, Professor da ICRANet, apresentou a palestra "Diffusive photospheres and thermal emission in early afterglows of gamma-ray bursts". ICGAC14 é a série de conferências bienais sobre Gravitação, Astrofísica e Cosmologia organizadas na região da Ásia-Pacífico com os objetivos de: promover a cooperação entre os países desta região e em um contexto internacional, promover estudos de alto nível, e incentivar jovens físicos nesses campos.
Site da conferência: https://icgac14.phy.ncu.edu.tw

6. Videoconferência IWARA 2020. "From Quarks to Cosmo" de 6 a 12 de setembro 2020


Prof. Remo Ruffini foi convidado para apresentar uma palestra plenária em ocasião da videoconferência IWARA 2020, realizada virtualmente de 6 a12 de Setembro na Cidade do México. No primeiro dia da confêrencia, no domingo, ele falou sobre "Discovery of energy extraction from a Kerr Black Hole by discrete Black-Holic quanta in GRB 190114C, GRB 130427A, GRB 160509A and GRB 160625B". Abstract: Almost fifty years after the paper "Introducing the Black Hole" by Ruffini and Wheeler and the Black Hole (BH) mass energy formula by Christodoulou, Ruffini and Hawking, we can finally assert that we have been observing the moment of creation of a BH in the BdHN I in GRB 190114C, GRB 130427A, GRB 160509A and GRB 160625B, with the corresponding rotational energy extraction process. The first appearance of the Supernova, the SN-rise, triggering the BdHN has been identified. The hypercritical accretion on the SN ejecta on the new NS (νNS) created in the SN, is shown to originate the X-ray afterglow observed by the NASA Neil-Gehrels SWIFT satellite (SWIFT). The hypercritical accretion of the SN on the NS binary companion in the BdHN I model leads to the formation of the newly formed BH. The onset of the GeV radiation coinciding with the BH formation has revealed self similar structures in the time resolved spectral analysis of all sources. Consequently, we find evidence for quantized-discrete-emissions in all sources, with energy quanta of 1037 ergs with repetition time of 10-14 sec. GRBs are the most complex systems ever successfully analyzed in Physics and Astrophysics, and they may well have a role in the appearance of life in the Cosmos. These results have been made possible by a long-lasting theoretical activity, a comprehensive unprecedented high quality data analysis, an observational multi-messenger effort by the astronomical, the physical and the space research communities. This observational effort is well epitomized by the original Vela Satellites, the NASA Compton space mission (CGRO), the Italo-Dutch Beppo SAX satellite, the Russian Konus Wind Satellite, the SWIFT satellite, the Italian AGILE satellite, the NASA FERMI mission and most recently the Chinese satellite HXMT. These space missions have been assisted by radio and optical equally outstanding observational facilities from the ground.
Site da conferência: https://indico.cern.ch/event/822124/

7. Quarto Encontro virtual Zeldovich de 7 a 11 de Setembro de 2020

O Quarto Encontro virtual Zeldovich, realizado de 7 a 11 de setembro de 2020 e fruto da colaboração entre a ICRANet (organizadora) e a Academia Nacional de Ciências da Bielorrússia, registrou número recorde de participantes registrados: cerca de 150 provenientes de todos os continentes.

Figure 2. Final greetings at the end of the meeting.

Todos os dias, foram organizadas três sessões: duas na manhã e uma na tarde. Particparam das sessões da manhã a maioria dos palestrantes asiáticos, africanos e europeus enquanto os participantes americanos, tanto do Norte como do Sul, se juntaram à reunião na sessão da tarde. As sessões incluíram os seguintes tópicos: Gravidade, Explosões de Raios Gama, Relatividade Geral e o Quântico, Missões Espaciais, Campos Magnéticos, Relatividade Geral e Teorias Alternativas, Universo Primitivo, Horizontes do Buraco Negro, Multi-Messenger Astrophysics, Astrofísica e Partículas Elementares, Estrutura em Grande Escala do Universo, Explosão Estelar e Matéria Escura no Universo, Exoplanetas e Astrobiologia, Matéria Escura e Energia Escura, Supernovas e Gravidade. No total, foram apresentadas 89 palestras. Os debates sobre os resultados observacionais foram extremamente interessantes; estre estes: os primeiros resultados do SRG Orbital Observatory e da missão HXMT, as observações terrestres de Neutrinos pelo ICECube Observatory, os raios gama de alta energia por telescópios MAGIC e observações ópticas imediatas pela rede MASTER, as observações do Galactic Center pela colaboração GRAVITY e Black Hole Shadow em M87 *, as novas observações e análises de dados de Gamma-Ray Bursts, Exoplanets e estrutura em larga escala do Universo. Além disso, foram amplamente discutidos os seguintes temas: progresso teórico na teoria da explosão de raios gama e mecanismos de Supernovas, Dínamo magnético em galáxias, Gravidade Quântica, teorias de gravidade alternativa, Física de Neutrinos, origem da matéria escura, distorções espectrais CMB, e muitos outros tópicos. As observações finais, resumindo os novos e importantes resultados científicos apresentados ao longo da reunião, foram proferidas pelo Acadêmico Sergei Kilin, Vice-Presidente da Academia Nacional de Ciências da Bielorrússia, NASB, pelo Prof. Remo Ruffini, Diretor do ICRANet e pelo Prof. Gregory Vereshchagin. Os proceedings serão publicados na revista Astronomy Reports, a principal revista russa de Astronomia e Astrofísica. Site da revista: https://www.springer.com/journal/11444.
As reuniões anteriores da série de encontros dedicados a Ya. B. Zeldovich foram realizadas de 23 a 27 de abril de 2018 em Minsk, de 20 a 23 de abril de 2009 em Minsk (organizado conjuntamente pelo ICRANet e a Bielo-Rússia State University BSU, comemorando também o Ano da Astronomia de 2009) e de 11 a 14 de março , 2014, comemorando o 100º aniversário de Ya. B. Zeldovich.
Para os vídeos das sessões acesse o canal YouTube da ICRANet:
Para as apresentações dos palestrantes acesse: http://www.icranet.org/index.php?option=com_content&task=view&id=1339
Site da conferência: http://www.icranet.org/zeldovich4

8. 106° Congresso Nacional da Sociedade Italiana de Física - SIF, de 14 a 18 de setembro de 2020

A Sociedade Italiana de Física SIF realizou virtualmente seu 106º Congresso Nacional de 14 a 18 de setembro. O Prof. Remo Ruffini e o Prof. Jorge Rueda, Professor da ICRANet, gravaram um vídeo das palestras relatando os últimos resultados científicos: o Prof. Ruffini gravou a palestra "Magnetic fields and afterglows of BdHNe: Inferences from GRB 130427A, GRB 160509A, GRB 160625B, GRB 180728A and GRB 190114C", e o Prof. Rueda gravou a palestra "On the inner engine of the high-energy (GeV) emission of gamma-ray bursts".
Para mais informações, acesse o site da conferência: https://www.sif.it/attivita/congresso/106

9. "Dante e Astronomia" podcast meeting, 13 de setembro de 2020

C. Sigismondi, ICRA/Sapienza

A fama de Dante é internacional, como na época. As lembranças de sua passagem na Universidade de Paris ainda são visíveis. Suas peregrinações, por motivos políticos e profissionais, estão enquadradas nos versos da Divina Comédia. Sua poesia foi capaz de incluir todos os aspectos culturais, artísticos, teológicos, bem como científicos e religiosos de sua época. A reunião de podcast inaugurada em 13 de setembro de 2020 é expressamente dedicada a Dante e Astronomia. Começaram as comemorações do sétimo centenário da morte de Dante, ocorridas em Ravenna na noite de 13 a 14 de setembro de 1321. Dante é um ícone da cultura medieval, onde ciência e fé estavam profundamente unidas.

Figure 3. Dante Alighieri (1265-1321).

“e nove Muse mi dimostran l'Orse” (Par. II, 9)
é o verso escolhido para o título do evento: nove musas, todas artes, contribuem para mostrar a Ursae, para manter o Norte, a direção correta na viagem extraordinária que Dante (não Enéias, herói clássico, nem São Paulo, o apóstolo ... como ele escreveu) era capaz de realizar. Mas não apenas um Norte figurativo, uma bússola ideal no mar duro da vida humana... Dante mostra várias fotos de observações genuínas de fenômenos físicos e o temor de eventos astronômicos como ele mesmo experimentou. Astronomia como linguagem codificada, observações astronômicas repletas de sensações nostálgicas, corpos astronômicos como testemunhos silenciosos das fases da vida humana, antes e depois da passagem para o Outro Mundo, do qual Dante é o cantor por excelência.
Contribuições de cientistas e dantistas foram incluídas neste encontro dedicado especialmente aos jovens estudantes e a todos os estimadores de Dante. O podcast foi apresentado pelo ICRANet em Pescara com a participação do Observatório Astrofísico de Asiago e da Academia de Lincei. O patrocínio para a IAU Comissão III de História da Astronomia foi solicitado.
Para mais informações sobre o encontro: http://www.icranet.org/index.php?option=com_content&task=view&id=1334
Comunicado à imprensa (em Italiano) no canal de tv regional Rete 8: https://www.rete8.it/cronaca/icranet-dante-e-lasrtronomia/

10. Últimas publicações

N. Sahakyan, D. Israyelyan, G. Harutyunyan, M. Khachatryan and S. Gasparyan, Multiwavelength Study of High-Redshift Blazars, accepted for publication in MNRAS.
High-redshift blazars are among the most powerful objects in the Universe. The spectral and temporal properties of thirty-three distant blazars (z > 2.5) detected in the high energy γ-ray band are investigated by analyzing the Fermi-LAT and Swift UVOT/ XRT data. The considered sources have soft time averaged γ-ray spectra (Γγ ≥ 2.2) whereas those that have been observed in the X-ray band have hard X-ray spectra (ΓX = 1.01 − 1.86). The γ-ray flux of high-redshift blazars ranges from 4.84 × 10−10 to 1.50 × 10−7 photon cm−2 s−1 and the luminosity is within (0.10 − 5.54) × 1048 erg s−1 which during the γ-ray flares increases up to (0.1 − 1) × 1050 erg s−1. In the X-ray band, only the emission of PKS 0438-43, B2 0743+25 and TXS 0222+185 is found to vary in different Swift XRT observations whereas in the γ-ray band, the emission is variable for fourteen sources: the flux of B3 1343+451 and PKS 0537-286 changes in sub-day scales, that of PKS 0347-211 and PKS 0451-28 in day scales, while the γ-ray variability of the others is in week or month scales. The properties of distant blazar jets are derived by modeling the multiwavelength spectral energy distributions within a one-zone leptonic scenario assuming that the X-ray and γ-ray emissions are produced from inverse Compton scattering of synchrotron and dusty torus photons. From the fitting, the emission region size is found to be ≤0.05 pc and the magnetic field and the Doppler factor are correspondingly within 0.10 − 1.74 G and 10.0 − 27.4. By modeling the optical-UV excess, we found that the central black hole masses and accretion disk luminosities are within Ld ≃ (1.09 − 10.94) × 1046 erg s−1 and (1.69 − 5.35) × 109 M, respectively.
DOI: https://doi.org/10.1093/mnras/staa2477
Link: https://ui.adsabs.harvard.edu/abs/2020arXiv200809675S/abstract

N. Sahakyan, G. Harutyunyan, D. Israyelyan and M. Khachatryan, Exploring the Origin of Multiwavelength Emission from High-Redshift Blazar B3 1343 + 451, published in Astrophysics, Volume 63, Issue 3, p.334-348, 2020.
B3 1343 + 451 is a distant ( z = 2.534 ) and bright flat-spectrum radio quasar observed in the γ -ray band. The results from the multiwavelength observations of B3 1343 + 451 with Fermi-LAT and Swift are reported. In the γ -ray band, strong flares were observed on 05 December 2011 and on 13 December 2009 when the flux increased up to (8.78 ± 0.83).10-7 photon cm-2 s-1. The hardest photon index Γ = 1.73 ± 0.24 has been observed on MJD 58089 which is not common for flat-spectrum radio quasars. The analysis of Swift XRT data shows that in 2014 the X-ray flux of the source increased ~2 times as compared to 2009, but in both periods the X-ray emission is characterized by a hard photon index of ΓX-ray = 1.2-1.3. During the γ -ray flares, the shortest flux halving timescale was ~2.34 days, implying the emission had been produced in a very compact region, R ≤ δ ct /(1 + z) = 3.43.1016 cm (when δ = 20). The spectral energy distribution of B3 1343 + 451 is modeled during the quiescent and flaring periods assuming a compact emitting region outside the BLR. It is found that the flares can be explained by only changing the bulk Lorentz factor of the emitting region without significant modification of the emitting electron parameters and luminosity of the jet.
DOI: https://doi.org/10.1007/s10511-020-09638-z
Link: https://ui.adsabs.harvard.edu/abs/2020Ap.....63..334S/abstract

MAGIC collaboration, Testing two-component models on very high-energy gamma-ray-emitting BL Lac objects, Astronomy & Astrophysics, Volume 640, id.A132, 29 pp., 2020.
Context. It has become evident that one-zone synchrotron self-Compton models are not always adequate for very high-energy (VHE) gamma-ray-emitting blazars. While two-component models perform better, they are difficult to constrain due to the large number of free parameters.
Aims: In this work, we make a first attempt at taking into account the observational constraints from very long baseline interferometry (VLBI) data, long-term light curves (radio, optical, and X-rays), and optical polarization to limit the parameter space for a two-component model and test whether or not it can still reproduce the observed spectral energy distribution (SED) of the blazars.
Methods: We selected five TeV BL Lac objects based on the availability of VHE gamma-ray and optical polarization data. We collected constraints for the jet parameters from VLBI observations. We evaluated the contributions of the two components to the optical flux by means of decomposition of long-term radio and optical light curves as well as modeling of the optical polarization variability of the objects. We selected eight epochs for these five objects based on the variability observed at VHE gamma rays, for which we constructed the SEDs that we then modeled with a two-component model.
Results: We found parameter sets which can reproduce the broadband SED of the sources in the framework of two-component models considering all available observational constraints from VLBI observations. Moreover, the constraints obtained from the long-term behavior of the sources in the lower energy bands could be used to determine the region where the emission in each band originates. Finally, we attempt to use optical polarization data to shed new light on the behavior of the two components in the optical band. Our observationally constrained two-component model allows explanation of the entire SED from radio to VHE with two co-located emission regions.
DOI: https://doi.org/10.1051/0004-6361/202037811
Link: https://ui.adsabs.harvard.edu/abs/2020A%26A...640A.132M/abstract

D. Maričić, B. Vršnak, A. M. Veronig, M. Dumbović, F. Šterc, D. Roša, M. Karlica, D. Hržina & I. Romštajn, Sun-to-Earth Observations and Characteristics of Isolated Earth-Impacting Interplanetary Coronal Mass Ejections During 2008-2014, published in Sol Phys 295, 91 (2020).
A sample of isolated Earth-impacting interplanetary coronal mass ejections (ICMEs) that occurred in the period January 2008 to August 2014 is analyzed to study in detail the ICME in situ signatures, with respect to the type of filament eruption related to the corresponding CME. Observations from different vantage points provided by the Solar and Heliospheric Observatory (SOHO) and the Solar Terrestrial Relations Observatory Ahead and Behind (STEREO-A and B) are used to determine whether each CME under study is Earth directed or not. For Earth-directed CMEs, a kinematical study was performed using the STEREO-A and B COR1 and COR2 coronagraphs and the Heliospheric Imagers (HI1), to estimate the CME arrival time at 1 AU and to link the CMEs with the corresponding in situ solar wind counterparts. Based on the extrapolated CME kinematics, we identified interacting CMEs, which were excluded from further analysis. Applying this approach, a set of 31 isolated Earth-impacting CMEs was unambiguously identified and related to the in situ measurements recorded by the Wind spacecraft. We classified the events into subsets with respect to the CME source location, as well as with respect to the type of the associated filament eruption. Hence, the events are divided into three subsamples: active region (AR) CMEs, disappearing filament (DSF) CMEs, and stealthy CMEs. The related three groups of ICMEs were further divided into two subsets: magnetic obstacle (MO) events (out of which four were stealthy), covering ICMEs that at least partly showed characteristics of flux ropes, and ejecta (EJ) events, not showing such characteristics. In this way, 14 MO-ICMEs and 17 EJ-ICMES were identified. The solar source regions of the non-stealthy MO-ICMEs are found to be located predominantly (9/10, 90%) within ±30∘±30∘ from the solar central meridian, whereas EJ-ICMEs originate predominantly (16/17, 94%) from source regions that are outside ±30∘±30∘. In the next step, MO-events were analyzed in more detail, considering the magnetic field strength and the plasma characteristics in three different segments, defined as the turbulent sheath (TS), the frontal region (FR), and the MO itself. The analysis revealed various well-defined correlations for AR, DSF, and stealthy ICMEs, which we interpreted considering basic physical concepts. Our results support the hypothesis that ICMEs show different signatures depending on the in situ spacecraft trajectory, in terms of apex versus flank hits.
DOI: https://doi.org/10.1007/s11207-020-01658-4
Link: https://link.springer.com/article/10.1007/s11207-020-01658-4
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